Functional heterogeneity among peritoneal macrophages: II. Enzyme content of macrophage subpopulations

Abstract

Rabbit peritoneal exudate (PE) macrophages were separated into subpopulations on discontinuous density gradients of bovine serum albumin. Four such macrophage subpopulations, referred to as bands A, B, C, and D (from lightest to heaviest buoyant density), were examined for differences in enzyme content. With regard to three acid hydrolases—acid phosphatases, β-glucuronidase, and cathepsin D—cells in bands A and B had greater enzyme activity than cells in bands C and D. A similar distribution of activities was observed for acid p-nitrophenylphosphatase. Peroxidase activity was present only in band D. Lysozyme activity was greatest in band D cells and least in band A cells. Only small differences in cytochrome c oxidase activity were observed among the subpopulations. Arginase activity was found to be greater in cells from band A than cells in bands B, C, and D. Macrophage subpopulations derived from PE macrophages placed in tissue culture for 7 days and macrophage subpopulation cells cultured for 2 days showed differences in acid phosphatase content similar to those seen with freshly obtained subpopulations. These results extend previous work demonstrating heterogeneity among PE macrophages.