Intratumoral CD4+CD25+ regulatory T-cell-mediated suppression of infiltrating CD4+ T cells in B-cell non-Hodgkin lymphoma

Most non-Hodgkin lymphomas (NHLs) are of B-cell origin, but the tumor tissue can be variably infiltrated with T cells. In the present study, we have identified a subset of CD4(+)CD25(+) T cells with high levels of CTLA-4 and Foxp3 (intratumoral T(reg) cells) that are overrepresented in biopsy specimens of B-cell NHL (median of 17% in lymphoma biopsies, 12% in inflammatory tonsil, and 6% in tumor-free lymph nodes; P = .001). We found that these CD4(+)CD25(+) T cells suppressed the proliferation and cytokine (IFN-gamma and IL-4) production of infiltrating CD4(+)CD25(-) T cells in response to PHA stimulation. PD-1 was found to be constitutively and exclusively expressed on a subset of infiltrating CD4(+)CD25(-) T cells, and B7-H1 could be induced on intratumoral CD4(+)CD25(+) T cells in B-cell NHL. Anti-B7-H1 antibody or PD-1 fusion protein partly restored the proliferation of infiltrating CD4(+)CD25(-) T cells when cocultured with intratumoral T(reg) cells. Finally, we found that CCL22 secreted by lymphoma B cells is involved in the chemotaxis and migration of intratumoral T(reg) cells that express CCR4, but not CCR8. Taken together, our results suggest that T(reg) cells are highly represented in the area of B-cell NHL and that malignant B cells are involved in the recruitment of these cells into the area of lymphoma.     

CD70+ non-Hodgkin lymphoma B cells induce Foxp3 expression and regulatory function in intratumoral CD4+CD25 T cells

Foxp3 expression was initially thought to be restricted to the CD4(+)CD25(+) regulatory T-cell population. However, recent studies suggest that forkhead box P3 (Foxp3) is expressed in CD4(+)CD25(-) T cells in aged mice. In the present study in B-cell non-Hodgkin lymphoma (NHL), we found that a subset of intratumoral but not peripheral blood CD4(+)CD25(-) T cells, comprising about 15% of intratumoral CD4(+) T cells, express Foxp3 and are capable of suppressing the proliferation of autologous infiltrating CD8(+) T cells. In vitro activation with OKT3/anti-CD28 antibody (Ab) or dendritic cells (DCs) induced Foxp3 expression in a subset of these CD4(+)CD25(-)Foxp3(-) T cells. We found that the presence of lymphoma B cells during activation augmented activation-induced Foxp3 expression in CD4(+)CD25(-) T cells. We also found that CD70(+) lymphoma B cells significantly contributed to the activation-induced Foxp3 expression in intratumoral CD4(+)CD25(-) T cells. Furthermore, the blockade of CD27-CD70 interaction by anti-CD70 Ab abrogated lymphoma B-cell-mediated induction of Foxp3 expression in intratumoral CD4(+)CD25(-) T cells. Taken together, these studies reveal a novel role for NHL B cells in the development of intratumoral regulatory T cells.     

CD4+ T-cell induction of Fas-mediated apoptosis in Burkitt's lymphoma B cells

Cytotoxic function of CD4+ Th1 cells is mediated by Fas (CD95, APO-1) and its ligand (Fas ligand). Recent studies using nontransformed B cells and the Ramos Burkitt's lymphoma (BL) B-cell line cells show that CD40 ligation at the B-cell surface by activated, CD40 ligand (CD40L)- bearing, CD4+ T cells upregulates Fas expression on B cells and primes B cells for Fas-mediated death signals. In this work, we examine whether this CD4+ T-cell-dependent molecular pathway for Fas upregulation and B-cell apoptosis reflects a peculiarity of the Ramos B- cell line or is applicable to other Burkitt's tumors as well. In 5 of the 6 Epstein-Barr virus-negative BL cell lines examined, the cells constitutively express undetectable or low levels of Fas and are resistant to Fas-mediated signals induced by monoclonal anti-Fas antibody. All 6 of the BL cell line B cells upregulate Fas in response to CD40 ligation, and in 4 of the cases they become sensitive to Fas- mediated death signals. In one BL cell line, the cells are constitutively sensitive to Fas-mediated cytolysis and are unaffected by CD40 signals. Next, we applied these immunologic manipulations to cells from a refractory clinical sample and observed that the tumor cells could be induced to express Fas and undergo apoptosis in our system. These results establish CD4+ T cells and the Fas-Fas ligand system as important immune regulators of Burkitt's lymphoma B cells and indicate that the susceptibility of tumor cells to Fas-mediated death signals can be modulated by specific activation events at the cell surface.     

An early sympathetic nervous system influence exacerbates collagen-induced arthritis via CD4+CD25+ cells

OBJECTIVE: Activation of the sympathetic nervous system (SNS) ameliorates collagen-induced arthritis (CIA) in the late phase of the disease but aggravates it in the presymptomatic phase. The aim of the present study was to determine whether CD4+CD25+ T cells are influenced by the SNS of mice and play a disease-modifying role in the early symptomatic phase of the disease. METHODS: We tested the effects of the SNS on arthritis by transferring CD4+CD25+ T cells from sympathectomized mice immunized with type II collagen and from immunized, SNS-intact animals (controls). We further characterized transferred cells by studying forkhead box P3 (FoxP3) expression, cell proliferation, and cytokine secretion. RESULTS: Using anti-dopamine-beta-hydroxylase antibodies for systemic sympathectomy, we noticed a time-dependent disease amelioration (strongest when sympathectomy was performed 7 days before immunization, with no effect 30 days after immunization). When CD4+CD25+ T cells from immunized and sympathectomized animals were transferred into mice with CIA (on day 32), disease severity was reduced compared with that in controls. However, the number of CD4+CD25+FoxP3+ cells and the FoxP3 expression level in CD4+CD25+ cells were not changed by sympathectomy. In a mixed assay of donor CD4+CD25- and CD4+CD25+ cells, proliferation was reduced when cells from sympathectomized animals were studied. In the same assay, secretion of tumor necrosis factor, interleukin-17 (IL-17), IL-10, and IL-4 (not interferon-gamma) was markedly reduced when cells were taken from sympathectomized animals. Culture of CD4+CD25+ cells with norepinephrine (10(-5)M) for 24 hours before transfer worsened the arthritis. CONCLUSION: The SNS increases disease severity in the early phase of symptomatic CIA by stimulating several proinflammatory aspects of CD4+CD25+ T cells.     

Recipient CD4+ T cells that survive irradiation regulate chronic graft-versus-host disease

Chronic graft-versus-host disease (cGVHD) is an increasingly common cause of morbidity and mortality in allogeneic stem cell transplantation (alloSCT). Relative to acute GVHD (aGVHD), much less is understood about cGVHD. Using the B10.D2 --> BALB/c murine cGVHD model, which shares critical pathologic features with human cGVHD, we find that radiation-resistant host T cells regulate cGVHD. We initially observed that recipients lacking all lymphocytes developed accelerated and more severe cGVHD. Using genetically deficient recipients, we determined that alphabeta+CD4+ T cells were required to regulate cGVHD. Increased cGVHD severity was not due to the absence of T cells per se. Rather, the potency of regulation was proportional to host T-cell receptor (TCR) diversity. Only CD4+CD25+, and not CD4+CD25-, host T cells ameliorated cGVHD when added back, indicating that host T cells acted not via host-versus-graft activity or by reducing homeostatic proliferation but by an undefined regulatory mechanism. Thus, preparative regimens that spare host CD4+CD25+ T cells may reduce cGVHD. Donor CD4+CD25+ T cells also reduced cGVHD. Depletion of CD4+CD25+ cells from the inoculum exacerbated disease, whereas transplantation of additional CD4+CD25+ cells protected against severe cGVHD. Additional CD4+CD25+ cells also promoted healing of established lesions, suggesting that their effects persist during the evolution of cGVHD.     

Innate CD4+CD25+ regulatory T cells are required for oral tolerance and inhibition of CD8+ T cells mediating skin inflammation

To elucidate the role of CD4+CD25+ regulatory T cells in oral tolerance, we used the model of contact hypersensitivity (CHS) to 2,4-dinitrofluorobenzene (DNFB), which is mediated by CD8+ Tc1 effector cells independently of CD4+ T-cell help. Conversely to normal mice, invariant chain knock-out (KO) (Ii degrees / degrees ) mice, which are deficient in CD4+ T cells, cannot be orally tolerized and develop a chronic hapten-specific CHS response. Transfer of naive CD4+ T cells before hapten gavage into Ii degrees / degrees mice restores oral tolerance by a mechanism independent of interleukin-10 (IL-10) production by CD4+ T cells. That naturally occurring CD4+CD25+ T cells are critical for oral tolerance induction is demonstrated by the finding that (1) transfer of CD4+CD25+ but not CD4+CD25- T cells into Ii degrees / degrees recipients completely prevents the CHS response and skin infiltration by CD8+ T cells, by blocking development of hapten-specific CD8+ T cells; (2) in vivo depletion of CD4+CD25+ cells by antibody treatment in normal mice impairs oral tolerance; and (3) CD4+CD25+ T cells inhibit hapten-specific CD8+ T-cell proliferation and interferon gamma (IFN gamma) production, in vitro. These data show that naturally occurring CD4+CD25+ T cells are instrumental for orally induced tolerance and are key actors for the control of antigen-specific CD8+ T-cell effectors mediating skin inflammation.     

IL-10-dependent infectious tolerance after the treatment of experimental allergic encephalomyelitis with redirected CD4+CD25+ T lymphocytes

How small numbers of CD4+CD25+ regulatory T cells suppress autoimmune responses in vivo is unclear. In this report we analyze the immunomodulatory activity of CD4+CD25+ T cells that are antigen-specifically redirected against myelin basic protein (MBP)89-101-specific autoreactive T cells by a MBP89-101-IA(s)-zeta chimeric receptor. We have previously shown that these redirected regulatory T cells are highly potent in treating a model autoimmune disease, experimental allergic encephalomyelitis. We show here that they have only limited effect in vivo on autoreactive T cell proliferation and therefore do not act by deleting or suppressing the expansion of pathologic effector cells. Rather, the redirected CD4+CD25+ T cells divert the pathologic T helper 1 self-specific T cell response to one characterized by high IL-10 and lower IL-4 production. Significantly, when isolated from the inducing CD4+CD25+ regulatory T cells, these self-specific T cells can independently suppress the autoreactive T cell response and experimental allergic encephalomyelitis development in an IL-10-dependent manner. These results provide evidence that CD4+CD25+ regulatory T cells can manipulate the adaptive immune response in vivo through the infectious induction of tolerance, specifically by promoting the formation of antigen-specific, IL-10-secreting regulatory T cells.     

干扰素治疗慢性乙型肝炎患者HBeAg转阴率和CD4~+CD25~+调节性T淋巴细胞水平的关系

目的 观察干扰素抗病毒治疗前后慢性乙型肝炎患者外周血CD4+CD25+调节性T细胞(CD4+CD25+Treg)表达水平的变化和HBeAg转阴的关系.方法 选择用干扰素α-2b治疗的HBeAg阳性慢性乙型肝炎56例,分别于治疗前、48周时检测外周静脉血CD4+CD25+Treg占CD4+T细胞的比例,同时检测HBeAg、ALT和HBVdNA载量.结果 抗病毒治疗48周后HBeAg转阴组CD4+CD25+rreg水平[(9.12±2.45)％]较治疗前[(11.99±3.25)％]明显下降(P＜0.01);而HBeAg未转阴组较治疗前无明显下降(P＞0.05).结论 慢性乙型肝炎患者经干扰素α-2b抗病毒治疗,HBeAg血清转换者CD4+CD25+Treg水平降低,而未转阴者Treg下降不明显.     

Interleukin 4 content in chronic lymphocytic leukaemia (CLL) B cells and blood CD8+ T cells from B-CLL patients: impact on clonal B-cell apoptosis

B-chronic lymphocytic leukaemia (CLL) clonal B cells are characterized by resistance to apoptosis. We evaluated clonal B cells and blood T cells for interleukin 4 (IL-4) content as IL-4 is able to increase CLL cell resistance to apoptosis. The content of IL-4 in CD8+ T cells of CLL patients (n = 9) ranged from 37% to 63% of the total CD8+ T cells (mean level of 49% +/- 3.4) compared with a range of 5-10% for control CD8+ T cells. Clonal B cells positive for cytoplasmic IL-4 ranged from 1% to 97% (mean value 57.8 +/- 6.9%). CD8+ T cells and clonal B cells secreted detectable levels of IL-4, but only clonal CLL B cells (n = 4) secreted IL-4 in association with increasing cell numbers. Fludarabine (F-ara-AMP, 0.1-100 micromol/ml) was able to downregulate the IL-4 content of CD8+ T cells, but not clonal B-cell IL-4. Culture supernatant from CLL CD8+ T cells decreased the spontaneous apoptotic rate of clonal B cells that was reversed with anti-IL-4 and soluble IL-4 receptor. These findings show that IL-4 is present in the microenvironment of B-CLL. In addition, use of agents that can interfere with IL-4 presentation to clonal B cells can be effective in increasing clonal B-cell apoptosis.     

Rapamycin selectively expands CD4+CD25+FoxP3+ regulatory T cells

Rapamycin is an immunosuppressive compound that is currently used to prevent acute graft rejection in humans. In addition, rapamycin has been shown to allow operational tolerance in murine models. However, a direct effect of rapamycin on T regulatory (Tr) cells, which play a key role in induction and maintenance of peripheral tolerance, has not been demonstrated so far. Here, we provide new evidence that rapamycin selectively expands the murine naturally occurring CD4(+)CD25(+)FoxP3(+) Tr cells in vitro. These expanded Tr cells suppress proliferation of syngeneic T cells in vitro and prevent allograft rejection in vivo. Interestingly, rapamycin does not block activation-induced cell death and proliferation of CD4(+) T cells in vitro. Based on this new mode of action, rapamycin can be used to expand CD4(+)CD25(+)FoxP3(+) Tr cells for ex vivo cellular therapy in T-cell-mediated diseases.     

CD4+CD25+ T regulatory cells control anti-islet CD8+ T cells through TGF-beta-TGF-beta receptor interactions in type 1 diabetes

Pancreatic lymph node-derived CD4+CD25+ T regulatory (Treg) cells inhibit in situ differentiation of islet-reactive CD8+ T cells into cytotoxic T lymphocytes, thereby preventing diabetes progression. The mechanism by which these Treg cells suppress anti-islet CD8+ T cells is unknown. Here, we show by using a CD8+ T cell-mediated model of type 1 diabetes that transforming growth factor (TGF)-beta-TGF-beta receptor signals are critical for CD4+CD25+ Treg cell regulation of autoreactive islet-specific cytotoxic T lymphocytes. Transgenic expression of tumor necrosis factor alpha from birth to 25 days of age in the islets of B6 mice that constitutively express CD80 on their beta cells results in accumulation of CD4+CD25+TGF-beta+ cells exclusively in the islets and pancreatic lymph nodes, which delays diabetes progression. In contrast, expression of tumor necrosis factor alpha until 28 days of age prevents islet accumulation of CD4+CD25+TGF-beta+ Treg cells, resulting in acceleration to diabetes. Furthermore, adoptive transfer experiments demonstrated that CD4+CD25+ Treg cells could not control na?ve or activated islet-reactive CD8+ T cells bearing a dominant negative TGF-beta receptor type II. Our data demonstrate that, in vivo, TGF-beta signaling in CD8+ T cells is critical for CD4+CD25+ Treg cell suppression of islet-reactive CD8+ T cells in type 1 diabetes.     

CD30 ligand is expressed on resting normal and malignant human B lymphocytes

CD30, a member of the tumour necrosis receptor superfamily, is physiologically expressed on a subpopulation of T helper cells in normal individuals but is also expressed on several malignant and virally transformed cells. Its ligand (CD30L) is a pleiotropic cellular transmembrane protein that can induce cell death in several CD30⁺ cell lines. CD30L expression has been reported on activated human peripheral blood T lymphocytes and macrophages but not on B cells. Here we show that the CD30L is expressed on resting normal and on malignant B cells in addition to both CD4⁺ and CD8⁺ subsets of activated T cells, making it the second tumour necrosis family member, in addition to the CD27 ligand, that can be expressed on both T and B cells. These findings raise the possibility that the CD30L has a role in B-cell/T-cell communication and that B and T cells are likely to be involved in the growth regulation of CD30⁺ tumours.     

CD4+CD25+Foxp3+调节性T细胞在慢性乙型肝炎患者中的作用

目的 探讨CD4+CD25+Foxp3+调节性T细胞与乙型肝炎慢性化和病毒清除之间的关系.方法 收集慢性活动性乙型肝炎(CAH)患者19例、HBV携带者(AsC)21例、HBV感染恢复者12例和健康对照者15例.通过流式细胞术分析外周血CD4+CD25+Foxp3+T细胞的表型和频率,磁珠分选(MACS)CD4+CD25+T细胞,实时荧光定量PCR方法 分析Foxp3 mRNA基因在CD4+CD25+T细胞的表达水平.统计学处理采用单因素方差分析或非参数检验.结果CAH或AsC组外周血CD4+CD25+Foxp3+T细胞频率以及CD4+CD25+T细胞中Foxp3 mRNA的表达水平显著高于健康对照组或HBV感染恢复者(F=6.8,F=3.72,均P<0.05).免疫组织化学染色发现,CAH患者肝组织Foxp3'T细胞浸润累积较对照组明显增高,但AsC较CAH减少.HBeAg阳性患者(包括CAH和AsC)CD4'CD25'T细胞频率显著高于HBeAg阴性患者(t=2.3,P<0.05),抗-HBe阴性患者显著高于抗-HBe阳性患者(t=2.4,P<0.05).CD4+CD25+Foxp3+T细胞频率与慢性乙型肝炎患者血清中HBV病毒载量存在正相关(r=0.56,P<0.01).结论 慢性乙型肝炎患者CD4+CD25+Foxp3+调节性T细胞异常与乙型肝炎慢性化和病毒清除有关.     

Chronic graft-versus-host disease is associated with increased numbers of peripheral blood CD4+CD25high regulatory T cells

Chronic graft-versus-host disease (cGVHD) is characterized by a state of profound immunodeficiency in association with alloreactive and autoimmune phenomena. These observations indicate an impairment of immunologic tolerance that could involve both central and peripheral mechanisms. Defective thymic function may contribute to dysregulation of central tolerance, but few studies have addressed peripheral tolerance. Recently a population of CD4+CD25+ T cells (Treg cells) has been characterized, which controls immunologic reactivity in vivo and which on transfer can prevent experimental acute GVHD. We investigated the number and function of peripheral blood CD4+CD25high T cells in patients more than 100 days after allogeneic hematopoietic stem cell transplantation. Patients with cGVHD had markedly elevated numbers of CD4+CD25high T cells as compared to patients without GVHD. CD4+CD25high T cells derived from patients in both groups were of donor origin, lacked markers of recent activation, and expressed intracellular CD152. In contrast to controls, CD4+CD25high T cells derived from patients with cGVHD were characterized by lower surface CD62L expression. In vitro, CD4+CD25high T cells were hyporesponsive to polyclonal stimulation and suppressed the proliferation and cytokine synthesis of CD4+CD25- cells, an effect that was independent of interleukin 10. These results indicate that chronic graft-versus-host injury does not occur as a result of Treg cell deficiency.     

慢性乙型肝炎患者浆样树突状细胞体外诱导CD4+CD25+调节性T细胞的研究

目的 观察慢性乙型肝炎患者,乙型肝炎恢复者和健康人浆样树突状细胞(pDCs)体外诱导CD4+CD25+调节性T细胞(CD4+CD25+Treg)能力的差异,为阐明HBV感染慢性化的机制奠定基础.方法 采用免疫磁珠分离法体外分离46例慢性乙型肝炎患者,10例乙型肝炎恢复者和25名健康人外周血单个核细胞中pDCs,并将其分别与健康人CD4+CD45RA+初始T细胞共培养.采用HBcAg或破伤风毒素对去除CD25+细胞的外周血单个核细胞进行增殖刺激后,使用流式细胞仪及RT-PCR对pDCs-T共培养细胞中CD4+CD25+Treg的数量、表型及FOXP3基因表达情况进行测定;采用酶联免疫吸附法对共培养细胞上清液中的白细胞介素-10和转化生长因子β1进行了进一步检测.两组数据比较采用Mann Whitney U-test.结果 当细胞增殖刺激物为HBcAg时,细胞增殖幅度慢性乙型肝炎患者组为(7999.36±374.74)cpm,乙型肝炎恢复者组为(11 282.56±1174.46)cpm和健康人组为(12 304.58±1462.81)cpm,慢性乙型肝炎患者组细胞增殖幅度明显小于乙型肝炎恢复者组和健康人组,U=0～22.0,P值均<0.05·乙型肝炎恢复者组和健康人组间增殖幅度差异无统计学意义.当增殖刺激物为破伤风毒素时,细胞增殖幅度与阳性对照组之间,差异无统计学意义.CD4+CD25+Treg比例慢性乙型肝炎患者组为5.99%±1.85%,乙型肝炎恢复者组为3.04%±0.79%,健康人组为3.01%±1.53%,慢性乙型肝炎患者组中韵CD4+CD25+Treg比例明显高于乙型肝炎恢复者组和健康人组,U=6.0～71.5,P值均<0.05.3组人群pDCs-T共培养细胞的CD4+CD25+T细胞均检测到Fox p3 RNA,而在CD4+CD25 T细胞中,均未检测到Fox p3RNA.3组人群pDCs-T共培养细胞实验组上清液的白细胞介素-10和转化生长因子β1含量均明显高于阳性对照组.结论 pDCs以诱导CD4+CD25+Treg形式参与了乙型肝炎的慢性化.     

支气管哮喘大鼠CD4+CD25+T细胞的变化及地塞米松干预作用的研究

目的 研究支气管哮喘(简称哮喘)大鼠模型支气管肺泡灌洗液(BALF)、血液、脾脏CD4+CD25+T细胞的变化,及地塞米松对CD4+CD25+T细胞的影响.方法 50只SD大鼠随机分为5组,空白对照(A)组,哮喘(B)组,地塞米松1(C)组、地塞米松2(D)组,地塞米松3(E)组.A组第l天给予腹腔注射生理盐水l ml,第15～21天每天给予生理盐水雾化.B、C、D、E组用卵蛋白建立哮喘大鼠模型,第1天,每只大鼠腹腔注射抗原l ml(卵蛋白1 mg+灭活百日咳杆菌9×106个+氢氧化铝干粉100 mg)混悬液,第15～21天给予1%的卵蛋白雾化30 min,C、D、E组于雾化后分别给予腹腔注射地塞米松0.2 mg/kg、1 mg/kg、2 mg/kg.采用流式细胞仪检测的方法 ,观察大鼠体内BALF、外周血、脾脏CD4+CD25+T细胞的变化及使用不同剂量地塞米松后对其的影响.结果 B组BALF、外周血、脾脏CD4+CD25+T细胞表达占CD4+T细胞的百分比分别是(42.21±5.62)%、(12.69±2.70)%、(11.15±1.05)%,A组结果 分别是(18.76±5.85)%、(6.21±1.73)%、(7.85±2.13)%.B组与A组比较,差异均具有统计学意义(P＜0.01,P＜0.01,P＜0.05);C组、D组、E组BALF中CD4+CD25+T细胞占CD4+T细胞的百分比表达分别是(10.49±4.03)%、(13.28±5.12)%、(7.51±5.39)%,显著低于A组和B组,(P＜0.05,P＜0.01);外周血中,C组(6.03±1.43)%、D组(4.88±0.95)%与A组(6.21±1.73)%比较,差异无统计学意义,E组(3.49±0.62)%与C组、A组比较,差异有统计学意义(P＜0.05).脾脏中,C组(7.25±1.82)%、D组(8.63±3.18)%与A组(7.85±2.13)%比较,差异无统计学意义,E组(3.38±1.37)%与C组、D组、A组比较,差异有统计学意义(P＜0.05).结论 CD4+CD25+T细胞在哮喘大鼠体内有明显的优势表达,可能是哮喘发病的机制之一.地塞米松可以抑制CD4+CD25+T细胞的表达.BALF内CD4+CD25+T细胞的变化与外周血和脾脏的变化具有一致性,监测外周血或脾脏CD4+CD25+T细胞变化可了解肺部情况.     

CD4+CXCR5+ T cells activate CD27+IgG+ B cells via IL-21 in patients with hepatitis C virus infection

BACKGROUND: Chronic hepatitis C virus (HCV) infection causes the skewing and activation of B cell subsets, but the characteristics of IgG+ B cells in patients with chronic hepa-titis C (CHC) infection have not been thoroughly elucidated. CD4+CXCR5+ follicularhelperT(Tfh)cells,viainterleukin (IL)-21 secretion, activate B cells. However, the role of CD4+CXCR5+T cellsintheactivationof IgG+ BcellsinCHCpatientsis not clear.
METHODS: The frequency of IgG+ B cells, including CD27?IgG+B and CD27+IgG+ B cells,the expression of the activation markers (CD86 and CD95) in IgG+ B cells, and the percentage of circu-lating CD4+CXCR5+ T cells were detected by flow cytometry in CHC patients (n=70) and healthy controls (n=25). The con-centrations of serum IL-21 were analyzed using ELISA. The role of CD4+CXCR5+ T cells in the activation of IgG+ B cells was investigated using a co-culture system.
RESULTS: A significantly lower proportion of CD27+IgG+ B cells with increased expression of CD86 and CD95 was observed in CHC patients.The expression of CD95 was negatively correlated with the percentage of CD27+IgG+ B cells, and it contributed to CD27+IgG+ B cell apoptosis. Circulating CD4+CXCR5+ T cells and serum IL-21 were significantly increased in CHC patients. Moreover, circulating CD4+CXCR5+ T cells from CHC patients induced higher expressions of CD86 and CD95 in CD27+IgG+B cells in a co-culture system; the blockade of the IL-21 decreased the expression levels of CD86 and CD95 in CD27+IgG+ B cells.
CONCLUSIONS: HCV infection increased the frequency of CD4+CXCR5+ T cells and decreased the frequency of CD27+IgG+B cells. CD4+CXCR5+ T cells activated CD27+IgG+ B cells via the secretion of IL-21.     

Functional abnormalities of CD8+ T cells define a unique subset of patients with common variable immunodeficiency

A substantial subgroup of patients with common variable immunodeficiency (CVI) exhibit an abnormal T-cell phenotype characterized by a low CD4/CD8 ratio associated with a significant increase in the absolute number of CD8+ T cells (CVI4/8low patients). In the present study, we examined the phenotypic and functional properties of purified T-cell subsets in this group of CVI patients. CD8+ T cells from CVI4/8low patients manifested increased expression of HLA-DR and CD57 and decreased expression of CD45RA as compared with CD8+ T cells from normal controls. When stimulated with anti-CD3 and phorbol 12-myristate 13-acetate, purified patient CD8+ T cells exhibited significantly decreased proliferation, c-myc expression, and interleukin-2 (IL-2) production compared with that of normal CD8+ T cells. Nevertheless, mitogen-activated patient CD8+ T cells secreted elevated amounts of gamma-interferon and IL-5 and normal amounts of IL- 4. This abnormal pattern of proliferation and cytokine production was limited to the CD8+ T-cell subset as CD4+ T cells from these patients exhibited normal proliferation and cytokine production. In further functional studies, purified CD8+ T cells from CVI4/8low patients manifested increased cytotoxic T-lymphocyte activity and suppressor activity, as compared with normal CD8+ T cells, when they were tested in (1) an anti-CD3 "redirected" cytotoxicity assay and (2) a suppressor assay consisting of CD8+ T cells and Staphylococcus aureus Cowan I (SAC) plus IL-2-stimulated normal (allogeneic) B cells. In the latter case, patient CD8+ T cells suppressed IgG production, but not IgM production. Finally, in studies to evaluate the role of patient CD8+ T cells in the pathogenesis of hypogammaglobulinemia, we determined the capacity of SAC and IL-2 to induce Ig production in highly purified patient B cells, ie, in the absence of patient CD8+ T cells. We found that, whereas B cells from one patient produced normal amounts of IgG, B cells from three patients were unable to produce normal amounts of IgG under these conditions. These data establish the phenotypic and functional characteristics of CD8+ T cells in CVI4/8low and clearly distinguish CVI4/8low patients from other patients with this syndrome. The data do not support the contention that hypogammaglobulinemia in CVI4/8low patients is due to a direct effect of CD8+ T cells on terminal B-cell differentiation, except in the occasional patient. The abnormal CD8+ T cells may, nevertheless, have more subtle effects of lymphoid function that play a role in disease pathogenesis.