Neutralizing antibody levels detected early after mRNA-based vaccination do not predict by themselves subsequent breakthrough infections of SARS-CoV-2.

The development of mRNA vaccines represented a significant achievement in response to the global health crisis during the SARS-CoV-2 pandemic. Evaluating vaccine efficacy entails identifying different anti-SARS-CoV-2 antibodies, such as total antibodies against the Receptor Binding Domain (RBD) of the S-protein, or neutralizing antibodies (NAbs). This study utilized an innovative PETIA-based kit to measure NAb, and the investigation aimed to assess whether levels of anti-RBD IgG and NAb uniformly measured 30 days after vaccination could predict individuals at a higher risk of subsequent infection in the months following vaccination. Among a cohort of healthy vaccinated healthcare workers larger than 6,000, 12 mRNA-1273- and 115 BNT162b2-vaccinated individuals contracted infections after the first two doses. The main finding is that neither anti-RBD IgG nor NAb levels measured at day 30 post-vaccination can be used as predictors of breakthrough infections (BI). Therefore, the levels of anti-SARS-CoV-2 antibodies detected shortly after vaccination are not the pivotal factors involved in antiviral protection, and other characteristics must be considered in understanding protection against infection. Furthermore, the levels of anti-RBD and NAbs followed a very similar pattern, with a correlation coefficient of r = 0.96. This robust correlation would justify ceasing the quantification of NAbs, as the information provided by both determinations is highly similar. This optimization would help allocate resources more efficiently and speed up the determination of individuals' humoral immunity status.

Digital PCR Improves Sensitivity and Quantification in Monitoring CAR-T Cells in B Cell Lymphoma Patients.

Chimeric antigen receptor T cells (CAR-T) has emerged as a promising therapy, over 60% of patients fail to sustain a long-term response. The underlying factors that leads to the effectiveness of this therapy are not completely understood, CAR-T cell persistence and monitoring seems to be pivotal for ensuring a successful response. Various monitoring methods such as multiparametric flow cytometry (MFC) or quantitative PCR (qPCR) have been applied. Our objective is to develop digital PCR (dPCR) assays for detection and quantification of CAR-T cells, comparing them with MFC and qPCR. Samples taken at different follow-up times from 45 patients treated with CAR-T therapy were analyzed to assess the correlation between the different methodologies. dPCR presented a high correlation with MFC and qPCR (r = 0.97 and r = 0.87, respectively), while offering a higher sensitivity (0.01%) compared to MFC (0.1%) and qPCR (1%). dPCR emerged as an alternative and highly sensitivity method for monitoring CAR-T cell dynamics. This technique is well-suited for implementation in clinical practice as a complementary technique to MFC.

First-in-human therapy with Treg produced from thymic tissue (thyTreg) in a heart transplant infant.

Due to their suppressive capacity, regulatory T cells (Tregs) have attracted growing interest as an adoptive cellular therapy for the prevention of allograft rejection, but limited Treg recovery and lower quality of adult-derived Tregs could represent an obstacle to success. To address this challenge, we developed a new approach that provides large quantities of Tregs with high purity and excellent features, sourced from thymic tissue routinely removed during pediatric cardiac surgeries (thyTregs). We report on a 2-year follow-up of the first patient treated worldwide with thyTregs, included in a phase I/II clinical trial evaluating the administration of autologous thyTreg in infants undergoing heart transplantation. In addition to observing no adverse effects that could be attributed to thyTreg administration, we report that the Treg frequency in the periphery was preserved during the 2-year follow-up period. These initial results are consistent with the trial objective, which is to confirm safety of the autologous thyTreg administration and its capacity to restore the Treg pool.

Multidimensional analysis of immune cells from COVID-19 patients identified cell subsets associated with the severity at hospital admission.

BACKGROUND: SARS-CoV-2 emerged as a new coronavirus causing COVID-19, and it has been responsible for more than 760 million cases and 6.8 million deaths worldwide until March 2023. Although infected individuals could be asymptomatic, other patients presented heterogeneity and a wide range of symptoms. Therefore, identifying those infected individuals and being able to classify them according to their expected severity could help target health efforts more effectively. METHODOLOGY/PRINCIPAL FINDINGS: Therefore, we wanted to develop a machine learning model to predict those who will develop severe disease at the moment of hospital admission. We recruited 75 individuals and analysed innate and adaptive immune system subsets by flow cytometry. Also, we collected clinical and biochemical information. The objective of the study was to leverage machine learning techniques to identify clinical features associated with disease severity progression. Additionally, the study sought to elucidate the specific cellular subsets involved in the disease following the onset of symptoms. Among the several machine learning models tested, we found that the Elastic Net model was the better to predict the severity score according to a modified WHO classification. This model was able to predict the severity score of 72 out of 75 individuals. Besides, all the machine learning models revealed that CD38+ Treg and CD16+ CD56neg HLA-DR+ NK cells were highly correlated with the severity. CONCLUSIONS/SIGNIFICANCE: The Elastic Net model could stratify the uninfected individuals and the COVID-19 patients from asymptomatic to severe COVID-19 patients. On the other hand, these cellular subsets presented here could help to understand better the induction and progression of the symptoms in COVID-19 individuals.

IgG anti-RBD levels during 8-month follow-up post-vaccination with BNT162b2 and mRNA-1273 vaccines in healthcare workers: A one-center study.

Introduction: Since the COVID-19 outbreak, specific mRNA-based anti-SARS-CoV-2 vaccines have been developed and distributed worldwide. Because this is the first time that mRNA vaccines have been used, there are several questions regarding their capacity to confer immunity and the durability of the specific anti-SARS-CoV-2 response. Therefore, the objective of this study was to recruit a large cohort of healthcare workers from the Gregorio Marañón Hospital vaccinated with the mRNA-1273 or BNT126b2 vaccines and to follow-up on IgG anti-RBD levels at 8 months post-vaccination. Methods: We recruited 4,970 volunteers and measured IgG anti-RBD antibodies on days 30 and 240 post-vaccination. Results: We observed that both vaccines induced high levels of antibodies on day 30, while a drastic wane was observed on day 240, where mRNA-1273 vaccinated induced higher levels than BNT162b2. Stratifying by vaccine type, age, gender, and comorbidities, we identified that older mRNA-1273-vaccinated volunteers had higher antibody levels than the younger volunteers, contrary to what was observed in the BNT162b2-vaccinated volunteers. Discussion: In conclusion, we observed that mRNA-1273 has a higher capacity to induce a humoral response than BNT162b2 and that age is a factor in the specific response.

Cellular and Humoral Responses Follow-up for 8 Months after Vaccination with mRNA-Based Anti-SARS-CoV-2 Vaccines.

Vaccination against SARS-CoV-2 has become the main method of reducing mortality and severity of COVID-19. This work aims to study the evolution of the cellular and humoral responses conferred by two mRNA vaccines after two doses against SARS-CoV-2. On days 30 and 240 after the second dose of both vaccines, the anti-S antibodies in plasma were evaluated from 82 volunteers vaccinated with BNT162b2 and 68 vaccinated with mRNA-1273. Peripheral blood was stimulated with peptides encompassing the entire SARS-CoV-2 Spike sequence. IgG Anti-S antibodies (humoral) were quantified on plasma, and inflammatory cytokines (cellular) were measured after stimulation. We observed a higher response (both humoral and cellular) with the mRNA-1273 vaccine. Stratifying by age and gender, differences between vaccines were observed, especially in women under 48 and men over 48 years old. Therefore, this work could help to set up a vaccination strategy that could be applied to confer maximum immunity.

A Novel GMP Protocol to Produce High-Quality Treg Cells From the Pediatric Thymic Tissue to Be Employed as Cellular Therapy.

Due to their suppressive capacity, the adoptive transfer of regulatory T cells (Treg) has acquired a growing interest in controlling exacerbated inflammatory responses. Limited Treg recovery and reduced quality remain the main obstacles in most current protocols where differentiated Treg are obtained from adult peripheral blood. An alternate Treg source is umbilical cord blood, a promising source of Treg cells due to the higher frequency of naïve Treg and lower frequency of memory T cells present in the fetus' blood. However, the Treg number isolated from cord blood remains limiting. Human thymuses routinely discarded during pediatric cardiac surgeries to access the retrosternal operative field has been recently proposed as a novel source of Treg for cellular therapy. This strategy overcomes the main limitations of current Treg sources, allowing the obtention of very high numbers of undifferentiated Treg. We have developed a novel good manufacturing practice (GMP) protocol to obtain large Treg amounts, with very high purity and suppressive capacity, from the pediatric thymus (named hereafter thyTreg). The total amount of thyTreg obtained at the end of the procedure, after a short-term culture of 7 days, reach an average of 1,757 x106 (range 50 x 106 - 13,649 x 106) cells from a single thymus. The thyTreg product obtained with our protocol shows very high viability (mean 93.25%; range 83.35% - 97.97%), very high purity (mean 92.89%; range 70.10% - 98.41% of CD25+FOXP3+ cells), stability under proinflammatory conditions and a very high suppressive capacity (inhibiting in more than 75% the proliferation of activated CD4+ and CD8+ T cells in vitro at a thyTreg:responder cells ratio of 1:1). Our thyTreg product has been approved by the Spanish Drug Agency (AEMPS) to be administered as cell therapy. We are recruiting patients in the first-in-human phase I/II clinical trial worldwide that evaluates the safety, feasibility, and efficacy of autologous thyTreg administration in children undergoing heart transplantation (NCT04924491). The high quality and amount of thyTreg and the differential features of the final product obtained with our protocol allow preparing hundreds of doses from a single thymus with improved therapeutic properties, which can be cryopreserved and could open the possibility of an "off-the-shelf" allogeneic use in another individual.

A New Generation of Cell Therapies Employing Regulatory T Cells (Treg) to Induce Immune Tolerance in Pediatric Transplantation.

Kidney transplantation is the most common solid organ transplant and the preferred treatment for pediatric patients with end-stage renal disease, but it is still not a definitive solution due to immune graft rejection. Regulatory T cells (Treg) and their control over effector T cells is a crucial and intrinsic tolerance mechanism in limiting excessive immune responses. In the case of transplants, Treg are important for the survival of the transplanted organ, and their dysregulation could increase the risk of rejection in transplanted children. Chronic immunosuppression to prevent rejection, for which Treg are especially sensitive, have a detrimental effect on Treg counts, decreasing the Treg/T-effector balance. Cell therapy with Treg cells is a promising approach to restore this imbalance, promoting tolerance and thus increasing graft survival. However, the strategies used to date that employ peripheral blood as a Treg source have shown limited efficacy. Moreover, it is not possible to use this approach in pediatric patients due to the limited volume of blood that can be extracted from children. Here, we outline our innovative strategy that employs the thymus removed during pediatric cardiac surgeries as a source of therapeutic Treg that could make this therapy accessible to transplanted children. The advantageous properties and the massive amount of Treg cells obtained from pediatric thymic tissue (thyTreg) opens a new possibility for Treg therapies to prevent rejection in pediatric kidney transplants. We are recruiting patients in a clinical trial to prevent rejection in heart-transplanted children through the infusion of autologous thyTreg cells (NCT04924491). If its efficacy is confirmed, thyTreg therapy may establish a new paradigm in preventing organ rejection in pediatric transplants, and their allogeneic use would extend its application to other solid organ transplantation.

Hemophagocytic lymphohistiocytosis/macrophage activation syndrome (HLH/MAS) following treatment with tisagenlecleucel.

Chimeric antigen receptor (CAR) T cell-related HLH/MAS is an unusual manifestation of severe cytokine release syndrome (CRS) with poor prognosis and a challenging diagnosis. The establishment of specific diagnosis criteria is essential, and the combination of several techniques for CAR T-cell follow-up, allows a more precise management of this complication.

ABO blood group is involved in the quality of the specific immune response anti-SARS-CoV-2.

Since December 2019, the coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread throughout the world. To eradicate it, it is crucial to acquire a strong and long-lasting anti-SARS-CoV-2 immunity, by either natural infection or vaccination. We collected blood samples 12-305 days after positive polymerase chain reactions (PCRs) from 35 recovered individuals infected by SARS-CoV-2. Peripheral blood mononuclear cells were stimulated with SARS-CoV-2-derived peptide pools, such as the spike (S), nucleocapsid (N) and membrane (M) proteins, and we quantified anti-S immunoglobulins in plasma. After 10 months post-infection, we observed a sustained SARS-CoV-2-specific CD4+ T-cell response directed against M-protein, but responses against S- or N-proteins were lost over time. Besides, we demonstrated that O-group individuals presented significantly lower frequencies of specific CD4+ T-cell responses against Pep-M than non O-group individuals. The non O-group subjects also needed longer to clear the virus, and they lost cellular immune responses over time, compared to the O-group individuals, who showed a persistent specific immune response against SARS-CoV-2. Therefore, the S-specific immune response was lost over time, and individual factors might determine the sustainability of the body's defenses, which must be considered in the future design of vaccines to achieve continuous anti-SARS-CoV-2 immunity.

Induction of High Levels of Specific Humoral and Cellular Responses to SARS-CoV-2 After the Administration of Covid-19 mRNA Vaccines Requires Several Days.

Objectives: In the context of the Covid-19 pandemic, the fast development of vaccines with efficacy of around 95% preventing Covid-19 illness provides a unique opportunity to reduce the mortality associated with the pandemic. However, in the absence of efficacious prophylactic medications and few treatments for this infection, the induction of a fast and robust protective immunity is required for effective disease control, not only to prevent the disease but also the infection and shedding/transmission. The objective of our study was to analyze the level of specific humoral and cellular T-cell responses against the spike protein of SARS-CoV-2 induced by two mRNA-based vaccines (BNT162b2 and mRNA-1273), but also how long it takes after vaccination to induce these protective humoral and cellular immune responses. Methods: We studied in 40 healthy (not previously infected) volunteers vaccinated with BNT162b2 or mRNA-1273 vaccines the presence of spike-specific IgG antibodies and SARS-CoV-2-specific T cells at 3, 7 and 14 days after receiving the second dose of the vaccine. The specific T-cell response was analyzed stimulating fresh whole blood from vaccinated volunteers with SARS-CoV-2 peptides and measuring the release of cytokines secreted by T cells in response to SARS-CoV-2 stimulation. Results: Our results indicate that the immunization capacity of both vaccines is comparable. However, although both BNT162b2 and mRNA-1273 vaccines can induce early B-cell and T-cell responses, these vaccine-mediated immune responses do not reach their maximum values until 14 days after completing the vaccination schedule. Conclusion: This refractory period in the induction of specific immunity observed after completing the vaccination could constitute a window of higher infection risk, which could explain some emerging cases of SARS-CoV-2 infection in vaccinated people.

Differential effects of the second SARS-CoV-2 mRNA vaccine dose on T cell immunity in naive and COVID-19 recovered individuals.

The rapid development of mRNA-based vaccines against the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) led to the design of accelerated vaccination schedules that have been extremely effective in naive individuals. While a two-dose immunization regimen with the BNT162b2 vaccine has been demonstrated to provide a 95% efficacy in naive individuals, the effects of the second vaccine dose in individuals who have previously recovered from natural SARS-CoV-2 infection has not been investigated in detail. In this study, we characterize SARS-CoV-2 spike-specific humoral and cellular immunity in naive and previously infected individuals during and after two doses of BNT162b2 vaccination. Our results demonstrate that, while the second dose increases both the humoral and cellular immunity in naive individuals, COVID-19 recovered individuals reach their peak of immunity after the first dose. These results suggests that a second dose, according to the current standard regimen of vaccination, may be not necessary in individuals previously infected with SARS-CoV-2.

The Presence of a Marked Imbalance Between Regulatory T Cells and Effector T Cells Reveals That Tolerance Mechanisms Could Be Compromised in Heart Transplant Children.

Regulatory T cells (Treg) are crucial for the induction and maintenance of graft tolerance. In pediatric heart transplant procedures, the thymus is routinely excised, removing the primary source of T-cell replenishment. Consequently, thymectomy joined to the effects of immunosuppression on the T-cell compartment may have a detrimental impact on Treg values, compromising the intrinsic tolerance mechanisms and the protective role of Treg preventing graft rejection in heart transplant children. METHODS: A prospective study including 7 heart transplant children was performed, and immune cell populations were evaluated periodically in fresh peripheral blood at different time points before and up to 3 y posttransplant. RESULTS: Treg counts decreased significantly from the seventh-month posttransplant. Furthermore, there was a significant increase in effector memory and terminally differentiated effector memory T cells coinciding with the fall of Treg counts. The Treg/Teffector ratio, a valuable marker of the tolerance/rejection balance, reached values around 90% lower than pretransplant values. Additionally, a negative correlation between Treg count and T effector frequency was observed. Particularly, when Treg count decreases below 50 or 75 cells/µL in the patients, the increase in the frequency of T effector CD4+ and CD8+, respectively, experiences a tipping point, and the proportion of T-effector cells increases dramatically. CONCLUSIONS: These results reveal that interventions employed in pediatric heart transplantation (immunosuppression and thymectomy) could induce, as an inevitable consequence, a dysregulation in the immunologic status characterized by a marked imbalance between Treg and T effector, which could jeopardize the preservation of tolerance during the period with the higher incidence of acute rejection.

Ectopic FOXP3 Expression in Combination with TGF-ß1 and IL-2 Stimulation Generates Limited Suppressive Function in Human Primary Activated Thymocytes Ex Vivo.

Regulatory T cells (Tregs), which are characterized by the expression of the transcription factor forkhead box P3 (FOXP3), are the main immune cells that induce tolerance and are regulators of immune homeostasis. Natural Treg cells (nTregs), described as CD4+CD25+FOXP3+, are generated in the thymus via activation and cytokine signaling. Transforming growth factor beta type 1 (TGF-ß1) is pivotal to the generation of the nTreg lineage, its maintenance in the thymus, and to generating induced Treg cells (iTregs) in the periphery or in vitro arising from conventional T cells (Tconvs). Here, we tested whether TGF-ß1 treatment, associated with interleukin-2 (IL-2) and CD3/CD28 stimulation, could generate functional Treg-like cells from human thymocytes in vitro, as it does from Tconvs. Additionally, we genetically manipulated the cells for ectopic FOXP3 expression, along with the TGF-ß1 treatment. We demonstrated that TGF-ß1 and ectopic FOXP3, combined with IL-2 and through CD3/CD28 activation, transformed human thymocytes into cells that expressed high levels of Treg-associated markers. However, these cells also presented a lack of homogeneous suppressive function and an unstable proinflammatory cytokine profile. Therefore, thymocyte-derived cells, activated with the same stimuli as Tconvs, were not an appropriate alternative for inducing cells with a Treg-like phenotype and function.

Basiliximab impairs regulatory T cell (TREG) function and could affect the short-term graft acceptance in children with heart transplantation.

CD25, the alpha chain of the IL-2 receptor, is expressed on activated effector T cells that mediate immune graft damage. Induction immunosuppression is commonly used in solid organ transplantation and can include antibodies blocking CD25. However, regulatory T cells (Tregs) also rely on CD25 for their proliferation, survival, and regulatory function. Therefore, CD25-blockade may compromise Treg protective role against rejection. We analysed in vitro the effect of basiliximab (BXM) on the viability, phenotype, proliferation and cytokine production of Treg cells. We also evaluated in vivo the effect of BXM on Treg in thymectomized heart transplant children receiving BXM in comparison to patients not receiving induction therapy. Our results show that BXM reduces Treg counts and function in vitro by affecting their proliferation, Foxp3 expression, and IL-10 secretion capacity. In pediatric heart-transplant patients, we observed decreased Treg counts and a diminished Treg/Teff ratio in BXM-treated patients up to 6-month after treatment, recovering baseline values at the end of the 12-month follow up period. These results reveal that the use of BXM could produce detrimental effects on Tregs, and support the evidence suggesting that BXM induction could impair the protective role of Tregs in the period of highest incidence of acute graft rejection.

Comprehensive Flow Cytometry Profiling of the Immune System in COVID-19 Convalescent Individuals.

SARS-CoV-2 has infected more than 200 million people worldwide, with more than 4 million associated deaths. Although more than 80% of infected people develop asymptomatic or mild COVID-19, SARS-CoV-2 can induce a profound dysregulation of the immune system. Therefore, it is important to investigate whether clinically recovered individuals present immune sequelae. The potential presence of a long-term dysregulation of the immune system could constitute a risk factor for re-infection and the development of other pathologies. Here, we performed a deep analysis of the immune system in 35 COVID-19 recovered individuals previously infected with SARS-CoV-2 compared to 16 healthy donors, by flow cytometry. Samples from COVID-19 individuals were analysed from 12 days to 305 days post-infection. We observed that, 10 months post-infection, recovered COVID-19 patients presented alterations in the values of some T-cell, B-cell, and innate cell subsets compared to healthy controls. Moreover, we found in recovered COVID-19 individuals increased levels of circulating follicular helper type 1 (cTfh1), plasmablast/plasma cells, and follicular dendritic cells (foDC), which could indicate that the Tfh-B-foDC axis might be functional to produce specific immunoglobulins 10 months post-infection. The presence of this axis and the immune system alterations could constitute prognosis markers and could play an important role in potential re-infection or the presence of long-term symptoms in some individuals.

Analysis of the dysregulation between regulatory B and T cells (Breg and Treg) in human immunodeficiency virus (HIV)-infected patients.

This study examines the relationship between regulatory B (Breg) and T (Treg) compartments, which play crucial roles in the maintenance of immune homeostasis in the context of HIV. Using flow cytometry, the phenotypes of different Breg and Treg subsets from HIV-infected and healthy individuals were analyzed, along with the suppressive capacity of Breg. Peripheral blood samples of thirteen HIV+ treatment-naïve individuals, fourteen treated-HIV+ individuals with undetectable viral load and twelve healthy individuals were analyzed. The absolute counts of Breg and Treg subsets were decreased in HIV+ treatment-naïve individuals in comparison to treated-HIV+ and healthy individuals. Interestingly, correlations between Breg subsets (CD24hiCD27+ and PD-L1+ B cells) and IL-10-producing Breg observed in healthy individuals were lost in HIV+ treatment-naïve individuals. However, a correlation between frequencies of CD24hiCD38hi or TIM-1+-Breg subsets and Treg was observed in HIV+ treatment-naïve individuals and not in healthy individuals. Therefore, we hypothesized that various Breg subsets might have different functions during B and T-cell homeostasis during HIV-1 infection. In parallel, stimulated Breg from HIV-infected treatment-naïve individuals presented a decreased ability to suppress CD4+ T-cell proliferation in comparison to the stimulated Breg from treated-HIV+ or healthy individuals. We demonstrate a dysregulation between Breg and Treg subsets in HIV-infected individuals, which might participate in the hyper-activation and exhaustion of the immune system that occurs in such patients.

Immune dysregulation and Th2 polarization are associated with atopic dermatitis in heart-transplant children: A delicate balance between risk of rejection or atopic symptoms.

Atopic dermatitis (AD) has a high incidence in heart-transplant children, and the reason why there is more AD after transplantation is still unknown. We conducted a cross-sectional study comparing 11 AD and 11 non-AD age-matched heart-transplant children, to assess which immune alterations are related to AD in these patients. AD patients had been transplanted at a younger age compared to non-AD, indicating that age at transplant may be determinant in the onset of AD. The earlier thymectomy in AD heart-transplant children favored the presence of more differentiated phenotypes in the T cell compartment. We observed a clear reduction in the T-helper 1/T-helper 2 (Th1/Th2) ratio in AD children. This Th2 polarization was related to eosinophilia and high immunoglobulin E levels, but also to an impaired regulatory T cell (Treg) suppression, which could be secondary to an exhaustion of the Treg compartment. Interestingly, AD patients were free of rejection episodes (0/11) in comparison to non-AD children (4/11). We propose that a predominant Th2 phenotype may prevent the emergence of Th1 responses associated with graft rejection. A more differentiated Treg phenotype could also play a role in preventing acute rejection in the first year posttransplant. Our findings provide useful insights and knowledge for the better understanding of atopic disorders in transplanted children.

CD72/CD100 and PD-1/PD-L1 markers are increased on T and B cells in HIV-1+ viremic individuals, and CD72/CD100 axis is correlated with T-cell exhaustion.

In our work, we analyzed the role of the CD100/CD72 and PD-1/PD-L1 axes in immune response dysfunction in human immunodeficiency virus (HIV)-1 infection in which high expressions of PD-1 and PD-L1 were associated with an immunosuppressive state via limitation of the HIV-1-specific T-cell responses. CD100 was demonstrated to play a relevant role in immune responses in various pathological processes and may be responsible for immune dysregulation during HIV-1 infection. We investigated the function of CD72/CD100, and PD-1/PDL-1 axes on T and B cells in HIV-infected individuals and in healthy individuals. We analyzed the frequencies and fluorescence intensities of these four markers on CD4+, CD8+ T and B cells. Marker expressions were increased during active HIV-1 infection. CD100 frequency on T cells was positively associated with the expression of PD-1 and PD-L1 on T cells from HIV-infected treatment-naïve individuals. In addition, the frequency of CD72-expressing T cells was associated with interferon gamma (IFN-γ) production in HIV-infected treatment-naïve individuals. Our data suggest that the CD72/CD100 and PD-1/PD-L1 axes may jointly participate in dysregulation of immunity during HIV-1 infection and could partially explain the immune systems' hyper-activation and exhaustion.