Tachibana H, Kido I, Murakami H
Graduate School of Genetic Resources Technology, Kyushu University, Fukuoka, Japan.
J Biol Chem. 1994 Nov 18;269(46):29061-6.
Human HB4C5 hybridoma cells produce a lung cancer-specific human monoclonal antibody that possesses a lambda light chain on which a N-linked carbohydrate chain is attached at the first complementary determining region. Up to six light chains of various sizes are secreted by the original and concanavalin A (ConA)-resistant HB4C5 clones. Two of these six light chains are derived directly from the HB4C5 original and are 30 and 32 kDa in size. The structural difference between these two light chains has been shown to be a N-linked carbohydrate located at a single site. The other four variants, which are derived from ConA-resistant variants, have light chain sizes ranging from about 26 to 29 kDa. No changes in the secretory forms were observed when glycosylation was inhibited by the addition of tunicamycin, indicating that the heterogeneous light chain forms produced by these ConA-resistant variants resulted from the size differences of core polypeptides and not from N-glycosylation. Sequence analysis from one of the variant light chains revealed that its V lambda gene segment differs markedly from identified human V lambda gene segments (at most, 60% homology with known human V lambda subgroups) and, furthermore, the variant light chain shares 80% homology with the rabbit V lambda gene. In addition, the antigen binding ability of these variant antibodies changed significantly in both specificity and affinity. These results suggest that heterogeneous light chains expression by ConA-resistant variants may provide a new way for developing an antigen-specific human monoclonal antibody repertoire.
人HB4C5杂交瘤细胞产生一种肺癌特异性人单克隆抗体，该抗体具有一条λ轻链，在其第一个互补决定区连接有N-连接糖链。原始的和刀豆球蛋白A（ConA）抗性的HB4C5克隆分泌多达六种不同大小的轻链。这六种轻链中的两种直接来源于HB4C5原始细胞，大小分别为30 kDa和32 kDa。已证明这两种轻链之间的结构差异是位于单个位点的N-连接糖链。另外四种变体来源于ConA抗性变体，其轻链大小范围约为26至29 kDa。添加衣霉素抑制糖基化时，未观察到分泌形式的变化，这表明这些ConA抗性变体产生的异质性轻链形式是由核心多肽的大小差异而非N-糖基化导致的。对其中一种变体轻链的序列分析表明，其Vλ基因片段与已鉴定的人Vλ基因片段有显著差异（与已知的人Vλ亚组最多有60%的同源性），此外，该变体轻链与兔Vλ基因有80%的同源性。此外，这些变体抗体的抗原结合能力在特异性和亲和力方面都发生了显著变化。这些结果表明，ConA抗性变体的异质性轻链表达可能为开发抗原特异性人单克隆抗体库提供一种新方法。
