Ontogenic development of the reactivity of macrophages to antigenic stimulation

Experiments were performed to test the ability of macrophages from newborn mice to participate in immune reactions. It was found that peritoneal cells from 4-day-old mice injected at birth with thioglycollate did not reconstitute reactivity to Shigella in adult, irradiated mice, while normal adult macrophages did.The total yield of peritoneal exudate cells (PEC) was relatively low, yet the number of precursor cells of macrophages in the newborn spleen was found in significantly higher concentrations than in the adult. The number of precursor cells in the spleens of 0–3-day-old mice did not increase in response to antigenic stimulation, indicating that they too are unable at this stage to develop reactivity to immunological signals.