The effect of intravenous Corynebacterium parvum on gut associated mononuclear phagocytes in normal and tumour bearing rats.

Corynebacterium Parvum, which has been used in the treatment of human colorectal cancer, probably exerts its action through cells of the mononuclear phagocyte system (MPS). In this study the effect of systemically administered C. parvum has been measured on gut associated MPS cells in normal and colorectal cancer bearing rats. MPS cells are not normally found in samples of lymph obtained after cannulation of the thoracic duct (TDC). However, after total extirpation of the mesenteric lymph nodes, TDC yields samples in which up to 5% of the total cell population appear to be MPS cells. This procedure has been carried out in adult Wistar rats enabling an in vivo study to be made on the effect of C. parvum treatment on the effluent gut cells. Measurements have been made both of the number of cells found in thoracic duct lymph and of their capacity to phagocytose sensitized sheep red blood cells. These measurements were repeated in a mesenteric lymphadenectomized group of rats which had also undergone induction of colonic cancer using dimethylhydrazine. C. parvum treatment did not effect total cell, or phagocyte numbers in thoracic duct lymph (TDL). However rats with colonic cancers showed a marked reduction in the numbers of phagocytic cells in TDL irrespective of C. parvum treatment.