Specific and nonspecific stimulation of resistance to the growth and metastasis of the line 1 lung carcinoma.

The effects of specific dead tumor cell immunization and nonspecific immunostimulation with Corynebacterium parvum on the s.c. growth of the line 1 carcinoma in syngeneic BALB/c mice have been studied. Injection of heavily irradiated line ) carcinoma cells did not inhibit the transplantability or growth of the line 1 carcinoma, and in certain cases these treatments actually prolonged the period of rapid growth. This latter observation was traced to a mild inhibition of metastatic spread, which itself can slow the s.c. tumor growth. Treatment of the mice with 0.25 mg of C. parvum 7 days prior to transplant of the tumor had no effect on its growth by itself; but in combination with i.v.-injected tumor cells, which themselves had no effect on tumor growth, a 45% inhibition of tumor growth was induced. These data demonstrate that, in the weekly immunogenic line 1 carcinoma system, inhibition of s.c. transplants requires not only exposure to tumor antigens but also stimulation of the immunological reactivity.