OBJECTIVETo investigate the role of MHC class II Transactivator (C II TA) in expression of HLA molecules in five human malignant hematological cell lines.

METHODSThe expressions of HLA molecules and C II TA protein were detected by immunohistochemistry and flow cytometry. The expression of C II TA gene was detected by RT-PCR. The response of peripheral T cells after stimulation by Jurkat cells was detected by mixed lymphocyte reaction.

RESULTThe HLA II-positive tumor cells expressed the C II TA and IFN-gamma induced the expression of HLA I, II in tumor cells, which were able to express C II TA constitutively.

CONCLUSIONThere is a correlation between the inability of the tumor cells in response to IFN-gamma for HLA expression and the deficiency in the inducible expression of C II TA.