Natural cellular reactivities mediated by splenocytes from mice bearing three types of primary tumor.

The ability of splenocytes from mice bearing three types of primary tumor to lyse YAC-I target cells (NK activity) and to inhibit [125I]dUrd incorporation ([125I]dUrd I-I = cytostasis) into B16-F10 target cells was compared to the ability of normal splenocytes to perform such activities. The tumor systems used were urethane-induced lung adenomas in BALB/c mice, dimethylbenzanthracene (DMBA)-induced tumors in hormonally-stimulated BALB/c mice and mammary tumors in force-bred C3HeB mice. The two types of natural cellular reactivity in lung adenoma-bearing mice were unaffected. The NK activity of mice bearing DMBA and forced-breeding-induced tumors was suppressed. The cytostatic ability of splenocytes from mice bearing DMBA-induced tumors was significantly elevated. The spleens of mice bearing primary DMBA-induced tumors contained cells able to suppress NK activity or to compete against target cells for NK cells.