Jürgens J B, Gartland L A, Du Pasquier L, Horton J D, Göbel T W, Cooper M D
Department of Medicine, University of Alabama at Birmingham 35294, USA.
J Immunol. 1995 Nov 1;155(9):4218-23.
We identified a novel T cell Ag in the South African clawed toad (Xenopus laevis) by a mAb designated 2B1. This Ag is present in relatively high levels on most thymocytes, approximately 65% of splenocytes, 55% of PBL, and 65% of intestinal lymphocytes, but is rarely seen on IgM+ B cells in any of these tissues. Lymphocytes bearing the 2B1 Ag proliferate in response to stimulation with Con A or PHA, whereas the 2B1- lymphocytes are reactive to LPS. Biochemical analysis indicates that this Ag is a differentially phosphorylated glycoprotein of 71 to 82 kDa. The protein core of 64 kDa bears both N- and O-linked carbohydrate side chains. The amino-terminal protein sequence of the 2B1 Ag shares significant homology with both the macrophage scavenger receptor type 1 motif and the mammalian CD5/CD6 family. The biochemical characteristics and cellular distribution of the 2B1 Ag suggest that it represents the CD5 homologue in X. laevis. While T cells constitutively express this highly conserved molecule, Xenopus B cells acquire the CD5 homologue only when they are stimulated in the presence of T cells.
我们通过一种名为2B1的单克隆抗体在南非爪蟾（非洲爪蟾）中鉴定出一种新的T细胞抗原。这种抗原在大多数胸腺细胞、约65%的脾细胞、55%的外周血淋巴细胞和65%的肠道淋巴细胞中含量相对较高，但在这些组织中的任何一种IgM+B细胞上很少见到。携带2B1抗原的淋巴细胞在受到刀豆球蛋白A或植物血凝素刺激时会增殖，而2B1阴性淋巴细胞对脂多糖有反应。生化分析表明，这种抗原是一种71至82 kDa的差异磷酸化糖蛋白。64 kDa的蛋白质核心带有N-连接和O-连接的碳水化合物侧链。2B1抗原的氨基末端蛋白质序列与1型巨噬细胞清道夫受体基序和哺乳动物CD5/CD6家族都有显著同源性。2B1抗原的生化特性和细胞分布表明它代表了非洲爪蟾中的CD5同源物。虽然T细胞组成性表达这种高度保守的分子，但非洲爪蟾B细胞只有在T细胞存在的情况下受到刺激时才会获得CD5同源物。
