Parnes J R, Pan C
Department of Medicine, Stanford University School of Medicine, California, USA.
Immunol Rev. 2000 Aug;176:75-85. doi: 10.1034/j.1600-065x.2000.00608.x.
The ability of lymphocytes to respond to antigenic or mitogenic stimulation is regulated not only by specific receptor proteins, but also by both positive and negative regulatory proteins that set or fine-tune the threshold for responsiveness. CD72 is one such regulatory protein on B lymphocytes. It is a member of the C-type lectin superfamily and is expressed on the surface of B cells from the pro-B through the mature B-cell stage. Studies with anti-CD72 antibodies have suggested a positive regulatory role for CD72 in B-cell activation. However, the cytoplasmic tail of CD72 contains two potential immunoreceptor tyrosine-based inhibitory motifs, one of which has been shown to recruit the tyrosine phosphatase SHP- 1. These features suggest a negative regulatory role for CD72. We have generated CD72-deficient mice to elucidate the physiological role of CD72 in B-lymphocyte development and activation. Our analyses of these mice and their B-cell compartment demonstrate that CD72 is a nonredundant regulator of B-cell development and a negative regulator of B-cell responsiveness.
淋巴细胞对抗原或促有丝分裂刺激作出反应的能力不仅受特定受体蛋白的调节，还受设定或微调反应阈值的正向和负向调节蛋白的调控。CD72是B淋巴细胞上的一种此类调节蛋白。它是C型凝集素超家族的成员，在从前B细胞到成熟B细胞阶段的B细胞表面均有表达。用抗CD72抗体进行的研究表明CD72在B细胞活化中起正向调节作用。然而，CD72的胞质尾部含有两个潜在的基于免疫受体酪氨酸的抑制基序，其中一个已被证明可募集酪氨酸磷酸酶SHP-1。这些特征提示CD72具有负向调节作用。我们已培育出CD72缺陷小鼠，以阐明CD72在B淋巴细胞发育和活化中的生理作用。我们对这些小鼠及其B细胞区室的分析表明，CD72是B细胞发育的非冗余调节因子，也是B细胞反应性的负调节因子。
