Recognition Of Ligands By Natural Killer Cells

CD28在自然杀伤（NK）细胞系t - indy中起细胞毒性激活受体的作用。为了分析p56lck激酶对杀伤抑制受体功能的要求，我们转染了编码KIR2DL2的c143基因的p56lck阴性的YT-Indy细胞系。Prevanadate处理在YT-Indy-c143细胞系中显示KIR2DL2磷酸化，以及SHP1/SHP2募集。t - indy -c143细胞裂解表达HLA-Cw3 （KIR2DL2的配体）的靶细胞的能力受到抑制。这种抑制作用被抗kir2dl2或抗hla I类单抗阻断。CD28在YT-Indy-c143细胞上的交联增强了PLC-gamma 1的酪氨酸磷酸化。KIR2DL2与mAb的同时连接导致cd28诱导的PLC-gamma 1酪氨酸磷酸化减少，证实该蛋白的去磷酸化参与了KIR2DL2诱导的cd28介导的细胞毒性抑制。由于YT-Indy-c143细胞不表达可检测水平的p56lck，这些结果表明该激酶不是传递KIR2DL2连接产生的负信号所必需的。

CD28 functions as a cytotoxicity activation receptor in the natural killer (NK) cell line YT-Indy. To analyze the requirement of p56lck kinase in the function of killer inhibitory receptors, we transfected the p56lck negative YT-Indy cell line with the c143 gene encoding for KIR2DL2. Prevanadate treatment revealed KIR2DL2 phosphorylation in the YT-Indy-c143 cell line,as well as SHP1/SHP2 recruitment. YT-Indy-c143 cells were inhibited in their ability to lyse target cells expressing HLA-Cw3, a ligand for KIR2DL2. This inhibition was blocked by anti-KIR2DL2 or anti-HLA class I mAb. CD28 crosslinking on YT-Indy-c143 cells enhanced tyrosine phosphorylation of PLC-gamma 1. The simultaneous ligation of KIR2DL2 with mAb resulted in a decrease in CD28-induced tyrosine phosphorylation of PLC-gamma 1 confirming that dephosphorylation of this protein is involved in the KIR2DL2 induced inhibition of CD28-mediated cytotoxicity. As YT-Indy-c143 cells do not express detectable levels of p56lck, these results indicate that this kinase is not required for transmitting the negative signals generated by KIR2DL2 ligation.