REVACCINATION OF PATIENTS WITH SLE OR RA WITHOUT AN INITIAL COVID-19 VACCINE RESPONSE ELICITS SEROCONVERSION IN HALF OF THE PATIENTS

BackgroundTreatment with Rituximab (RTX) in patients with rheumatic diseases (RD) has presented a challenge during the COVID-19 pandemic, as RTX leads to markedly reduced and often undetectable antibody responses after COVID-19 vaccination (1).ObjectivesTo investigate the effect of COVID-19 mRNA revaccination (two doses) on the antibody response in patients with RD who were initial vaccine non-responders. Further, to examine if B-cell levels or T-cell responses before revaccination predicted seroconversion.MethodsFrom a RD cohort (COPANARD) vaccinated with the standard two-dose COVID-19 vaccinations, we enrolled cases without detectable antibody responses (n=17) and controls with detectable antibody response (n=29). Blood donors (n=32) were included as additional controls. Samples were collected before and six weeks after completed revaccination. Total antibodies (abs) and specific IgG, IgA, and IgM against SARS-CoV-2 spike protein, SARS-CoV-2 neutralizing abs, and SARS-CoV-2 reacting CD4+ and CD8+ T-cells were measured before and after revaccination. B-cells (CD19+CD45+) were quantified before revaccination. This study was funded by the Danish Rheumatism Association.ResultsPatient demographics are given in Table 1. Forty-seven percent of cases had detectable total SARS-CoV-2 abs and neutralizing abs after revaccination. However, antibody levels were significantly lower than in controls and blood donors (p<0.008), Figure 1A+B. Revaccination induced an antibody class switch in cases with a decrease in detectable IgM abs (Baseline 11/17, Followup 3/17) and increase in IgG. No significant difference was observed in T-cell responses before and after revaccination between the three groups, Figure 1C. The proportion of cases with detectable CD4+ T cells increased from 69% to 88% (p=0.25), and for CD8+ T cells, the proportion decreased from 88% to 82% (p=1.00). Only 29% of cases had measurable B-cells compared to 100% of controls and blood donors, Figure 1D. Fifty percent of revaccinated cases who seroconverted had measurable B-cells before revaccination, Figure 1D.Univariate logistic regression analysis was performed to analyze if active RTX treatment, the presence of B-cells, or a positive T-cell response prior to revaccination predicted seroconversion of total SARS-CoV-2-abs in the patient cohort. We did not find a significant explanatory effect of either variable in the univariate logistic models, data not shown.Table 1.DemographicsCases Revaccination, n=17Controls Boost, n=29Female sex, no(%)1482%2172%Age, median (IQR)6549 - 706762 - 72Disease duration, years1510 - 18229 - 31Rheumatoid Arthritis/SLE13/410/19None DMARD529%828%Prednisone424%13%Methotrexate741%1241%Hydroxychloroquine212%414%None biologic treatment424%931%Rituximab1271%0TNF-inhibitors16%724%JAK-inhibitors0621%IL-6-inhibitors, Abatacept, Benlysta0724%Previous rituximab treatmentAny rituximab treatment1694%13%RTX within the last 15 months, no1488%0Cumulative total dose, mg134-242Time from RTX to revaccination, months95-1249Figure 1.ConclusionIn conclusion, forty-seven percent of initial non-responders were able to seroconvert after two-dose revaccination. However, plasma concentrations of the antibodies against SARS-COV-2 and the levels of neutralizing capacity remained significantly lower than in immunocompetent blood donors. B-cell levels or T-cell responses before revaccination did not predict seroconversion. Our study suggests that patients with RDs who did not mount a detectable serological response to a COVID-19 mRNA vaccine have a T cell response similar to immunocompetent controls. Future studies should establish the antibody levels that identify RD patients without sufficient protection against SARS-CoV-2 infection.References[1]Troldborg A, et al. Time Since Rituximab Treatment Is Essential for Developing a Humoral Response to COVID-19 mRNA Vaccines in Patients With Rheumatic Diseases. J Rheumatol. 2022.AcknowledgementsThe Danish Rheumatism Association [grant number R203-A7217]. We acknowledge all patients and blood donors contributing to the stud for their invaluable participation. The authors would like to thank Sif Kaas Nielsen and Mads Engelhardt Knudsen, the Laboratory of Molecular Medicine at Rigshospitalet, for their excellent technical assistance in analyzing the samples.Disclosure of InterestsNone Declared.

Immunotherapy: FAMILIAL CD45RA DEPLETED T CELLS TO TREAT SEVERE REFRACTORY INFECTIONS IN IMMUNOCOMPROMISED PATIENTS

Background & Aim: Immunocompromised patients are susceptible to high-risk opportunistic infections and malignant diseases. If available, most antiviral and antifungal drugs are quite toxic, relatively ineffective, and induce resistance in the long term. Methods, Results & Conclusion(s): We have previously demonstrated the safety of adoptive cell therapy for COVID-19 patients with CD45RA negative cells containing SARS-CoV-2-specific T cells from a donor, chosen based on HLA compatibility and cellular response to SARS-CoV-2 peptide pools. After finishing a Phase 2 randomized multicenter clinical trial (RELEASE, NCT04578210), we concluded that the infusion is safe, effective, accelerates lymphocyte recovery and shows hallmarks of an immune response. To use adoptive cell therapy to treat COVID-19 it would be necessary to develop a biobank of living drugs. For that, we examined the immune evolution performing a longitudinal analysis from previously SARS-CoV-2 infected and infection- naive individuals covering 21 months from infection. Cellular responses were maintained over time while humoral responses increased after vaccination but were gradually lost. Therefore, the best donors would be recovered individuals and two months after vaccination. We also evaluated the effect of dexamethasone (current standard of care treatment for COVID-19 and other infections involving lymphopenia) and Interleukin-15 (cytokine involved in T-cell maintenance and survival) on CD45RA negative. Dexamethasone did not alter cell functionality, proliferation or phenotype at a clinical-practice concentration, while interleukin-15 increased the memory T-cell and T-regulatory cell activation state, and interferon gamma release. Furthermore, we applied the adoptive passive transfer of CD45RA negative cells containing pathogen-specific memory T-cells to other infectious diseases characterized by sustained lymphopenia. We infused six immunocompromised patients with Cytomegalovirus, BK virus, Aspergillus, and Epstein-Barr virus lymphoproliferative disease. Patients experienced pathogen clearance, resolution of symptoms and lymphocyte increase. Transient microchimerism was detected in three patients. The use of CD45RA negative cells containing specific memory T cells of a third-party donor for treating severe pathogenic diseases in immunocompromised patients is feasible, safe, and effective, and has an advantage over other cell therapies such as lower costs and a less complex regulatory environment.Copyright © 2023 International Society for Cell & Gene Therapy

SUBPOPULATION COMPOSITION OF PERIPHERAL BLOOD LYMPHOCYTES IN COVID-19.

The pathogenesis of severe coronavirus infection COVID-19 is associated with activation of immune system, cytokine storm, impaired blood clotting, microvascular thrombosis, organ ischemia and multiple organ dysfunction syndrome. The role of various lymphocyte subpopulations in COVID-19 is still debated. The aim of our study was to analyze the subpopulational profile of peripheral blood lymphocytes in COVID-19 patients as compared with healthy donors. The study included 20 COVID-19 patients (11 males and 9 females,) and 26 healthy donors. Average age of the patients was 52 and 56 years, respectively. Clinical examinations were performed by standard laboratory methods. Peripheral blood lymphocytes were isolated in the Ficoll gradient. The cells were stained with antibodies to specific antigens of main lymphocyte populations, endothelial cells, and apoptotic cell markers. The analysis was performed by flow cytometry. The results showed that all patients had elevated C-reactive protein (14- to 35-fold), ferritin (1.2- to 13-fold), D-dimers (1.2- to 90-fold). 55% of men had a decrease in the absolute number of lymphocytes, in women this index was at the low normal limit. Cytometric analysis showed that, among peripheral blood lymphocytes, the proportion of functional cells expressing the CD45 marker ranged from 2 to 12% in 70% of patients, as compared with 80-99% among the donors. The proportion of CD45+ lymphocytes significantly correlated with the level of hemoglobin, but not with the levels of inflammatory biochemical markers. Among the functional lymphocytes of patients, there was a decrease in the proportion of CD3+, CD4+, CD8+T cells, increased proportion of natural killer CD56+ and the apoptotic (AnnexinV+) cell contents, but the proportion of CD19 and HLA-DR+B cells was not changed. Analysis of the lymphocyte (LC) subpopulations that did not express CD45 marker showed that this fraction contained different lymphocyte subsets with reduced expression of CD4, CD8, CD19, CD56 etc. in the blood of patients and donors. Higher percentage of endothelial cells expressing CD62P marker made the difference between patients and donors. Laboratory determination of lymphocyte subsets in blood samples of COVID-19 patients does not reflect the real severity pattern of the disease, thus requiring studies of the CD45-expressing functional cell populations.Copyright © Svirshchevskaya E.V. et al., 2023 The article can be used under the Creative Commons Attribution 4.0 License.

CD40.SARS.CoV2 VACCINE, BUT NOT mRNA, INDUCES SPECIFIC CD8+ T MEMORY STEM CELLS

Background: Vaccination plays a major role in controlling SARS-CoV2 infection but faces the issue of short-term protection. Beyond the generation of Abs, induction of memory CD8+T cells with stem cell-like (Tscm) properties is essential for long-term immunity to viruses. We have designed a sub-unit CD40.CoV-2 vaccine which targets Spike (S) and nucleocapsid (N) regions from SARS-CoV-2 to antigen presenting cells with comparable immunogenicity and protective effect than mRNA BNT162b2 (Pfizer-BioNTech) in preclinical models (Coleon S. EBioMed 2022). We hypothesized that CD40.CoV2 vaccine will elicit CD8+ Tscm cells. Method(s): CD40.CoV2 vaccine is a fully humanized mAb fused to RBD (aa 318-541) and N (aa 276-411). Humanized (hu) NSG mice (HIS-mice) (n=6/ group) received: i) CD40.CoV2 (10 mug equal to 1.3 mug of RBD, i.p.) +/- poly-ICLC (TLR3 agonist;50mug) or ii) BNT162b2 (1mug, i.m.);iii) IgG4.CoV2 (10mug, i.p.) as non-CD40-targeting control. Phenotype and function of splenic S and N-specific T cells were assessed at W5. Result(s): The CD40.CoV2 vaccine +/- poly-CLC induced significant S and N-specific Th1 huCD4+, cytokines-secreting huCD8+ T cells and RBD-specific IgG-switched huB cells as compared to mock injections and non-targeted IgG4.CoV2. CD40.CoV-2 vaccine +/- adjuvant induced higher frequencies of huCD8+ Tscm (CD95+ CD45RA+ CD62L+ ;median, (IQR) 22.4% (12.3-27.4) and 23% (20.7-29.1) +/- adjuvant, respectively) and central memory (TCM;CD45RA- CD62L+) CD8+ T cells (2.7% (2.3-6.2) and 5.1% (3.8-7.8) +/- adjuvant, respectively). In contrast, BNT162b2 induced predominantly effector memory (TEM, CD45RA- CD62L- ;median, (IQR) 63.1% (47.3-72.3)) but not Tscm (1.6% (0.9-6.6)) (figure). CD40.CoV-2 induced huCD8+ Tscm cells exhibit ;i) a higher proliferation index than TCM and TEM;ii) a functional profile secreting TNF and IFNgamma after restimulation with RBD or N peptides;cardinal features of Tscm cells. Conclusion(s): The CD40.SARS.CoV2, but not BNT162b2 vaccine, stimulates selective enrichment in S-and N-specific CD8+ Tscm cells that support longlasting anti-viral immunity. CD40.CoV2 sub-unit is under clinical development as a booster vaccine aimed to maintain durable anti-viral T and humoral responses. (Figure Presented).

SUBPOPULATION COMPOSITION OF PERIPHERAL BLOOD LYMPHOCYTES IN COVID-19.

The pathogenesis of severe coronavirus infection COVID-19 is associated with activation of immune system, cytokine storm, impaired blood clotting, microvascular thrombosis, organ ischemia and multiple organ dysfunction syndrome. The role of various lymphocyte subpopulations in COVID-19 is still debated. The aim of our study was to analyze the subpopulational profile of peripheral blood lymphocytes in COVID-19 patients as compared with healthy donors. The study included 20 COVID-19 patients (11 males and 9 females,) and 26 healthy donors. Average age of the patients was 52 and 56 years, respectively. Clinical examinations were performed by standard laboratory methods. Peripheral blood lymphocytes were isolated in the Ficoll gradient. The cells were stained with antibodies to specific antigens of main lymphocyte populations, endothelial cells, and apoptotic cell markers. The analysis was performed by flow cytometry. The results showed that all patients had elevated C-reactive protein (14- to 35-fold), ferritin (1.2- to 13-fold), D-dimers (1.2- to 90-fold). 55% of men had a decrease in the absolute number of lymphocytes, in women this index was at the low normal limit. Cytometric analysis showed that, among peripheral blood lymphocytes, the proportion of functional cells expressing the CD45 marker ranged from 2 to 12% in 70% of patients, as compared with 80-99% among the donors. The proportion of CD45+ lymphocytes significantly correlated with the level of hemoglobin, but not with the levels of inflammatory biochemical markers. Among the functional lymphocytes of patients, there was a decrease in the proportion of CD3+, CD4+, CD8+T cells, increased proportion of natural killer CD56+ and the apoptotic (AnnexinV+) cell contents, but the proportion of CD19 and HLA-DR+B cells was not changed. Analysis of the lymphocyte (LC) subpopulations that did not express CD45 marker showed that this fraction contained different lymphocyte subsets with reduced expression of CD4, CD8, CD19, CD56 etc. in the blood of patients and donors. Higher percentage of endothelial cells expressing CD62P marker made the difference between patients and donors. Laboratory determination of lymphocyte subsets in blood samples of COVID-19 patients does not reflect the real severity pattern of the disease, thus requiring studies of the CD45-expressing functional cell populations.Copyright © Svirshchevskaya E.V. et al., 2023 The article can be used under the Creative Commons Attribution 4.0 License.

Donor selection for adoptive cell therapy with CD45RA- memory T cells for patients with coronavirus disease 2019, and dexamethasone and interleukin-15 effects on the phenotype, proliferation and interferon gamma release.

BACKGROUND AIMS: We have previously demonstrated the safety and feasibility of adoptive cell therapy with CD45RA- memory T cells containing severe acute respiratory syndrome coronavirus 2-specific T cells for patients with coronavirus disease 2019 from an unvaccinated donor who was chosen based on human leukocyte antigen compatibility and cellular response. In this study, we examined the durability of cellular and humoral immunity within CD45RA- memory T cells and the effect of dexamethasone, the current standard of care treatment, and interleukin-15, a cytokine critically involved in T-cell maintenance and survival. METHODS: We performed a longitudinal analysis from previously severe acute respiratory syndrome coronavirus 2-infected and infection-naïve individuals covering 21 months from infection and 10 months after full vaccination with the BNT162b2 Pfizer/BioNTech vaccine. RESULTS: We observed that cellular responses are maintained over time. Humoral responses increased after vaccination but were gradually lost. In addition, dexamethasone did not alter cell functionality or proliferation of CD45RA- T cells, and interleukin-15 increased the memory T-cell activation state, regulatory T cell expression, and interferon gamma release. CONCLUSIONS: Our results suggest that the best donors for adoptive cell therapy would be recovered individuals and 2 months after vaccination, although further studies with larger cohorts would be needed to confirm this finding. Dexamethasone did not affect the characteristics of the memory T cells at a concentration used in the clinical practice and IL-15 showed a positive effect on SARS-CoV-2-specific CD45RA- T cells.

Analise Da Resposta Imunologica Celular Em Idosos Apos Vacinacao Com Coronavac

Objetivos: A COVID-19 e uma doenca infecciosa, onde a maioria dos infectados desenvolve quadros leves, no entanto, idosos e individuos com comorbidades estao relacionados aos casos mais graves. A fim de conter a propagacao da doenca, foram desenvolvidas vacinas com a finalidade de inducao de memoria imunologica. Entretanto, estudos sobre a efetividade da imunizacao em idosos ainda sao escassos e nao se sabe exatamente como sera o comportamento nessa populacao. Dessa forma, o objetivo desta pesquisa foi avaliar esta resposta imune celular em idosos de Instituicoes de Longa Permanencia (ILPS) no estado de Sergipe, Brasil, induzida pela vacina CoronaVac. Material e Metodos: Este estudo prospectivo foi realizado com idosos (grupo idosos-GI) e profissionais (grupo controle-GC) de ILPS. Todos receberam a vacina CoronaVac e as analises foram feitas 30 dias apos a administracao da segunda dose da vacina. Respeitando-se os aspectos eticos e legais, os participantes foram submetidos a um questionario estruturado, e foram coletadas amostras de sangue periferico para analise das populacoes de linfocitos T CD4+ e CD8+ e os subtipos de memoria que foram avaliados por citometria de fluxo multiparametrica. Resultados: Foram avaliados 28 individuos, sendo 23 idosos (GI) e cinco profissionais (GC). No GI, nove eram do sexo feminino e 14 do masculino, com medias de idade 81,6 (67-89) e 74,1 (64-89), respectivamente. O grupo GC foi composto por duas mulheres e tres homens, e as medias de idades foram de 36,5 (24 e 49) para as mulheres e 45,0 (30-64) para os homens. Foi observado aumento da expressao dos linfocitos TCD3+ e TCD4+ nos idosos vacinados (p=0,0010 e p=0,0383) em comparacao ao GC. Os idosos tambem apresentaram aumento de LTCD4+ e LTCD8+, ambos de memoria efetora (CD45RA-CCR7-) demonstrando p=0,0471 e 0,0138, respectivamente. Avaliando as diferencas entre os sexos dos idosos, observou-se que os homens apresentaram aumento no numero total de LTCD8+ (p=0,0464) e LTCD8+ de memoria efetora (p=0,0199);e diminuicao nos LTCD4+ de memoria central (CD45RA-CCR7+) quando comparados com as mulheres (p= 0,0440). Discussao: Apesar de todos os avancos no controle da doenca e melhoria nos desfechos dos pacientes mais graves, inumeras questoes ainda permanecem sem resposta: As vacinas conferem a mesma protecao da infeccao ou sao fatores sinergicos? Idosos apresentam a mesma resposta aos imunizantes que os jovens? Nas infeccoes por SARS-CoV-2, as respostas dos LT sao detectadas em quase todos os casos, sendo as respostas das LT CD4+ mais proeminentes do que as respostas dos LT CD8+. Diferentemente das situacoes relatadas apos a infecao pelo SARS-CoV-2, avaliando a resposta ao imunizante CoronaVac, o presente trabalho demonstrou que idosos apresentaram maior producao de LTCD4+ quando comparados aos jovens. Entretanto, apesar de os LTCD8+ nao terem respostas diferentes entre os grupos (idosos e jovens), apresentaram maior resposta nos idosos do sexo masculino. Conclusao: Neste trabalho, foi observado que os homens parecem apresentar memoria efetora rapida maior que das mulheres, entretanto, as mulheres apresentaram memoria central maior, sugerindo imunidade prologada maior nas mulheres idosas do que nos homens. Copyright © 2022

Immunotherapy: TIMING OF DONOR SELECTION ON CD45RA-MEMORY T CELLS AS ADOPTIVE CELL THERAPY FOR COVID-19

Background & Aim: The COVID-19 pandemic has resulted in significant morbidity and mortality worldwide. The vaccines had dramatically decreased infection rates, number of deaths, and hospitalizations, but they are not 100% effective and immunity is lost gradually over time. We have previously shown how we are able to detect, isolate and produce at clinical scale SARS-CoV-2-specific T cells within CD45RA-memory T cells from COVID-19 convalescent donors. In a phase I clinical trial we have proved that treatment with these cells of hospitalized patients with moderate/severe COVID-19 is safe and feasible. Understanding the durability and the level of cellular immunity within the CD45RA- memory T cells and how changes with immunization are critical for the development of a biobank of living drugs to treat future COVID-19 patients. We performed a longitudinal exploratory analysis of the SARS-CoV-2 specific humoral and cellular immunity within the memory CD45RA- T cells in naive and previously infected individuals at different time points after two doses of BNT162b2 BioNTech/Pfizer vaccine Methods, Results & Conclusion: We studied the cellular and humoral response of SARS-CoV-2 specific memory T cells from recovered patients and controls at different time points: 2 weeks after recovering from COVID-19, 9 months after the infection/just before mRNA immunization, 10 and 65 days after full immunization. Detection of SARSCoV- 2- Specific Memory T Cells was performed by IFNg assay after exposure of cells to the M, N, and S SARS-CoV-2 peptides. Our data shows that memory T cell responses within the CD45RA- memory T cell subpopulation and most of the subsets tend to be higher in recovered individuals at all time points. The cellular response produced by control individuals to the S peptide is like the one from recovered patients at the same time point. Humoral responses were higher in recovered individuals after full immunization. Antibodies titer was not boosted after the late vaccine time point. An exploratory analysis of non-parametric Spearman’s rho correlation of humoral and cellular responses shows a positive correlation after infection with the 3 peptides and 65 days after immunization. In conclusion: We have analyzed the SARS-COV-2 specific T cells within the CD45RA- memory T cell subpopulation and the different subsets at different time points after (Figure Presented) (Figure Presented) infection and fully vaccinated. We claim that the best donors would be immunized individuals recovered from COVID-19 ideally in a time frame not higher than 6 months.

Differential Regulation of CD45 Expression on Granulocytes, Lymphocytes, and Monocytes in COVID-19.

CD45 is a transmembrane glycoprotein and protein tyrosine phosphatase expressed on the surface of all nucleated hematopoietic cells. While there is increasing evidence demonstrating the involvement of CD45 in immune system regulation, no information on CD45 expression in inflammation and sepsis is currently available. Therefore, we determined the CD45 surface expression on granulocytes, lymphocytes, and monocytes in patients with COVID-19 and healthy volunteers in both absence and presence of lipopolysaccharide (LPS). Following approval by the local ethics committee, whole blood samples were obtained from patients with COVID-19 infection on day 1 of hospital admission and healthy volunteers. Samples were incubated in absence and presence of LPS and CD45 was measured in granulocytes, lymphocytes, and monocytes using flow cytometry. In comparison with healthy individuals, COVID-19 patients showed an increased CD45 expression on the surface of granulocytes (+35%, p < 0.02) and lymphocytes (+39%, p < 0.0001), but a reduced CD45 expression on monocytes (-35%, p < 0.0001). LPS incubation of whole blood from healthy individuals increased the CD45 expression on granulocytes (+430%, p < 0.0001), lymphocytes (+32%, p = 0.0012), and monocytes (+36%, p = 0.0005), respectively. LPS incubation of whole blood samples from COVID-19 patients increased the CD45 expression on granulocytes and monocytes, and decreased the CD45 expression on lymphocytes. In conclusion, CD45 expression on leucocytes is altered: (1) in COVID-19 patients, and (2) in in vitro endotoxemia in a complex cell-specific way, thus representing a new immunoregulatory mechanism.

HUMORAL AND CELLULAR IMMUNE RESPONSES AFTER BOOSTER DOSE WITH BNT162B2 VACCINE IN HEMODIALYSIS PATIENTS AND KIDNEY TRANSPLANT RECIPIENTS

BACKGROUND AND AIMS: Mortality due to SARS-COV-2 infection in hemodialysis (HD) patients and kidney transplant recipients(KTRs) is high. Despite increased rates of administration of two doses of mRNA vaccines among these vulnerable populations, the adequacy of the respective generated immune responses is reported lower than general population, especially in KTRs. A third booster dose has been officially recommended in these immunocompromised patients while the humoral and cellular immune responses to SARS-COV-2 vaccination remains to be elucidated in HD patients and KTRs. The aim of our study was to investigate the antibody (Ab) response status together with vaccine-induced alterations in circulating lymphocytes subsets, following the administration of three doses of the BNT162b2 vaccine in a cohort of maintenance HD patients and KTRs. METHOD: The initial cohort of this prospective study (ClinicalTrials.gov, NCT04932876) included 34 HD patients and 54 KTRs who received two doses of the BNT162b2 (Pfizer-BioNTech). Of this cohort, 24 HD patients and 30 KTRs, who remained free of SARS-CoV2 infection and receive a third dose 6 months after the second dose, were finally analyzed. Lymphocyte subpopulations, including B cells, CD4+and CD8+T cells as well as naïve and memory T lymphocytes subpopulations among others, were analyzed by flow cytometry at four time points, before vaccination (T0), before the second dose (T1), 2 weeks after the second dose (T2) and 2-3 weeks after the third dose (T3). The anti-SARS-CoV2 antibody (Ab) response was assessed by using the ARCHITECT IgG II Quant test (Abbott). Titers >50 arbitrary units (AU)/mL were considered positive for seroconversion at T1 and at T2 and T3. RESULTS: Of the initial cohort 31 HD patients (91.8%) and 16 KTRs (29.6%) became seropositive at T2. Of the final cohort (24 HD and 30 KTRs), almost all HD patients (23, 96%) became seropositive since T2 and this finding remained at T3 (Figure 1). In KTRs the percentage of responders was doubled between T2 and T3, T2 9 KTRs (30%) versus T3 18 KTRs (60%) (Figure 1). KTRs who developed Ab at T1 “respond” better to the third dose, maximizing the levels of Ab. HD patients who became seropositive at T1 displayed higher CD19+B lymphocytes compared with their seronegative HD counterparts. In HD patients, a positive correlation was established between CD19+B cells counts and Ab titers at all time-points (P < 0.001). In KTRs, Ab at T1 showed an inverse correlation with T+B+NK at T1 (P = 0.006). T2-Ab showed inverse correlation with CD45RA+CD45RO at T0 (P = 0.01) and with CD3+at T3 (P = 0.02). T3-Ab showed positive correlation with CD3+CD16+56+at T2 (P = 0.003) and with CD3-CD16+56+at T3 (P = 0.01). CD19+at T3 correlated positively with Ab at T1 and T3 (P = 0.003 and P = 0.03, respectively). CONCLUSION: Our study confirms the improved immunogenicity after the third dose of BNT162b2 vaccine in KTRs. The positive correlation between CD19+B cells and Ab in both groups of patients, more stable and constant in HD patients in comparison with KTR, possibly reflects successful humoral immunity. However, a big proportion of kidney patients remain at high risk for COVID-19 infection considering the new more transmissible variants such as the Omicron variant. (Figure Presented).

Depletion of γδ T Cells Leads to Reduced Angiogenesis and Increased Infiltration of Inflammatory M1-like Macrophages in Ischemic Muscle Tissue

γδ T cells, a small subset of T cells in blood, play a substantial role in influencing immunoregulatory and inflammatory processes. The functional impact of γδ T cells on angiogenesis in ischemic muscle tissue has never been reported and is the topic of the present work. Femoral artery ligation (FAL) was used to induce angiogenesis in the lower leg of γδ T cell depleted mice and wildtype and isotype antibody-treated control groups. Gastrocnemius muscle tissue was harvested 3 and 7 days after FAL and assessed using (immuno-)histological analyses. Hematoxylin and Eosin staining showed an increased area of tissue damage in γδ T cell depleted mice 7 days after FAL. Impaired angiogenesis was demonstrated by lower capillary to muscle fiber ratio and decreased number of proliferating endothelial cells (CD31+/BrdU+). γδ T cell depleted mice showed an increased number of total leukocytes (CD45+), neutrophils (MPO+) and neutrophil extracellular traps (NETs) (MPO+/CitH3+), without changes in the neutrophils to NETs ratio. Moreover, the depletion resulted in a higher macrophage count (DAPI/CD68+) caused by an increase in inflammatory M1-like macrophages (CD68+/MRC1−). Altogether, we show that depletion of γδ T cells leads to increased accumulation of leukocytes and M1-like macrophages, along with impaired angiogenesis.

Cancer patients display diminished viral RNA clearance and altered T cell responses during SARS-CoV-2 infection

Cancer patients display immunomodulation related to malignancy and anti-cancer therapies, but how these factors impact COVID-19 remains unknown. To investigate immune responses in cancer patients with COVID-19, we undertook a prospective case-control study, enrolling hospitalized solid tumor patients with acute COVID-19, as well as age-, gender-, and comorbidity-matched COVID-19 patients without cancer as controls. Using biospecimens collected during hospitalization, we performed virologic measurements as well as in-depth immunophenotyping of cellular, antibody and cytokine responses. We enrolled 17 cancer patients (cases) admitted to Yale-New Haven Hospital between March 15 and June 30, 2020 with COVID-19, as well as 17 matched non-cancer patients (controls) admitted with COVID-19. No significant differences were observed between cases and controls based on patient characteristics (age, gender, race, co-morbidities, smoking history, days from symptom onset to COVID-19 diagnosis) or outcomes (COVID-19 severity, length of hospital stay, rate of intubation or mortality). The most common primary tumor sites were lung (4/17) and gastrointestinal (4/17);all cases had received cancer-directed therapy within 6 months of COVID-19 diagnosis, with 13/17 receiving treatment less than 1 month prior to hospitalization. Three of 17 cases had received immune checkpoint inhibitor therapies. Despite having similar SARS-CoV-2 viral RNA loads at the time of COVID-19 diagnosis when compared with controls, cancer cases had increased viral RNA abundance during hospitalization, suggesting slower clearance. Antibody responses against SARS-CoV-2 were preserved in cancer cases, with cases displaying similar levels of IgM and IgG antibodies directed against SARS-CoV-2 epitopes compared to controls. Cytokine profiling revealed higher plasma levels of CCL3, IL1A and CXCL12 in cancer cases compared to controls. Using flow cytometric immunophenotyping, we found that innate immune and non-T cell adaptive immune parameters were similar between cases and controls hospitalized with COVID-19. However, among cancer cases on conventional therapies, T cell lymphopenia was more profound, and these cases demonstrated higher levels of CD8+ exhausted (CD8+CD45RA-PD1+TIM3+ ), CD8+GranzymeB+ and CD4+CD38+HLA-DR+ and CD8+CD38+HLA-DR+ activated T cells when compared with controls;interestingly, these differences were not observed in patients who had received immune checkpoint inhibition. Thus, we found reduced viral RNA clearance and specific alterations in T cell and cytokine responses in cancer patients hospitalized with COVID-19 compared with matched controls with COVID-19. This dysregulated T cell response in cancer patients, which may reflect immune modulation due to chronic antigen stimulation as well as cancer therapies, may lead to altered virologic and clinical outcomes in this population.

The Humoral Immune Response to BNT162b2 Vaccine Is Associated With Circulating CD19+ B Lymphocytes and the Naïve CD45RA to Memory CD45RO CD4+ T Helper Cells Ratio in Hemodialysis Patients and Kidney Transplant Recipients.

Background: The humoral and cellular immune responses to SARS-COV-2 vaccination remain to be elucidated in hemodialysis (HD) patients and kidney transplant recipients (KTRs), considering their baseline immunosuppressed status. The aim of our study was to assess the associations of vaccine-induced antibody responses with circulating lymphocytes sub-populations and their respective patterns of alterations in maintenance HD patients and KTRs. Materials and Methods: We included 34 HD patients and 54 KTRs who received two doses of the mRNA-vaccine BNT162b2. Lymphocyte subpopulations were analyzed by flow cytometry before vaccination (T0), before the second vaccine dose (T1) and 2 weeks after the second dose (T2). The anti-SARS-CoV2 antibody response was assessed at T1 and at T2. Results: 31 HD patients (91.8%) and 16 KTRs (29.6%) became seropositive at T2. HD patients who became seropositive following the first dose displayed higher CD19+ B lymphocytes compared to their seronegative HD counterparts. A positive correlation was established between CD19+ B cells counts and antibody titers at all time-points in both groups (p < 0.001). KTRs showed higher naïve CD4+CD45RA+ T helper cells compared to HD patients at baseline and T2 whereas HD patients displayed higher memory CD45RO+ T cells compared to KTRs at T2. The naïve CD4+CD45RA to memory CD4+CD45RO+ T helper cells fraction was negatively associated with antibody production in both groups. Conclusions: Our study provides a potential conceptual framework for monitoring vaccination efficacy in HD patients and KTRs considering the correlation established between CD19+ B cells, generation of memory CD4+ T helper cells and anti SARS-CoV2 antibody response to vaccination.

A Phase I/II Dose-Escalation Multi-Center Study to Evaluate the Safety of Infusion of Natural Killer Cells or Memory T Cells As Adoptive Therapy in Coronavirus Pneumonia and/or Lymphopenia: (RELEASE NCT04578210)

Background: Adoptive cell immunotherapies for opportunistic virus in immunocompromised patients using haploidentical memory T cells have shown to be safe and effective. Since severe cases of COVID-19 present a dysregulated immune system with T cell lymphopenia and a hyper-inflammatory state we have proposed that a similar strategy could be proven to be efficient for COVID-19 patients. This is a study protocol of an open-label, multicenter, double-arm, randomized, dose-finding phase I/II clinical trial to evaluate the feasibility, safety, tolerability, and efficacy of the administration of a single dose of allogenic SARS-CoV-2 specific memory CD45RA - T cells and Natural Killer (NK) cells in COVID-19 patients with lymphopenia and pneumonia. The aim of the study is to find efficient treatments for patients with moderate/severe COVID-19. Identification of Specific memory T cells and NK cells: i)Memory T Cells: we first determined the existence of SARS-CoV-2 specific T cells within the CD45RA - T memory cells of the blood of convalescent donors. Memory T cells can respond quickly to the infection and provide long-term immune protection to reduce the severity of the COVID-19 symptoms without inducing classically T cell alloreactivity. Also, CD45RA - memory T cells confer protection for other pathogens the donors encountered in their life. ii)NK cells: we determined the phenotype of NK cells after COVID-19 and the main characteristic of SARS-CoV-2 specific NK population in the blood of convalescent donors, as it has been shown for cytomegalovirus infections. Also, NK cells confer protection for other pathogens the donors encountered in their life. Pilot Phase I- Safety, feasibility, and dose escalation: Between September and November 2020 a phase 1, dose-escalation, single-center clinical trial was conducted to evaluate the safety and feasibility of the infusion of CD45RA - memory T cells containing SARS-CoV-2 specific T cells as adoptive cell therapy against moderate/severe cases of COVID-19. Nine participants with pneumonia and/or lymphopenia and with at least one human leukocyte antigen (HLA) match with the donor were infused. The first three subjects received the lowest dose (1x10 5 cells/kg), the next three received the intermediate dose (5x10 5 cells/kg) and the last three received the highest dose (1x10 6 cells/kg) of CD45RA - memory T cells. Clinicaltrials.gov registration: NCT04578210. Findings: All participants' clinical status measured by National Early Warning Score (NEWS) and 7-category point ordinal scales showed improvement six days after infusion. No serious adverse events were reported. Inflammatory parameters were stabilized post-infusion and the participants showed lymphocyte recovery two weeks after the procedure. Donor microchimerism was observed at least for three weeks after infusion in all patients. Interpretation: This study provides preliminary evidence supporting the idea that treatment of COVID-19 patients with moderate/severe symptoms using convalescent SARS-CoV-2 specific CD45RA - memory T cells is feasible and safe. We did not find dose-liming toxicity. The Recommended Phase 2 dose was 1x10 6 CD45RA - T cells. Phase II- Efficacy: Between January 2021 and July 2021 patients have been enrolled based on the matched with the HLA genotype of the convalescent donors and following the protocol inclusion/exclusion criteria. The primary outcome is the incidence of patient recovery at day 14, defined as normalization of fever and oxygen saturation or lymphopenia recovery. Secondary outcomes are the time to normal level of lymphocytes, the proportion of patients showing clinical improvement at day 7, time to first negative SARS-CoV-2 PCR, the incidence of treatment-related adverse events, duration of hospitalization, time to discharge, time to improvement by one category a 7-point ordinal scale or NEWS score, the proportion of patients requiring intensive care unit, and all-cause mortality. In addition, lymphocyte recovery by multiparametric flow cytometry and donor chimerism by real-time PCR in the e perimental arm was monitored weekly during the first month. This study provides preliminary evidence supporting the idea that treatment of COVID-19 patients with moderate/severe symptoms using convalescent CD45RA - memory T cells is safe and feasible. The phase II clinical trial is ongoing to demonstrate efficacy. [Formula presented] Disclosures: Soria: Celgene: Other: Fees;Gilead: Other: Fees;AbbVie: Other: Fees.

Downregulation of CD45 Signaling in COVID-19 Patients Is Reversed by C24D, a Novel CD45 Targeting Peptide.

CD45, the predominant transmembrane tyrosine phosphatase in leukocytes, is required for the efficient induction of T cell receptor signaling and activation. We recently reported that the CD45-intracellular signals in peripheral blood mononuclear cells (PBMCs) of triple negative breast cancer (TNBC) patients are inhibited. We also reported that C24D, an immune modulating therapeutic peptide, binds to CD45 on immune-suppressed cells and resets the functionality of the immune system via the CD45 signaling pathway. Various studies have demonstrated that also viruses can interfere with the functions of CD45 and that patients with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are immune-suppressed. Given the similarity between the role of CD45 in viral immune suppression and our findings on TNBC, we hypothesized that the C24D peptide may have a similar "immune-resetting" effect on PBMCs from COVID-19 patients as it did on PBMCs from TNBC patients. We tested this hypothesis by comparing the CD45/TCR intracellular signaling in PBMCs from ten COVID-19 patients vs. PBMCs from ten healthy volunteers. Herein, we report our findings, demonstrating the immune reactivating effect of C24D via the phosphorylation of the tyrosine 505 and 394 in Lck, the tyrosine 493 in ZAP-70 and the tyrosine 172 in VAV-1 proteins in the CD45 signaling pathway. Despite the relatively small number of patients in this report, the results demonstrate that C24D rescued CD45 signaling. Given the central role played by CD45 in the immune system, we suggest CD45 as a potential therapeutic target.

Usefulness of the New Hematological Parameter: Reactive Lymphocytes RE-LYMP with Flow Cytometry Markers of Inflammation in COVID-19.

Identification of patients with activation of the immune system which indicates the presence of infection is essential, especially in the times of the global coronavirus 2019 (COVID-19) pandemic. The aim of the present study was to evaluate the reactive lymphocytes (RE-LYMP) parameter in COVID-19 and to correlate it with activation lymphocytes markers by flow cytometry. The study group consisted of 40 patients: with COVID-19 infection (n = 20) and with others virus infections without COVID-19 (COVID-19(-) virus (n = 20)) and 20 healthy donors (HC). Blood count and flow cytometry were performed. The COVID-19(+) group had significantly lower RE-LYMP parameter than the COVID-19(-) virus group (5.45 vs. 11.05, p < 0.05). We observed higher proportion of plasmablasts in the COVID-19(+) and COVID-19(-) virus groups than HC (8.8 vs. 11.1 vs. 2.7, p < 0.05). In the COVID-19(+) there was a lower proportion of CD4+ CD38+ cells than in the other groups (significant differences between COVID-19(+) and COVID-19(-) virus groups). RE-LYMP correlated with activated T lymphocytes CD38+ and HLA-DR+ in the COVID-19(-) virus group, however in the COVID-19(+) group correlations with T lymphocytes CD25+ and CD45RO+ were observed. In summary the analysis of the RE-LYMP together with flow cytometric activation markers can be helpful in identifying and distinguishing patients with COVID-19(+) from other viruses and HC.

Predictive Nomogram for Severe COVID-19 and Identification of Mortality-Related Immune Features.

BACKGROUND: Patients with severe 2019 novel coronavirus disease (COVID-19) have a high mortality rate. The early identification of severe COVID-19 is of critical concern. In addition, the correlation between the immunological features and clinical outcomes in severe cases needs to be explored. OBJECTIVE: To build a nomogram for identifying patients with severe COVID-19 and explore the immunological features correlating with fatal outcomes. METHODS: We retrospectively enrolled 85 and 41 patients with COVID-19 in primary and validation cohorts, respectively. A predictive nomogram based on risk factors for severe COVID-19 was constructed using the primary cohort and evaluated internally and externally. In addition, in the validation cohort, immunological features in patients with severe COVID-19 were analyzed and correlated with disease outcomes. RESULTS: The risk prediction nomogram incorporating age, C-reactive protein, and D-dimer for early identification of patients with severe COVID-19 showed favorable discrimination in both the primary (area under the curve [AUC] 0.807) and validation cohorts (AUC 0.902) and was well calibrated. Patients who died from COVID-19 showed lower abundance of peripheral CD45RO+CD3+ T cells and natural killer cells, but higher neutrophil counts than that in the patients who recovered (P = .001, P = .009, and P = .009, respectively). Moreover, the abundance of CD45RO+CD3+ T cells, neutrophil-to-lymphocyte ratio, and neutrophil-to-natural killer cell ratio were strong indicators of death in patients with severe COVID-19 (AUC 0.933 for all 3). CONCLUSION: The novel nomogram aided the early identification of severe COVID-19 cases. In addition, the abundance of CD45RO+CD3+ T cells and neutrophil-to-lymphocyte and neutrophil-to-natural killer cell ratios may serve as useful prognostic predictors in severe patients.