Evaluation of naturally occurring cell-mediated cytotoxic activity in normal and UV-irradiated mice.

The levels of NCMC activity residing in the spleens of normal and UV-irradiated mice (subsequent to augmentation with polyinosinic.polycytidylic acid [poly I.C]) were evaluated using tumor target cells from both lymphoid and solid tumor sources. Early in the UV-irradiation protocols a low-level, transient depression in NCMC function was detected. The levels of NCMC activity in mice that had received daily UV-exposures for a period of 5-10 weeks, however, were found to be equivalent to, or greater than, those detected in normal mice. Furthermore, regressor and progressor tumor cell lines that had been cloned from individual UV-induced tumors exhibited low, but similar, levels of sensitivity to NCMC cells obtained either from normal or from UV-irradiated mice. Poly I.C treatment of normal and UV-irradiated mice was found to have no effect on the outcome of subsequently implanted UV-induced regressor tumors; normal and poly I.C pretreated normal mice rejected the tumor implants, although both untreated and poly I.C pretreated, UV-irradiated mice grew the tumors at equivalent rates.