The Experimental Study On HLA-G1 Inducting K562 Cell Immunotolerant In Vitro

Objective: To study the immune functions of HLA-G1 molecule transfected to K562 cell on inhibition to NK cell cytolysis and apoptosis to CD8+ antigen-specific cytotoxic T lymphocyte(CTL) of K562 cell line in vitro, furthermore, to explore its chemism and significance in immunotolerance.Methods : HLA-G1 cDNA obtained by Reverse transcription polymerase chain reaction(RT-PCR) was transfected into HLA-G-negative K562 cell with lipofectin. Then the stable transfected K562-G1 cell line was co-cultured(the mixed lymphocyte reaction,MLR) with normal bone marrow mononuclear cells(MNCs) as the model of allo-geneic transplant rejection in vitro. The effect of inhibition of NK cytolysis and CTL apoptosis were observed. The HLA-G-positive JEG-3 cell and null plasmid transfected K562 cell were respectively controlled positively and negatively.Results: RT-PCR was used to detect the expression of HLA-G1(0.1mg/mL) on the K562 cell, and the transfected K562 cell was co-cultured with normal bone marrow cells. The result indicated the transfected K562 cell could increase the inhibition rate to NK cytolysis (P<0.05). In addition apoptosis was found by FCM analysis and it's suggested that the HLA-G1 molecule may also induct K562 cell apoptosis and regulate the T cell proliferation.Conclusion: HLA-Gs can inhibit NK cell killing effect, induct K562 cell apoptosis and possess the unique immunotolerance function different from HLA classâ… molecule. These indicted that it may be useful to induct and prolong the graft tolerance with detecting and increasing HLA-G expression in transplantation.