Increased expression of CD30 and CD57 molecules on CD4(+) T cells from children with atopic asthma: a preliminary report.

T helper type 2 (Th2) cells play an important role in the onset and persistence of allergic airway inflammation. Consequently, many authors have attempted to identify cell surface markers associated with a Th2 phenotype. This work was aimed at correlating CD30 and CD57 expression on CD4(+) T cells with interleukin (IL)-4 production in peripheral blood mononuclear cells (PBMCs) from allergic patients. PBMCs from 17 children with atopic asthma and 12 nonatopic healthy control children were analyzed. The CD28, CD30, CD40L, CD57, CD62L, CD69, IL-4, and IFN-gamma expressions on CD4(+) T cells were determined by double immunofluorescence and flow cytometry in PBMCs ex vivo and after phorbol-12-myristate-13-acetate plus ionomycin (PMA/I) stimulation. An increased percentage of peripheral CD4(+)CD30(+) T cells was observed in asthmatic patients (p < 0.001). In addition, the percentage of CD4(+) T cells expressing IL-4, IFN-gamma, CD30, CD40L, CD57, or CD69 significantly increased (p < 0.01) after PMA/I stimulation, in asthmatic patients. The CD30 expression on CD4(+) T cells from asthmatic patients, after stimulation, correlated with both IL-4 and IFN-gamma production, whereas CD57 expression only correlated with IL-4 production. These data suggest that the expression of CD30 and CD57 cell markers on T cells could reflect circulating effector T cell early activation in the allergic airway disease.     

Cytokine profile in Behçet's disease patients. Relationship with disease activity

OBJECTIVE: To analyse proinflammatory Th1 and Th2 cytokines in patients with Beh?et's disease (BD) in relation to disease activity. METHODS: Forty-five BD patients (25 in active stage) were investigated with ELISA for estimation of cytokines levels. Furthermore, cytokines intracellular synthesis (IL-4 and IFN-gamma) of CD4+ T cells was studied. RESULTS: Active and in remission BD patients showed increased serum levels of Th1 (IFN-gamma, IL-12) and Th2 (IL-4, IL-6 and IL-10) cytokines. Active BD was characterized by a higher increase of IL-6, IL-10 and a striking increase of IL-17, IL-18 and IFN-gamma, compared to remission RD. Upon in vitro stimulation, the percentages of CD4+ T cells containing IFN-gamma and CD40L were higher in active BD compared to healthy controls. CONCLUSION: Our results suggest that the microenvironment of CD4+ T cells in active BD may induce the production of more cells committed to Th1 than in BD patients in remission and healthy controls.     

Ex vivo CD(+) T-cell cytokine expression from patients with Sjögren's syndrome following in vitro stimulation to induce proliferation

OBJECTIVE: To assess ex vivo CD4(+) T-cell cytokine expression from patients with primary Sj?gren's syndrome (SS) following in vitro stimulation to induce proliferation, as proliferation is closely related to differentiation of cytokine-producing cells. METHODS: Peripheral blood mononuclear cells (PBMCs) separated from primary SS patients (n = 28) and controls (n = 25) were analysed. PBMCs were stimulated with concanavalin A followed by phorbol 12-myristate 13-acetate and ionomycin. Intracellular interferon-gamma (IFN-gamma) and interleukin-4 (IL)-4 in proliferating CD4(+) T cells were assessed by flow cytometry. The proportion of cytokine-producing cells and proliferating cells in each division cycle was assessed using [5(and 6)-carboxyfluorescein diacetate, succinimidyl ester]-labelled CD4(+/-) T cells. RESULTS: The proportion of IFN-gamma+ proliferating CD4(+) T cells in each cell division cycle from extraglandular SS was increased in glandular SS patients compared glandular SS patients with controls (P<0.05 approximately 0.01). The percentage of IFN-gamma single positive proliferating CD4(+) T cells was greater in extraglandular SS patients (26.7+/-14.1%) compared with glandular SS (9.9 +/- 9.1%) (P<0.01) and controls (9.4 +/- 5.8%) (P<0.001). There was no significant difference in the percentages of IL-4(+) proliferating CD4(+) T cells among the groups. However, the proliferating response of CD4(+) T cells was significantly decreased in extraglandular SS patients (percentage of proliferating cells 38.4 +/- 18.6%) compared with that in glandular SS patients (64.2 +/- 17.2%) (P<0.05) and controls (63.1+/-10.6%) (P<0.01). CONCLUSIONS: CD4(+) T cells from extraglandular SS patients may have a predisposition for entry into the IFN-gamma-producing effector pathway as a result of the stimulations. These results are helpful for understanding the immunological difference between glandular and extraglandular SS and the mechanisms of disease progression.     

Immunological and virological impact of highly active antiretroviral therapy initiated during acute HIV-1 infection

The immunological and virological impact of short-term treatment initiated during acute human immunodeficiency virus type 1 (HIV-1) infection was assessed prospectively in 20 subjects, 12 of whom initiated highly active antiretroviral therapy (HAART) for 24 weeks and then terminated treatment. Treatment resulted in suppression of viremia, an increase in the CD4+ T cell count, enhanced differentiation of HIV-1-specific CD8(+) T cells from effector memory to effector cells at week 24 of HAART, and significantly higher virus-specific interferon- gamma+ CD8+ T cell responses after viral rebound (at week 48). However, despite these immunological changes, no differences in viremia or in the CD4+ T cell count were found 6 months after HAART was stopped, when treated subjects were compared with untreated subjects.     

CD4(+) T-cell responses to Epstein-Barr virus (EBV) latent membrane protein 1 in infectious mononucleosis and EBV-associated non-Hodgkin lymphoma: Th1 in active disease but Tr1 in remission

Primary infection with Epstein-Barr virus (EBV) in childhood is usually asymptomatic, whereas infection in adolescence may result in infectious mononucleosis (IM) often followed by a fatigue syndrome. EBV latent membrane protein 1 (LMP1) is expressed in latency and in many EBV-associated tumours, including non-Hodgkin lymphoma (NHL). Given the regulatory nature of the CD4(+) T-cell response against LMP1 previously reported in healthy donors, we investigated whether patients with active EBV-driven disease can nevertheless mount effector [T-helper cell, type 1 (Th1)] anti-LMP1 responses. We therefore performed a longitudinal study of the nature of CD4(+) T-cell responses to LMP1 in four patients with IM, and five patients with NHL. In both groups, responses changed with time. During symptomatic infection or active tumour growth, responses were dominated by a Th1 effector phenotype, but switched to a regulatory interleukin-10 response upon recovery. In addition, the fine specificities of the T cells driving these responses evolved. This study showed the dynamic nature of CD4(+) T-cell responses to LMP1, and demonstrated that, although patients can mount Th1 effector responses, recovery from IM and NHL is associated with regulatory responses.     

Abnormalities of T lymphocyte subsets in Beh?et's disease demonstrated with anti-CD45RA and anti-CD29 monoclonal antibodies.

We assessed T cell subpopulations using 2-color flow cytometry with phycoerythrin conjugated anti-CD45RA and anti-CD29 and fluorescein conjugated anti-CD4 and anti-CD8 monoclonal antibodies, on peripheral blood lymphocytes from 19 patients with Beh?et's disease (BD) and 18 healthy control subjects. The percentage of CD4+ cells was significantly lower in patients with BD (34 +/- 2%) than in control subjects (46 +/- 3%) (p less than 0.001). Among CD4+ cells, the percentage of suppressor-inducer (CD4+CD45RA+) cells was significantly lower in patients with BD (31 +/- 4%) than in control subjects (45 +/- 2%) (p less than 0.01), while the percentages of helper-inducer (CD4+CD29+) cells were similar in patients and controls. The percentage of CD8+ cells was significantly higher in patients with BD (36 +/- 2%) than in control subjects (26 +/- 2%) (p less than 0.001) involving both CD45RA+ and CD29+ subpopulations. Within CD4+ cells, the percentage of suppressor-inducer (CD4+CD45RA+) cells was significantly decreased in patients with active BD (26 +/- 3%) compared with control subjects (45 +/- 2%) (p less than 0.001), whereas in patients with inactive BD the difference was statistically insignificant. Our results suggest that the defective suppressive function in patients with active BD may be related to the decreased suppressor-inducer subpopulation (CD4+CD45RA+).     

Effektor-Memory-T‑Zellen in der Pathogenese von ANCA-assoziierten Vaskulitiden

Patients with antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitides (AAV) have an expansion of effector memory T?cells in peripheral blood. The enlarged effector memory cell population contains distinct cell subsets, including T?helper type 1 (Th1) CD4+ T?cells lacking co-stimulatory CD28 expression and Th17 cells in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) and Th2 type and Th17 cells in eosinophilic granulomatosis with polyangiitis (EGPA). The cytokine response of autoreactive proteinase 3 (PR3)-specific effector memory T?cells is skewed towards an increase of Th2 type, Th17 and Th22 cell fractions in GPA. Anomalous effector memory CD4+ T?cell co-stimulation is suggested by the aberrant expression of P?selectin glycoprotein ligand?1, beta?2 integrin, chemokine receptors, natural-killer group 2 member D (NKG2D) and other activating receptors. The increased expression of these receptors is accompanied by T?cell activation and migration to inflamed tissues. The T?cells are abundant and secrete proinflammatory cytokines in inflammatory lesions in AAV. The T?cell mediated tissue damage correlates with renal outcome, whereas B-cell infiltration does not. Activation of lesional CD4+NKG2D+ effector memory T?cells is independent of the antigen; moreover, CD4+NKG2D+ effector memory T?cells display NK-cell-like cytotoxicity towards microvascular endothelial cells in vitro. Thus, effector memory T?cells play an important role in tissue damage and disease progression in AAV. Sequentially administered or combined with B-cell depleting therapy, T?cell-directed therapies, especially those directed against effector memory CD4+ T?cells, may further improve the outcome and help to achieve long-term remission in AAV.     

Suppressive T cell function of Epstein-Barr virus induced B cell activation in active Beh?et's disease.

B and T cell function were studied in 10 patients with active Beh?et's disease (BD) and in 10 normal subjects. Peripheral B lymphocytes infected with Epstein-Barr virus (EBV) were cultured for 20 days in the presence or absence of autologous T cells. Immunoglobulin M and G secretions into the supernatants were assessed with an enzyme-linked immunosorbent assay. The extent of suppression of EBV-induced B cell activation by autologous T cells was significantly decreased in active BD patients as compared to normal subjects at a T:B ratio of 1:1, whereas the suppression ratio was in the normal range at a T:B ratio of 4:1. The IgM and IgG secretions in purified B cell cultures were significantly higher in active BD patients as compared to control subjects. Thus, an increased B cell function associated with a defective EBV-specific T cell suppressive function could explain at least in part the immunological disorders in BD patients.     

Immunosuppression during active tuberculosis is characterized by decreased interferon- gamma production and CD25 expression with elevated forkhead box P3, transforming growth factor- beta , and interleukin-4 mRNA levels

The balance between effector and regulatory responses after Mycobacterium tuberculosis infection may dictate outcome and progression to active disease. We investigated effector and regulatory T cell responses in bacille Calmette-Guerin (BCG)-stimulated peripheral blood mononuclear cells and whole blood cultures from persons with active tuberculosis (TB), persons with TB at the end of 6 months of treatment, and healthy control subjects with latent TB infection. All 3 groups displayed BCG-induced increases in effector and regulatory T cell phenotypes as defined by CD4(+)CD25(lo) and CD4(+)CD25(hi) T cells, respectively. In case patients with active disease, BCG stimulation induced the lowest increase of CD25, CD4(+)CD25(hi), CTLA-4, and interferon- gamma . However, these case patients expressed the highest mRNA levels of forkhead box P3, transforming growth factor (TGF)- beta , and interleukin (IL)-4 and a lower T-bet : GATA-3 ratio. There were no significant differences in IL-4 delta 2, IL-10, or TGF- beta receptor-II mRNA expression between groups. Together, these results suggest that immunosuppression seen after mycobacterial stimulation in case patients with active TB is associated with naturally occurring regulatory T cells.     

T Helper Cells Profile and CD4+CD25+Foxp3+Regulatory T Cells in Polycystic Ovary Syndrome

Background: Polycystic ovary syndrome (PCOS) is considered as the most common cause of female infertility that affects 4-10% of women in the reproductive age. Previous studies have shown the role of a balanced immune response in a successful pregnancy and fertility. Objective: To investigate the T helper cells type 1 (Th1) /Th2/Th17/Treg paradigms in peripheral blood of infertile PCOS compared with normal fertile women. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated at the late follicular phase from 10 PCOS and 10 fertile women. PBMCs were stimulated with PMA and ionomycin in the presence of Berefeldin A as Golgi stop agent to detect intracellular cytokine production (IFN-γ, IL-17, and IL-4) from CD3+CD4+T cells population indicating T helper (Th) cells subsets by flowcytometry. Moreover, regulatory T cells were enumerated using CD25 and Foxp3 markers. Results: In this study, we report that the frequency of Th1 cells was increased compared to Th2 cells in infertile PCOS when considering Th1/Th2 ratio (P=0.05). Analysis of Th17/Th2 ratio showed a significant difference with a bias toward Th17 dominancy in PCOS (P=0.02). The proportion of CD4+CD25+Foxp3+ regulatory T cells was significantly lower in PCOS patients than that of healthy fertile women (P=0.02). Conclusion: In summary, Th1 and Th17 bias and reduction of Treg and Th2 cells as regulators of immune responses might be involved in the pathogenesis of PCOS. These results are suggestive of an altered immune response to inflammatory status in PCOS patients, likely causing some complications such as infertility in these patients.     

Hepatitis C‐specific effector and regulatory CD4 T‐cell responses are associated with the outcomes of primary infection

Clearance of primary hepatitis C virus (HCV) infection has been associated with strong and broadly targeted cellular immune responses. This study aimed to characterize HCV‐specific CD4+ effector and regulatory T‐cell numbers and cytokine production during primary infection. Antigen‐specific CD4+ T‐cell responses were investigated in a longitudinal cohort of subjects from pre‐infection to postoutcome, including subjects who cleared [n=12] or became chronically infected [n=17]. A cross‐sectional cohort with previously cleared, or chronic infection [n=15 for each], was also studied. Peripheral blood mononuclear cells were incubated with HCV antigens and surface stained for T‐effector (CD4+CD25^highCD134+CD39‐) and T‐regulatory (CD4+CD25^highCD134+CD39+) markers, and culture supernatants assayed for cytokine production. Contrary to expectations, the breadth and magnitude of the HCV‐specific CD4+ T‐cell responses were higher in subjects who became chronically infected. Subjects who cleared the virus had HCV‐specific CD4+ T‐cell responses dominated by effector T cells and produced higher levels of IFN‐γ, in contrast to HCV‐specific CD4+ T‐cell responses dominated by regulatory T cells and more IL‐10 production in those who became chronically infected. Better understanding of the role of antigen‐specific CD4+ T‐cell responses in primary HCV will further define pathogenesis and help guide development of a preventative vaccine.     

强直性脊柱炎患者外周血CD4+CD25+调节性T细胞的研究

目的 观察强直性脊柱炎(AS)患者外周血CD4+CD25调节性T细胞(Treg)的数量、功能及肿瘤坏死因子(TNF)-a 抑制剂治疗的影响.方法 活动性AS患者25例,10例给予etanercept治疗12周,健康对照21名,分离外周血单个核细胞(PBMC),流式细胞术检测CD4+CD25high T细胞比例;实时定量聚合酶链反应检测FOXP3 mRNA表达;免疫磁珠法去除CD25+细胞,可溶性噻唑盐(WST-1)法检测T细胞增殖.结果 活动性AS组CD4+CD25high T细胞比例与对照组差异尤统计学意义,但FOXP3 mRNA表达明显低于对照组(P＜0.01),并与C反应蛋白(CRP)呈负相关(P＜0.01).两组的CD4+CD25+细胞体外均能抑制T细胞增殖(P均＜0.01). Etanercept治疗明显增加CD4+CD25highT细胞比例和FOXP3 mRNA表达(P均＜0.01),与CRP降低呈负相关(P＜0.05;P＜0.01).结论 AS患者外周血表达FOXP3的CD4+CD25+Treg细胞异常,可能参与AS发生和发展;Etanercept治疗上调Treg细胞,可能是抗TNF-α治疗的一个机制.     

Analysis of Th1 and Th2 cytokines expressing CD4+ and CD8+ T cells in rheumatoid arthritis by flow cytometry

OBJECTIVE: A Th1/Th2 cytokine imbalance with a predominance of Th1 cytokines has been suggested to be of pathogenetic importance in rheumatoid arthritis (RA). To evaluate the role of Th1/Th2 cytokines in RA, we used intracellular cytokine flow cytometry to determine cytokine profiles of CD4+ and CD8+ T cells in 34 peripheral blood (PB) and 10 synovial fluid (SF) samples from patients with RA. Results were compared with 10 PB samples from healthy controls (HC) and 5 SF samples from patients with non-RA synovitis. METHODS: After stimulating cells with PMA and ionomycin or alternatively with anti-CD3/CD28 in the presence of brefeldin A, intracellular levels of Th1 [interleukin 2 (IL-2), interferon-gamma (IFN-gamma)] and Th2 cytokines (IL-4, IL-5, IL-10, IL-13) were determined for CD3+CD8- (i.e., CD4+ Th1 and Th2 cells) and CD3+CD8+ (i.e., CD8+ Tc1 and Tc2 cells) T cells. RESULTS: The percentages of CD4+ and CD8+ Th1 and Th2 cytokines producing T cells (PB) were similar in patients with RA and healthy controls (HC), with a clear predominance of Th1 cytokines expressing, T cells. With regard to T cell subsets, IFN-gamma-producing T cells were significantly more frequently detected in the CD8+ subset [CD8+: median 45.1% (RA; p < 0.001), 38.2% (HC; p = 0.009) vs CD4+: 10.8%(RA), 17.0% (HC)]. Conversely, IL-2 was found in a higher percentage of CD4+ T cells [CD4+: median 33.4% (RA), 17.9% (HC) vs CD8+: 23.6% (RA), 12.3% (HC)]. Patients not in disease remission tended to have more IFN-gamma-producing CD8+ and IL-2-producing CD4+ T cells than patients in remission [CD8+: median 45.9% (IFN-gamma) vs 23.0% (IFN-gamma); CD4+: median 34.1% (IL-2) vs 18.2% (IL-2)1. In all PB samples, the proportion of T cells producing the Th2 cytokines IL-4, IL-5, IL-10, and IL-13 did not exceed 2%. Cytokine profiles did not differ between patients receiving immunosuppressive treatment and patients treated only with nonsteroidal antiinflammatory drugs. In comparison to PB, RA SF analysis revealed a significant increase in the percentage of IFN-gamma-producing CD4+ (p < 0.001) and CD8+ T cells (p < 0.001). In addition, the percentage of IL-10-producing CD4+ (p < 0.001) as well as CD8+ T cells (p = 0.001) was significantly elevated in SF. However, production of the other Th2 cytokines (IL-4, IL-5, IL-13) was similar in SF and PB. CONCLUSION: These data indicate similar cytokine profiles of T cells in PB of RA patients and healthy controls, with a strong predominance of Th1 cytokines producing T cells in the CD4+ and CD8+ T cell subset of both groups. PB cytokine profiles did not significantly differ in patients with active and non-active disease or between patients receiving and those not receiving immunosuppressive medication. In SF, the proportion of Th1 and Tcl cells was significantly elevated compared to PB, emphasizing the local importance of these cells for inflammation. CD8+ T cells (Tc1 cells) mainly contributed to the production of IFN-gamma, indicating an underestimated role of this cell subset for local cytokine production. The upregulation of IL-10-producing Th2 and Tc2 cells in SF may reflect an insufficient effort to down-regulate chronic inflammation in the joint. Modifying this cytokine imbalance in the joints may be a promising therapeutic approach in RA.     

Th1 and Th17 cell subpopulations are enriched in the peripheral blood of patients with systemic juvenile idiopathic arthritis

Objective. The role of the adaptive immune system has not been explored in detail compared with the innate immune system in systemic JIA (sJIA) pathogenesis. The aim of this study was to examine the phenotype of circulating peripheral blood CD4(+) T-cell subpopulations in a cross-sectional study of sJIA patients during disease remission on medication and during acute flare of the disease. Methods. Flow cytometry was used to examine the phenotype and cytokine production of IFNγ-, IL-4- and IL-17-producing CD4(+) T cells in the peripheral blood of 10 sJIA patients with active disease, 9 sJIA with inactive disease, 14 JIA patients with oligoarticular onset, 10 adult control subjects and 10 age-matched control subjects. In parallel, we examined the proportion of FoxP3(+) Tregs. Results. IFNγ- and IL-17-producing CD4(+) T cells and IL-17-producing CD3(+)CD4(-) T cells were present at higher proportions in the peripheral blood of sJIA patients, irrespective of their disease status. Our data also confirm the known increase of the proportions of IFNγ-producing Th1 cells with increasing age and suggest an increase with age in the IL-17-producing CD4(+) T-cell population. Conclusion. This study is the first to describe significantly higher proportions of Th1 and Th17 T helper cell subsets in the peripheral blood of sJIA patients. These proinflammatory cells may play a pathogenic role in sJIA. Our data also emphasize the importance of using paediatric age-matched control subjects when evaluating the T-cell cytokine profile in JIA.     

Impaired Th1 cytokine production in spondyloarthropathy is restored by anti-TNFα

OBJECTIVES: To evaluate the effect of anti-TNFalpha on the Th1 and Th2 cytokines in patients with spondyloarthropathy (SpA). METHODS: Peripheral blood mononuclear cells (PBMC) were obtained from 20 patients with active SpA treated with infliximab (5 mg/kg). For comparison, PBMC were also obtained from 15 healthy controls and 19 patients with active rheumatoid arthritis (RA). After stimulation with PMA/ionomycin, the intracellular cytokines interleukin (IL)2, IL4, IL10, and interferon (IFN)gamma were determined in CD3+ T cells and in CD3+/CD56+ natural killer (NK) T cells by flow cytometry. RESULTS: At baseline the percentage of T cells positive for IFNgamma (p=0.020) and IL2 (p=0.046) was decreased in patients with SpA compared with healthy controls, while IL10 (p=0.001) was increased. This cytokine profile, confirmed by the mean fluorescence intensities (MFI), was more pronounced in CD3+/CD8- cells and contrasted with higher IL2 production in RA. NK T cells, characterised by high IL4 and IL10 numbers, were also increased in patients with SpA (p=0.017). Treatment with infliximab induced a significant and persistent increase in IFNgamma and IL2 in patients with SpA. Moreover, there was a transient decrease in IL10 and NK T cells in patients with high baseline values, resulting in values comparable with those of healthy controls. This switch in cytokine profile was seen in both the CD3+/CD8- and CD3+/CD8+ subsets. CONCLUSIONS: Before treatment patients with SpA had an impaired Th1 cytokine profile compared with healthy controls and patients with RA. TNFalpha blockade induced restoration of the Th1 cytokines, resulting in a normal cytokine balance. These data confirm the effect of anti-TNFalpha on the immune changes in SpA, and provide insights into the mechanisms involved in TNFalpha blockade.     

Assessment of immune function by lymphoproliferation underestimates lymphocyte functional capacity in HIV patients treated with highly active antiretroviral therapy

The objective of this study was to evaluate T cell responses in HIV-infected patients after highly active antiretroviral therapy (HAART), using four assays of immune function, and to determine which best reflects the presence of CD4(+) T cells able to respond to CMV antigen. Peripheral blood mononuclear cells from 41 HIVinfected patients and 31 healthy HIV-seronegative controls were cultured with mitogen (PMA/Ca(2+) ionophore) or antigen (CMV). Production of interferon gamma (IFN-gamma) determined by ELISpot assay was compared with lymphoproliferation, IFN-gamma production assessed by ELISA, and CD69 expression and intracellular IFN-gamma assessed by flow cytometry. Cells from patients whose CD4(+) T cells counts increased 4-fold or to >200 cells/microl after HAART responded as well as control cells when assessed by IFN-gamma production and CD69 expression after mitogenic stimulation, but lymphoproliferation responses were depressed by about 52%. Patients who did not meet these criteria for immune reconstitution had lymphoproliferative responses up to 30-fold lower than control subjects, while intracellular IFN-gamma and CD69 expression and ELISpot counts were less than 3-fold lower. Responses to CMV antigen could not be detected by flow cytometry, but were readily detected by ELISpot in CMV-seropositive patients whose CD4(+) T cell counts had increased after HAART. This included patients with low responses assessed by lymphoproliferation. Moreover, ELISpot responses measured with fresh and frozen cells were comparable, while lymphoproliferation assays required fresh cells. In conclusion, the ELISpot assay is a sensitive and efficient technique for detecting CMV-specific IFN-gamma responses in samples that display poor responses when assessed by lymphoproliferation assays.     

Activation of Th1 and Tc1 cell adenosine A2A receptors directly inhibits IL-2 secretion in vitro and IL-2-driven expansion in vivo

To evaluate the direct effect of adenosine on cytokine-polarized effector T cells, murine type 1 helper T cells (Th1) and type 1 cytotoxic T lymphocytes (Tc1) and Th2/Tc2 cells were generated using an antigen-presenting cell (APC)-free method. Tc1 and Tc2 cells had similar adenosine signaling, as measured by intracellular cyclic AMP (cAMP) increase upon adenosine A(2A) receptor agonism by CGS21680 (CGS). CGS greatly reduced Tc1 and Tc2 cell interleukin 2 (IL-2) and tumor necrosis factor alpha (TNF-alpha) secretion, with nominal effect on interferon gamma (IFN-gamma) secretion. Tc2 cell IL-4 and IL-5 secretion was not reduced by CGS, and IL-10 secretion was moderately reduced. Agonist-mediated inhibition of IL-2 and TNF-alpha secretion occurred via A(2A) receptors, with no involvement of A(1), A(2B), or A(3) receptors. Adenosine agonist concentrations that abrogated cytokine secretion did not inhibit Tc1 or Tc2 cell cytolytic function. Adenosine modulated effector T cells in vivo, as CGS administration reduced CD4(+)Th1 and CD8(+)Tc1 cell expansion to alloantigen and, in a separate model, reduced antigen-specific CD4(+) Th1 cell numbers. Remarkably, agonist-mediated T-cell inhibition was abrogated by in vivo IL-2 therapy. Adenosine receptor activation therefore preferentially inhibits type I cytokine secretion, most notably IL-2. Modulation of adenosine receptors may thus represent a suitable target primarily for inflammatory conditions mediated by Th1 and Tc1 cells.     

Direct inhibition of CD40L expression can contribute to the clinical efficacy of daclizumab independently of its effects on cell division and Th1/Th2 cytokine production

Humanized anti-CD25 antibodies (eg, daclizumab) have been successfully used to treat several autoimmune diseases. Paradoxically, IL-2 blockade in mice can induce autoimmunity. An interspecies difference in the relative contribution of IL-2 to CD25(+) T regulatory cell (CD25(+)Treg) versus CD25(+) effector cell function might explain this conundrum. Consistent with this are reports that daclizumab inhibits human CD25(+) effector cell cytokine production by blocking the expression of CD40L. However, in mice, IL-4 and IL-12 regulate CD40L expression. As human Th1/Th2 cytokine production is also dependent on IL-2, daclizumab's inhibition of CD40L expression could be due to an indirect, rather than a direct, effect of IL-2. Here, we clarify the mechanisms underlying CD40L expression. In contrast to the mouse, human CD40L is regulated by CD28 signaling and IL-2, not the principal Th1/Th2-polarizing cytokines. We find that CD40L is expressed on naive and memory cells and inhibited by daclizumab independently of cell division. Collectively, our results indicate that daclizumab could inhibit CD25(+) effector T-cell function in vivo by directly blocking CD40L expression. This difference between mice and human may help explain the paradoxical effects of IL-2R blockade in the 2 species.     

Characterization of subsets of CD4+ memory T cells reveals early branched pathways of T cell differentiation in humans

The pathways for differentiation of human CD4(+) T cells into functionally distinct subsets of memory cells in vivo are unknown. The identification of these subsets and pathways has clear implications for the design of vaccines and immune-targeted therapies. Here, we show that populations of apparently naive CD4(+) T cells express the chemokine receptors CXCR3 or CCR4 and demonstrate patterns of gene expression and functional responses characteristic of memory cells. The proliferation history and T cell receptor repertoire of these chemokine-receptor(+) cells suggest that they are very early memory CD4(+) T cells that have "rested down" before acquiring the phenotypes described for "central" or "effector" memory T cells. In addition, the chemokine-receptor(+) "naive" populations contain Th1 and Th2 cells, respectively, demonstrating that Th1/Th2 differentiation can occur very early in vivo in the absence of markers conventionally associated with memory cells. We localized ligands for CXCR3 and CCR4 to separate foci in T cell zones of tonsil, suggesting that the chemokine-receptor(+) subsets may be recruited and contribute to segregated, polarized microenvironments within lymphoid organs. Importantly, our data suggest that CD4(+) T cells do not differentiate according to a simple schema from naive --> CD45RO(+) noneffector/central memory --> effector/effector memory cells. Rather, developmental pathways branch early on to yield effector/memory populations that are highly heterogeneous and multifunctional and have the potential to become stable resting cells.