Grafton G, Goodall M, Gregory C D, Gordon J
Department of Immunology, Medical School, University of Birmingham, Edgbaston, UK.
Cell Immunol. 1997 Nov 25;182(1):45-56. doi: 10.1006/cimm.1997.1205.
The present study has used a panel of 23 monoclonal antibodies to IgM and 4 to IgD in order to probe parameters influencing sIg-dependent apoptosis in an IgM/IgD-expressing Burkitt lymphoma line. No direct correlation was observed between the capacity of the different anti-mu to drive cells into apoptosis and either their domain specificity or their affinity for sIgM. There was, however, a direct correlation between the functional outcome and the ability of the monoclonal antibodies to elicit a rise in intracellular Ca2+. For apoptosis to occur, the Ca2+ response had to attain a threshold value of approximately 100 nM. A direct role for Ca2+ in the delivery of the apoptotic signal was demonstrated using thapsigargin to raise intracellular Ca2+ levels. Antigen receptor ligation was linked to Ca2+ increases by tyrosine kinases as revealed by direct analysis of protein tyrosine phosphorylation and the effects of selective protein tyrosine kinase-inhibiting tyrphostins. These findings reveal a central role for the antigen receptor-generated Ca2+ signal in driving apoptosis in human B lymphoma cells and stresses the need to use a panel of reagents when probing function with presumed ligand-mimetic monoclonal antibodies.
本研究使用了一组针对IgM的23种单克隆抗体和针对IgD的4种单克隆抗体，以探究影响IgM/IgD表达的伯基特淋巴瘤细胞系中sIg依赖性凋亡的参数。不同抗μ抗体促使细胞凋亡的能力与其结构域特异性或对sIgM的亲和力之间未观察到直接相关性。然而，功能结果与单克隆抗体引发细胞内Ca2+升高的能力之间存在直接相关性。为了使凋亡发生，Ca2+反应必须达到约100 nM的阈值。使用毒胡萝卜素提高细胞内Ca2+水平，证明了Ca2+在传递凋亡信号中起直接作用。通过对蛋白质酪氨酸磷酸化的直接分析以及选择性蛋白质酪氨酸激酶抑制剂曲古抑菌素的作用表明，抗原受体连接通过酪氨酸激酶与Ca2+增加有关。这些发现揭示了抗原受体产生的Ca2+信号在驱动人B淋巴瘤细胞凋亡中的核心作用，并强调在使用假定的配体模拟单克隆抗体探测功能时需要使用一组试剂。
