DIFFERENTIAL GROWTH-INHIBITION AND ENHANCEMENT OF MAJOR HISTOCOMPATIBILITY COMPLEX CLASS-I ANTIGEN EXPRESSION BY INTERFERONS IN A SMALL-CELL LUNG-CANCER CELL-LINE AND ITS DOXORUBICIN-SELECTED MULTIDRUG-RESISTANT VARIANT

Expression of class I and class II major histocompatibility complex antigens on a human small-cell lung cancer cell line and its multidrug-resistant variant was examined before and after exposure to interferon-alpha (IFN-alpha) and IFN-gamma by flow cytometry. Neither IFN-alpha nor IFN-gamma induced class II antigen expression on the drug-sensitive or resistant cell line. Induction of class I antigen expression along with an inhibition of proliferation was observed in both cell lines after IFN-alpha treatment. On the other hand, IFN-gamma treatment resulted in growth inhibition and enhancement of class I antigen expression in the sensitive cell line but not the resistant cell line. The differential response of the two cell lines to IFN-gamma cannot be directly attributed to the acquisition of drug resistance but it suggests that further investigation of the possibility that drug-sensitive and resistant small-cell lung tumors may respond differently to immunotherapies that include IFN-gamma is warranted.