Phagocytic activity mediated via Fc gamma R, Fc mu R, and CR3 and H2O2 release during ontogeny of mouse macrophages.

Mouse macrophage phagocytic activity was studied during ontogenetic development by comparing the abilities of infant and adult mouse macrophages to ingest opsonized particles via Fc gamma R, Fc mu R, or CR3. These studies were performed on resident, BCG-, and thioglycollate-stimulated peritoneal macrophages. The percent of ingestion and the index of maximal phagocytosis mediated via Fc gamma R is lower in infant than in adult mouse macrophages. However, the adherence mediated by Fc gamma R is similar to that seen with adult cells. Similar results were obtained when phagocytosis was mediated via Fc mu R or CR3, reaching adult levels during ontogenetic development. We also studied the age-dependent release of H2O2 by peritoneal cells before and after incubation with phorbol myristate acetate. Interestingly, the capacity of peritoneal cells from infant animals to generate H2O2 after BCG infection is similar to that observed in adult mice. Our results suggest that the adherence and phagocytosis mediated by Fc gamma R, although at lower levels than in adults, and the production of microbicidal H2O2 may be relevant for mouse survival during the first days of life.