Interferon gamma induced oncolysis. An effect on head and neck squamous carcinoma cultures.

We have measured an oncolytic effect of recombinant human interferon gamma on squamous cell carcinoma (SCC) tissue cultures. The decrease in viable cells from an established culture was visually observed directly and measured by the loss of cell protein mass as determined by the staining of cultures with naphthol blue-black dye. We avoided confusion with tumor necrosis factor effects by using recombinant human interferon gamma cloned from a single gene as opposed to natural human interferon gamma. Oncolysis induced by recombinant human interferon gamma requires four days after exposure for a significant loss of total cellular protein to be measured, although changes can be observed visually after one day. This sensitivity to recombinant human interferon gamma was observed in SCC cultures obtained from head and neck mucosa, in addition to those from cervix and skin. Several head and neck cultures are sensitive to the oncolytic effect of recombinant human interferon gamma at less than 30 U/mL concentration. The actual time of treatment observations dictates changes in current recombinant human interferon gamma treatment regimens if the oncolytic effect is desired.