Mononuclear phagocytic cells in peritoneal exudates of guinea pigs: a comparison of inducing agents.

Peritoneal macrophages are used for immunologic assessment of the lymphokine, migration inhibitory factor (MIF). For this purpose, these cells are induced intraperitoneally in animals with inflammatory agents such as mineral oil (MO) and peptone water (PW). Purpose of the present study was two-fold: To assess the changes in biologic properties of guinea pig macrophages induced peritoneally with MO or PW as compared to control cells after administration of normal saline (NS); and to examine the suitability of induced macrophages to respond to MIF in vitro. Peritoneal exudate cells were harvested from guinea pigs 7 days following intraperitoneal injection of MO, PW or NS. They were enumerated in hemocytometers, their differential counts determined by Wright's stain and morphologic characteristics assessed by scanning electron microscopy. Functional activation of peritoneal macrophages was determined by lysosomal enzyme functions, as well as by yeast phagocytosis in vitro. Random cell migration and responses to migration inhibitory factor (MIF) were determined in Mackaness chambers. Mineral oil injection resulted in significantly higher yield of peritoneal macrophages. Greater than 70% of peritoneal exudate cells were macrophages in all three groups. Spread out structures and ruffled borders were seen in electron micrographs of MO induced cells. Such structures were less evident in PW induced cells and were absent in controls. Acid phosphatase (ACP) and beta-N-acetylglucosaminidase (B-NAG) activities as well as yeast phagocytosis significantly increased in MO and PW induced cells. Random migration and responses to MIF in Mackaness chambers remained comparable in the three experimental groups.