Golay J T, Clark E A, Beverley P C
J Immunol. 1985 Dec;135(6):3795-801.
Two monoclonal antibodies, 1F5 and B1, directed against the CD20 (Bp35) antigen were found to have both stimulatory and inhibitory effects on B cells. 1F5, but not B1, induces small resting tonsillar B cells and prolymphocytic leukemia cells to enlarge, to rapidly increase their RNA synthesis, and to become responsive to growth factors present in mixed lymphocyte reaction supernatants. In addition, 1F5 induces a moderate increase in thymidine uptake, which is accompanied by enhanced viability of the cells, but not by any increase in total cell number or by any detectable entry into S phase or mitosis. Taken together, these observations suggest that 1F5 can initiate transition from the G0 to the G1 phase of the cell cycle. The fact that all the changes observed can be inhibited by low concentrations (I50 = 50 ng/ml) of cyclosporin A is further evidence that 1F5 is involved at an early stage of B cell activation. Because both 1F5 and B1 belong to the IgG2a subclass, differences in their activities are likely to reflect their different epitope specificities. Although only 1F5 had stimulatory activity, both 1F5 and B1 strongly inhibited B cell differentiation to immunoglobulin secretion. Possible explanations for the dual activities of 1F5 and implications for the role of the CD20 antigen in B cell differentiation are discussed.
发现两种针对CD20（Bp35）抗原的单克隆抗体1F5和B1对B细胞具有刺激和抑制作用。1F5可诱导静止的小扁桃体B细胞和幼淋巴细胞白血病细胞增大，迅速增加其RNA合成，并对混合淋巴细胞反应上清液中存在的生长因子产生反应，而B1则无此作用。此外，1F5可使胸苷摄取适度增加，这伴随着细胞活力增强，但细胞总数未增加，也未检测到进入S期或有丝分裂的情况。综合这些观察结果表明，1F5可启动细胞周期从G0期到G1期的转变。低浓度（I50 = 50 ng/ml）的环孢素A可抑制所有观察到的变化，这进一步证明1F5参与了B细胞激活的早期阶段。由于1F5和B1都属于IgG2a亚类，它们活性的差异可能反映了其不同的表位特异性。虽然只有1F5具有刺激活性，但1F5和B1都强烈抑制B细胞向免疫球蛋白分泌的分化。文中讨论了1F5双重活性的可能解释以及CD20抗原在B细胞分化中的作用。
