Antigen-specific CD4 T-cell help rescues exhausted CD8 T cells during chronic viral infection

CD4 T cells play a critical role in regulating CD8 T-cell responses during chronic viral infection. Several studies in animal models and humans have shown that the absence of CD4 T-cell help results in severe dysfunction of virus-specific CD8 T cells. However, whether function can be restored in already exhausted CD8 T cells by providing CD4 T-cell help at a later time remains unexplored. In this study, we used a mouse model of chronic lymphocytic choriomeningitis virus (LCMV) infection to address this question. Adoptive transfer of LCMV-specific CD4 T cells into chronically infected mice restored proliferation and cytokine production by exhausted virus-specific CD8 T cells and reduced viral burden. Although the transferred CD4 T cells were able to enhance function in exhausted CD8 T cells, these CD4 T cells expressed high levels of the programmed cell death (PD)-1 inhibitory receptor. Blockade of the PD-1 pathway increased the ability of transferred LCMV-specific CD4 T cells to produce effector cytokines, improved rescue of exhausted CD8 T cells, and resulted in a striking reduction in viral load. These results suggest that CD4 T-cell immunotherapy alone or in conjunction with blockade of inhibitory receptors may be a promising approach for treating CD8 T-cell dysfunction in chronic infections and cancer.     

Cooperation of Tim-3 and PD-1 in CD8 T-cell exhaustion during chronic viral infection

Inhibitory receptors play a crucial role in regulating CD8 T-cell function during chronic viral infection. T-cell Ig- and mucin-domain–containing molecule–3 (Tim-3) is well known to negatively regulate T-cell responses, but its role in CD8 T-cell exhaustion during chronic infection in vivo remains unclear. In this study, we document coregulation of CD8 T cell exhaustion by Tim-3 and PD-1 during chronic lymphocytic choriomeningitis virus infection. Whereas Tim-3 was only transiently expressed by CD8 T cells after acute infection, virus-specific CD8 T cells retained high Tim-3 expression throughout chronic infection. The majority (approximately 65% to 80%) of lymphocytic choriomeningitis virus–specific CD8 T cells in lymphoid and nonlymphoid organs coexpressed Tim-3 and PD-1. This coexpression of Tim-3 and PD-1 was associated with more severe CD8 T-cell exhaustion in terms of proliferation and secretion of effector cytokines such as IFN-γ, TNF-α, and IL-2. Interestingly, CD8 T cells expressing both inhibitory receptors also produced the suppressive cytokine IL-10. Most importantly, combined blockade of Tim-3 and PD-1 pathways in vivo synergistically improved CD8 T cell responses and viral control in chronically infected mice. Taken together, our study defines a parameter for determining the severity of CD8 T cell dysfunction and for identifying virus-specific CD8 T cells that produce IL-10, and shows that targeting both PD-1 and Tim-3 is an effective immune strategy for treating chronic viral infections.During chronic viral infection, virus-specific CD8 T cells become unresponsive to viral antigens and persist in a nonfunctional exhausted state (1). These exhausted CD8 T cells are characterized by the inability to produce immune-stimulatory cytokines, lyse virally infected cells, and proliferate (1). After CD8 T-cell exhaustion was initially characterized in the murine lymphocytic choriomeningitis virus (LCMV), such a functional impairment has been a common feature in human chronic viral infections such as, HIV, hepatitis B virus, and hepatitis C virus (HCV) (2). These functional defects in responding T cells are probably a primary reason for failure of immunological control of these persisting pathogens.Recent studies have focused on the crucial role of inhibitory receptors in regulating T-cell exhaustion during chronic viral infections. Programmed death 1 (PD-1), an inhibitory receptor of the CD28 superfamily, was shown to be highly expressed on exhausted CD8 T cells compared with functional memory T cells in the LCMV system, and in vivo blockade of this pathway restored the function of virus-specific CD8 T cells, resulting in enhanced viral control (3). Involvement of the PD-1 pathway has also been shown in various chronic viral infections including HIV, hepatitis B virus, and HCV in humans (4, 5), and during simian immunodeficiency virus infection in nonhuman primates (6). These studies have suggested that PD-1 could be a major inhibitory pathway during chronic infection and manipulation of this pathway may have therapeutic potential. However, blockade of PD-1 pathway does not completely restore T-cell function (4, 5, 7), indicating the involvement of other negative regulatory pathways in CD8 T-cell exhaustion. Gene expression profiling studies have identified the presence of a number of other potential inhibitory receptors on exhausted CD8 T cells such as 2B4, LAG-3, CTLA-4, PirB, GP49, and CD160 (8). Moreover, considerable evidence indicates that the expression of these receptors is important for regulating multiple functional aspects of CD8 T-cell exhaustion (7, 9). Therefore, a more thorough understanding of the importance of inhibitory receptors in CD8 T-cell exhaustion may reveal potential therapeutic targets leading to the restoration of CD8 T-cell function and better viral control.T-cell Ig- and mucin-domain–containing molecule-3 (Tim-3) was initially identified as a molecule expressed on T helper (Th) 1, but not Th2 (10). Interaction of Tim-3 with its ligand, galectin-9, regulates Th1 responses by promoting the death of Th1 cells and induces peripheral tolerance (11). Recently, it was reported that Tim-3 was expressed by virus-specific T cells during HIV-1 and HCV infections, and the expression levels correlated with the state of CD8 T-cell exhaustion (12, 13). In addition, blockade of Tim-3 improved the responsiveness of the exhausted T cells in vitro (12, 13), suggesting Tim-3 as another inhibitory marker of exhausted T cells during chronic viral infection. However, it is currently unclear whether Tim-3 regulates CD8 T cell exhaustion in cooperation with PD-1 during chronic viral infection. Furthermore, it will be important to explore the possibility of a synergistic effect of blocking both the Tim-3 and PD-1 pathways for providing new opportunities in antiviral therapy.In this study, we longitudinally investigated the expression of Tim-3 on virus-specific CD8 T cells during acute and chronic LCMV infection. We were especially interested in determining the coexpression of Tim-3 and PD-1 on CD8 T cells to identify populations with differential dysfunction during chronic viral infection. In addition, we examined the effect of in vivo blockade of Tim-3 and PD-1 regulatory pathways on the reversal of exhausted CD8 T cells and viral control.     

Differential CD4(+) and CD8(+) T-cell responsiveness in hepatitis C virus infection

This study was performed to compare the vigor and phenotype of virus-specific CD4(+) and CD8(+) T-cell responses in patients with different virologic and clinical outcomes after hepatitis C virus (HCV) infection. The results show that a vigorous and multispecific CD4(+) proliferative T-cell response is maintained indefinitely after recovery from HCV infection whereas it is weak and focused in persistently infected patients. In contrast, the HCV-specific CD8(+) T-cell response was quantitatively low in both groups despite the use of sensitive direct ex vivo intracellular interferon gamma (IFN-gamma) staining. Furthermore, although HCV-specific cytolytic CD8(+) memory T cells were undetectable ex vivo, they were readily expanded from the peripheral blood of chronically HCV-infected patients but not from recovered subjects after in vitro stimulation, suggesting that ongoing viremia is required to maintain the HCV-specific memory CD8(+) T-cell response. HCV-specific CD8(+) T cells displayed a type 1 cytokine profile characterized by production of IFN-gamma despite persistent HCV viremia. The paradoxical observation that HCV-specific CD4(+) T cells survive and CD8(+) T cells are lost after viral clearance while the opposite occurs when HCV persists suggests the existence of differential requirements for the maintenance of CD4(+) and CD8(+) T-cell memory during HCV infection. Furthermore, the relative rarity of circulating CD8(+) effector T cells in chronically infected patients may explain the chronic insidious nature of the liver inflammation and also why they fail to eliminate the virus.     

Surface expression patterns of negative regulatory molecules identify determinants of virus-specific CD8+ T-cell exhaustion in HIV infection

A highly complex network of coinhibitory and costimulatory receptors regulates the outcome of virus-specific CD8(+) T-cell responses. Here, we report on the expression patterns of multiple inhibitory receptors on HIV-specific, cytomegalovirus-specific, and bulk CD8(+) T-cell memory populations. In contrast to cytomegalovirus-specific CD8(+) T cells, the majority of HIV-specific CD8(+) T cells exhibited an immature phenotype and expressed Programmed Death-1, CD160 and 2B4 but not lymphocyte activation gene-3. Notably, before antiretroviral therapy, simultaneous expression of these negative regulators correlated strongly with both HIV load and impaired cytokine production. Suppression of HIV replication by antiretroviral therapy was associated with reduced surface expression of inhibitory molecules on HIV-specific CD8(+) T cells. Furthermore, in vitro manipulation of Programmed Death-1 and 2B4 inhibitory pathways increased the proliferative capacity of HIV-specific CD8(+) T cells. Thus, multiple coinhibitory receptors can affect the development of HIV-specific CD8(+) T-cell responses and, by extension, represent potential targets for new immune-based interventions in HIV-infected persons.     

Absence of CD4 T-cell help provides a robust CD8 T-cell response while inducing effective memory in a preclinical model of melanoma

Immunotherapy strategies for cancer are focused on inducing effective and specific cytotoxic responses mediated by CD8 T cells. On the other hand, immunosuppressive mechanisms induced by the tumor, such as the generation of tumor-specific CD4(+)CD25(+)FoxP3(+) Tregs, conspire against the efficacy of immunotherapies. It has been considered that, similar to what has been observed in the context of immunological responses towards microbes, CD4 help is indispensable for the development of a successful and long-lasting (memory) CD8 immune response. In the recent article, C?té et al. reported that, in a mouse model of melanoma, total ablation of CD4 help does not hamper the development of a specific antitumor memory CD8 response. In addition, ablation of CD4 was more successful than strategies to deplete CD25 Tregs in generating memory CD8 T cells. These data opens the door for therapies destined to induce effective antitumor immune responses by ablation of whole CD4 T-cell populations.     

Role of antigen persistence and dose for CD4+ T-cell exhaustion and recovery

It is currently not understood how some chronic infections exhaust antigen-specific T cells over time and which pathogen components contribute to exhaustion. Here, we dissected the behavior of primed CD4(+) T cells exposed to persistent antigen using an inducible transgenic mouse system that allowed us to control antigen presentation as the only experimental variable, independent of the persistent inflammation and disease progression that complicate infectious models. Moreover, this system restricted antigen presentation to dendritic cells (DCs) and avoided confounding B, CD8(+) T, or innate cell responses. When antigen presentation was extended beyond the expansion phase, primed CD4(+) T cells survived, but exhibited reduced memory functionality in terms of their proliferative capacity and cytokine expression potential. The effect was antigen dose and time dependent, not associated with increased PD-1 expression or reduced calcium influx, but impaired Jun phosphorylation in response to TCR engagement. Upon antigen removal, the cells regained the ability to proliferate, but remained unable to produce high levels of IL-2 and TNF-α. These data show that persistent antigen by itself rapidly induces a dysfunctional state in CD4(+) T cells that is only partially reversible upon antigen removal. These findings have implications for vaccine optimization and for the possible reinvigoration of CD4(+) T cells during chronic infection.     

TLR3 ligand stimulates fully functional memory CD8+ T cells in the absence of CD4+ T-cell help

We investigated whether Toll-like receptor ligands (TLR-Ls) can bypass the requirement for CD4(+) T-cell help in the induction of fully efficient memory CD8(+) T cells (cytotoxic T lymphocytes [CTLs]). "Helpless" CTLs were induced by a synthetic CD8(+) T-cell epitope administered with TLR3-L and TLR9-L, but not with TLR2/6-L, TLR4-L, or TLR7-L. The up-regulation of MHC-I and costimulatory molecules by dendritic cells following TLR stimulation was not sufficient for the priming of "helpless" CTLs, which depended essentially on the induction of a strong IFN-alpha/beta response. The "helpless" CTLs induced by TLR-Ls differentiated into fully functional memory CTLs able to proliferate as well as their "helped" counterparts upon challenge, in the absence of CD4(+) T-cell help.     

Nadir CD4+ T-cell count and numbers of CD28+ CD4+ T-cells predict functional responses to immunizations in chronic HIV-1 infection

OBJECTIVE: To ascertain whether delaying the initiation of highly active antiretroviral therapy (HAART) compromises functional immune reconstitution in HIV-1 infection in persons who regain 'normal' CD4 T-cell counts after suppressive antiretroviral therapies. DESIGN: Prospective open-label study carried out at two University-affiliated HIV-outpatient clinics in the USA. SUBJECTS AND METHODS: Response to immunization was used as a model for in vivo functional immune competence in 29 HIV-1 infected patients with CD4 T-cell counts > 450 x 106 cells/l and HIV-RNA < 400 copies/ml for > 12 months after HAART and nine HIV-1 seronegative controls. After immunization with tetanus toxoid, diphtheria-toxoid, and keyhole limpet hemocyanin, immune response scores (IRS) were calculated using postimmunization antibody concentrations, lymphocyte proliferation, and delayed-type hypersensitivity responses to vaccine antigens. RESULTS: Despite normal numbers of circulating CD4 T-cells, the CD4 T-cell nadir before HAART initiation predicted the immune response to immunization (rho = 0.5; P < 0.005) while current CD4 T-cell count did not. Likewise, CD4 T-lymphocyte expression of the co-stimulatory molecule CD28 was also an independent predictor of response to immunization (rho = 0.5; P < 0.005). CONCLUSIONS: Even among persons who controlled HIV replication and normalized CD4 T-cell counts with HAART, pretreatment CD4 T-cell count and numbers of circulating CD4+CD28+ T-cells at immunization, but not current CD4 T-cell count, predict the ability to respond to vaccination. Delaying the initiation of HAART in chronic HIV-1 infection results in impaired functional immune restoration despite normalization of circulating CD4 T-cell numbers.     

Activated CD4+ and CD8+ T-cell subsets in Wegener's granulomatosis

Several lines of evidence argue in favour of an involvement of T cells in the pathogenesis of Wegener's granulomatosis (WG). These include the presence of highly specific IgG autoantibodies to proteinase 3, perivascular T-cell infiltrates and elevated amounts of soluble interleukin-2 (IL-2) receptors in patient's serum. In order to further address this question we evaluated by double immunoflourescence and flow cytometry the expression of several cell surface molecules associated with T-cell activation. As compared to healthy controls (n=15), the CD4⁺ subset was significantly diminished, while the percentage of CD8⁺ T cells was elevated in WG patients (n=24). Within the CD4⁺ T-cell subset we found a highly significant increase in activation/memory markers (CD25, CD29, HLA-DR). Within the CD8⁺ T-cell subset the expression of CD11b, CD29 and CD57 was significantly elevated, while the expression of VD28 was reduced. The use of 10 V-, 1 V-and 1 V-specific monoclonal reagents failed to reveal any significant bias in the peripheral T-cell receptor V-gene repertoire of WG patients. There was also no correlation between T-cell activation markers and laboratory parameters [C-reactive protein (CRP), ESR], disease duration or therapy. A significant correlation was found only for the degree of organ involvement and the increase in CD4⁺ T cells coexpressing HLA-DR, as well as the increase in CD57 expression on CD8⁺ T cells. In conclusion, both CD4⁺ and CD8⁺ T-cell subsets were activated in WG. Cytotoxic CD8⁺ CD57⁺ CD11b⁺ CD28^– T cells may directly contribute to damage of vascular endothelium.     

CTLA-4 dysregulation of self/tumor-reactive CD8+ T-cell function is CD4+ T-cell dependent

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) maintains peripheral tolerance by suppressing T-cell activation and proliferation but its precise role in vivo remains unclear. We sought to elucidate the impact of CTLA-4 expression on self/tumor-reactive CD8(+) T cells by using the glycoprotein (gp) 100-specific T-cell receptor (TCR) transgenic mouse, pmel-1. pmel-1 CLTA-4(-/-) mice developed profound, accelerated autoimmune vitiligo. This enhanced autoimmunity was associated with a small but highly activated CD8(+) T-cell population and large numbers of CD4(+) T cells not expressing the transgenic TCR. Adoptive transfer of pmel-1 CLTA-4(-/-) CD8(+) T cells did not mediate superior antitumor immunity in the settings of either large established tumors or tumor challenge, suggesting that the mere absence of CTLA-4-mediated inhibition on CD8(+) T cells did not directly promote enhancement of their effector functions. Removal of CD4(+) T cells by crossing the pmel-1 CLTA-4(-/-) mouse onto a Rag-1(-/-) background resulted in the complete abrogation of CD8(+) T-cell activation and autoimmune manifestations. The effects of CD4(+) CLTA-4(-/-) T cells were dependent on the absence of CTLA-4 on CD8(+) T cells. These results indicated that CD8(+) CLTA-4(-/-) T-cell-mediated autoimmunity and tumor immunity required CD4(+) T cells in which the function was dysregulated by the absence of CTLA-4-mediated negative costimulation.     

CD3+, CD4-, CD8- large granular T-cell lymphoproliferative disorder.

Large granular T-cell lymphoproliferative disorder (LGTLD) is a heterogeneous disorder covering a broad spectrum of diseases and requiring further subdivision. Most reported cases emphasized its suppressor phenotype (T gamma cell or CD8+), but we encountered two cases of CD3+, CD4-, CD8- LGTLD. Both cases had a benign clinical course and required no chemotherapy despite persistent lymphocytosis. This unique phenotype has been reported in a few cases of acute lymphoblastic leukemia expressing the T-cell receptor (TcR) gamma chain gene and is considered the counterpart of thymocytes at the intermediate stage between early precursors and mature thymocytes. Our case 1 provides further evidence that the CD3+, CD4-, CD8- phenotype, indeed, expresses the TcR gamma chain gene. However, the negative reaction to terminal deoxynucleotidyl transferase in our case 1 indicates that this phenotype represents proliferation of peripheral T-cells, in which about 2% bear the CD3+, CD4-, CD8- phenotype in the normal population. The selective use of CD3, CD4, CD8, HNK-1 monoclonal antibodies and of cytochemical stains (acid phosphatase and alpha-naphthyl butyrate esterase) for characterization of this disorder is discussed.     

CD4-CD8- T-cell polymyositis in a patient with chronic active Epstein-Barr virus infection

We describe a 17-year-old woman with chronic active Epstein-Barr virus infection (CAEBV), who developed EBV+CD4-CD8- T-cell polymyositis. At 14 years of age, CAEBV was diagnosed with fever, cytopenia, liver dysfunction, and hepatosplenomegaly. Despite the transient remission of interferon-alpha therapy, migratory lesions emerged in back and extremities. MRI indicated polymyositis. Biopsy specimens revealed intramuscular infiltration of CD3+, CD4-, CD8-, CD56-, and EBV-encoded RNA 1+ cells. Circulating CD4-CD8-Vdelta2/Vgamma9 cells increased. gammadeltaT-cells contained 20-200 times higher EBV-DNA (2 x 10(4) copies/microgDNA) than alphabetaT-cells or NK-cells. The ominous polymyositis might denote the musculotropic invasion of EBV+gammadeltaT-cell lymphoproliferative disease as a consequence of CAEBV.     

Lung CD4 lymphocytes predict survival in asymptomatic HIV infection

BACKGROUND: Plasma viral load and blood CD4 counts are accepted indicators of severity of illness in patients with HIV-1. Lung CD4 counts have not been evaluated in asymptomatic HIV-1 patients as indicators of disease severity. OBJECTIVE: To determine if lung lymphocyte counts in asymptomatic subjects with HIV compare with plasma viral loads and blood CD4 counts in predicting survival. DESIGN: Retrospective, cross-sectional analysis. SETTING: Midwestern urban community, December 1996 to August 1998. PARTICIPANTS: HIV-seropositive subjects (n = 95) without AIDS-related pulmonary complications. MEASUREMENTS: Plasma viral load, blood hemoglobin and blood lymphocyte subtypes, lung lymphocyte subtypes from BAL, body mass index, and mortality. RESULTS: Eight of the 95 subjects (8.4%) had died at the 4-year follow-up. Lung CD4 counts were significantly related to mortality by univariable analysis (2.5 x 10(3)/mL vs 0.9 x 10(3)/mL, median values for survivors vs nonsurvivors, respectively, p = 0.010). Modeling using exact methods further showed lung CD4 counts to be a significant predictor of survival after individually adjusting for potential confounders, including plasma viral load and blood CD4 count. CONCLUSIONS: Lung CD4 counts in patients with HIV-1 infection may provide an independent predictor of survival.     

CD4+ T-cell counts, CD4+/CD8+ T-cell count ratios, and antibody levels in migrant fishermen infected with Schistosoma japonicum in the Dongting Lake, China

In this study, CD4(+) and CD8(+) T cells and antibody levels were measured in 94 migrant fishermen infected with Schistosoma japonicum from Dongting Lake, China. Prevalence among these fishermen was high (63.8%), with a mean infection intensity of 61.4 +/- 3.8 epg, and included a high proportion of individuals (39.4%) with substantial parenchymal fibrosis (stages > or = 2/3). The CD4(+)/CD8(+) ratio in men (1.34 +/- 0.11) was significantly lower than that of women (1.58 +/- 0.15). CD4(+) T cells and the ratio of CD4(+)/CD8(+) were significantly decreased both in subjects infected with S. japonicum and those with parenchymal fibrosis. However, levels of total IgA, IgM, and anti-schistosome egg antigen IgG correlated positively with infection intensity and pathologic lesion number. These results suggest an imbalance between cell-mediated and humoral immunity in these fishermen, the precise cause of which remains undetermined.     

CD4+ and CD8+ lymphocytes and HIV RNA in HIV infection: high baseline counts and in particular rapid decrease of CD8+ lymphocytes predict AIDS

OBJECTIVE: To study the progression of HIV infection in relation to immunological and virological variables with emphasis on the role of CD8+ lymphocytes. DESIGN: Prospective follow-up from October 1991 of patients observed for at least 18 months allowing nucleoside analogue monotherapy. Peripheral CD4+ and CD8+ lymphocyte counts, HIV RNA, and soluble CD8 were analysed by statistics allowing the evaluation of serial data, avoiding time points with concurrent infections. SETTING: Tertiary university clinic. PATIENTS: Forty-nine patients were followed for 52.6 months, baseline CD4+ count of 300 x 10(6)/l, sample interval of 5.9 months (medians). MAIN OUTCOME MEASURES: AIDS, death, and CDC groups B- or C-related events. RESULTS: AIDS developed in 28% of patients. Baseline CD8+ counts above the median were significantly associated with AIDS development; the best Cox model included CD8+ cells and the log10RNA/CD4 ratio. A decline in CD8+ counts relative to baseline most significantly predicted AIDS, along with higher baseline RNA and actual CD4+ counts of less than 200 x 10(6)/l. Levels of soluble CD8 in the blood relative to total CD8+ cells significantly increased in patients developing AIDS. Death occurred in 16% of the patients, and was only predicted by high CD8+ cell counts at baseline. CDC B- and C-related events occurred in 35% of the patients and were best predicted by high baseline CD8+ counts and high RNA levels. CONCLUSIONS: The serial quantitation of CD8+ lymphocytes gave highly significant predictive information on the natural progression of HIV infection in patients with moderate to severe immune deficiency. Our data suggest that the hyperactivation of CD8+ lymphocytes is an important factor leading to a numerical decrease of CD8+ lymphocytes in progressive HIV infection.     

Discordant role of CD4 T-cell response relative to neutralizing antibody and CD8 T-cell responses in acute hepatitis C

BACKGROUND & AIMS: Acute hepatitis C virus (HCV) infection becomes chronic in the majority of patients. Although HCV-specific CD4 T-cell response is associated with HCV clearance, less is known about virus-specific CD8 T-cell or neutralizing antibody (nAb) responses and the role of CD4 help in their induction during acute infection. METHODS: HCV-specific CD4, CD8, and HCV pseudoparticle (HCVpp) nAb responses were monitored in acutely HCV-infected patients to define their relative contributions to viral clearance. RESULTS: Our results show that the outcome of acute hepatitis C is associated with a functional hierarchy in HCV-specific CD4 T-cell response and the scope of virus-specific, total T-cell interferon-gamma response. HCV-specific CD8 T-cell response was readily detectable in acutely HCV-infected patients regardless of virologic outcome or virus-specific CD4 T-cell response. In contrast, HCVpp-specific nAbs were readily detected in patients with chronic evolution and impaired virus-specific CD4 T-cell response but not in patients who cleared infection with robust virus-specific CD4 T-cell response. CONCLUSIONS: The outcome of acute hepatitis C is associated with efficient virus-specific CD4 T-cell response(s) without which HCV-specific CD8 T-cell and heterologous nAb responses may develop but fail to clear viremia. Furthermore, HCV-specific nAb responses may not be induced despite robust virus-specific CD4 T-cell response.     

Clinical responders to antiviral therapy of chronic HCV infection show elevated antiviral CD4+ and CD8+ T-cell responses

Summary. Chronic hepatitis C virus (HCV) infection is characterized by attenuated antiviral T‐cell responses, making their detection and characterization a technological challenge. The role and the dynamics of antiviral T‐cell responses during antiviral therapy are incompletely understood. To assess HCV‐specific T‐cell responses during antiviral therapy of genotype‐1‐infected patients, we adopted a flow cytometric approach to comprehensively evaluate virus‐specific CD4+ and CD8+ T‐cell proliferative responses against pools of genotype‐ and subtype‐specific serial, overlapping peptides spanning the entire virus. Studies in cross‐sectional cohorts of treatment‐naïve (TN) patients , early and sustained clinical virological responders (EVRs and SVRs) or clinical nonresponders (NRs) showed that this proliferative assay had significantly greater sensitivity in detecting HCV‐specific responses, compared with ex vivo cytokine flow cytometry. At the same time, it could be used to detect and quantify both CD4+ and CD8+ responses simultaneously. EVRs and SVRs showed significantly more HCV‐specific CD4+ and CD8+ responses, compared with either TN patients or NRs. This corresponded to a higher magnitude of responses as well as a greater breadth of reactivity with higher responses against the core/E1, NS3, NS4 and NS5b regions of the virus. Interestingly, both clinical responders and NRs showed higher cytomegalovirus‐specific CD4+ responses, compared with TN patients. These results demonstrate an association between clinically successful antiviral therapy and enhanced magnitude and breadth of antiviral responses. Moreover, the study demonstrates the clinical relevance of this flow cytometric proliferation assay system, in combination with an unbiased library of viral peptides, in evaluating the biology of antiviral T‐cell responses during infection and therapy.     

CD8+T cell exhaustion statuses in patients with human immunodeficiency virus infection,Mycobacterium tuberculosis infection and coinfection

<正>Objective To analyze the statuses of CD8+T cell exhaustion in patients with human immunodeficiency virus(HIV) infection,Mycobacterium tuberculosis(MTB) infection and co-infection.Methods A total of87 patients infected with HIV and/or MTB in Wuxi Fifth People’s Hospital and Taicang First People’s Hospital from August 2019 to January 2020 were enrolled,