Figure 8.

Effect of HLA-G1 and HLA-G2 expression on sensitivity to cytotoxicity of the YT2C2 clone. K562 transfected with either the vector alone, HLA-G1, or HLA-G2 were used as targets. The results are expressed as the percentage lysis recorded in a 4-h ⁵¹Cr-release assay. The standard deviation of the mean of the triplicates was below 5%, and the spontaneous release never exceeded 10% of the maximum release. This experiment was repeated at least five times, giving the same pattern of protection. The expression of NKIRs on the YT2C2 clone was assessed by cytofluorometry. YT2C2 cells were labeled by indirect immunofluorescence with the following primary mAbs: EB6 (IgG1, anti-p58.1 or NKIR1), GL183 (IgG1, anti-p58.2 or NKIR2), and HP-3B1 (IgG2a, anti-CD94). Controls were the same cells stained with an isotype-matched control antibody. After washing, cells were stained with phycoerythrin-conjugated F(ab′)₂ goat anti-mouse IgG. One of four representative experiments is shown.