Interleukin-7 improves reconstitution of antiviral CD4 T cells

We evaluated whether long-term (2 months) administration of interleukin-7 (IL7) hastens immune recovery in baboons rendered severely lymphopenic by total body irradiation and antithymocyte globulin (ATG). Four baboons were treated with recombinant baboon IL7 and three baboons with placebo. Median CD4 T cell count at the end of IL7/placebo treatment was higher in the IL7-treated animals (2262 vs. 618/microl, P = 0.03). This appeared to be a result of peripheral expansion rather than de novo generation. Median cytomegalovirus (CMV)-specific IFNgamma-producing CD4 T cell count at the end of IL7/placebo treatment was higher in the IL7-treated animals (122 vs. 1/microl, P = 0.03). All animals were pretransplant cytomegalovirus-seropositive. One animal died at the end of IL7 treatment; necropsy showed extensive T cell infiltration of kidneys and lungs. In conclusion, IL7 stimulates the expansion of CD4 T cells, including functional antiviral cells. Clinical risk-benefit ratio needs to be evaluated.     

Novel promiscuous HLA-DQ HIV Nef peptide that induces IFN-gamma-producing memory CD4+ T cells

We describe the highly conserved sequence 56-68 of the HIV Nef protein as the first promiscuous HLA-DQ HIV-derived peptide. The Nef peptide exhibits an albeit rare capacity to bind 6 different HLA-DQ molecules whereas no binding is observed with the 10 HLA-DR molecules tested. In agreement with these data, after immunization with the Nef peptide, HLA-DQ transgenic Abeta degrees mice display a vigorous cellular and humoral response while the specific immune response of HLA-DR expressing mice is minimal. The promiscuous potentiality of the Nef 56-68 peptide in humans has been confirmed by ex vivo immunization experiments with CD4+ T cells from 14 healthy donors expressing different HLA genotypes. Nef 56-68 specific CD4+ T cells rapidly acquire a memory cell phenotype and are characterized by the preferential usage of the TCR Vbeta 6.1 gene segment and predominant production of IFN-gamma. Taken together, these data indicate that the Nef 56-68 peptide constitutes an attractive component of vaccines aiming at inducing or enhancing HIV-specific T cell immunity.     

Expansion of regulatory T cells from umbilical cord blood and adult peripheral blood CD4+CD25+ T cells

CD4⁺CD25⁺ regulatory T cells (Treg), if properly expanded from umbilical cord blood (UCB), may provide a promising immunotherapeutic tool. Our previous data demonstrated that UCB CD4⁺CD25⁺ T cells with 4-day stimulation have comparable phenotypes and suppressive function to that of adult peripheral blood (APB) CD4⁺CD25⁺ T cells. We further examined whether 2-week culture would achieve higher expansion levels of Tregs. UCB CD4⁺CD25⁺ T cells and their APB counterparts were stimulated with anti-CD3/anti-CD28 in the presence of IL-2 or IL-15 for 2 weeks. The cell proliferation and forkhead box P3 (FoxP3) expression were examined. The function of the expanded cells was then investigated by suppressive assay. IL-21 was applied to study whether it counteracts the function of UCB and APB CD4⁺CD25⁺ T cells. The results indicate that UCB CD4⁺CD25⁺ T cells expanded much better than their APB counterparts. IL-2 was superior to expand UCB and APB Tregs for 2 weeks than IL-15. FoxP3 expression which peaked on Day 10–14 was comparable. Most importantly, expanded UCB Tregs showed greater suppressive function in allogeneic mixed lymphocyte reaction. The addition of IL-21, however, counteracted the suppressive function of expanded UCB and APB Tregs. The results support using UCB as a source of Treg cells.     

Sialylation regulates peripheral tolerance in CD4+ T cells

Decreased binding by the 6C10 auto-antibody serves as a unique marker for CD4+ T cell unresponsiveness after the induction of T cell tolerance in Vbeta8.1 TCR transgenic mice. We further define the nature of the epitope recognized by the 6C10 antibody to be a subset of Thy-1 bearing incompletely sialylated N-linked glycans, and furthermore, we demonstrate that tolerant CD4+ T cells have an increased degree of cell-surface sialylation. To test the significance of the altered glycosylation state identified by the 6C10 auto-antibody in the tolerant CD4+ T cell population, surface sialic acid was cleaved enzymatically. Treatment of purified peripheral CD4+ T cells with Vibrio cholerae sialidase (VCS) leads to increased 6C10 binding, significantly enhances proliferation in the tolerant CD4+ population and corrects defects in phosphotyrosine signaling observed in the tolerant CD4+ T cell. Furthermore, in vivo administration of VCS enhances proliferation in both tolerant and naive CD4+ T cell subsets. These studies suggest that sialylation of glycoproteins on the surface of the CD4+ T cell contributes to the regulation of T cell responsiveness in the tolerant state.     

Neuropilin-1+T细胞与CD4+CD25+调节性T细胞的比较

目的:分析Neuropilin-1 T细胞(Nrp-1 T细胞)与经典CD4 CD25 调节性T细胞(Treg)的关系并比较二者的免疫调节作用。方法:流式细胞术分析BALB/c小鼠脾脏T细胞上Nrp-1与CD4、CD25的表达关系并分选Nrp-1 T细胞及CD4 CD25 Treg,通过B16-F10-luc-G5黑色素肿瘤细胞体外培养实验并利用萤光成像系统,观察比较两种细胞对NK细胞杀伤B16-F10-luc-G5黑色素瘤细胞的影响。结果:CD4 CD25 Treg中表达Nrp-1的比例为(27.28±1.17)%,明显高于CD4 CD25-T细胞的(1.63±0.08)%(P<0.01);在体外实验中,Nrp-1 T细胞与CD4 CD25 Treg均能抑制NK细胞杀伤B16-F10-luc-G5黑色素瘤细胞,Nrp-1 T细胞组的肿瘤细胞数目在6、24、48、72h分别为984±15、1015±14、1261±21、1323±38,高于CD4 CD25 Treg组的931±4、983±8、1201±18、1256±18,两组肿瘤细胞数目在各时间点均有统计学意义(P<0.01)。结论:经典CD4 CD25 Treg中表达Nrp-1的细胞比例较高,Nrp-1 T细胞有负性免疫调节作用,抑制功能比CD4 CD25 Treg更强,可以作为一类新的Treg亚群。     

Interleukin-11 modulates Th1/Th2 cytokine production from activated CD4+ T cells.

Recombinant human interleukin-11 (rHuIL-11) is a pleiotropic cytokine with effects on multiple cell types. rHuIL-11 reduces activated macrophage activity and downregulates production of proinflammatory mediators, such as tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO). In vitro and in vivo, rHuIL-11 inhibits production of key immunostimulatory cytokines, including IL-12 and interferon-gamma (IFN-gamma). rHuIL-11 has recently demonstrated immunomodulatory activity to downregulate IFN-gamma production, increase IL-4 production, and reduce inflammatory tissue injury in a human psoriasis clinical trial. The cellular mechanisms of these effects are not fully elucidated. We demonstrate here that expression of gp130 and IL-11 receptor (IL-11R) alpha mRNA, components of the IL-11R complex, are detected in human and murine CD4(+) and CD8(+) lymphocytes, suggesting that rHuIL-11 can directly interact with T cells. In a cell culture model of murine T cell differentiation, rHuIL-11 acts to inhibit IL-2 production as well as IL-12-induced IFN-gamma production and enhances IL-4 and IL-10 production. rHuIL-11 had no effect on T cell proliferation. The ability of rHuIL-11 to modulate cytokine production from activated CD4(+) T cells provides a mechanism through which rHuIL-11 may ameliorate such inflammatory diseases as psoriasis.     

Analyses of regulatory CD4+CD25+FOXP3+ T cells and observations from peripheral T cell subpopulation markers during the development of type 1 diabetes in children

Our aim was to study whether the aberrant amount or function of regulatory T cells is related to the development of type 1 diabetes (T1D) in children. We also set out to investigate the balance of different T cell subtype markers during the T1D autoimmune process. Treg cells were quantified with flow cytometric assay, and the suppression capacity was analysed with a carboxyfluorescein succinimidyl ester (CFSE)‐based T cell suppression assay in children in various phases of T1D disease process and in healthy autoantibody‐negative control children. The mRNA expression of different T cell subpopulation markers was analysed with real‐time qPCR method. The proportion and suppression capacity of regulatory T cells were similar in seroconverted children at an early stage of beta cell autoimmunity and also in children with T1D when compared to healthy and autoantibody‐negative children. Significant differences were observed in the mRNA expression of different T cell subpopulation markers in prediabetic children with multiple (≥2) autoantibodies and in children with newly diagnosed T1D when compared to the control children. In conclusion, there were no quantitative or functional differences in regulatory T cells between the case and control groups in any phase of the autoimmune process. Decreased mRNA expression levels of T cell subtype markers were observed in children with multiple islet autoantibodies and in those with newly diagnosed T1D, probably reflecting an exhaustion of the immune system after the strong immune activation during the autoimmune process or a generally aberrant immune response related to the progression of the disease.     

卵巢癌细胞培养上清诱导CD4+CD25-T细胞分化为CD4+CD25+调节性T细胞

目的研究卵巢癌细胞培养上清液是否能诱导外周血CD4^＋CD25^- T细胞转变为CD4^＋CD25^＋调节性T细胞。方法将外周血CD4^＋CD25^- T细胞分离后，对照组用CD3和CD28单抗活化，实验组在对照基础上加用卵巢癌细胞株SKOV3培养上清，72h后分离各组的CD25^＋和CD25^-T细胞，溴化脱氧尿嘧啶掺入标记法测定增殖能力及对静息的自体同源CD4^＋CD25^- T细胞的增殖抑制能力，流式细胞仪测定细胞糖皮质激素诱发型TNF受体（glucocorticoid-induced TNFR,GITR）与CTLA-4分子的表达，RT-PCR检测细胞卿mRNA的表达。结果与对照组相反，实验组的CD4^＋CD25^＋T细胞具有免疫抑制功能，自身增殖能力下降，GITR和CTLA-4分子的表达和CD4^＋CD25^＋调节性T细胞相似，并被诱导表达转录因子Foxp3 mRNA。结论卵巢癌细胞分泌的可溶性物质能诱导外周血CD4^＋CD25^-T细胞转化为CD4^＋CD25^＋调节性T细胞。     

CD4+ CD25+调节性T细胞AICD机制的研究

目的探讨CD4^＋CD25^＋调节性T细胞活化诱导的细胞死亡（AICD）发生的机制。方法CD4^＋CD25^＋T细胞以磁性细胞分离器（MACS）从BALB／c小鼠或DO11．10小鼠的静息T细胞分离纯化。体外细胞增殖抑制实验证实其免疫调节作用。CD4^＋CD25^＋T细胞的AICD以CD3／CD28单克隆抗体活化或以特异性OVA323-339肽、抗原提呈细胞活化等两种方法获得。CD4^＋CD25^＋T细胞凋亡相关基因的表达通过实时定量PCR检测。流式细胞仪检测细胞的凋亡率。进一步观察FasL中和抗体、TRAIL中和抗体及caspase抑制剂zVAD-fmk对CD4^＋CD25^＋T细胞凋亡的影响。结果MACS成功分离CD4^＋CD25^＋T细胞，纯度可达98％，该细胞可特异性表达Foxp3基因，能明显抑制效应性T细胞的体外增殖。CD3／CD28抗体以及OVA特异性抗原活化8d的CD4^＋CD25^＋调节性T细胞AICD达39％～45％。活化前后的CD4^＋CD25^＋调节性T细胞死亡受体家族表达发生明显变化；FasL、TRAIL中和抗体及zVAD-fmk可明显抑制CD4^＋CD25^＋调节性T细胞的凋亡。结论FasL／Fas及其他凋亡相关分子可能参与了CD4^＋CD25^＋调节性T细胞的凋亡。     

IL-15 and dendritic cells induce proliferation of CD4+CD25+ regulatory T cells from peripheral blood

CD4(+)CD25(+) regulatory T cells (Tregs) have recently been the subject of intense research due to their strong immunosuppressive effect. Increasing evidence suggests that IL-15 plays an important role in Tregs biology. Nevertheless, the mechanism by which IL-15 performs this function remains to be fully elucidated. To address this question, we isolated Tregs from human peripheral blood, and utilized IL-15, dendritic cells (DCs), or DCs combined with IL-15, to examine the proliferation of Tregs and to explore related molecular mechanisms. Here, we show that IL-15 can induce the proliferation of Tregs in the presence of DCs. The induction is mediated by DCs presenting IL-15 in trans to Tregs. Simultaneously, DCs-derived IL-2, regulated by IL-15, may also play a supportive role. After IL-15 withdrawal, IL-15 trans-endosomal recycling in DCs contributes to the proliferation of Tregs. The activation of Akt, Erk1/2 and STAT(5), and the degradation of p27(kip1) may be involved in this process. These findings might explain the proliferation of Tregs in the absence of IL-2 in vivo and provide a novel method to achieve large-scale proliferation of Tregs in vitro in order to obtain cell numbers sufficient for immunotherapy.     

Endogenous retroviral superantigen presentation by B cells induces the development of type 1 CD4+ T helper lymphocytes

The endogenous retroviral superantigen, minor lymphocyte stimulating antigen (Mls 1^a, encoded by Mtv-7), when presented by highly purified B cells induced the development of a highly polarized population of T helper (Th)1 cells from naive peripheral CD4⁺ T cells in vitro. Immobilized anti-Vβb6⁺ antibodies similarly generated highly polarized, largely Vβ6⁺, Th 1 populations in vitro. In the presence of exogenous interleukin-4, both stimuli were capable of generating Th 2, rather than Th 1 populations. Mls 1^a presentation by B cells in vivo led to the development of an equally polarized Th 1 population. Using monoclonal antibodies against interferon-γ and transforming growth factor-β it was demonstrated that maximal Th 1 development with either stimulus in vitro was dependent on the endogenous production of these two cytokines. Thus, our results demonstrate that the retroviral encoded superantigen, Mls 1^a, drives the development of Th 1 cells both in vitro and in vivo, and they suggest that B cell presentation does not, in itself, lead to the generation of Th 2 cells.     

A novel peripheral CD4+CD8+ T cell population: Inheritance of CD8α expression on CD4+ T cells

In this study we show the inheritance of a CD4⁺CD8⁺ peripheral T cell population in the H.B15 chicken strain. A large proportion of αβ T cells in peripheral blood (20–40%), spleen (10–20%) and intestinal epithelium (5–10%) co-express CD4 and CD8α, but not CD8β. CD4⁺ CD8αα cells are functionally normal T cells, since they proliferate in response to mitogens and signals delivered via the αβT cell receptor as well as via the CD28 co-receptor. These cells induce in vivo a graft versus host-reaction, providing further evidence for their function as CD4⁺ T cells. The CD4⁺CD8αα T cell population was found in 75% of the first progeny and in 100% of further progenies, demonstrating that co-expression of CD4 and CD8 on peripheral T cells is an inherited phenomenon. In addition, cross-breeding data suggest a dominant Mendelian form of inheritance. The hereditary expression of CD8α on peripheral CD4⁺ T cells in chicken provides a unique model in which to study the regulation of CD4 and CD8 expression.     

Regulated secretion from CD4+ T cells

The regulated secretion of cellular proteins is central to the correct function of many cell types, including immune cells. Lymphocyte control of the storage, transport and exocytosis of immunomodulatory molecules is a highly specialised task triggered by T cell receptor engagement. The regulated secretory pathway in CD8+ T and NK cells has been the focus of much research, and recent advances have provided insight into the molecular mechanisms governing secretory organelle biogenesis, trafficking and killing. By contrast, regulated secretory pathways in CD4+ T cells have not been studied extensively. Aside from their physiological function in normal T cells, components of CD4+ T cell secretory pathways might be implicated in the assembly of HIV-1. Here, we review findings that shed light on CD4+ T cell secretion in health and disease.     

Intravenous tolerization with type II collagen induces interleukin-4-and interleukin-10-producing CD4+ T cells

Intravenous (i.v.) administration of type II collagen (CII) is an effective way to induce tolerance and suppress disease in the collagen-induced arthritis (CIA) model. In this study, we demonstrated that a single i.v. dose of CII (as low as 0.1 mg/mouse) completely prevented the development of CIA. This suppression was accompanied by decreases in levels of antibody specific for the immunogen, bovine CII and autoantigen, mouse CII. Splenocytes obtained from CII-tolerized mice and stimulated with CII in vitro produced predominantly the T helper 2 (Th2)-type cytokines interleukin-4 (IL-4) and interleukin-10 (IL-10). In contrast, cells obtained from mice immunized with CII produced predominantly interferon-gamma (IFN-gamma). Two-colour flow cytometric analysis of cytokine expression and T-cell phenotype demonstrated that CD4+ cells and not CD8+ or gammadelta+ cells were the predominant regulatory cells producing IL-4 and IL-10. Transgenic mice bearing a T-cell receptor (TCR) specific for CII had a greater increase in the number of IL-4-secreting CD4+ cells, as well as a marked increase of IL-4 in culture supernatants. This cytokine was produced by transgene-bearing T cells. Elucidation of mechanisms for the induction of tolerance in mature T cells is an important line of study in autoimmune models because of the potential application for treating organ-specific autoimmune disease.     

Interleukin-7 specifically induces the B7/BB1 antigen on human cord blood and peripheral blood T cells and T cell clones

B7/BB1 is a cell surface molecule and member of the Ig superfamily that is constitutively expressed on dendritic cells.In addition, B7 is expressed on B cells, macrophages, T cells,and T cell clones following activation. Interaction of B7 withits natural ligand CD28 is required for optimal stimulationof T cells, activated via the TCR-CD3 complex, which is thoughtto be due to stabilization of cytokine mRNA. Here we demonstratethat the expression of B7 on T cells can specifically be inducedby IL-7. Induction of B7 expression on T cells and T cell clonesrequires at least 5 – 7 days of culture and representsa late activation event. Results of studies using T cell clones,as well as resting purified B7^– T cells, demonstrate thatB7 is induced on a substantial proportion of T cells after IL-7activation and is not due to an outgrowth of pre-existing B7+T cells. In addition, CD4+ as well as CD8+ T cells could beinduced to express B7. Stimulation of purified cord blood Tcells with cross-linked anti-CD3 mAb resulted in a relativelyfast (48 h) induction of B7, which could not be inhibited bya neutralizing anti-IL-7 mAb, whereas no endogenous IL-7 productionby activated T cells and T cell clones could be detected. Together,these results indicate that the B7 molecule can be induced onT cells by IL-7, but also by an IL-7 independent pathway involvingtriggering of the TCR-CD3 complex.     

HIV-1 gp120 induces NFAT nuclear translocation in resting CD4+ T-cells

The replication of human immunodeficiency virus (HIV) in CD4+ T-cells is strongly dependent upon the state of activation of infected cells. Infection of sub-optimally activated cells is believed to play a critical role in both the transmission of virus and the persistence of CD4+ T-cell reservoirs. There is accumulating evidence that HIV can modulate signal-transduction pathways in a manner that may facilitate replication in such cells. We previously demonstrated that HIV gp120 induces virus replication in resting CD4+ T cells isolated from HIV-infected individuals. Here, we show that in resting CD4+ T-cells, gp120 activates NFATs and induces their translocation into the nucleus. The HIV LTR encodes NFAT recognition sites, and NFATs may play a critical role in promoting viral replication in sub-optimally activated cells. These observations provide insight into a potential mechanism by which HIV is able to establish infection in resting cells, which may have implications for both transmission of HIV and the persistence of viral reservoirs.