Pesando J M, Bouchard L S, McMaster B E
Biomembrane Institute, Seattle, Washington 98119.
J Exp Med. 1989 Dec 1;170(6):2159-64. doi: 10.1084/jem.170.6.2159.
The pan-B and B cell-specific sIg and CD19 antigens are functionally and physically associated in the presence of anti-Ig mAb. Incubation of B cells with anti-Ig antibodies causes rapid, specific, reversible, concentration-dependent, and unidirectional comodulation of CD19 on every mature B cell studied. Comodulation is produced by mAbs specific for the gamma, mu, kappa, and lambda chains of Ig, and by at least one idiotype-specific mAb. Comodulation is observed using 15 CD19-specific mAbs that detect at least three different CD19 epitopes. Of 18 surface antigens studied, only CD19 is comodulated. Loss of sIg and CD19 occurs concurrently during anti-Ig modulation and demonstrates a comparable dependence on anti-Ig concentration, suggesting that these are parallel rather than serial events. Incubation with anti-Ig specifically cocaps and suggests internalization of anti-CD19 mAb. Comodulation of sIg and CD19 by anti-Ig but not anti-CD19 mAbs suggests that ligand binding enables sIg to then interact with CD19. We propose that CD19 is a component of the B cell antigen receptor and suggest that it could facilitate signal transduction by sIg-antigen complexes.
在抗Ig单克隆抗体存在的情况下，全B细胞和B细胞特异性表面免疫球蛋白（sIg）及CD19抗原在功能和物理上相互关联。用抗Ig抗体孵育B细胞会导致所研究的每个成熟B细胞上的CD19发生快速、特异性、可逆、浓度依赖性和单向的共调节。这种共调节由针对Ig的γ、μ、κ和λ链的特异性单克隆抗体以及至少一种独特型特异性单克隆抗体产生。使用检测至少三种不同CD19表位的15种CD19特异性单克隆抗体可观察到共调节现象。在所研究的18种表面抗原中，只有CD19发生共调节。在抗Ig调节过程中，sIg和CD19同时丧失，并且显示出对抗Ig浓度具有相似的依赖性，这表明这些是平行而非连续的事件。用抗Ig孵育会特异性地使抗CD19单克隆抗体共包被并提示其内化。抗Ig而非抗CD19单克隆抗体对sIg和CD19的共调节表明，配体结合使sIg能够随后与CD19相互作用。我们提出CD19是B细胞抗原受体的一个组成部分，并认为它可以促进sIg-抗原复合物的信号转导。
