HLA-G1 and HLA-G5 isoforms have an additive effect on NK cytolysis

The immunotolerant HLA-G could generate seven isoforms including HLA-G1--G7. The suppressive function of either HLA-G1 or HLA-G5 isoform to NK cell cytolysis has been well established. Whether HLA-G1 and HLA-G5 isoform have an additive effect on the cytolysis of NK cells remain to be explored. In this study, effects of expression of HLA-G1 and HLA-G5 isoforms and their combination on NK cytolysis was investigated. NK cell cytolysis was analyzed by detecting the NK cell surface CD107a expression. In this study, data showed that the inhibition capacity is dependent on the level of both HLA-G1 and HLA-G5 expression, but the HLA-G5 isoform has a more potent inhibition effect on the NK cytolysis (p<0.01). Furthermore, HLA-G1 and HLA-G5 have an additive effect on the suppression of NK cell cytolysis. Our study provided further understanding for the roles of HLA-G1 and HLA-G5 isoform expression in target cells immune escaping from NK cells.