Macrophages and resistance to tumors. IV. Influence of age on susceptibility of mice to anti-inflammatory and antimacrophage effects of tumor cell products.

Supernatants from cultures of mouse tumors inhibited delayed-type hypersensitivity (DTH) reactions to sheep red blood cells (SRBC) in immunized (C57BL/6J X A/J)F1 and CBA/J mice. In mice older than 17 weeks, two activities were detectable. Material having an apparent molecular weight of less than 10,000 (by membrane filtration) inhibited only the early phase of the reactions: material having a higher molecular weight inhibited only the later phase. In younger mice, DTH reactions were not inhibited. Susceptibility of resistance could not be conferred on young or old mice by reciprocal transfer of spleen cells or sera. Only older SW or A/J mice treated with tumor supernatants displayed reduced inflammation following intradermal injection of concanavalin A (Con A) and depressed cellular responses to Con A injected ip. Supernatant fractions containing material of lower molecular weight inhibited migration and phagocytosis of opsoniazid SRBC in vitro by peritoneal macrophages from both young and old (C57BL/6J X A/J)F1 and CBA/J mice.