On the origin of peritoneal resident macrophages. II. Recovery of the resident macrophage population in the peritoneal cavity and in the milky spots after peritoneal cell depletion.

A kinetic study of the resident macrophage population in the peritoneal cavity and in the milky spots was done in mice depleted of peritoneal cells by repeated peritoneal washing. According to the distribution of the peroxidatic activity, four types of peritoneal macrophages could be distinguished. The size of each of these subpopulations depends on the length of the interval after peritoneal-cell depletion. Tritiated thymidine experiments revealed in the peritoneal cavity and in the milky spots local DNA synthesis by resident and PO-negative macrophages but not by monocytes or exudate macrophages and exudate/resident macrophages. The relationships between the various types of macrophages are discussed. No evidence was found for a relationship between resident macrophages and monocytes or macrophages with PO-positive granules. The PO-negative macrophage population was suggested to be heterogeneous, part of it being derived from monocytes and part having a relationship with the resident macrophages.