The amalgam of naive CD4+ T cell transcriptional states is reconfigured by helminth infection to dampen the amplitude of the immune response.

Naive CD4+ T cells in specific pathogen-free (SPF) mice are characterized by transcriptional heterogeneity and subpopulations distinguished by the expression of quiescence, the extracellular matrix (ECM) and cytoskeleton, type I interferon (IFN-I) response, memory-like, and T cell receptor (TCR) activation genes. We demonstrate that this constitutive heterogeneity, including the presence of the IFN-I response cluster, is commensal independent insofar as being identical in germ-free and SPF mice. By contrast, Nippostrongylus brasiliensis infection altered this constitutive heterogeneity. Naive T cell-intrinsic transcriptional changes acquired during helminth infection correlated with and accounted for decreased immunization response to an unrelated antigen. These compositional and functional changes were dependent variables of helminth infection, as they disappeared at the established time point of its clearance in mice. Collectively, our results indicate that the naive T cell pool is subject to dynamic transcriptional changes in response to certain environmental cues, which in turn permutes the magnitude of the immune response.

Signaling via a CD27-TRAF2-SHP-1 axis during naive T cell activation promotes memory-associated gene regulatory networks.

The interaction of the tumor necrosis factor receptor (TNFR) family member CD27 on naive CD8+ T (Tn) cells with homotrimeric CD70 on antigen-presenting cells (APCs) is necessary for T cell memory fate determination. Here, we examined CD27 signaling during Tn cell activation and differentiation. In conjunction with T cell receptor (TCR) stimulation, ligation of CD27 by a synthetic trimeric CD70 ligand triggered CD27 internalization and degradation, suggesting active regulation of this signaling axis. Internalized CD27 recruited the signaling adaptor TRAF2 and the phosphatase SHP-1, thereby modulating TCR and CD28 signals. CD27-mediated modulation of TCR signals promoted transcription factor circuits that induced memory rather than effector associated gene programs, which are induced by CD28 costimulation. CD27-costimulated chimeric antigen receptor (CAR)-engineered T cells exhibited improved tumor control compared with CD28-costimulated CAR-T cells. Thus, CD27 signaling during Tn cell activation promotes memory properties with relevance to T cell immunotherapy.

Programmed death receptor 1 (PD-1) ligand Fc fusion proteins reduce T-cell proliferation in vitro independently of PD-1.

Programmed death receptor 1 (PD-1) is an inhibitory receptor on T cells shown to restrain T-cell proliferation. PD-1 immune checkpoint blockade has emerged as a highly promising approach in cancer treatment. Much of our understanding of the function of PD-1 is derived from in vitro T-cell activation assays. Here we set out to further investigate how T cells integrate inhibitory signals such as PD-1 in vitro using the PD-1 agonist, PD-1 ligand 1 (PD-L1) fusion protein (PD-L1.Fc), coimmobilized alongside anti-CD3 agonist monoclonal antibody (mAb) on plates to deliver PD-1 signals to wild-type and PD-1-/- CD8+ T cells. Surprisingly, we found that the PD-L1.Fc fusion protein inhibited T-cell proliferation independently of PD-1. This PD-L1.Fc inhibition was observed in the presence and absence of CD28 and interleukin-2 signaling. Binding of PD-L1.Fc was restricted to PD-1-expressing T cells and thus inhibition was not mediated by the interaction of PD-L1.Fc with CD80 or other yet unknown binding partners. Furthermore, a similar PD-1-independent reduction of T-cell proliferation was observed with plate-bound PD-L2.Fc. Hence, our results suggest that the coimmobilization of PD-1 ligand fusion proteins with anti-CD3 mAb leads to a reduction of T-cell engagement with plate-bound anti-CD3 mAb. This study demonstrates a nonspecific mechanism of T-cell inhibition when PD-L1.Fc or PD-L2.Fc fusion proteins are delivered in a plate-bound coimmobilization assay and highlights the importance of careful optimization of assay systems and reagents when interpreting their influence on T-cell proliferation.

CCL21-Ser expression in melanoma cells recruits CCR7+ naïve T cells to tumor tissues and promotes tumor growth.

CCL21-Ser, a chemokine encoded by the Ccl21a gene, is constitutively expressed in the thymic epithelial cells and stromal cells of secondary lymphoid organs. It regulates immune cell migration and survival through its receptor CCR7. Herein, using CCL21-Ser-expressing melanoma cells and the Ccl21a-deficient mice, we demonstrated the functional role of cancer cell-derived CCL21-Ser in melanoma growth in vivo. The B16-F10 tumor growth was significantly decreased in Ccl21a-deficient mice compared with that in wild-type mice, indicating that host-derived CCL21-Ser contributes to melanoma proliferation in vivo. In Ccl21a-deficient mice, tumor growth of melanoma cells expressing CCL21-Ser was significantly enhanced, suggesting that CCL21-Ser from melanoma cells promotes tumor growth in the absence of host-derived CCL21-Ser. The increase in tumor growth was associated with an increase in the CCR7+ CD62L+ T cell frequency in the tumor tissue but was inversely correlated with Treg frequency, suggesting that naïve T cells primarily promote tumor growth. Adoptive transfer experiments demonstrated that naïve T cells are preferentially recruited from the blood into tumors with melanoma cell-derived CCL21-Ser expression. These results suggest that CCL21-Ser from melanoma cells promotes the infiltration of CCR7+ naïve T cells into the tumor tissues and creates a tumor microenvironment favorable for melanoma growth.

SATB1 ensures appropriate transcriptional programs within naïve CD8+ T cells.

Special AT-binding protein 1 (SATB1) is a chromatin-binding protein that has been shown to be a key regulator of T-cell development and CD4+ T-cell fate decisions and function. The underlying function for SATB1 in peripheral CD8+ T-cell differentiation processes is largely unknown. To address this, we examined SATB1-binding patterns in naïve and effector CD8+ T cells demonstrating that SATB1 binds to noncoding regulatory elements linked to T-cell lineage-specific gene programs, particularly in naïve CD8+ T cells. We then assessed SATB1 function using N-ethyl-N-nitrosourea-mutant mice that exhibit a point mutation in the SATB1 DNA-binding domain (termed Satb1m1Anu/m1Anu ). Satb1m1Anu/m1Anu mice exhibit diminished SATB1-binding, naïve, Satb1m1Anu/m1Anu CD8+ T cells exhibiting transcriptional and phenotypic characteristics reminiscent of effector T cells. Upon activation, the transcriptional signatures of Satb1m1Anu/m1Anu and wild-type effector CD8+ T cells converged. While there were no overt differences, primary respiratory infection of Satb1m1Anu/m1Anu mice with influenza A virus (IAV) resulted in a decreased proportion and number of IAV-specific CD8+ effector T cells recruited to the infected lung when compared with wild-type mice. Together, these data suggest that SATB1 has a major role in an appropriate transcriptional state within naïve CD8+ T cells and ensures appropriate CD8+ T-cell effector gene expression upon activation.

Induction of memory-like CD8+ T cells and CD4+ T cells from human naive T cells in culture.

Memory T cells are crucial players in vertebrate adaptive immunity but their development is incompletely understood. Here, we describe a method to produce human memory-like T cells from naive human T cells in culture. Using commercially available human T-cell differentiation kits, both purified naive CD8+ T cells and purified naive CD4+ T cells were activated via T-cell receptor signaling and appropriate cytokines for several days in culture. All the T-cell activators were then removed from the medium and the cultures were continued in hypoxic condition (1% O2 atmosphere) for several more days; during this period, most of the cells died, but some survived in a quiescent state for a month. The survivors had small round cell bodies, expressed differentiation markers characteristic of memory T cells and restarted proliferation when the T-cell activators were added back. We could also induce memory-like T cells from naive human T cells without hypoxia, if we froze the activated T cells or prepared the naive T cells from chilled filter buffy coats.

Reference range of naïve T and T memory lymphocyte subsets in peripheral blood of healthy adult.

Naïve T and T memory cell subsets are closely related to immune response and can provide important information for the diagnosis and treatment of immunological and hematological disorders. Lymphocyte compartment undergoes dramatic changes during adulthood; age-related reference values derived from healthy individuals are crucial. However, extensively detailed reference values of peripheral blood lymphocytes in the whole spectrum of adulthood detected by multi-color flow cytometry on a single platform are rare. Three hundred and nine healthy adult volunteers were recruited from Tianjin in China. The absolute counts and percentages of CD3+CD4+ T cells, CD3+CD8+ T cells, naïve T cells (Tn), T memory stem cells (Tscm), central memory T cells (Tcm), effector memory T cells (Tem), and terminal effector T cells (Tte) were detected by flow cytometry with single platform technologies. Reference range of absolute counts and percentage of T lymphocyte subsets were formulated by different age and gender. The results showed that Tn and Tscm cells, which had stem cell properties, decreased with aging; while, Tcm and Tem increased with aging, which increased from 18 to 64 years old but presented no significant change over the 65 years old. Gender had an influence on the fluctuation of lymphocyte subsets, the absolute count of CD3+CD8+, CD8+Tcm, CD8+Tem in males were higher than those in females. The reference values of percentages and absolute numbers of naïve T and T memory cell subsets can help doctors to understand the immune state of patients and evaluate conditions of prognosis then adjust the treatment for patients. (Chinese Clinic Trial Registry number: ChiCTR-IOR-17014139.).

The role of PD-1/PD-Ls in the pathogenesis of IgG4-related disease.

OBJECTIVE: To investigate the role of programmed cell death protein 1 (PD-1) and its two ligands, PD-L1 and PD-L2, in the pathogenesis of IgG4-related disease (IgG4-RD). METHODS: Patients with IgG4-RD (n = 43) and healthy controls (n = 34) were recruited. Expression levels of PD-1, PD-L1 and PD-L2 in plasma, submandibular gland and T cell subsets were determined by ELISA, immunohistochemistry and flow cytometry. Naïve T cells were stimulated with or without PD-L1/PD-L2 or anti-PD-L1/anti-PD-L2 for 7 days and the proportion of CD4+CD25+ Treg cells was detected by flow cytometry. RESULTS: The expression of PD-1, PD-L1 and PD-L2 in the plasma, submandibular gland and on the surface of Treg cells was increased in IgG4-RD patients. Plasma soluble (s)PD-1 was positively correlated with serum IgG, IgG1, IgG3, IgG4, IgG4-RD responder index and numbers of organs involved, and negatively correlated with serum IgM, IgA, C3 and C4. Plasma sPD-L2 was positively correlated with serum IgG1, and plasma sPD-L1 was positively correlated with sPD-L2 and negatively correlated with C3. Stimulation of PD-L1 but not PD-L2 promoted the differentiation of naïve T cells from IgG4-RD patients into CD4+CD25+ Treg cells. CONCLUSION: Plasma concentrations of sPD-1, sPD-L1 and sPD-L2 were significantly increased in patients with IgG4-RD, and the expression of PD-1 and PD-L2 on Treg cells was upregulated. PD-1-PD-L1 can promote the differentiation of naïve T cells into Treg cells and thus participate in the pathogenesis of IgG4-RD.

Variances in Antiviral Memory T-Cell Repertoire of CD45RA- and CD62L-Depleted Lymphocyte Products Reflect the Need of Individual T-Cell Selection Strategies to Reduce the Risk of GvHD while Preserving Antiviral Immunity in Adoptive T-Cell Therapy.

INTRODUCTION: Viral infections and reactivations still remain a cause of morbidity and mortality after hematopoietic stem cell transplantation due to immunodeficiency and immunosuppression. Transfer of unmanipulated donor-derived lymphocytes (DLI) represents a promising strategy for improving cellular immunity but carries the risk of graft versus host disease (GvHD). Depleting alloreactive naïve T cells (TN) from DLIs was implemented to reduce the risk of GvHD induction while preserving antiviral memory T-cell activity. Here, we compared two TN depletion strategies via CD45RA and CD62L expression and investigated the presence of antiviral memory T cells against human adenovirus (AdV) and Epstein-Barr virus (EBV) in the depleted fractions in relation to their functional and immunophenotypic characteristics. METHODS: T-cell responses against ppEBV_EBNA1, ppEBV_Consensus and ppAdV_Hexon within TN-depleted (CD45RA-/CD62L-) and TN-enriched (CD45RA+/CD62L+) fractions were quantified by interferon-gamma (IFN-γ) ELISpot assay after short- and long-term in vitro stimulation. T-cell frequencies and immunophenotypic composition were assessed in all fractions by flow cytometry. Moreover, alloimmune T-cell responses were evaluated by mixed lymphocyte reaction. RESULTS: According to differences in the phenotype composition, antigen-specific T-cell responses in CD45RA- fraction were up to 2 times higher than those in the CD62L- fraction, with the highest increase (up to 4-fold) observed after 7 days for ppEBV_EBNA1-specific T cells. The CD4+ effector memory T cells (TEM) were mainly responsible for EBV_EBNA1- and AdV_Hexon-specific T-cell responses, whereas the main functionally active T cells against ppEBV_Consensus were CD8+ central memory T cells (TCM) and TEM. Moreover, comparison of both depletion strategies indicated that alloreactivity in CD45RA- was lower than that in CD62L- fraction. CONCLUSION: Taken together, our results indicate that CD45RA depletion is a more suitable strategy for generating TN-depleted products consisting of memory T cells against ppEBV_EBNA1 and ppAdV_Hexon than CD62L in terms of depletion effectiveness, T-cell functionality and alloreactivity. To maximally exploit the beneficial effects mediated by antiviral memory T cells in TN-depleted products, depletion methods should be selected individually according to phenotype composition and CD4/CD8 antigen restriction. TN-depleted DLIs may improve the clinical outcome in terms of infections, GvHD, and disease relapse if selection of pathogen-specific donor T cells is not available.

Mycobacterium tuberculosis RpfE-Induced Prostaglandin E2 in Dendritic Cells Induces Th1/Th17 Cell Differentiation.

Prostaglandin E2 (PGE2) is an important biological mediator involved in the defense against Mycobacterium tuberculosis (Mtb) infection. Currently, there are no reports on the mycobacterial components that regulate PGE2 production. Previously, we have reported that RpfE-treated dendritic cells (DCs) effectively expanded the Th1 and Th17 cell responses simultaneously; however, the mechanism underlying Th1 and Th17 cell differentiation is unclear. Here, we show that PGE2 produced by RpfE-activated DCs via the MAPK and cyclooxygenase 2 signaling pathways induces Th1 and Th17 cell responses mainly via the EP4 receptor. Furthermore, mice administered intranasally with PGE2 displayed RpfE-induced antigen-specific Th1 and Th17 responses with a significant reduction in bacterial load in the lungs. Furthermore, the addition of optimal PGE2 amount to IL-2-IL-6-IL-23p19-IL-1ß was essential for promoting differentiation into Th1/Th17 cells with strong bactericidal activity. These results suggest that RpfE-matured DCs produce PGE2 that induces Th1 and Th17 cell differentiation with potent anti-mycobacterial activity.

Reference intervals for lymphocyte subsets in preterm and term neonates without immune defects.

BACKGROUND: In 6.5 years of newborn screening for severe combined immunodeficiency in California, 3,252,156 infants had DNA from dried blood spots (DBSs) assayed for T-cell receptor excision circles. Infants with T-cell receptor excision circle values of less than a designated cutoff on a single DBS, 2 DBS samples with insufficient PCR amplification, or known genetic risk of immunodeficiency had peripheral blood complete blood counts and lymphocyte subsets assayed in a single flow cytometry laboratory. Cases in which immune defects were ruled out were available for analysis. OBJECTIVE: We sought to determine reference intervals for lymphocyte subsets in racially/ethnically diverse preterm and term newborns who proved to be unaffected by any T-lymphopenic immune disorder. METHODS: Effective gestational age (GA) was defined as GA at birth plus postnatal age at the time of sample collection. After determining exclusion criteria, we analyzed demographic and clinical information, complete and differential white blood cell counts, and lymphocyte subsets for 301 infants, with serial measurements for 33 infants. Lymphocyte subset measurements included total T cells, helper and cytotoxic T-cell subsets, naive and memory phenotype of each T-cell subset, B cells, and natural killer cells. RESULTS: Reference intervals were generated for absolute numbers and lymphocyte subsets from infants with effective GAs of 22 to 52 weeks. Sex and ethnicity were not significant determinants of lymphocyte subset counts in this population. Lymphocyte counts increased postnatally. CONCLUSION: This study provides a baseline for interpreting comprehensive lymphocyte data in preterm and term infants, aiding clinicians to determine which newborns require further evaluations for immunodeficiency.

Running to Stand Still: Naive CD8+ T Cells Actively Maintain a Program of Quiescence.

CD8+ T cells play a pivotal role in clearing intracellular pathogens and combatting tumours. Upon infection, naïve CD8+ T cells differentiate into effector and memory cells, and this program is underscored by large-scale and coordinated changes in the chromatin architecture and gene expression. Importantly, recent evidence demonstrates that the epigenetic mechanisms that regulate the capacity for rapid effector function of memory T cells are shared by innate immune cells such as natural killer (NK) cells. Thus, it appears that the crucial difference between innate and adaptive immunity is the presence of the naïve state. This important distinction raises an intriguing new hypothesis, that the naïve state was evolutionary installed to restrain a default program of effector and memory differentiation in response to antigen recognition. We argue that the hallmark of adaptive T immunity is therefore the naïve program, which actively maintains CD8+ T cell quiescence until receipt of appropriate activation signals. In this review, we examine the mechanistic control of naïve CD8+ T cell quiescence and summarise the multiple levels of restraint imposed in naïve cells in to limit spontaneous and inappropriate activation. This includes epigenetic mechanisms and transcription factor (TF) regulation of gene expression, in addition to novel inhibitory receptors, abundance of RNA, and protein degradation.

Longitudinal immunosequencing in healthy people reveals persistent T cell receptors rich in highly public receptors.

BACKGROUND: The adaptive immune system maintains a diversity of T cells capable of recognizing a broad array of antigens. Each T cell's specificity for antigens is determined by its T cell receptors (TCRs), which together across all T cells form a repertoire of millions of unique receptors in each individual. Although many studies have examined how TCR repertoires change in response to disease or drugs, few have explored the temporal dynamics of the TCR repertoire in healthy individuals. RESULTS: Here we report immunosequencing of TCR ß chains (TCRß) from the blood of three healthy individuals at eight time points over one year. TCRß repertoires of all peripheral-blood T cells and sorted memory T cells clustered clearly by individual, systematically demonstrating that TCRß repertoires are specific to individuals across time. This individuality was absent from TCRßs from naive T cells, suggesting that the differences resulted from an individual's antigen exposure history, not genetic background. Many characteristics of the TCRß repertoire (e.g., diversity, clonality) were stable across time, although we found evidence of T cell expansion dynamics even within healthy individuals. We further identified a subset of "persistent" TCRßs present across all time points. These receptors were rich in clonal and highly public receptors and may play a key role in immune system maintenance. CONCLUSIONS: Our results highlight the importance of longitudinal sampling of the immune system, providing a much-needed baseline for TCRß dynamics in healthy individuals. Such a baseline will improve interpretation of changes in the TCRß repertoire during disease or treatment.

Paths to expansion: Differential requirements of IRF4 in CD8+ T-cell expansion driven by antigen and homeostatic cytokines.

Interferon regulatory factor 4 (IRF4) regulates the clonal expansion and metabolic activity of activated T cells, but the precise context and mechanisms of its function in these processes are unclear. In this issue of the European Journal of Immunology, Miyakoda et al. [Eur. J. Immunol. 2018. 48: 1319-1328] show that IRF4 is required for activation and expansion of naïve and memory CD8+ T cells driven by T-cell receptor (TCR) signaling, but dispensable for memory CD8+ T-cell maintenance and homeostatic proliferation driven by homeostatic cytokines. The authors show that the function of IRF4 in CD8+ T-cell expansion is partially dependent upon activation of the PI3K/AKT pathway through direct or indirect attenuation of PTEN expression. These data shed light upon the differential intracellular pathways required for naïve and memory T cells to respond to self-antigens and/or homeostatic cytokines, and highlight the potential translational relevance of these findings in the context of immune reconstitution such as following allogeneic stem cell transplantation.

Robust Identification of Suitable T-Cell Subsets for Personalized CMV-Specific T-Cell Immunotherapy Using CD45RA and CD62L Microbeads.

Viral infections and reactivations remain a serious obstacle to successful hematopoietic stem cell transplantation (HSCT). When antiviral drug treatment fails, adoptive virus-specific T-cell transfer provides an effective alternative. Assuming that naive T cells (TN) are mainly responsible for GvHD, methods were developed to generate naive T-cell-depleted products while preserving immune memory against viral infections. We compared two major strategies to deplete potentially alloreactive T cells: CD45RA and CD62L depletion and analyzed phenotype and functionality of the resulting CD45RA-/CD62L- naive T-cell-depleted as well as CD45RA⁺/CD62L⁺ naive T-cell-enriched fractions in the CMV pp65 and IE1 antigen model. CD45RA depletion resulted in loss of terminally differentiated effector memory T cells re-expressing CD45RA (TEMRA), and CD62L depletion in loss of central memory T cells (TCM). Based on these differences in target cell-dependent and target cell-independent assays, antigen-specific T-cell responses in CD62L-depleted fraction were consistently 3⁻5 fold higher than those in CD45RA-depleted fraction. Interestingly, we also observed high donor variability in the CD45RA-depleted fraction, resulting in a substantial loss of immune memory. Accordingly, we identified donors with expected response (DER) and unexpected response (DUR). Taken together, our results showed that a naive T-cell depletion method should be chosen individually, based on the immunophenotypic composition of the T-cell populations present.

CD45RA depletion in HLA-mismatched allogeneic hematopoietic stem cell transplantation for primary combined immunodeficiency: A preliminary study.

BACKGROUND: Combined immunodeficiencies (CIDs) form a heterogeneous group of inherited conditions that affect the development, function, or both of T cells. The treatment of CIDs with allogeneic hematopoietic stem cell transplantation (HSCT) is complicated by a high incidence of life-threatening infections and an increased risk of graft-versus-host disease (GVHD). OBJECTIVE: In view of the growing evidence that alloreactivity is mainly derived from human naive T cells, the selective depletion of naive T cells from allografts might constitute a way of reducing alloreactivity while maintaining memory T-cell responsiveness to pathogens. METHODS: Five consecutive patients with CIDs and chronic viral infections underwent an allogeneic, HLA-mismatched HSCT. Given the patients' infection status and the potential risk of severe GVHD in the mismatched setting, the CD34(-) fraction of the allograft was depleted of naive T cells by using magnetic CD45RA beads. RESULTS: Engraftment occurred in 4 of the 5 patients. No severe GVHD occurred. In the 4 engrafted patients viral infections were cleared within 2 months of the HSCT, and both cellular and humoral immunity were re-established within a year of the HSCT. An early T-cell response against viral pathogens was documented in 2 patients. CONCLUSION: The present pilot study shows that clinical-grade depletion of naive T cells from an allograft through the use of magnetic CD45RA beads seems to be a feasible and efficacious option for the treatment of patients with CIDs at high risk of GVHD, infection, or both in an HLA-mismatched setting.

High number of memory t cells is associated with higher risk of acute graft-versus-host disease after allogeneic stem cell transplantation.

The pathophysiology of acute graft-versus-host disease (GVHD) remains poorly understood in humans. Although T cell subsets have been identified to play a major role in disease initiation in rodents, clinical data on the effect of these different subsets are scarce and conflicting. To address this question, immunophenotyping analyses were performed on the graft in 210 patients. The onset of acute GVHD was retrospectively correlated with these subpopulations. In an adjusted analysis, only the absolute count of CD45lo/CD62Llo CD8(+) T cells (effector memory T cells) was significantly associated with the onset of grade 2 to 4 acute GVHD. Thus, in contrast to experimental data, we found that the number of effector memory but not of naïve T cells was associated with the onset of GVHD. These results should be kept in mind while clinical trials, which aim to deplete naïve T cells, are underway in several institutions.

An immunological biomarker to predict MTX response in early RA.

OBJECTIVES: The therapeutic goal for patients with rheumatoid arthritis (RA) is clinical remission. This is best achieved by early diagnosis and appropriate therapeutic intervention. RA is associated with dysregulation of T-cell subsets (naïve, regulatory (Treg) and inflammation-related cells (IRC)) early in the disease. Our aim was to test the hypothesis that T-cell subset quantification can predict the achievement of clinical remission with early treatment in RA. METHODS: T-cell subsets were quantified in 108 drug-naïve, early RA patients commencing methotrexate (MTX) or MTX+antitumor necrosis factor (anti-TNF) and in 105 healthy controls (HC). The primary outcome assessed was remission (DAS28<2.6). A pilot study used frozen cells (38 patients and 35 HCs, see online supplementary material) and was validated with fresh blood (70 patients and 70 HCs). RESULTS: Immune dysregulation in early RA was confirmed with an association between age and reduced naïve cells compared with HCs (p=0.006), a lower age-adjusted Treg and higher IRC frequency (p=0.001). Anticitrullinated peptide antibody (ACPA) positivity was associated with lower naïve (p=0.031) and Treg frequencies (p=0.039). In 50 patients treated with MTX, ACPA/age-adjusted analysis demonstrated that higher naïve cell frequency (relative to HC) was associated with remission (OR 5.90 (1.66 to 20.98), p=0.006, sensitivity/specificity 62%/79%, Positive Predictive Value (PPV)/Negative Predictive Value (NPV) 66%/76%). Remission with MTX+anti-TNF (n=20) was not found to be associated with naïve cell frequency, and for patients with reduced naïve cells the remission rate increased from 24% (MTX) to 42% (MTX+anti-TNF). CONCLUSIONS: Baseline T-cell subset analysis has a value in predicting early RA remission with first therapy with MTX. Immunological analysis could be used in conjunction with clinical/serological features to predict response to MTX and help select the most appropriate therapy at disease presentation.

Reduced thymic output in elite athletes.

Athletes undergoing intensive training schedules have chronic exposure to stress-induced hormones such as cortisol that can depress immune function. We compared the circulating levels of T cell receptor excision circles (TREC), a marker of recent thymic emigrants, as well as the levels of naïve and memory subsets in a group of elite endurance athletes and in controls. The athletes showed a reduction in absolute numbers of naïve T cells, particularly in CD4 T cells. In contrast, memory cells were increased. TREC levels in the athletes were significantly reduced compared to age-matched controls. Such changes resemble premature ageing of the T cell component of the immune system. Since thymic production of T cells naturally decline with age, these results raise the concern that prolonging high intensity exercise into the 4th decade of life may have deleterious consequences for athletes' health.

The profile and prognostic significance of bone marrow T-cell differentiation subsets in adult AML at diagnosis.

Background: T lymphocytes in tumor microenvironment play a pivotal role in the anti-tumor immunity, and the memory of T cells contributes to the long-term protection against tumor antigens. Compared to solid tumors, studies focusing on the T-cell differentiation in the acute myeloid leukemia (AML) bone marrow (BM) microenvironment remain limited. Patients and methods: Fresh BM specimens collected from 103 adult AML patients at diagnosis and 12 healthy donors (HDs) were tested T-cell differentiation subsets by multi-parameter flow cytometry. Results: CD4 and CD8 T-cell compartments had different constituted profiles of T-cell differentiated subsets, which was similar between AML patients and HDs. Compared to HDs, AML patients as a whole had a significantly higher proportion of CD8 effector T cells (Teff, P = 0.048). Moreover, the T-cell compartment of AML patients with no DNMT3A mutations skewed toward terminal differentiation at the expense of memory T cells (CD4 Teff: P = 0.034; CD8 Teff: P = 0.030; CD8 memory T: P = 0.017), whereas those with mutated DNMT3A had a decrease in CD8 naïve T (Tn) and CD4 effector memory T cells (Tem) as well as an increase in CD4 central memory T cells (Tcm) (P = 0.037, 0.053 and 0.053). Adverse ELN genetic risk correlated with a lower proportion of CD8 Tn. In addition, the low proportions of CD4 Tem and CD8 Tn independently predicted poorer relapse-free survival (RFS, HR [95%CI]: 5.7 (1.4-22.2), P = 0.017 and 4.8 [1.3-17.4], P = 0.013) and event-free survival (EFS, HR [95% CI]: 3.3 (1.1-9.5), P = 0.029; 4.0 (1.4-11.5), P = 0.010), respectively. Conclusions: AML patients had abnormal profiles of BM T-cell differentiation subsets at diagnosis, which was related to DNMT3A mutations. The low proportions of CD4 Tem and CD8 Tn predicted poor outcomes.