[Effect of silica on the anti-tumour activity of "Corynebacterium parvum" (author's transl)]

Silica, a specifically toxic substance for macrophages, has been used to study the role of these cells in the Corynebacterium parvum-induced anti-tumour protection. In the two experimental tumours studied, silica, C. parvum and tumour cells were injected by the same route: the intravenous route in the case of lymphosarcoma in XVII mice and the intraperitoneal in that of mammary carcinoma in C3H mice. The inhibition of the anti-tumour effect of C. parvum by the administration of silica was more pronounced in C3H than in XVII mice. Silica administration has only a weak and transient depressive effect on the stimulation of macrophage phagocytic activity induced by C. parvum. In addition, silica injection increased the adjuvant effect of C. parvum on the sheep red blood cell antibody response. These results suggest that the silica induced abrogation of the anti-tumour effect of C. parvum could be due to a local inhibition of macrophage stimulation at the tumour inoculation site.