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

本研究旨在阐明1型糖尿病胰岛细胞体外破坏的机制，并探讨防止胰岛细胞破坏的方法。由于未处理的NOD小鼠新鲜分离的脾脏细胞在体外不损伤胰岛细胞，我们使用注射了环磷酰胺的NOD小鼠。注射环磷酰胺后脾脏细胞数量明显减少。NOD小鼠的细胞数量恢复比Balb/c小鼠晚，提示NOD小鼠骨髓的脆弱性。表面标记研究表明，与Balb/c小鼠相比，NOD小鼠中null细胞的增加较小，特别是在随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小鼠脾脏细胞的杀伤活性高于注射环磷酰胺的C3H小鼠。脾细胞与Con破坏的胰岛细胞孵育。聚adp核糖合成酶抑制剂、烟酰胺、吡啶酰胺和3-氨基苯甲酰胺可减弱Con a刺激细胞的胰岛细胞毒性。经Con A培养的脾细胞条件培养基显示胰岛细胞毒性，提示细胞因子参与了胰岛细胞损伤。胰岛细胞在干扰素-r （IFN-r）和肿瘤坏死因子（TNF）的共同作用下培养4天后被破坏。细胞因子诱导的胰岛细胞破坏也可被聚腺苷核糖合成酶抑制剂所阻止。

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.