Further studies on the effect of a transplanted methylcholanthrene-induced fibrosarcoma on humoral immunity in CBA mice.

The immunodepressive effect of transplanted methylcholanthrene-induced fibrosarcoma cells on the humoral response to alum BSA could be potentiated by delaying the injection of antigen until several days after tumour transplantation. Cell transfer studies indicated that the spleen cells from animals exhibiting depressed responses to BSA were as effective as normal spleen cells at restoring the response to this antigen in sublethally irradiated syngeneic recipients. Other experiments showed that the simultaneous administration of tumour cells preferentially suppressed the IgG1 splenic PFC response to SRBC, while in animals with established tumours the IgM and IgG2b responses to this antigen were elevated. There was no evidence that simultaneously transplanted or established tumour depressed the PFC response of draining lymph nodes following SRBC challenge.