The Effect of C. Parvum Therapy on Intratumoral Macrophage Subpopulations

Abstract

Systemic administration of Corynebacterium parvum can cause partial or in a few instances complete (1,2) regression of subcutaneously growing transplanted tumors (3). It is reasonable to suggest that tumor regression of this kind is macrophage mediated in light of the knowledge that C. parvum injected by the same route stimulated the mononuclear phagocyte system into intense prolonged activity (3). In order to test this hypothesis, it seems best to examine the most relevant macrophage population which is within the tumor itself. Previous reports (4,5,6) had suggested that the intratumoral macrophages did not alter in number during C. parvum therapy. We therefore examined activation of Fc receptor expression. In addition to being a useful discriminating index, Fc receptors appear to equate with other indices of macrophage stimulation/activation (7,8,9).