CONCANAVALIN-A IS MITOGENIC FOR RESIDENT PERITONEAL-MACROPHAGES

Con A, a known T‐cell mitogen, is also mitogenic for resident peritoneal macrophages. The stimulated cells morphologically resemble macrophages and are actively phagocytic. The concentration of con A (30 μg/ml) required to stimulate 3H‐TdR incorporation is ten times that required for T‐cell activation. Con A must be present throughout the entire culture period to produce the maximum effect, and con A‐depleted supernatant fluids from con A‐stimulated cells cannot replace the con A requirement. Stimulation of 3H‐TdR incorporation occurs after a 48‐hour lag period and is maximal on the fifth to seventh day of culture. At the peak of the response, 20–30% of the macrophages can be stimulated to incorporate 3H‐TdR, but little or no increase in the total number of cells present in the culture occurs. This and pulse‐chase experiments indicate that only a single cycle of replication occurs in the stimulated cells. Con A‐responsive peritoneal macrophages appear to be a distinct subpopulation and might play a different role in the interaction with T cells and B cells in the immune response than the con A‐non‐responsive cells. Copyright © 1979 Wiley‐Liss, Inc.