[Analysis of early changes in lymphocyte subpopulations after liver transplantation and their correlation with clinical manifestations].

This study aimed to investigate the differences in peripheral blood lymphocyte subsets among patients with different immune statuses in the early postoperative period after liver transplantation, as well as the dynamic changes during the early post-transplantation period. A retrospective study was conducted, selecting a total of 82 patients who underwent liver transplantation at the General Hospital of PLA Southern Theater Command from January, 2018 to December, 2023. Based on the patients' postoperative immune status, they were categorized into stable group (n=40), infection group (n=21), and rejection group (n=21). Peripheral blood samples of 2-3 ml were collected from patients at weeks 1 to 4 postoperatively, and flow cytometry was employed to measure the absolute values of peripheral blood lymphocyte subsets. For metric data conforming to normal distribution and homogeneity of variance, multiple group comparisons were conducted using ANOVA and Bonferroni multiple comparisons; for non-normally distributed data, the Kruskal Wallis test was used. Friedman test was used to compare different time periods within 4 weeks after liver transplantation. The results showed that there were no statistically significant differences in the absolute values of lymphocyte subsets among the three groups in the first week after liver transplantation (P>0.05); however, significant differences were observed in the absolute values of lymphocyte subsets among the three groups in the second, third, and fourth weeks postoperatively (P<0.05). In the second week, the rejection group showed significantly higher absolute counts of T cells, CD4+T cells, CD8+T cells, NK cells, and B cells compared to the infection group (585.0 vs. 199.0; 324.0 vs.113.0; 188.0 vs.56.0; 57.0 vs.11.0; 145.0 vs.65.0 cells/µl), with statistically significant differences (Z=-3.972, P<0.001; Z=-3.590, P=0.001; Z=-3.978, P<0.001; Z=-3.072, P=0.006; Z=-2.472, P=0.040). In the third week, the rejection group showed significantly higher absolute counts of T cells, CD4+T cells, and CD8+T cells compared to the infection group (660.0 vs.216.0; 350.0 vs.123.0; 184.0 vs.76.0 cells/µl), with statistically significant differences (Z=-3.019, P=0.008; Z=-3.492, P=0.001; Z=-2.845, P=0.013). In the fourth week, the rejection group showed significantly higher absolute counts of T cells, CD4+T cells, CD8+T cells, and B cells compared to the infection group (690.0 vs.273.0; 405.0 vs.168.0; 214.0 vs.96.0; 117.0 vs.48.0 cells/µl), with statistically significant differences (Z=-3.379, P=0.002; Z=-3.068, P=0.006; Z=-3.007, P=0.0086; Z=-2.330, P=0.020). Within 4 weeks after liver transplantation, the absolute values of T cells, CD8+T cells, and NK cells in the fourth week were higher than those in the first week, with statistically significant differences (Z=-3.825, P=0.001; Z=-3.466, P=0.003; Z=-3.526, P=0.003); however, the absolute values of B cells showed an overall decreasing trend, and were significantly lower in the fourth week than in the first and second weeks, with statistically significant differences (Z=3.705, P=0.001; Z=2.630, P=0.009). The changes in lymphocyte subset absolute values in the rejection group were more significant than those in the infection group, with T cells, CD4+T cells, and CD8+T cells showing significant increases in the second, third, and fourth weeks postoperatively compared with the first week, with statistically significant differences (Z=-3.466, P=0.003; Z=-4.661, P<0.001; Z=-5.020, P<0.001; Z=-2.749, P=0.036; Z=-4.422, P<0.001; Z=-4.542, P<0.001; Z=-3.466, P=0.003; Z=-3.765, P=0.001; Z=-4.482, P<0.001); NK cell absolute values in the third and fourth weeks postoperatively were significantly higher than those in the first week, with statistically significant differences (Z=-2.570, P=0.061; Z=-3.765, P=0.001). In summary, monitoring the differences and dynamic changes of lymphocyte subsets in patients after liver transplantation may have certain guiding significance for evaluating the immune function status of patients and adjusting treatment plans.

Differential expression of lymphocyte subpopulations in the peripheral blood of patients with COVID-19: Implications for disease severity and prognosis.

OBJECTIVE: To investigate the expression patterns and clinical significance of specific lymphocyte subsets in the peripheral blood of patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. METHODS: Between December 2022 and February 2023, a cohort of 165 patients from the First Affiliated Hospital of Guangzhou University of Chinese Medicine were analyzed. The participants represented various stages of coronavirus infection severity: mild, moderate, severe, and critical. Additionally, 40 healthy individuals constituted the control group. The FC 500MPL flow cytometer and associated reagents for flow cytometry. RESULTS: Compared with the healthy control group, activated B lymphocytes witnessed a pronounced increase (p < .05). A significant decrease was observed in the levels of Breg, Cytotoxic T cells or Suppressor T-cell (Tc/s), late-activated T, late-activated Th, and late-activated Tc/s lymphocytes (p < .05). Th, initial Th, initial Tc/s, total Treg, natural Treg, induced Treg, early activated T, and early activated Th lymphocyte levels showed no significant difference (p > .05). As the disease progressed, there was an uptick in midterm activated T lymphocytes (p < .05), while Breg, T, Tc/s, senescent Tc/s, and total senescent T levels dwindled (p < .05). Noteworthy patterns emerged across different groups for B1, T-lymphocytes, Tc/s, B2, CD8+ Treg cells, and other subsets, highlighting variance in immune responses relative to disease severity. When juxtaposed, no significant difference was found in the expression levels of lymphocyte subsets between patients who died and those deemed critically ill (p > .05). CONCLUSION: Subsets of Treg and B-cells could act as yardsticks for the trajectory of SARS-CoV-2 infection and might have potential in forecasting patient trajectories. A comprehensive evaluation of lymphocyte subsets, especially in real-time, holds the key to discerning the clinical severity in those with COVID-19. This becomes instrumental in monitoring treatment outcomes, tracking disease evolution, and formulating prognostications. Moreover, the results provide a deeper understanding of the cellular immune defense mechanisms against the novel coronavirus infection.

Characterization of innate lymphoid cell subsets infiltrating melanoma and epithelial ovarian tumors.

The innate lymphoid cell (ILC) family is composed of heterogeneous innate effector and helper immune cells that preferentially reside in tissues where they promote tissue homeostasis. In cancer, they have been implicated in driving both pro- and anti-tumor responses. This apparent dichotomy highlights the need to better understand differences in the ILC composition and phenotype within different tumor types that could drive seemingly opposite anti-tumor responses. Here, we characterized the frequency and phenotype of various ILC subsets in melanoma metastases and primary epithelial ovarian tumors. We observed high PD-1 expression on ILC subsets isolated from epithelial ovarian tumor samples, while ILC populations in melanoma samples express higher levels of LAG-3. In addition, we found that the frequency of cytotoxic ILCs and NKp46+ILC3 in tumors positively correlates with monocytic cells and conventional type 2 dendritic cells, revealing potentially new interconnected immune cell subsets in the tumor microenvironment. Consequently, these observations may have direct relevance to tumor microenvironment composition and how ILC subset may influence anti-tumor immunity.

Spatial Distribution of Macrophage and Lymphocyte Subtypes within Tumor Microenvironment to Predict Recurrence of Non-Muscle-Invasive Papillary Urothelial Carcinoma after BCG Immunotherapy.

Non-muscle-invasive papillary urothelial carcinoma (NMIPUC) of the urinary bladder is the most common type of bladder cancer. Intravesical Bacille Calmette-Guerin (BCG) immunotherapy is applied in patients with a high risk of recurrence and progression of NMIPUC to muscle-invasive disease. However, the tumor relapses in about 30% of patients despite the treatment, raising the need for better risk stratification. We explored the potential of spatial distributions of immune cell subtypes (CD20, CD11c, CD163, ICOS, and CD8) within the tumor microenvironment to predict NMIPUC recurrence following BCG immunotherapy. Based on analyses of digital whole-slide images, we assessed the densities of the immune cells in the epithelial-stromal interface zone compartments and their distribution, represented by an epithelial-stromal interface density ratio (IDR). While the densities of any cell type did not predict recurrence, a higher IDR of CD11c (HR: 0.0012, p-value = 0.0002), CD8 (HR: 0.0379, p-value = 0.005), and ICOS (HR: 0.0768, p-value = 0.0388) was associated with longer recurrence-free survival (RFS) based on the univariate Cox regression. The history of positive repeated TUR (re-TUR) (HR: 4.93, p-value = 0.0001) and T1 tumor stage (HR: 2.04, p-value = 0.0159) were associated with shorter RFS, while G3 tumor grade according to the 1973 WHO classification showed borderline significance (HR: 1.83, p-value = 0.0522). In a multivariate analysis, the two models with a concordance index exceeding 0.7 included the CD11c IDR in combination with either a history of positive re-TUR or tumor stage. We conclude that the CD11c IDR is the most informative predictor of NMIPUC recurrence after BCG immunotherapy. Our findings highlight the importance of assessment of the spatial distribution of immune cells in the tumor microenvironment.

Alterations in Peripheral Lymphocyte Subsets under Immunochemotherapy in Stage IV SCLC Patients: Th17 Cells as Potential Early Predictive Biomarker for Response.

UICC stage IV small-cell lung cancer (SCLC) is a highly aggressive malignancy without curative treatment options. Several randomized trials have demonstrated improved survival rates through the addition of checkpoint inhibitors to first-line platin-based chemotherapy. Consequently, a combination of chemo- and immunotherapy has become standard palliative treatment. However, no reliable predictive biomarkers for treatment response exist. Neither PD-L1 expression nor tumor mutational burden have proven to be effective predictive biomarkers. In this study, we compared the cellular immune statuses of SCLC patients to a healthy control cohort and investigated changes in peripheral blood B, T, and NK lymphocytes, as well as several of their respective subsets, during treatment with immunochemotherapy (ICT) using flow cytometry. Our findings revealed a significant decrease in B cells, while T cells showed a trend to increase throughout ICT. Notably, high levels of exhausted CD4+ and CD8+ cells, alongside NK subsets, increased significantly during treatment. Furthermore, we correlated decreases/increases in subsets after two cycles of ICT with survival. Specifically, a decrease in Th17 cells indicated a better overall survival. Based on these findings, we suggest conducting further investigation into Th17 cells as a potential early predictive biomarkers for response in patients receiving palliative ICT for stage IV SCLC.

Advances in Mechanism of HIV-1 Immune Reconstitution Failure: Understanding Lymphocyte Subpopulations and Interventions for Immunological Nonresponders.

In individuals diagnosed with AIDS, the primary method of sustained suppression of HIV-1 replication is antiretroviral therapy, which systematically increases CD4+ T cell levels and restores immune function. However, there is still a subset of 10-40% of people living with HIV who not only fail to reach normal CD4+ T cell counts but also experience severe immune dysfunction. These individuals are referred to as immunological nonresponders (INRs). INRs have a higher susceptibility to opportunistic infections and non-AIDS-related illnesses, resulting in increased morbidity and mortality rates. Therefore, it is crucial to gain new insights into the primary mechanisms of immune reconstitution failure to enable early and effective treatment for individuals at risk. This review provides an overview of the dynamics of key lymphocyte subpopulations, the main molecular mechanisms of INRs, clinical diagnosis, and intervention strategies during immune reconstitution failure, primarily from a multiomics perspective.

Characteristics of Virology and Immune Inflammation of Epstein-Barr Virus Infection Related Non-Neoplastic Diseases in Children.

BACKGROUND: The goal was to study the difference of virological, immunologic, and inflammatory indicators between Epstein-Barr associated infectious mononucleosis (EBV-IM) and EBV associated hemophagocytic lymphohistiocytosis (EBV-HLH) and to explore the evaluation indicators for monitoring the therapeutic efficacy of EBV-HLH. METHODS: Twenty children with EBV-IM (IM group) and 10 children with EBV-HLH (HLH group) were selected. Virology indicators were detected; the absolute count of lymphocyte, and lymphocyte subsets were detected; the levels of immunoglobulin and ferritin were assayed. RESULTS: Compared to the IM group, the HLH group showed a decrease in EBV-specific VCA-IgM antibody levels (U = 29.0, p = 0.006) and an increase in EBV-specific NA-IgG antibody levels (U = 17.0, p = 0.001), while there was no significant difference in EB-DNA loads (t = 0.417, p = 0.680). The counts of lymphocytes, and various lymphocyte subsets in the HLH group were lower than those in the IM group. Inflammatory markers in the HLH group were significantly higher than those in IM group. Dynamic monitoring of virological, immunological, and inflammatory indicators in HLH patients during treatment showed that EBV DNA gradually decreased in patients with good prognosis. Inflammatory indicators significantly decreased and returned to normal, lymphocyte count significantly increased and returned to normal during treatment. However, patients with poor prognosis showed rebound increase in EBV DNA and inflammatory indicators in the later stage of treatment, while lymphocyte count further decreased with the recurrence of the disease. CONCLUSIONS: Exhausted and damaged immune function in host by persistent stimulation of EB viral antigen is one of the main pathogeneses of EB-HLH. Lymphocyte count and serum ferritin level are effective indicators to monitor the therapeutic efficacy during the treatment to HLH.

Natural killer cell subsets and their functional molecules in peripheral blood of the patients with breast cancer.

BACKGROUND: Natural killer (NK) cells, CD3- lymphocytes, are critical players in cancer immune surveillance. This study aimed to assess two types of CD3- NK cell classifications (subsets), that is, convectional subsets (based on CD56 and CD16 expression) and new subsets (based on CD56, CD27, and CD11b expression), and their functional molecules in the peripheral blood of patients with breast cancer (BC) in comparison with healthy donors (HDs). METHODS: Thirty untreated females with BC and 20 age-matched healthy women were enrolled. Peripheral blood samples were collected and directly incubated with fluorochrome-conjugated antibodies against CD3, CD56, CD16, CD27, CD11b, CD96, NKG2C, NKG2D, NKp44, CXCR3, perforin, and granzyme B. Red blood cells were then lysed using lysing solution, and the stained cells were acquired on four-color flow cytometer. RESULT: Our results indicated 15% of lymphocytes in peripheral blood of patients with BC and HDs had NK cells phenotype. However, the frequency of total NK cells (CD3-CD56+), and NK subsets (based on conventional and new classifications) was not significantly different between patients and HDs. We observed mean fluorescent intensity (MFI) of CXCR3 in total NK cells (p = .02) and the conventional cytotoxic (CD3-CD56dim CD16+) NK cells (p = .03) were significantly elevated in the patients with BC compared to HDs. Despite this, the MFI of granzyme B expression in conventional regulatory (CD3-CD56brightCD16- /+) NK cells and CD3-CD56-CD16+ NK cells (p = .03 and p = .004, respectively) in the patients was lower than healthy subjects. CONCLUSION: The higher expression of chemokine receptor CXCR3 on total NK cells in patients with BC may be associated with increased chemotaxis-related NK cell infiltration. However, lower expression of granzyme B in conventional regulatory NK cells and CD3-CD56-CD16+ NK cells in the patients compared to HDs suggests reduced cytotoxic activity of the NK cells in BC. These results might demonstrate accumulating NK subsets with a dysfunctional phenotype in the peripheral blood of patients with BC.

Predictive modeling of co-infection in lupus nephritis using multiple machine learning algorithms.

This study aimed to analyze peripheral blood lymphocyte subsets in lupus nephritis (LN) patients and use machine learning (ML) methods to establish an effective algorithm for predicting co-infection in LN. This study included 111 non-infected LN patients, 72 infected LN patients, and 206 healthy controls (HCs). Patient information, infection characteristics, medication, and laboratory indexes were recorded. Eight ML methods were compared to establish a model through a training group and verify the results in a test group. We trained the ML models, including Logistic Regression, Decision Tree, K-Nearest Neighbors, Support Vector Machine, Multi-Layer Perceptron, Random Forest, Ada boost, Extreme Gradient Boosting (XGB), and further evaluated potential predictors of infection. Infected LN patients had significantly decreased levels of T, B, helper T, suppressor T, and natural killer cells compared to non-infected LN patients and HCs. The number of regulatory T cells (Tregs) in LN patients was significantly lower than in HCs, with infected patients having the lowest Tregs count. Among the ML algorithms, XGB demonstrated the highest accuracy and precision for predicting LN infections. The innate and adaptive immune systems are disrupted in LN patients, and monitoring lymphocyte subsets can help prevent and treat infections. The XGB algorithm was recommended for predicting co-infection in LN.

Establishment and assessment of mortality risk prediction model in patients with sepsis based on early-stage peripheral lymphocyte subsets.

This study is aimed to explore the value of lymphocyte subsets in evaluating the severity and prognosis of sepsis. The counts of lymphocytes, CD3+ T cells, CD4+ T cells, CD8+ T cells, CD19+ B cells, and NK cells significantly decreased between day 1 and day 3 in both the survivor and the non-survivor groups. The peripheral lymphocyte subsets (PLS) at day 1 were not significantly different between the survivor and the non-survivor groups. However, at day 3, the counts of lymphocytes, CD3+ T cells, CD4+ T cells, and NK cells were remarkably lower in the non-survivor group. No significant differences in CD8+ T cells, or CD19+ B cells were observed. The PLS index was independently and significantly associated with the 28-day mortality risk in septic patients (OR: 3.08, 95% CI: 1.18-9.67). Based on these clinical parameters and the PLS index, we developed a nomograph for evaluating the individual mortality risk in sepsis. The area under the curve of prediction with the PLS index was significantly higher than that from the model with only clinical parameters (0.912 vs. 0.817). Our study suggests that the decline of PLS occurred in the early stage of sepsis. The new novel PLS index can be an independent predictor of 28-day mortality in septic patients. The prediction model based on clinical parameters and the PLS index has relatively high predicting ability.

Male patients with primary Sjögren's syndrome have unique clinical manifestations and circulating lymphocyte profiles.

OBJECTIVES: We aimed to explore the relationship between clinical characteristics and circulating lymphocyte profiles in Chinese male patients with primary Sjögren's syndrome (pSS). METHOD: Data from 397 patients with pSS were analyzed retrospectively. 37 were male, which is a prevalence of 9.3%. The clinical, laboratory, and immunophenotypic profiles of peripheral blood lymphocyte subsets were compared between male and female pSS patients. RESULTS: Male patients with primary Sjögren's syndrome have unique clinical manifestations and circulating lymphocyte profiles. Male patients complained more about xerophthalmia and presented with more extra-glandular manifestations as compared with female patients. The CD4+/CD8+ ratio (P = 0.030), the prevalence of CD4-CD8- T cells in lymphocytes (P = 0.020), the absolute number of CD4-CD8- T cells (P = 0.035), the prevalence of CD4+ T cells in lymphocytes (P < 0.001), and the absolute number of CD4+ T cells (P = 0.023) were significantly lower in male patients compared to female patients. On the other hand, the prevalence of CD8+CD28+ T cells (P = 0.030) and CD4+CD25high T cells (P = 0.040) in lymphocytes was significantly higher in male patients than in female patients. Moreover, compared to females with pSS, an elevated serum IgG level, low C3 and C4 levels, anti-SSB positivity, and ANA titers of ≥ 1:160 positivity were more frequent in male with pSS. CONCLUSIONS: Male patients with pSS have distinctive peripheral blood lymphocyte subpopulations, present with more severe clinical symptoms and immunological features, and have an unfavorable prognosis. Key Points • Male patients with pSS have more severe clinical symptoms and specific characteristics of peripheral blood lymphocyte subsets. • Male pSS patients exhibit a higher intensity of the disease (as evaluated by ESSDAI). • Male patients with pSS require individualized treatment regimens and closer follow-up.

Group 1 ILCs: Heterogeneity, plasticity, and transcriptional regulation.

Group 1 innate lymphoid cells (ILCs), comprising ILC1s and natural killer cells (NK cells), belong to a large family of developmentally related innate lymphoid cells that lack rearranged antigen-specific receptors. NK cells and ILC1s both require the transcription factor T-bet for lineage commitment but additionally rely on Eomes and Hobit, respectively, for their development and effector maturation programs. Both ILC1s and NK cells are essential for rapid responses against infections and mediate cancer immunity through production of effector cytokines and cytotoxicity mediators. ILC1s are enriched in tissues and hence generally considered tissue resident cells whereas NK cells are often considered circulatory. Despite being deemed different cell types, ILC1s and NK cells share many common features both phenotypically and functionally. Recent studies employing single cell RNA sequencing (scRNA-seq) technology have exposed previously unappreciated heterogeneity in group 1 ILCs and further broaden our understanding of these cells. Findings from these studies imply that ILC1s in different tissues and organs share a common signature but exhibit some unique characteristics, possibly stemming from tissue imprinting. Also, data from recent fate mapping studies employing Hobit, RORγt, and polychromic reporter mice have greatly advanced our understanding of the developmental and effector maturation programs of these cells. In this review, we aim to outline the fundamental traits of mouse group 1 ILCs and explore recent discoveries related to their developmental programs, phenotypic heterogeneity, plasticity, and transcriptional regulation.

Long-term lymphocyte subset number reconstitution is unique but comparable between umbilical cord blood and unrelated bone marrow transplantation.

The number of umbilical cord blood transplantation (U-CBT) procedures has been growing annually, but little research has been done on long-term immune recovery after U-CBT. Infection risk is high in U-CBT recipients, and this can be partially attributed to immature immunocompetent cells in umbilical cord blood. In this study, we analyzed lymphocyte subset (LST) number to determine the long-term recovery timeline. We included 36 U-CBT and 10 unrelated bone marrow transplantation (U-BMT) recipients who survived more than 2 years after transplantation, and followed them for up to 10 years post-transplant. Recovery kinetics in the early phase post-transplant was different for each LST. Recovery of CD19+ B cells was faster after U-CBT than after U-BMT in the first 5 years after transplantation. Although CD4+ T cells increased in the first several months after U-CBT, long-term cell count recovery was impaired in approximately 20% of patients. Thus, although the LST recovery pattern after U-CBT was unique, LST number recovery was statistically comparable between U-CBT and U-BMT past 5 years post-transplantation.

Disease pathogenesis and barrier functions regulated by group 3 innate lymphoid cells.

The mucosal surface is in constant contact with foreign antigens and is regulated by unique mechanisms that are different from immune responses in the peripheral organs. For the last several decades, only adaptive immune cells such as helper T (Th) cells, Th1, Th2, or Th17 were targeted to study a wide variety of immune responses in the mucosal tissues. However, since their discovery, innate lymphoid cells (ILCs) have been attracting attention as a unique subset of immune cells that provide border defense with various functions and tissue specificity. ILCs are classified into different groups based on cell differentiation and functions. Group 3 innate lymphoid cells (ILC3s) are particularly in close proximity to mucosal surfaces and therefore have the opportunity to be exposed to a variety of bacteria including pathogenic bacteria. In recent years, studies have also provided much evidence that ILC3s contribute to disease pathogenesis as well as the defense of mucosal surfaces by rapidly responding to pathogens and coordinating other immune cells. As the counterpart of helper T cells, ILC3s together with other ILC subsets establish the immune balance between adaptive and innate immunity in protecting us from invasion or encounter with non-self-antigens for maintaining a complex homeostasis. In this review, we summarize recent advances in our understanding of ILCs, with a particular focus on the function of ILC3s in their involvement in bacterial infection and disease pathogenesis.

An automatic analysis and quality assurance method for lymphocyte subset identification.

OBJECTIVES: Lymphocyte subsets are the predictors of disease diagnosis, treatment, and prognosis. Determination of lymphocyte subsets is usually carried out by flow cytometry. Despite recent advances in flow cytometry analysis, most flow cytometry data can be challenging with manual gating, which is labor-intensive, time-consuming, and error-prone. This study aimed to develop an automated method to identify lymphocyte subsets. METHODS: We propose a knowledge-driven combined with data-driven method which can gate automatically to achieve subset identification. To improve accuracy and stability, we have implemented a Loop Adjustment Gating to optimize the gating result of the lymphocyte population. Furthermore, we have incorporated an anomaly detection mechanism to issue warnings for samples that might not have been successfully analyzed, ensuring the quality of the results. RESULTS: The evaluation showed a 99.2 % correlation between our method results and manual analysis with a dataset of 2,000 individual cases from lymphocyte subset assays. Our proposed method attained 97.7 % accuracy for all cases and 100 % for the high-confidence cases. With our automated method, 99.1 % of manual labor can be saved when reviewing only the low-confidence cases, while the average turnaround time required is only 29 s, reducing by 83.7 %. CONCLUSIONS: Our proposed method can achieve high accuracy in flow cytometry data from lymphocyte subset assays. Additionally, it can save manual labor and reduce the turnaround time, making it have the potential for application in the laboratory.

Prior SARS-CoV-2 Infection Enhances Initial mRNA Vaccine Response with a Lower Impact on Long-Term Immunity.

Spike-encoding mRNA vaccines in early 2021 effectively reduced SARS-CoV-2-associated morbidity and mortality. New booster regimens were introduced due to successive waves of distinct viral variants. Therefore, people now have a diverse immune memory resulting from multiple SARS-CoV-2 Ag exposures, from infection to following vaccination. This level of community-wide immunity can induce immunological protection from SARS-CoV-2; however, questions about the trajectory of the adaptive immune responses and long-term immunity with respect to priming and repeated Ag exposure remain poorly explored. In this study, we examined the trajectory of adaptive immune responses following three doses of monovalent Pfizer BNT162b2 mRNA vaccination in immunologically naive and SARS-CoV-2 preimmune individuals without the occurrence of breakthrough infection. The IgG, B cell, and T cell Spike-specific responses were assessed in human blood samples collected at six time points between a moment before vaccination and up to 6 mo after the third immunization. Overall, the impact of repeated Spike exposures had a lower improvement on T cell frequency and longevity compared with IgG responses. Natural infection shaped the responses following the initial vaccination by significantly increasing neutralizing Abs and specific CD4+ T cell subsets (circulating T follicular helper, effector memory, and Th1-producing cells), but it had a small benefit at long-term immunity. At the end of the three-dose vaccination regimen, both SARS-CoV-2-naive and preimmune individuals had similar immune memory quality and quantity. This study provides insights into the durability of mRNA vaccine-induced immunological memory and the effects of preimmunity on long-term responses.

Altered Fatty Acid Oxidation in Lymphocyte Populations of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a disabling multisystem illness in which individuals are plagued with fatigue, inflammatory symptoms, cognitive dysfunction, and the hallmark symptom, post-exertional malaise. While the cause of this disease remains unknown, there is evidence of a potential infectious component that, along with patient symptoms and common onsets of the disease, implicates immune system dysfunction. To further our understanding of the state of ME/CFS lymphocytes, we characterized the role of fatty acids in isolated Natural Killer cells, CD4+ T cells, and CD8+ T cells in circulation and after overnight stimulation, through implicit perturbations to fatty acid oxidation. We examined samples obtained from at least 8 and as many as 20 subjects for immune cell fatty acid characterization in a variety of experiments and found that all three isolated cell types increased their utilization of lipids and levels of pertinent proteins involved in this metabolic pathway in ME/CFS samples, particularly during higher energy demands and activation. In T cells, we characterized the cell populations contributing to these metabolic shifts, which included CD4+ memory cells, CD4+ effector cells, CD8+ naïve cells, and CD8+ memory cells. We also discovered that patients with ME/CFS and healthy control samples had significant correlations between measurements of CD4+ T cell fatty acid metabolism and demographic data. These findings provide support for metabolic dysfunction in ME/CFS immune cells. We further hypothesize about the consequences that these altered fuel dependencies may have on T and NK cell effector function, which may shed light on the illness's mechanism of action.

Clinical utility of immune function based on IFN-γ monitoring of lymphocyte subsets for parvovirus B19 infection in renal recipients.

BACKGROUND: There should be a heightened index of suspicion for Parvovirus B19 (PVB19)-related anemia in organ transplant recipients. Thus far, there is no consensus or recommendation for clinical routine monitoring methods of PVB19 recipients to allow tailoring of immunosuppression. METHODS: We conducted a retrospective study to evaluate the utility of the function (represented by the abilities to secrete IFN-γ) and numbers of lymphocyte subsets in monitoring PVB19 infections in renal recipients posttransplant. The enrolled 109 patients were split into 2 groups according to whether the recipients had an occurrence of PVB19 infection: 37 (33.94%) recipients developed PVB19 infection and 72 (66.06%) immune-stable recipients. RESULTS: The PVB19 infected group had significantly lower absolute counts and functions of different lymphocyte subsets compared with immune-stable recipients. We showed that the frequencies of IFN-γ + CD4 + T cells, IFN-γ + CD8 + T cells, and IFN-γ + NK cells increased markedly after treatment when compared to the occurrence in patients with timepoint before therapy, especially the percentages of IFN-γ + CD4 + T cells were significantly higher. Receiver operating characteristic (ROC) analysis showed that the optimal infection indicator was IFN-γ + NK cells frequency, with an auROC curve of 0.925. Concomitantly, Cox regression analysis indicated that the post-therapy increasing level of IFN-γ secreting function was significantly predictive of recurrent infections (P < 0.001). CONCLUSIONS: We recommend prospective risk stratification for the high-risk population at risk of early-onset PVB19 infection and its recurrence involves screening strategies of immune-based surveillance with the sensitive IFN-γ + secreting monitoring for antiviral prophylaxis and preemptive therapy goal. Clinical Trial Notation: clinical trial registration number: chiCTR-ROC-17010756.

SARS-CoV-2 Immunization Orchestrates the Amplification of IFNγ-Producing T Cell and NK Cell Persistence.

A successful vaccination would represent the most efficient means to control the pandemic of Coronavirus Disease-19 (COVID-19) that led to millions of deaths worldwide. Novel mRNA-based vaccines confer protective immunity against SARS-CoV-2, but whether immunity is immediately effective and how long it will remain in recipients are uncertain. We sought to assess the effectiveness of a two-dose regimen since the boosts are often delayed concerning the recommended intervals. Methods: A longitudinal cohort of healthcare workers (HCW, N = 46; 30.4% men; 69.6% women; mean age 36.05 ± 2.2 years) with no SARS-CoV-2 infection as documented by negative polymerase chain reaction was immunophenotyped in PBMC once a week for 4 weeks from the prime immunization (Pfizer mRNA BNT162b2) and had received 2 doses, to study the kinetic response. Results: We identified three risk groups to develop SARS-CoV-2 infection IgG+-based (late responders, R-; early responders, R+; pauci responders, PR). In all receipts, amplification of B cells and NK cells, including IL4-producing B cells and IL4-producing CD8+ T cells, is early stimulated by the vaccine. After the boost, we observed a growing increase of NK cells but a resistance of T cells, IFNγ-producing CD4+T cells, and IFNγ-producing NK cells. Also, hematologic parameters decline until the boost. The positive association of IFNγ-producing NK with IFNγ-producing CD4+T cells by the multiple mixed-effect model, adjusted for confounders (p = 0.036) as well as the correlation matrix (r = 0.6, p < 0.01), suggests a relationship between these two subsets of lymphocytes. Conclusions: These findings introduce several concerns about policy delay in vaccination: based on immunological protection, B cells and the persistent increase of NK cells during 2 doses of the mRNA-based vaccine could provide further immune protection against the virus, while CD8+ T cells increased slightly only in the R+ and PR groups.

Interferon gamma constrains type 2 lymphocyte niche boundaries during mixed inflammation.

Allergic immunity is orchestrated by group 2 innate lymphoid cells (ILC2s) and type 2 helper T (Th2) cells prominently arrayed at epithelial- and microbial-rich barriers. However, ILC2s and Th2 cells are also present in fibroblast-rich niches within the adventitial layer of larger vessels and similar boundary structures in sterile deep tissues, and it remains unclear whether they undergo dynamic repositioning during immune perturbations. Here, we used thick-section quantitative imaging to show that allergic inflammation drives invasion of lung and liver non-adventitial parenchyma by ILC2s and Th2 cells. However, during concurrent type 1 and type 2 mixed inflammation, IFNγ from broadly distributed type 1 lymphocytes directly blocked both ILC2 parenchymal trafficking and subsequent cell survival. ILC2 and Th2 cell confinement to adventitia limited mortality by the type 1 pathogen Listeria monocytogenes. Our results suggest that the topography of tissue lymphocyte subsets is tightly regulated to promote appropriately timed and balanced immunity.