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.