Inbred C3H mice were inoculated subcutaneously with syngeneic, methylcholanthrene-induced sarcomas. During tumor growth, tumors were measured, and a cutaneous paw test carried out with viable tumor cells as antigen. In general, tumor paw tests were more reactive in mice with small tumors than in non-tumor-bearing control mice. When mice developed large tumors, their paw test reactivity decline, approaching that of unsensitized controls as tumors grew. The inverse correlation between tumor paw test reactivity and tumor volume is discussed. Side-to-side comparison of footpad reactivity indicated that the tumor paw test is highly reproducible. This model system in inbred mice appears useful for study of this and similar phenomena observed with some human neoplasms.

Suppression of PPHA and PPD paw test was observed in mice with a transplantable methylcholanthrene-induced sarcoma. Serum from tumor-bearing mice contained a factor which suppressed paw test reactivity in normal mice. Less suppression of paw test was seen in mice previously injected with complete Freund adjuvant. It is suggested that these observations form the basis of an experimental model for study of tumor-associated cutaneous anergy.