What is the relevance of exudate-resident macrophages?

In vivo in the animal model peritoneal macrophages show four different peroxidatic activity (PA) patterns characterizing exudate macrophages, exudate-resident macrophages, resident macrophages, and PA-negative macrophages. Cultured in vitro, rat and human blood monocytes and rat, mouse and human exudate macrophages acquire the characteristic PA pattern of resident macrophages via the transitional stage of cells with the characteristics of exudate-resident macrophages. The cytochemistry, the occurrence of this cell type in vivo, and the kinetics in vitro, indicate that exudate-resident macrophages represent a transitional form between the exudate and the resident macrophages. The results obtained in vivo and in vitro strongly suggest that divergent PA patterns of mononuclear phagocytes represent differences in the stage of development of these cells in the sequence, monoblast, promonocyte, monocyte, exudate macrophage, exudate-resident macrophage, (PA-negative macrophage), resident macrophage. This means that in general resident macrophages are provided by recruitment from the blood via the transitional stage of exudate-resident macrophages.