HLA-G1-transfected K562 cells do not inhibit NK-cell-mediated lysis in europium release cytotoxicity assay.
The class Ia of HLA molecules are recognised by NK-cells either by inhibitory or stimulatory NK-receptors. When inhibitory signals prevail over stimulatoryones, the target cells expressing the class Ia of HLA molecules are not lysed by NK-cells. Similarly, class Ib of HLA molecules have been reported to induce the inhibitory signal in NK-cells. The cell line K562 is deprived of both class Ia and class Ib of HLA molecules, respectively, the fact of which enhances the lysis of K562 cells when they are co-cultivated with NK-cells. To study the role of HLA-G molecules in NK-cell cytotoxic activity, HLA-G tranfected K562 cells were used as target cells. NK-cells were isolated from the peripheral blood of 4 unrelated persons using Miltenyi's Biotec isolation system. The purity of directly isolated NK cells (CD56 Multisort kit) was 74.1%, and that of indirectly isolated NK-cells (NK-cell isolation kit) 69.4%. The europium release cytotoxicity assay was used in all experiments. The percentage of cytotoxicity ranged from 19% to 24% when K562 target cells were used. Similar results were obtained with the HLA-G1-transfected target cells: the percentage of cytotoxicity ranged from 17% to 29%. Our preliminary results indicate that NK-cells are able to lyse both, K562 cells and the HLA-G1-transfected K562 cells. (Tab. 1, Fig. 8, Ref. 21.).
Sapak
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Department of Immunology, Faculty of Medicine, Comenius University, Bratislava, Slovakia. michals@pobox.sk
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D000328:Adult; D003601:Cytotoxicity Tests, Immunologic; D003602:Cytotoxicity, Immunologic; D005063:Europium; D006680:HLA Antigens / Q000276:immunology*; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000276:immunology*; D008875:Middle Aged; D014162:Transfection
D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; D005063:Europium