Subversion of host defense mechanisms by malignant tumors: an established tumor as a privileged site for bacterial growth.

Abstract

Mice carrying any 1 of 3 murine tumors in their right hind foot pad were incapable of eliminating an inoculum of Listeria monocytogenes from the progressive tumor. They were as capable as control mice in efficiently eliminating the organism from their contralateral tumor-free foot pad, and from their lymph nodes and livers. Conditions within an established tumor are apparently not only antagonistic to the expression of concomitant anti-tumor immunity, but they are also antagonistic to the expression of T[thymus-derived]-cell-mediated anti-bacterial immunity. The tumor may contain factors that act pharmacologically to locally suppress the function of sensitized T cells and activated macrophages.