To investigate the HLA-linked disease-contorolling gene(s) for Buergers disease, we have genotyped 72 unrelated Japanese patients and 224 healthy controls for HLA-B, DRB 1 and MICA genes. It was revealed that the frequencies of HLA-B and DRB1 were significantly increased in the patients (B^* 5401;27.8% in the patients vs. 11.6% in the controls, OR=2.35,p=0.0.012, and DRB1 ^* 1501;31.9% vs. 9.4%, OR=4.53,pc＜0.0001), while the frequency of MICA 1.4 allele, which is in strong linkage disequibrium with HLA-B^* 5401 in the Japanese population, was not significantly deviated between the patients and controls. A comparison of odds ratio for the risk of disease conferred by HLA-B and DRB1^* 1501has suggested that these disease-associated alleles may be independent genetic risk factors of Buergers disease or that there might he at least 2 different etiologies; one is associated with HLA-B 1 and the other is associated with HLA-DRB1^* 1501. On the other hand, the frequency of MICA 1.2 allele was significantly decreased in the patients (30.6% vs. 48.2%, OR=0.47, pc=0.04). These observations suggest that both the susceptibility and resistance to Buergers disease are linked to BLA, hut they are controlled by different genes in the HLA region. The HLA system comprises a complex array of genes encoding for polymorphic cell surface glycoproteins that play fundmental roles in immune responses to foreign as well as self antigens and may control the susceptibility and/or resistance to various diseases including autoimmune diseases. There are two distinct types of HLA molecules; classI (HLA-A, B and C) and classII (HLA-DR, DQ and DP). The polymorphisms of the HLA molecules have been analyzed by serological typing system utilizing the complement-dependent cytotoxicity assay and panels of selected antisera. However, recent development of typing technology at the DNA level has revealed that there are many alleles which could not he distinguished by the serological typing (1). Therefore, the associations between HLA and certain diseases are now analyzed in more detail at the DNA level by using PCR-based DNA typing technologies (2). Buergers disease (thromboangiitis obliterans) is characterized by thrombotic obstruction of middle- and small-sized arteries with inflammation (3). Its etiology or pathogenesis remains unknown, although smoking is a known risk factor of the disease (4). On the other hand, the incidence of disease is more frequent in Asian countries than in European countries, suggesting that there are ethnic differences in the susceptibility and/or resistance to the disease (5). Because HLA shows ethnic differences in the allele frequencies and is involved in the inflammatory process, analysis of HLA may be important in understanding the pathogenesis of Buergers disease. In this respect, serological analysis of HLA in Buergers disease had been performed and it was reported that HLA-B54 and DR2 were associated with the disease in Japanese (6, 7), while no definite positive association between the disease and HLA was confirmed in Caucasians (8, 9). Because relatively small numbers of patients were analyzed in these serological studies, the association still remains to he confirmed. To investigate the association between HLA and Buergers disease in more precise way, we have analyzed polymorphisms of HLA-B, DRB 1 and MICA genes in the Japanese patients at the DNA level.

近年, MHCの系統発生学的な解析が分子レベルで進められた結果, クラスI,II,III遺伝子が連鎖して存在するという基本構造が, 哺乳類, 鳥類, 両生類を通じて良く保存されていることが明らかになった. それに対して, ゼブラフィッシュ, メダカをモデルに進められている硬骨魚類での解析では, この3領域が連鎖せずに別々の染色体に存在すること, ただしクラスIとその抗原提示に重要な役割を果たすTAP,LMPなどの遺伝子は連鎖していることが判明した. この結果はMHCの本来の役割がクラスI抗原提示システムの確立にあったことを示唆している. ヒトMHCは第6染色体短腕に存在する約4Mbにわたる領域で, 免疫応答を司る遺伝子, 何らかの形で免疫反応に関与する遺伝子, 及び免疫とは無関係な遺伝子等200以上の遺伝子から構成されている（1）. MHCの遺伝子構成の意義と起源に関しては, 1）いくつかの遺伝子間の連鎖には生理的意義が存在し, その遺伝子構成は自然選択により出来上がった, 2）連鎖には生理的意義はなく, その遺伝子構成は偶然の産物である, 3）遺伝子構成は偶然の産物であるが, 連鎖には生理的意義がある, 等様々な解釈が存在する. 近年急速な進展をみせている哺乳類以外の脊椎動物における解析は, MHCの遺伝子構成にも脊椎動物の進化の歴史を通じて良く保存されている部分と, 大きく変化している部分とがあることを明らかにし, MHCの意義と起源を考えるうえでの有益な情報を提供している. ここでは硬骨魚類のMHCの遺伝子構成を哺乳類, 鳥類, 両生類のものと比較することにより, MHCの意義を系統発生学的に考察してみたい.

血清学タイピングによりHLAクラスI抗原が既知の337パネルのアリルタイピングを, PCR-RFLP,PCR-Lis-MPH,PcR-SSP法により実施し, 血清学によるHLAクラスI抗原タイピングの結果とDNAタイピングの結果を比較, 検討した. HLA-A座, B座のタイピング結果において, 両方法の違いによる血清学レベルでの不一致は全く存在しなかったが, HLA-C座においては12例の不一致が存在した. アリルが規定する抗原に対応する抗血清がないために識別ができなかったケースが4例, 抗原を決定するのに1種類の抗血清しか使用しなかったため偽陰性となったケースが3例, それぞれみられた. また, 他の抗原により血清学的にマスクされるため識別できなかったケースが5例であった. さらに, 血清学レベルタイピングでHLA-A座ホモ接合体と判定されたパネルがアリルタイピングで17例中10例が, HLA-B座で11例中4例が, HLA-C座で22例中9例が, それぞれヘテロ接合体であった. 血清学的方法によりHLA-A座で31アリル, B座で47アリル, C座で18アリルが識別可能であった.