Mechanism of Corynebacterium Parvum anti-tumour activity. II. Protective effect in T-cell-deprived mice.

The natural resistance to syngeneic mammary carcinoma was reduced by thymectomy alone in adult C3H mice or in mice thymectomized, lethally irradiated and restored with bone-marrow cells (Tx RB). The protective effect of C. parvum was not modified by adult thymectomy but it was reduced in Tx RB mice. The injection of thymic cells to Tx RB mice or the elimination of T cell precursors in bone-marrow cells injected in Tx RB mice did not increase the protective effect of C. parvum. These results were compatible with the hypothesis that T cells do not intervene in the mechanism of C. parvum protective effect.