EXPRESSION OF HLA CLASS-IA ON TUMOR CELL LINES AND THEIR SUSCEPTIBILITY TO NK CELL

Natural Killer cells (NKs), are considered an important first line of defence and were originally defined by their ability to kill certain tumor cells and virally infected cells. Our aim is to study expression of HLA class-Ia on tumor cell lines and their susceptibility of NK cells. In this study MDA-MB-468 tumor cell line (NCB1, C208) That derived from human breast adenocarcinoma, is selected as a model which expresses total alleles of HLA class I. To test HLA class I expression, we used the F.I.T.C conjugatedm Ab W6/32 which recognize assembled HLA-A, B and C locus products. Surface expression of HLA class I on the cell line are determined with single- color flowcytometry analysis. NK cells are obtained from PBL of healthy donors. Results of our study indicate that expression of HLA class I molecules on MDA- MB- 468 Tumor cell line are increased after IFN-γ Treatment. Cytolytic activity of NK cells have direct correlation (r =1) with up- regulation of HLA class I expression on the MDA- MB- 468 tumor cell line. Therefore, on the basis of this results, we suggest that, on the surface of NK cells may exsist activating receptors that recognize allogenic HLA class I molecules and/or non HLA class I ligand that is upregulated by IFN- & treatment, and cause lysis of target cells.