Response of V beta 8.1+ T cell clones to self Mls-1a: implications for the origin of autoreactive T cells.

Clonal deletion and anergy are two major mechanisms of self-tolerance. However, the molecular mechanisms underlying clonal deletion and anergy, as well as the threshold of TCR affinity/avidity required for these processes, are not known. Expression of the V beta 8.1 TCR correlates with the reactivity of the T cells to the minor lymphocyte stimulating locus-1a (Mls-1a) and T cells expressing this TCR are deleted in the thymus of Mls-1a mice. Similarly, in TCR V beta 8.1 transgenic mice, the number of CD4+CD8-T cells is reduced in Mls-1a mice. However, small numbers of CD4+CD8-T cells remain in the periphery of adult Mls-1a transgenic mice. We have generated T cell clones from TCR V beta 8.1 transgenic mice by stimulation of lymph node T cells with C57BL/6 alloantigens. Interestingly, CD4+CD8-V beta 8.1+ clones isolated from the transgenic mice of Mls-1a background responded to the self-antigen Mls-1a, to which they did not respond in primary assay. Reactive patterns of the clones were compared with clones derived from Mls-1b mice. Proliferation and cytokine production of the clones from Mls-1a mice to the self-antigen Mls-1a were generally reduced when compared with clones from Mls-1b mice. More importantly, T cell clones from Mls-1a mice required more Mls-1a antigen for their activation, and were more susceptible to the inhibitory effects of anti-CD4 antibody on the proliferative responses to Mls-1a than those from Mls-1b mice. These results suggest that the T cell receptor on clones derived from Mls-1a mice have functional but reduced affinity/avidity for self-antigen Mls-1a.     

骨髓增生异常综合症几项实验指标研究进展

本文对MDS染色体、骨髓祖细胞体外培养及免疫功能几项实验指标的研究进展予以介绍。     

rhIL－1α对小鼠骨髓细胞长周期培养中造血细胞增殖的影响

应用小鼠骨髓细胞长周期培养（ＬＴＢＭＣ）体系，观察重组人白细胞介素－１α（ｒｈＩＬ－１α）对造血细胞增殖的影响。结果显示，经ｒｈｌＬ－１α作用后，小鼠ＬＴＢＭＣ中悬浮细胞数增多，其中粒单系祖细胞（ＣＦＵ－ＧＭ）数量也明显增加，维持时间延长。表明ｒｈＩＬ－１α能促进小鼠造血细胞在体外ＬＴＢＭＣ中增殖并分化，而且与剂量有关系。ｒｈＩＬ－１α加入的时间，以骨髓细胞２次接种时同时加入为好，延迟加入则作用减弱。本实验对骨髓干、祖细胞体外扩增和自体骨髓移植等方面的研究有一定意义。     

小鼠实验性糖尿病对胰腺腺泡细胞形态学的影响

为了探讨实验性糖尿病对胰腺腺泡细胞的影响，我们用四氧嘧啶对小鼠建造糖尿病模型。８ｗｋ后，取小鼠胰尾组织作光镜和电镜观察。结果：实验性糖尿病小鼠胰腺内部分腺泡细胞萎缩、细胞排列松散，并有大量慢性炎症细胞浸润。电镜下可见粗面内质网扩张，线粒体嵴紊乱、空泡变性，胞浆内出现髓样小体，酶原颗粒减少。表明实验性糖尿病对小鼠胰腺腺泡细胞的结构有一定的损害作用，进而使胰腺外分泌部的分泌功能受到影响。     

再生医学技术在烧伤传统治疗无效病人中的应用(附38例报告)

目的：总结重度烧伤传统疗法无效改为再生医学(MEBT/MEB0)技术治疗变化规律和临床验．方法：将我科l995年5月至2002年5月收治的院外采用传统疗法无效改用MEBT/MEBO技术治疗的38例重度烧伤病人临床资料进行回顾性总结，病人一旦入院创面均改用MEBT/MEBO治疗，初始予以彻底清创，规范用药、规范操作，规范认识；全身实行系统综合治疗措施．以临床观察和病人感觉评价治疗效果。结果：本组38例全部治愈，末植皮自行愈合者21例．占55.26％．深Ⅲ度创面自愿要求植皮者17例，占44.74％。经随访多数无增生性瘢痕，部分愈后有局限性瘢癌，质软无残废。结论：重度烧伤经传统疗法久治不愈或疗效欠佳病人．病情复杂，并发症较多治疗难度也较大，再生医学可有效改善以上缺陷和病症．是重度烧伤病人传统治疗无效时的理想疗法。     

Inhibition of IL-2 synthesis by donor-pecific suppressor T cells in a renal transplant recipient

Abstract A study was conducted to elucidate the mechanism of donor-pecific Mixed Lymphocyte Reaction (MLR and Cell Mediated Lymphotoxicity (CML) unresponsiveness in a renal transplant recipient with a long-term well-functioning kidney. The peripheral blood lymphocytes (PBL) of the recipient, who had not shown rejection since his transplantation 5 years previously, and those of his mother (donor), his father and two healthy third parties were examined. MLR, CML, semimicro MLR in a double chamber, interleukin-2 (IL-2) synthesis assay and limiting dilution assay were performed. This recipient showed donor-pecific MLR and CML unresponsiveness. IL-2 assay showed that the PBL of the recipient produced less IL-2 against the donor than against the father and the third parties. The addition of exogenous recombinant IL-2 (rIL-2; Takeda Co.) to the priming MLR caused a recovery of CML against the donor. A limiting dilution assay indicated that cytotoxic T cell precursor (CTLp) frequencies against the donor and father did not differ. The suppressor assay in a double chamber indicated that the PBL of the recipient stimulated by the donor PBL had a non-pecific suppressive effect on MLR, CML and IL-2 synthesis of the PBL across the Major Histocompatibility Complex (MHC) barrier. This suppressive effect was abolished by OKT3 or OKT8 monoclonal antibody and complement. Thus, the recipient had donor-pecific suppressor T cells that produced a humoral non-pecific suppressive factor only when stimulated by the donor PBL, and this factor suppressed PLR and CML by inhibiting IL-2 synthesis of the PBL.     

The effect of racemic ketamine on the large conductance Ca-activated potassium (BK) channels in GH3 cells

Recently, inhalation anesthetics have been reported to block BK channels in adrenal chromaffin cells. To determine if BK block was characteristic only of inhalation anesthetics or was also a property of other general anesthetics we examined the effects of ketamine, an intravenous general anesthetic which is structurally different than inhalation anesthetics. Cell-attached and excised patch single channel and standard whole cell recording techniques were used to examine the effect of racemic ketamine on the BK channel activity in GH₃ cells. When solutions containing 150 mM KCl are used in both the pipette and bath, the BK channels are characterized as a voltage-dependent channel with a unit conductance of 150–300 pS. Racemic ketamine (at clinically relevant concentrations; 2–500 μM) selectively blocked BK channels in a dose-dependent, reversible manner as evidenced by decreases in NP_o (number of channels × open probability). This decrease was due to both a decrease in mean open time and an increase in the mean closed time but without a decrease in single-channel current amplitude. Ketamine shifts the P_o vs voltage curve to higher potentials without a change in the slope of the voltage dependence. Ketamine also shifts the P_o vs [Ca⁺²] relationship to higher Ca⁺² concentrations. The IC₅₀ for the single-channel block by ketamine is 20.3 ± 15.9 μM. In an effort to confirm that the effect of ketamine was predominantly due to a block of the BK channels, standard whole cell techniques were utilized. As with the single-channel experiments, ketamine (2–500 μM) produced a dose-dependent, voltage-independent and reversible decrease in outward current with an IC₅₀ of 23.7 ± 11.5 μM. Addition of 100 μM ketamine to cells pretreated with the BK channel blocker, charybdotoxin (ChTX), did not result in a further decrease in outward current. These results demonstrate a selective effect of ketamine at clinically relevant concentrations which is consistent with results reported for inhalation anesthetics.     

煤焦沥青烟雾提取物的细胞毒性和遗传毒性研究

采用人外周血淋巴细胞非程序DNA合成(UDS)试验和人胚肺成纤维细胞转化试验,测试了煤焦沥青烟雾提取物(ECTPF)对人体细胞的细胞毒性和遗传毒性。UDS试验结果表明,ECTPF可使淋巴细胞UDS值明显增加,并有剂量一反应关系。引起半数淋巴细胞死亡的浓度(LC50)为33.8μg/ml。细胞转化试验表明,ECTPF能诱发人胚肺成纤维细胞明显的形态学转化,且转化细胞具有部分恶性转化细胞的特性。引起半数人胚肺成纤维细胞生长抑制的浓度为41.3μg/ml。实验结果提示,ECTPF是一种具有细胞毒性和遗传毒性的物质。     

Vascular cell adhesion molecule-1 modulation by tumor necrosis factor in experimental allergic encephalomyelitis

Anti-tumor necrosis factor (TNF) antibodies inhibit passively transferred experimental allergic encephalomyelitis (EAE) in SJL mice. The possibility that this occurs through interference in TNF's upregulation of endothelial cell adhesion molecules was investigated. Expression of both vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) on spinal cord vessels increased during EAE. The upregulation of VCAM-1 was markedly reduced or prevented by anti-TNF treatment. Leukocytic infiltration was 15-fold lower in anti-TNF-treated than diseased animals. Spinal cord endothelial expression of VCAM-1, though not ICAM-1 or fibronectin, positively correlated with the extent of T cell, B cell or monocyte infiltration in each animal.