Rollins-Smith L A, Blair P
Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Dev Immunol. 1990;1(2):97-104. doi: 10.1155/1990/25197.
Class II major histocompatibility complex (MHC) antigens are expressed predominantly on B lymphocytes and macrophages of tadpoles of the South African clawed frog, Xenopus laevis, as is the pattern in lymphocyte populations of most mammals. However, unlike most mammals, young postmetamorphic frogs show expression of class II MHC antigens on a high proportion of thymocytes and most peripheral T and B lymphocytes. Using the J-strain of Xenopus and the anticlass II monoclonal antibody, 14A2, we have studied, by indirect immunofluorescence, whether inhibition of metamorphosis would alter the pattern of expression of class II antigens during ontogeny. In control animals, class II antigens were virtually absent from thymic lymphocytes and peripheral T cells of normal untreated larvae, but could be found in increasing numbers in both populations after metamorphosis (10-12 weeks of age). In contrast, larvae, whose metamorphosis was inhibited by treatment with sodium perchlorate, had relatively few class II+ thymic lymphocytes throughout the 6-month period of study, and the proportion of class II+ splenic lymphocytes was approximately equal to that of IgM+ B lymphocytes. Thus, perchlorate-treated animals retained the larval pattern of class II expression, suggesting that emergence of class II+ T cells is dependent on metamorphosis.
II类主要组织相容性复合体（MHC）抗原主要在南非爪蟾（非洲爪蟾）蝌蚪的B淋巴细胞和巨噬细胞上表达，大多数哺乳动物的淋巴细胞群体也是这种表达模式。然而，与大多数哺乳动物不同的是，变态后的幼蛙在很大比例的胸腺细胞以及大多数外周T和B淋巴细胞上都有II类MHC抗原的表达。我们利用非洲爪蟾的J品系和抗II类单克隆抗体14A2，通过间接免疫荧光法研究了变态抑制是否会改变个体发育过程中II类抗原的表达模式。在对照动物中，正常未处理幼虫的胸腺淋巴细胞和外周T细胞中几乎没有II类抗原，但在变态后（10 - 12周龄），这两个群体中的II类抗原数量都有所增加。相比之下，用高氯酸钠处理以抑制变态的幼虫，在整个6个月的研究期间，II类阳性胸腺淋巴细胞相对较少，II类阳性脾淋巴细胞的比例与IgM阳性B淋巴细胞的比例大致相等。因此，经高氯酸盐处理的动物保留了幼虫的II类表达模式，这表明II类阳性T细胞的出现依赖于变态。
