Kanner S B, Grosmaire L S, Blake J, Schieven G L, Masewicz S, Odum N, Ledbetter J A
Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, Washington, USA.
Tissue Antigens. 1995 Sep;46(3 ( Pt 1)):145-54. doi: 10.1111/j.1399-0039.1995.tb03113.x.
Ligation of major histocompatibility complex (MHC) class II antigens expressed on antigen-activated human CD4+ T-lymphocytes induces early signal transduction events including the activation of tyrosine kinases, the tyrosine phosphorylation of phospholipase-C gamma 1 and the mobilization of intracellular calcium. Similar responses have been observed in B-cells following stimulation of MHC class II molecules, including the increased production of intracellular cAMP. In this report, we demonstrate that the ZAP-70 tyrosine kinase is a responsive signaling element following cross-linking of HLA-DR in class II+ T-cells, and that the homologous tyrosine kinase p72syk is stimulated in B-cells following ligation of class II antigens. Antibody mediated co-ligation of the T-cell antigen receptor (TCR/CD3) with class II molecules resulted in augmented tyrosine phosphorylation of ZAP-70. Comparable to antibody induced receptor ligation, bacterial superantigen (SEA and SEB) treatment of HLA-DR+ T-cells stimulated ZAP-70 tyrosine phosphorylation, consistent with class II transmembrane signaling by ligation of HLA-DR and V beta in cis. Modulation of the TCR/CD3 led to abrogation of class II induced ZAP-70 tyrosine phosphorylation, but did not result in sequestering of ZAP-70 from the cellular cytoplasm. Hyperphosphorylated ZAP-70 was associated with TCR/CD3 zeta-chain following cross-linking of HLA-DR, suggesting a mechanism for the TCR/CD3-dependence of class II induced signals in alloantigen-activated human T-cells. In both tonsillar B-lymphocytes and B-cell leukemia lines, p72syk was rapidly phosphorylated on tyrosine residues following HLA-DR cross-linking. Tyrosine phosphorylation of p72syk induced through ligation of either the B-cell antigen receptor or class II molecules was potently inhibited by herbimycin A. MHC class II ligation on B-lymphocytes resulted in cell death, which was both qualitatively distinct from Fas-induced apoptosis and partially protected by herbimycin A pretreatment. Thus, ligation of MHC class II molecules expressed on human lymphocytes stimulates the ZAP-70/p72syk family of tyrosine kinases, leading functionally to a tyrosine kinase-dependent pathway of receptor-induced cell death.
连接抗原激活的人类CD4+ T淋巴细胞上表达的主要组织相容性复合体（MHC）II类抗原可诱导早期信号转导事件，包括酪氨酸激酶的激活、磷脂酶Cγ1的酪氨酸磷酸化以及细胞内钙的动员。在MHC II类分子刺激后的B细胞中也观察到了类似的反应，包括细胞内cAMP产生的增加。在本报告中，我们证明ZAP-70酪氨酸激酶是II类+ T细胞中HLA-DR交联后的一个反应性信号元件，并且同源酪氨酸激酶p72syk在II类抗原连接后的B细胞中受到刺激。抗体介导的T细胞抗原受体（TCR/CD3）与II类分子的共连接导致ZAP-70的酪氨酸磷酸化增强。与抗体诱导的受体连接类似，用细菌超抗原（SEA和SEB）处理HLA-DR+ T细胞可刺激ZAP-70酪氨酸磷酸化，这与通过顺式连接HLA-DR和Vβ进行的II类跨膜信号传导一致。TCR/CD3的调节导致II类诱导的ZAP-70酪氨酸磷酸化被消除，但并未导致ZAP-70从细胞质中隔离。HLA-DR交联后，过度磷酸化的ZAP-70与TCR/CD3 ζ链相关，这表明在同种异体抗原激活的人类T细胞中，II类诱导信号依赖TCR/CD3的机制。在扁桃体B淋巴细胞和B细胞白血病系中，HLA-DR交联后p72syk的酪氨酸残基迅速被磷酸化。通过连接B细胞抗原受体或II类分子诱导的p72syk酪氨酸磷酸化被除草菌素A强烈抑制。B淋巴细胞上的MHC II类连接导致细胞死亡，这在性质上不同于Fas诱导的细胞凋亡，并且部分受到除草菌素A预处理的保护。因此，连接人类淋巴细胞上表达的MHC II类分子可刺激ZAP-70/p72syk家族的酪氨酸激酶，在功能上导致受体诱导的细胞死亡的酪氨酸激酶依赖性途径。
