NK cells extract HLA-G1 antigen from K562-G1 cells via trogocytosis

Objective To investigate the mechanism of acquisition of HLA-G1 antigen by NK cells.Methods K562 cells stably expressing HLA-G1 antigen （K562-G1） were constructed.K562-G1 cells, K562 cells and shed HLA-G1 were respectively co-cultured with NK-92MI cells to observe the acquisi-tion of HLA-G by NK cells.To further investigate the mechanism , NK-92MI cells with blockage HLA-G re-ceptors were further co-cultured with K562-G1 cells and HLA-G1 proteins expressing on K 562-G1 cells were blocked and then co-cultured with NK-92MI cells. Acquisition of HLA-G 1 by NK-92MI cells was analyzed by flow cytometry and fluorescence microscopy .The effects of HLA-G1 expression on the cytotoxicity of NK-92MI cell were evaluated by flow cytometry analysis based on CD 107a labeling.R esults NK-92MI cells could quickly acquire HLA-G1 from K562-G1 cells in co-culture experiments .Blockade of HLA-G1 or its re-ceptors KIR2DL4 and ILT2 with specific mAbs did not affect the acquisition of HLA-G1 by NK-92MI cells. Moreover, HLA-G1 could significantly inhibit the cytotoxicity of NK cell （ P〈0.01）.Conclu sion NK-92MI cells acquire HLA-G1 from K562-G1 cells via trogocytosis , which is not associated with affinity be-tween receptor and ligand , extracellular domain of HLA-G1 or passive adhesion . Key words: HLA-G1;  NK cell;  Trogocytosis