Circulating specific antibodies enhance systemic cross-priming by delivery of complexed antigen to dendritic cells in vivo

Increasing evidence suggests that antibodies can have stimulatory effects on T‐cell immunity. However, the contribution of circulating antigen‐specific antibodies on MHC class I cross‐priming in vivo has not been conclusively established. Here, we defined the role of circulating antibodies in cross‐presentation of antigen to CD8⁺ T cells. Mice with hapten‐specific circulating antibodies, but na?ve for the T‐cell antigen, were infused with haptenated antigen and CD8⁺ T‐cell induction was measured. Mice with circulating hapten‐specific antibodies showed significantly enhanced cross‐presentation of the injected antigen compared with mice that lacked these antibodies. The enhanced cross‐presentation in mice with circulating antigen‐specific antibodies was associated with improved antigen capture by APCs. Importantly, CD11c⁺ APCs were responsible for the enhanced and sustained cross‐presentation, although CD11c^? APCs had initially captured a significant amount of the injected antigen. Thus, in vivo formation of antigen‐antibody immune complexes improves MHC class I cross‐presentation, and CD8⁺ T‐cell activation, demonstrating that humoral immunity can aid the initiation of systemic cellular immunity. These findings have important implications for the understanding of the action of therapeutic antibodies against tumor‐associated antigens intensively used in the clinic nowadays.     

Coexistence of Th1/Th2 and Th17/Treg imbalances in patients with allergic asthma

Background  Recent recognition is that Th2 response is insufficient to fully explain the aetiology of asthma. Other CD4⁺ T cells subsets might play a role in asthma. We investigated the relative abundance and activities of Th1, Th2, Th17 and CD4⁺CD25⁺ Treg cells in patients with allergic asthma.

Methods  Twenty-two patients with mild asthma, 17 patients with moderate to severe asthma and 20 healthy donors were enrolled. All patients were allergic to house dust mites. Plasma total IgE, pulmonary function and Asthma Control Questionnaire were assessed. The proportions of peripheral blood Th1, Th2, Th17 and CD4⁺CD25⁺ Treg cells were determined by flow cytometry. The expression of cytokines in plasma and in the culture supernatant of peripheral blood mononuclear cells was determined by enzyme linked, immunosorbent assay.

Results  The frequency of blood Th2 cells and IL-4 levels in plasma and culture supernatant of peripheral blood mononuclear cells were increased in all patients with allergic asthma. The frequency of Th17 cells and the plasma and culture supernatant levels of IL-17 were increased, whereas the frequency of CD4⁺CD25⁺ Treg cells and plasma IL-10 levels were decreased in patients with moderate to severe asthma. Dermatophagoides pteronyssinus specific IgE levels were positively correlated with the percentage of blood Th2 cells and plasma IL-4 levels. Forced expiratory volume in the first second was negatively correlated with the frequency of Th17 cells and plasma IL-17 levels, and positively correlated with the frequency of Treg cells. However, mean Asthma Control Questionnaire scores were positively correlated with the frequency of Th17 cells and plasma IL-17 levels, and negatively correlated with the frequency of Treg cells.

Conclusions  Imbalances in Th1/Th2 and Th17/Treg were found in patients with allergic asthma. Furthermore, elevated Th17 cell responses, the absence of Tregs and an imbalance in Th17/Treg levels were associated with moderate to severe asthma. 

     

环磷酰胺对人γδT细胞杀伤胃癌细胞SGC-7901作用的影响

目的探讨环磷酰胺对人γδT细胞杀伤胃癌细胞SGC-7901作用的影响。方法异戊烯焦磷酸法体外扩增人外周血γδT细胞,不同浓度的环磷酰胺诱导γδT细胞24 h,四甲基偶氮唑蓝（MTT）法检测环磷酰胺对γδT细胞增殖率的影响,LDH法检测γδT细胞对胃癌细胞的杀伤活性,流式细胞仪检测诱导前后的γδT细胞的凋亡率及NKG2D受体表达水平。结果γδT细胞培养10天时从扩增前4.21%增加到70.35%,当环磷酰胺浓度在0.05~2.0 ng/L时能够促进人γδT细胞的生长,增殖率随着该药物浓度的增高而增高,浓度大于2.0 ng/L时抑制γδT细胞的生长,γδT细胞杀伤活性与对照组比较明显增高,凋亡率与对照组比较明显降低,且γδT细胞表面NKG2D表达水平明显高于对照组。结论环磷酰胺在一定的浓度范围内,促进γδT细胞的增殖,提高γδT细胞对胃癌细胞的杀伤活性,抑制γδT细胞的凋亡,增强γδT细胞表面NKG2D的表达水平,为环磷酰胺在肿瘤免疫治疗中提供了一定的理论依据。     

Regulation of T-cell responses by PTEN

Summary: The phosphoinositide 3-kinase (PI3K) signaling pathway plays a critical role in the development, activation, and homeostasis of T cells by modulating the expression of survival and mitogenic factors in response to a variety of stimuli. Ligation of the antigen receptor, costimulatory molecules, and cytokine receptors activate PI3K, resulting in the production of the lipid second messenger phosphatidylinositol-3,4,5-triphosphate (PIP₃). A number of molecules help to regulate the activity of this pathway, including the lipid phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome 10). By limiting the amount of PIP₃ available within the cell, PTEN directly opposes PI3K activity and influences the selection of developing thymocytes as well as the activation requirements of mature T cells. T cells with unchecked PI3K activity, as a result of PTEN deficiency, contribute to the development of both autoimmune disease and lymphoma. This review dissects our current understanding of PI3K and PTEN and discusses why appropriate balance of these molecules is necessary to maintain normal T-cell responses.     

碱性髓鞘蛋白反应的CD~（4＋）细胞及被动转移诱导实验性变态反应性脑脊髓炎

用碱性髓鞘蛋白加福氏完全佐剂免疫ＳＪＬ／Ｊ小鼠，建立实验性变态反应性脑脊髓炎动物模型。取发病动物淋巴结作细胞培养，并用碱性髓鞘蛋白激活培养３周。其间２次经Ｆｉｃｏｌｌ－Ｈｙｐａｑｕｅ分离纯化激活的细胞，并加Ｘ线照射的脾细胞，应用３Ｈ－ＴｄＲ掺入法测定细胞对碱性髓鞘蛋白的反应状况。细胞经ＰＫＨ２－ＧＬ标记及ＰＥ－抗ＣＤ４荧光染色，流式细胞仪分析细胞阳性情况。ＰＫＨ２－ＧＬ标记的细胞静脉注入同品系健康小鼠，约１０天后，动物发生典型的实验性变态反应性脑脊髓炎症状。随之分离发病动物的中枢神经系统和淋巴结淋巴细胞，发现于中枢神经系统中ＰＫＨ２－ＧＬ标记细胞中４５％为ＣＤ４＋细胞，其中９０％以上细胞为激活的母细胞。而在淋巴结中ＣＤ４＋细胞低于４％，母细胞少于１０％，结果说明对碱性髓鞘蛋白反应的ＣＤ４＋细胞，可选择性地进入中枢神经系统并介导实验性变态反应性脑脊髓炎的免疫病理反应。     

CTLA-4: a key regulatory point in the control of autoimmune disease

Summary: Chronic autoimmune disease in humans is the result of a failure to control autoreactive immune cells in the periphery. This control is largely achieved by inhibition of newly activated and memory cells. A number of negative immune regulatory pathways have been characterized. The cell surface coreceptor cytotoxic T-lymphocyte antigen-4 (CTLA-4) has emerged as a critical attenuator of T-cell activation and an essential component of the regulatory systems that serve to maintain peripheral tolerance. CTLA-4 expression is induced on the surface of T cells after they have received a costimulatory signal from antigen-presenting cells (APCs) via engagement of CD28 on the T-cell surface. CTLA-4 attenuates this costimulation by competing for CD28 ligands and through direct effects on APCs via the same ligands utilized by CD28. A large number of genetic association studies suggest that the CTLA-4 gene is a locus of susceptibility to autoimmune disease. However, specific functional defects in the CTLA-4 gene in patients have not been identified to date. Elucidating the role of CTLA-4 in immune tolerance has also led to a number of therapeutic applications, particularly in the treatment of malignancy and autoimmune disease.     

Prognostic value of CD57<Superscript>+</Superscript> T lymphocytes in the peripheral blood of patients with advanced gastric cancer

Background  Natural killer (NK)-like T cells comprising CD56⁺ T cells and CD57⁺ T cells belong to a subset of CD1d-independent NKT cells playing an important role in regulating immune responses. Although NK-like T cells are reported to increase in patients with advanced gastric carcinomas, it remains unknown how NK-like T cells are involved in disease progression in gastric cancer patients. Methods  The proportions of Th1 cells (interferon [IFN]-γ-producing CD4⁺ T cells), Th2 cells (IL-4-producing CD4⁺ T cells), and NK-like T cells (CD56⁺ T cells and CD57⁺ T cells) in the peripheral blood of 48 gastric cancer patients and 20 healthy controls were measured by two-color flow cytometry analysis and by intracellular cytokine analysis to investigate an association of these immune cells with the survival rate of gastric cancer patients. Results  Univariate analysis showed that Th1 cells and CD57⁺ T cells, as well as some clinicopathological factors, significantly influenced the survival rate. CD57-high (≧18%) patients survived for a significantly shorter period after surgery compared to CD57-low patients (P = 0.046; Kaplan-Meier, log-rank test) in the stage III–IV patients, but not in the stage I–II patients. Further, multivariate analysis showed that lymphatic invasion was a statistically significant independent risk factor in all the gastric cancer patients, but the proportion of CD57⁺ T cells as well as depth of tumor were statistically significant independent risk factors in patients with advanced carcinomas (stage III–IV). Conclusion  An increased proportion (≧18%) of CD57⁺ T cells in the peripheral blood of patients with advanced gastric carcinomas could indicate a poor prognosis.     

CD4+CD25+调节性T细胞在多种类型疫苗中作用的研究进展

CD4⁺CD25⁺ 调节性T细胞具有免疫抑制作用。CD4⁺CD25⁺ 调节性T细胞可由多种类型肿瘤、病原体诱导产生。一方面抑制炎症,防止机体组织损伤;另一方面阻碍机体清除肿瘤细胞和病原体,有利于肿瘤和病原体逃避宿主免疫攻击。使用抗体阻断CD4⁺CD25⁺ 调节性T细胞或干扰其抑制功能则利于机体清除肿瘤和病原体。同样,多种类型疫苗可诱导宿主产生CD4⁺CD25⁺ 调节性T细胞,因而抑制了疫苗引起的免疫反应。使用抗体如抗CD25单克隆抗体等封闭CD4⁺CD25⁺ 调节性T细胞或者抑制其分泌的细胞因子如白细胞介素-10(IL-10)、转化生长因子-β(TGF-β),可增强疫苗的免疫保护效果,从而为寻找更有效的疫苗提供新的思路。     

甲状旁腺激素对维持性血液透析患者调节性T细胞和微炎症的影响

目的观察甲状旁腺激素（PTH）对维持性血液透析患者外周血调节性T细胞（Treg）和微炎症的影响。方法选取27例合并甲状腺旁腺功能亢进的血液透析患者（高PTH组）、18例无甲状腺旁腺功能亢进的血液透析患者（低PTH组）和20名健康人,采用流式细胞术检测各组外周血中CD4＋、CD25＋、CD127-来定义其外周血中Treg细胞表达的百分比,同时通过免疫比浊法和酶联免疫吸附法（ELISA）检测各组血清C-反应蛋白（CRP）、血清白细胞介素-6（IL-6）、肿瘤坏死因子-α（TNF—α）。结果两组血液透析患者的Treg细胞较健康对照组明显减少（P〈0．05）,而两组的CRP,IL-6,TNF—α均显著增高（P〈0．05）;血液透析伴高PTH组的Treg细胞显著低于低PTH组（P〈0．05）,而其CRP,IL-6,TNF—α水平显著高于低PTH组（P〈0．05）。结论高PTH可抑制T细胞分化,减少Treg产生,促使炎症因子增高。积极清除PTH,可能对改善血液透析患者免疫功能有益。     

γ干扰素上调吉兰一巴雷综合征患者外周血中CD4^＋CD25^＋调节性T细胞的研究

目的探讨γ干扰素（IFN-γ）诱导吉兰-巴雷综合征（GBS）患者外周血CD4^＋CD25 T细胞转化为CD4^＋CD25^＋调节性T细胞的可行性。方法不同浓度IFN-γ刺激GBS患者外周血中的CD4^＋CD25T细胞。Real-timePCR检测诱导CD4^＋CD25^＋调节性T细胞中FoxP3的表达,共培养检测其抑制功能;结果与健康人中天然的CD4^＋CD25^＋调节性T细胞比较。结果IFN-γ可诱导CD4^＋CD25^＋T细胞转化为CD4^＋CD25^＋调节性T细胞。IFN-γ40ng.mL^-1诱导的CD4^＋CD25^＋调节性T细胞中FoxP3表达含量最高,但仍然低于天然的CD4^＋CD25^＋调节性T细胞;其抑制能力最强,与天然的CD4^＋CD25^＋调节性T细胞比较差异无统计学意义。结论IFN-γ可诱导GBS患者外周血CD4^＋CD25^＋T细胞转化为CD4^＋CD25^＋调节性T细胞,IFN-γ,40ng.mL^-1诱导的CD4^＋CD25^＋调节性T细胞表型和功能与天然的CD4^＋CD25^＋调节性T细胞相当。