L-5178-Y LYMPHOMA ASSOCIATED IMMUNOSUPPRESSION IN BALB C MICE/

Lymphoma L-5178-Y bearing Balb/c mice were unable to mount a delayed-t ype hypersensitivity reaction to dinitrofluorobenzene (DNFB). A suppre ssor factor present in the ascitis of these mice inhibited the respons e if given during DNFB sensitization, but not during challenge. The fa ctor was not present in lymphoma-bearing Balb/c nu/nu mice. It appeare d to be a 35-66 kDa protein. Non-specific esterase staining indicated that the spleens of tumor-bearing and ascitis-injected mice contained a large excess of macrophages. Our observation that the suppressor fac tor prevented the very start of the immune response may indicate why i mmunostimulation is difficult to obtain in cancer bearing hosts.