Chemical characterization of specific pulmonary macrophage cell surface antigen.

Abstract

Pulmonary macrophages of mice have a unique cell surface antigen not shared by other cell types. In the study reported here, the cell surface proteins of pulmonary macrophages were labeled with125I, dissociated by the detergent NP-40, and reacted with either specific guinea pig anti-mouse pulmonary macrophage serum or normal guinea pig serum. Goat anti-guinea pig IgG was used for immunoprecipitation, and molecular weights of the precipitated surface proteins were determined by SDS-polyacrylamide gel electrophoresis. Specific pulmonary macrophage antigen had a molecular weight of 110,000 daltons and was sensitive to proteolysis. Fc receptor activity was not associated with the 110,000 dalton antigen, but was detected in 40,000 dalton material. Using125I labeled lectins, no carbohydrate was associated with the antigen. Tube gel electrophoresis was used to isolate the antigen and lipid studies were done by thin layer chromatography. Phosphatidyl serine was associated with the antigen. Isolation and characterization of macrophage surface structures are important steps in understanding their function.