Studies on the mechanism of islet cell destruction in type I diabetes mellitus.

本研究旨在阐明体外培养的I型糖尿病胰岛细胞破坏的机制，并探索预防胰岛细胞破坏的方法。由于未处理的NOD小鼠的新鲜分离的脾细胞在体外不损伤胰岛细胞，我们使用注射环磷酰胺的NOD小鼠。注射环磷酰胺后，脾细胞数量明显减少。NOD小鼠骨髓细胞数的恢复较Balb/c小鼠晚，提示NOD小鼠骨髓的脆弱性。表面标志物研究表明，NOD小鼠脾细胞的空细胞数较Balb/c小鼠增加较少，尤其是在以后发生糖尿病的小鼠中，NOD小鼠脾细胞的同种异体杀伤活性基本正常。然而，注射环磷酰胺的NOD小鼠的脾细胞显示出比注射环磷酰胺的C3 H小鼠更高的杀伤活性。脾细胞与Con A共同孵育可破坏胰岛细胞。胰岛细胞毒性的Con A刺激的细胞衰减聚（ADP-核糖）合成酶抑制剂，烟酰胺，吡啶酰胺，和3-氨基苯甲酰胺。脾细胞条件培养液与ConA共同孵育4天后，胰岛细胞受到破坏，提示细胞因子参与了胰岛细胞的损伤。聚（ADP-核糖）合成酶抑制剂也可防止精氨酸诱导的胰岛细胞破坏。

This study was performed in order elucidate the mechanism of islet cell destruction in type I diabetes in vitro, and to develop the method of preventing the destruction. Since freshly isolated spleen cells of non-treated NOD mice did not damage islet cells in vitro, we used cyclophos-phamide-injected NOD mice. The number of spleen cells markedly decreased after a cyclophosphamide injection. Recovery of cell number was later in NOD mice than in Balb/c mice, suggesting the fragility of NOD mouse bone marrow. Surface marker studies showed that the increase of null cells was small in NOD mice, especially in the mice which developed diabetes afterwards, when compared to Balb/c mice.Allokiller activity of NOD mouse spleen cells was almost normal. However, spleen cells of cyclophosphamide-injected NOD mice showed higher killing activity than those of cyclophosphamide-injected C3H mice. Spleen cells incubated with Con a destructed islet cells. Islet cell toxicity of Con A-stimulated cells was attenuated by poly(ADP-ribose) synthetase inhibitors, nicotinamide, picolinamide, and 3-aminobenzamide. Conditioned medium of spleen cells incubated with Con A showed islet cell toxicity, suggesting the involvement of cytokines in islet cell damage.Islet cells were destructed when cultured in the presence of both interferon-r (IFN-r) and tumor necrosis factor (TNF) for 4 days. the cytokine-induced islet cell destruction was also prevented by poly(ADP-ribose) synthetase inhibitors.