Development of a method for regulation of auto-reactive B cells using transgenic mouse carrying genes encoding an anti-self-erythrocyte antibody.

为了鉴定和分析参与自身免疫性疾病发病机制的自身反应性B淋巴细胞，并阐明其激活机制，我们建立了携带抗自身红细胞抗体基因的转基因小鼠系统，从而使转基因小鼠中几乎所有的B淋巴细胞都被编程产生抗自身红细胞抗体。通过对转基因小鼠的分析，我们发现了以下几点。由于自身反应性B淋巴细胞被清除，大部分外周淋巴组织如脾或外周血中几乎检测不到B淋巴细胞。同时，CD5~+淋巴细胞的数量几乎正常，仅见于腹腔和胃肠粘膜固有层。大约一半的转基因小鼠个体自发地患有自身免疫性溶血性贫血，这是由于激活的CD5~+B淋巴细胞在腹腔内产生的自身抗体引起的。给非贫血转基因小鼠口服脂多糖(LPS)后，其症状与胃肠和腹腔CD5~+B淋巴细胞活化所致的自发性贫血十分相似。然而，肌肉注射或静脉注射的内毒素不能激活它们。当注射红细胞，即抗原本身时，腹腔中的CD5~+B淋巴细胞因凋亡而死亡。这些结果表明，胃肠和腹腔中CD5~+B淋巴细胞的活化在自身免疫性疾病的发生中起重要作用，自身反应性B淋巴细胞可以通过与自身抗原的接触而被消除。我们的研究至少在一定程度上阐明了自身免疫性疾病的发病机制，并找到了一种可能的治疗方法。

In order to identify and analyze auto-reactive B lymphocytes those involved in pathogenesis of auto-immune diseases, and to elucidate mechanism of their activation, we developed transgenic mouse system carrying genes encoding an anti-self-erythrocyte antibody and thus almost all the B lymphocytes in the transgenic mice are programd to produce the anti-self-erythrocyte antibody. By analyzing the transgenic mice, we found the following things.1. B lymphocytes are hardly detected in most of peripheral lymphatic tissues such as spleen or peripheral blood due to the elimination of self-reactive B lymphocytes. Hoerver, almost normal number of CD5^+ lymphocytes is found only in the abdominal cavity and the lamina propria of gastro-intestinal mucosa.2. Approximately half of the transgenic mouse individuals spontaneously suffered from auto-immune hemolytic anemia caused by the auto-antibody produced by the activated CD5^+ B lymphocytes in the abdominal cavity.3. When lipopolysaccharide (LPS) was orally administrated to non-anemic transgenic mice, they showed quite resembled symptoms with the spontaneously occurred anemia by activation of CD5^+ B lymphocytes in the gastro-intestine and abdominal cavity. However, they were not activated by LPS administrated by intra-muscular or intra-venous injection.4. CD5^+ B lymphocytes in the abdominal cavity died by apoptosis when the erythrocytes, i.e., the antigen itself, were injected. By repeated injection of erythrocytes into the abdominal cavity, the affected mice were recovered from anemia.These results indicate, in summary, that activation of CD5^+ B lymphocytes in the gastro-intestine and abdominal cavity is important for the onset of auto-immune diseases, and that auto-reactive B lymphocytes can be eliminated by their contact with auto-antigen. Our research clearly elucidated onset mechanism of auto-immune disease at least some part, and found a way of possible treatment of the diseases.