Effect of Corynebacterium parvum on cellular and humoral antitumoral immune effector mechanisms

In an attempt to characterize the mechanism of action of Corynebacterium parvum (C. parvum) an analysis was performed of the changes in specific antitumoral immune effector mechanisms in C₃H mice showing increased protection against challenge with high inocula of the allogeneic L1210 leukemia after treatment with this immunoadjuvant. C. parvum-treated spleens displayed an increase in DNA synthesis, total cell number and in the percentage of macrophages; the percent of theta bearing lymphocytes was concomitantly decreased whereas no modification in the percent of EA-rosette forming cells was observed. Although the efficiency of target cell lysis by immune splenocytes was unchanged, the raise in spleen cellularity of C. parvum-treated mice resulted in a marked increase in this organ's capacity to express cell-mediated cytotoxicity. Treatment with this adjuvant produced also a sizable increase in the spleen capacity to mediate antibody-dependent cellular cytotoxicity whereas arming and potentiating serum activities and the levels of complement-dependent cytolytic antibody were not modified.