Steps at which plasmin(ogen) can regulate phagocytosis by macrophages. (1) “Find me” signals are released from “prey bodies,” resulting in chemotaxis by macrophages. Previous studies have established that plasminogen is required for recruitment of macrophages to sites of inflammation.2 Das et al show that (2) there is some effect of plasmin on prey bodies in the ability to be recognized by macrophages; (3) the primary effect of plasmin is on macrophages so that engulfment occurs more efficiently; and (4) expression of genes that regulate phagosome maturation and processing is down-regulated in plasminogen deficient compared with wild-type mice.
