免疫细胞ACTH受体测定方法建立及大鼠胸腺ACTH受体的发现

本文介绍了免疫细胞ACTH受体(ACTHR)测定法并首次报道了大鼠胸腺细胞具有高亲和力和低亲和力两类ACTHR。方法学研究表明,胸腺细胞数量以1～2×10~6个/管、反应时间20分钟较佳;竞争结合实验结果表明,非标记ACTH的IC_(50)值为800nM;当加入的~(125)I-ACTH为2.5 nM时,胸腺细胞ACTHR已基本饱和,根据饱和曲线进行Scatchard作图分析表明,大鼠胸腺细胞具有两类亲和力不同的ACTHR。应激可致胸腺细胞ACTHR急骤减少。     

蛋白质缺乏对小鼠胸腺细胞花生凝集素受体的影响

本文用异硫氰酸荧光素标记花生凝集素(FITC-PNA)测定蛋白质缺乏小鼠胸腺细胞表面花生凝集素(PNA)受体的变化。结果表明,给予缺蛋白饲料后,小鼠体重不断减轻,胸腺组织逐渐萎缩,PNA阳性细胞数减少,荧光反应强度减弱。小鼠体重下降与胸腺细胞表面PNA受体的减少呈显著正相关(P<0.01)。提示蛋白质缺乏可对小鼠胸腺细胞的分化、成熟产生不良影响。     

实验性体内外胸腺细胞凋亡的超微结构研究

目的对糖皮质激素诱导的大鼠体内、外胸腺细胞凋亡进行系统超微结构观察。方法在培养的胸腺细胞中加入糖皮质激素,分别作扫描和透射电镜观察;对大鼠进行腹腔内氢化可的松注射,对胸腺组织进行透射电镜观察。结果胸腺细胞显示了细胞凋亡各阶段的超微结构改变。结论糖皮质激素诱导胸腺细胞发生凋亡,体外培养细胞出现典型的凋亡小体,而组织内主要改变是凋亡细胞或凋亡小体被上皮性网状细胞或巨噬细胞吞噬、降解。     

小肠移植免疫抑制方案的发展历史、现状和展望

经过近20多年的发展，小肠移植已成为肠衰竭患者最为理想的临床治疗方式。然而，小肠作为一个特殊的免疫器官，移植肠排斥反应成为影响小肠移植成功的最主要障碍，因此免疫抑制方案的改进在所有小肠移植技术进步中最为关键。本文首先阐述小肠的免疫学特点，然后结合美国器官获取和移植网络／器官移植受者科学登记系统最新资料、全球各主要小肠移植中心的免疫抑制方案演变和我国临床小肠移植实践经验，评述小肠移植免疫抑制方案发展历程，以期预示其今后的发展。     

Comparative analysis of thymic subpopulations during different modes of atrophy identifies the reactive oxygen species scavenger,N-acetyl cysteine,to increase the survival of thymocytes during infection-induced and lipopolysaccharide-induced thymic atrophy

The development of immunocompetent T cells entails a complex pathway of differentiation in the thymus. Thymic atrophy occurs with ageing and during conditions such as malnutrition, infections and cancer chemotherapy. The comparative changes in thymic subsets under different modes of thymic atrophy and the mechanisms involved are not well characterized. These aspects were investigated, using mice infected with Salmonella Typhimurium, injection with lipopolysaccharide (LPS), an inflammatory but non-infectious stimulus, etoposide (Eto), a drug used to treat some cancers, and dexamethasone (Dex), a steroid used in some inflammatory diseases. The effects on the major subpopulations of thymocytes based on multicolour flow cytometry studies were, first, the CD4⁻ CD8⁻ double-negative (DN) cells, mainly DN2–4, were reduced with infection, LPS and Eto treatment, but not with Dex. Second, the CD8⁺ CD3^lo immature single-positive cells (ISPs) were highly sensitive to infection, LPS and Eto, but not Dex. Third, treatment with LPS, Eto and Dex reduced all three subpopulations of CD4⁺ CD8⁺ double-positive (DP) thymocytes, i.e. DP1, DP2 and DP3, but the DP3 subset was relatively more resistant during infection. Fourth, both CD4⁺ and CD8⁺ single-positive (SP) thymocytes were lowered by Eto and Dex, but not during infection. Notably, LPS lowered CD4⁺ SP subsets, whereas the CD8⁺ SP subsets were relatively more resistant. Interestingly, the reactive oxygen species quencher, N-acetyl cysteine, greatly improved the survival of thymocytes, especially DNs, ISPs and DPs, during infection and LPS treatment. The implications of these observations for the development of potential thymopoietic drugs are discussed.     

Anti‐thymocyte globulin plus etanercept as therapy for myelodysplastic syndromes (MDS): a phase II study

Immunosuppressive therapies have proven valuable in treating patients with myelodysplastic syndromes (MDS). We evaluated the combination of equine anti‐thymocyte globulin (ATGAM^®) and the soluble tumour necrosis factor receptor, etanercept (Enbrel^®), in a phase II trial. Twenty‐five patients with MDS [4‐refractory anaemia (RA), 2‐RA with ring sideroblasts, 15‐refractory cytopenia with multilineage dysplasia (RCMD), 3‐RCMD and ring sideroblasts, 1‐RA with excess blasts type 1] in International Prognostic Staging System risk groups low (n = 11) or intermediate‐1 (n = 14) were enrolled. All patients were platelet or red cell transfusion‐dependent. Nineteen patients completed therapy with ATG at 40 mg/kg per day for four consecutive days, followed by etanercept, 25 mg subcutaneous twice a week for 2 weeks, every month for 4 months. Thirteen patients had haematological improvement (HI)‐erythroid, 2 HI‐neutrophil, and 6 HI‐platelet. One patient with a co‐existing diagnosis of multiple sclerosis and rheumatoid arthritis had a complete remission. The overall response by intent to treat analysis among the 25 patients was 56% (95% confidence interval 35–56%). Four patients did not complete their first course of therapy and one patient did not survive to the 8‐week post‐treatment assessment. Among patients who completed treatment and survived to the 8‐week assessment, 70% had at least haematological responses lasting for at least 5 to more than 36 months. Thus, combination therapy with ATG and etanercept was active and safe in patients with MDS.     

Herpesvirus saimiri immortalization of {alpha}{beta} and {gamma}{delta} human T-lineage cells derived from CD34+ intrathymic precursors in vitro

Herpesvirus saimiri (HVS), an agent that can infect many humancell types, has been shown to immortalize selectively TCR ß⁺CD3⁺T lymphocytes. Human T cell precursors defined as CD34⁺CD3^–CD4^–CD8^–were isolated from thymic samples and exposed to HVS in thepresence of either IL-2 or IL-7. Cultures lacking the viruswere non-viable by day 15. Test cultures, in contrast, showeda sustained proliferative activity lasting >5 months, allowingthe phenotypical and molecular analysis of the cellular progeny.In the presence of IL-7, TCR ß⁺ cells with three differentphenotypes (mainly CD4⁺CD8^–, but also CD4⁺CD8⁺ and CD4^–CD8⁺)were immortalized, whereas no TCR ⁺ cells were recovered. Kineticstudies showed that the expansion of immortalized TCR ß⁺cells was preceded by a gradual loss of CD34⁺ cells followedby a transient accumulation of two distinct cell subsets: firstCD1⁺CD4⁺CD3^– cells and then CD4⁺CD8⁺ thymocytes. Thisresembles early phenotypic changes occurring during normal intrathymicT cell development. In the presence of IL-2, in contrast, onlyTCR ⁺ cells were immortalized (mainly CD4^–CD8⁺, but alsoCD4^–CD8^–). The results show that HVS can be usedto read the CD3⁺ cellular outcome of T cell differentiationassays, including ⁺ CD4^–CD8⁺, ⁺CD4^–CD8^–, ß⁺CD4⁺CD8^–,ß⁺CD4^–CD8⁺ and ß⁺CD4⁺CD8⁺ T cells.A clear role for different cytokines (IL-2 for ⁺ cells, IL-7for ß⁺ cells) in early T cell commitment was alsoapparent.     

CD25(+)CD4(+) regulatory T cells exert in vitro suppressive activity independent of CTLA-4

Cytotoxic T lymphocyte antigen-4 (CTLA-4) is constitutively expressed on CD25(+)CD4(+) regulatory T cells (Treg) and is suggested to play a role in Treg-mediated suppression. However, the results of analysis with anti-CTLA-4 have been controversial. We addressed this issue by analyzing mice over-expressing or deficient in CTLA-4. For over-expression, CTLA-4 transgenic mice expressing a full-length (FL) or a truncated (TL) mutant of CTLA-4 were analyzed. FL T cells expressed similar levels of CTLA-4 to Treg, whereas TL T cells expressed much higher levels on the cell surface. The number of Treg in both mice was decreased, although Foxp3 expression was not altered. Treg from both mice exerted suppressive activity, whereas CD25(-) T cells from FL mice showed no suppression. Furthermore, CD25(+)CD4 thymocytes from young CTLA-4-deficient mice were analyzed and found to exhibit suppressive activity. These results indicate that Treg exert in vitro suppressive activity independent of CTLA-4 expression.