Increased phagocytic activity in mice treated by a mouse granuloma protein.

Intravenous injection of a protein extracted from a talc-induced granuloma (MGP) enhanced the blood clearance of a highly virulent strain of Salmonella typhimurium. This protein was able to enhance mouse resistance to systemic infection with Listeria monocytogenes when injected one or two days prior to infection. Furthermore, since MGP-treated athymic mice were also protected against Listeria infection, mature T cells were most likely not involved in this enhanced resistance. These findings suggest that this increased resistance to infection correlates with an activation of liver and spleen macrophages. This protective effect of MGP was not due to possible endotoxin contamination of the preparation, as the MGP activity was destroyed by heating.