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.
NIH ExPorter
NIH ExPorter