Identification of autoantigens recohnized by auto-react T cells in Vogt-Koyanagi-Harada disease

Vogt-Koyanagi-Harada病（VKH）可能是由多种组织中针对黑色素细胞的自身免疫反应引起的。由于VKH的发生机制尚不清楚，我们试图鉴定自身抗原。为了鉴定抗原，我们使用了可能含有VKH抗原特异性抗体的血清。虽然Western blot分析未发现VKH特异性条带，但免疫沉淀分析发现，在黑色素瘤细胞Skme123中观察到46 kDa条带，而在K562细胞中没有，在VKH血清中观察到46 kDa条带，而在健康人血清中没有，这表明该蛋白可能与VKH相关。用7例VKH患者血清筛选Skme123表达cDNA文库，分离出26个基因。但未发现黑素细胞特异性抗原。从2例患者血清中获得的cDNA克隆鉴定为晶状体上皮源性生长因子。在12例VKH患者中有4例和6例健康患者中有3例检测到该蛋白的抗体，提示该蛋白可能与VKH无关。脑脊液中单核细胞增多可能含有与脑脉络丛黑素细胞反应的T细胞。我们从VKH脑脊液中克隆T细胞。T细胞克隆识别来自黑素细胞和黑色素瘤的蛋白质，但不能识别来自非黑素细胞的蛋白质。该反应被抗dr抗体阻断，并报道了VKH与HLA-DRB*0405和DQB1*0401的显著相关性。因此，这些结果提示HLA-DR限制了黑色素细胞特异性的CD4+ T细胞可能参与了VKH的发生。

Vogt-Koyanagi-Harada disease (VKH) may be caused by autoimmune responses against melanocytes in various tissues. Since the mechanism for development of VKH has not been clear yet, we attempted to identify the autoantigens. To identify antigens, we used sera that might contain specific antibodies for the VKH antigens. Although Western blot analysis did not show VKH specific bands, by immunoprecipitation analysis, a 46 kDa band was observed in melanoma cells, Skme123, but not in K562 cells, with sera from VKH, but not with sera from healthy individual, suggesting that this protein may be associated with VKH. An expression cDNA library from Skme123 was screened with sera from 7 VKH, and 26 genes were isolated. However, melanocyte specific antigen was not identified. The cDNA clones obtained with sera from 2 patients were identified to be lens epithelium derived growth factor. The antibody for this protein was detected in 4 of 12 VKH and 3 of 6 healthy individuals, suggesting that this protein might not be associated with VKH. Increased mononuclear cells in cerebrospinal fluid may contain T cells reacted to melanocytes in choroid plexus of brain. We cloned T cells from cerebrospinal fluid of VKH. The T cell clones recognized proteins from melanocytes and melanoma, but not those from nonmelanocytic cells. This reaction was blocked by anti-DR antibody, and the significant association of VKH with HLA-DRB*0405 and DQB1*0401 was reported. Therefore, these results suggested that HLA-DR restricted CD4+ T cells specific for melanocytes may be involved in the development of VKH.