Calvo C F, Watanabe S, Métivier D, Senik A
Eur J Immunol. 1986 Jan;16(1):25-30. doi: 10.1002/eji.1830160106.
Fc gamma receptor-bearing U937 cells, when incubated in serum-free buffer, were found to release spontaneously a suppressor material for pokeweed mitogen-drigen IgG synthesis which could be retained on Sepharose 4B-IgG immunosorbents. Immunosorbents coupled with IgM or F (ab')2 fragments of IgG were unable to retain the inhibitory activity of U937-derived material, suggesting a binding specificity for the Fc gamma fragment of IgG. This suppressor material corresponds therefore by definition to an IgG-binding factor (IgG-BF). The mechanism for in vitro suppression of the antibody response by U937-derived IgG-BF was investigated. It did not interfere with cell proliferation and displayed maximum effect when added at day 3 of the culture period. Tested for its effect on IgG, IgM and IgA synthesis, IgG-BF suppressed antibody production following a pattern specific for IgG. Finally gel filtration of the suppressor material gave rise to two peaks of inhibitory activity with an apparent molecular mass comprised between 30 to 40 kDa and 60 to 73 kDa, respectively.
携带Fcγ受体的U937细胞在无血清缓冲液中孵育时，被发现会自发释放一种抑制物，该抑制物可抑制商陆丝裂原驱动的IgG合成，且能被琼脂糖4B-IgG免疫吸附剂保留。与IgM或IgG的F(ab')2片段偶联的免疫吸附剂无法保留U937来源物质的抑制活性，这表明其对IgG的Fcγ片段具有结合特异性。因此，根据定义，这种抑制物对应于一种IgG结合因子（IgG-BF）。对U937来源的IgG-BF体外抑制抗体反应的机制进行了研究。它不干扰细胞增殖，在培养期第3天添加时显示出最大效果。测试其对IgG、IgM和IgA合成的影响时，IgG-BF以一种特异性针对IgG的模式抑制抗体产生。最后，对抑制物进行凝胶过滤，产生了两个抑制活性峰，其表观分子量分别在30至40 kDa和60至73 kDa之间。
