Effects of Corynebacterium parvum on murine myeloid leukaemia.

The effects of C. parvum on RFM/UN myeloid leukaemia were studied. Mice inoculated with 7.0 mg but not 0.7 mg C. parvum i.p. survived significantly longer than untreated leukaemic mice (P less than 0.001). Administration of silica abrogated the effects of C. parvum, whilst polyvinyl pyridine-N-oxide prevented the inhibitory effects of silica. These studies demonstrate that a single large dose of C. parvum, either before or after leukaemic-cell passage, can significantly prolong the survival of RFM mice bearing myeloid leukaemia. The effects of silica and PVNO on C. parvum suggest a critical role for macrophages in C. parvum effects on myeloid leukaemia.