Quantitative studies of the growth and rejection of allogeneic tumour cells in mouse cerebrospinal fluid. Elimination in the absence of H-2 differences.

Following intracerebral (i.c.) inoculation DBA/2 (H-2d) mastocytoma cells (P815) grow to concentrations of greater than 10,000/mul in cerebrospinal fluid (CSF) of H-2 compatible BALB/c mice, but are completely eliminated from 90% of such animals within 12 days. A similar pattern occurs in allogeneic C57BL (H-2b) and random-bred WEHI mice, whereas syngeneic DBA/2 mice die within 7 days from unrestricted tumour growth. Rejection in BALB/c mice is enhanced by prior exposure to the tumour, but is severely depressed by pretreatment with cyclophosphamide. Leucocytes responsible for eliminating the mastocytoma are apparently not active against sarcoma 180 cells injected simultaneously. Subsequent to intraperitoneal inoculation with mastocytoma cells both BALB/c and C57BL mice generate significant cytotoxic activity in spleen, as measured by an in vitro 51Cr release assay. Cytolysis is abrogated by prior incubation of spleen cells with AKR anti-O ascitic fluid and complement, but not by normal AKR ascitic fluid and complement. Following i.c. exposure, however, much lower levels of cytotoxic activity are found in spleen, though specifically sensitized lymphocytes are also present in lymph nodes of the cervical chain.