Expression of MHC-class-I antigens in human carcinomas and sarcomas analyzed by isoelectric focusing

We analyzed the expression of class-I antigens in ex vivo human tumor cells by isoelectric focusing (IEF) the anti-class-I mAb W6/32 immunoprecipitates prepared from cell lysates. Out of 42 experiments, 27 were technically successful. The patient's blood lymphocytes were used as controls. In vitro exposure of the tumor cells to IFN gamma and TNF alpha elevated class-I antigen expression. In 11 cases, defects in MHC-class-I-antigen expression were observed. In 2 cases the antigens were detected only in the cytokine-treated tumor samples, probably due to a defect in the association between beta 2m and class-I heavy chains. Selective changes in the expression of alleles were seen in 10 cases and might involve HLA A, B and C antigens. Alterations in class-I expression as compared with the lymphocytes were observed in 9 of 13 cases in which the tumor cells were collected from metastases, and only in 2 of 14 primary tumors.