Immunological Studies on the Induction Mechanism of Experimental Autoimmune Gastritis in Mice

在BALB/c小鼠出生后3天，通过新生儿胸腺切除术诱导实验性自身免疫性胃炎（AIG），其定义为出现针对壁细胞的自身抗体。临床表现为维生素B_<12>吸收量和内在因子下降，与人类恶性贫血相似。免疫方面，AIG小鼠对壁细胞表现出延迟型超敏反应（DTH）；提示DTH参与了组织损伤的机制。事实上，细胞荧光和免疫组织化学分析显示，早期（胸腺切除术后1-3个月）就有T细胞浸润。然而，B细胞也在晚期浸润；这意味着除了B细胞产生的自身抗体外，B细胞本身也参与了疾病的发展。因此，T细胞和B细胞识别的自身抗原在诱导疾病中起着重要的作用。为了分析壁细胞的自身抗原，我们用携带壁细胞循环自身抗体的AIG小鼠建立了产生壁细胞单克隆自身抗体的杂交瘤。在获得的三个克隆中，两个（2B6和2G10）与蛋白质反应，一个（1H9）可能与碳水化合物反应，使用Triton-X100溶解胃提取物进行ELISA检测。2G10被识别为种特异性抗原，而2B6和1H9被识别为种间特异性抗原决定因子。该分子分子量约为600KD，由70KD糖蛋白亚基组成。三种抗体识别的表位不同，但分布在细胞内分泌小管和细胞质小管囊泡中的相同分子上，彼此靠近，与HCl的产生有关。下一个重要的问题是，自身反应性T细胞和B细胞是否通过识别相同的抗原表位而被激活。

Experimental autoimmune gastritis (AIG), defined by the appearance of autoantibodies to parietal cells, was induced by neonatal thymectomy in BALB/c mice three days after birth. Clinical findings, such as decrease in Vitamin B_<12> absorption and intrinsic factor, indicate similarity to humal pernicious anemia. Immunologically, AIG mice exhibited delayed type hypersensitivity(DTH) reaction to parietal cells; suggesting that DTH is involved in the mechanism of tissue damage. In fact, cytofluorometric and immunohistochemical analysis revealed T cell infiltration at an early stage (1-3 mo. after thymectomy). However, B cells also infiltrate at a late stage; implying that B cells themselves in addition to autoantibodies produced by B cells, are involved in the development of the disease. Thus, autoantigens recognized by T and B cedlls must play an important fole for induction of the disease. To analyze the autoantigens of parietal cells, hybridomas producing monoclonal autoantibodies to parietal cells were establishedfrom an AIG mouse bearing circulating autoantibody to parietal cells. Among three clones thus obtained, two (2B6 and 2G10) reacted with protein while one (1H9) with perhaps carbohydrate when assayed by ELISA using Triton-X100 solubilized gastric extracts. 2G10 recognized species-specific, while 2B6 and 1H9 interspecies-specific antigenic determinants. Molecular weight of this molecules is approximately 600KD, consisting of 70KD glycoprotein subunits. Hte epitopes recognizedthe three antibodies are diferent, but locate close to each other on the same molecules whichdistribute in the intracellular secretory canaliculi and cytoplasmic tubulovesicules, relating to HCl production. It is the next important problem whether autoreactive T and B cells are activated by recognizing the same epitopes of not.