Natural and induced antisera specific for pulmonary macrophages.

Abstract

Pulmonary macrophages of mice and hamsters but not rats have antigens on their surfaces which were absent from resident peritoneal macrophages, BCG stimulated pertioneal macrophages, and macrophages in other tissues. Antibodies to these antigens were found in the normal sera of rabbits from a variety of sources, and higher titers were induced by inoculation of rabbits with pulmonary macrophages. After absorption with peripheral blood cells and peritoneal macrophages, a highly specific anti-pulmonary macrophage serum was produced. Although usually absent in normal guinea pig sera, this antibody was induced in guinea pigs. To identify a specific antigen in mice, cell surface proteins of pulmonary and peritoneal macrophages were labelled with125I, disassociated by the detergent NP-40, and reacted with either specific guinea pig anti-mouse pulmonary macrophage serum or normal guinea pig serum. The precipitated surface proteins were identified by SDS-polyacrylamide gel electrophoresis. Specific pulmonary macrophage antigen had a molecular weight of 110,000. It was identified with specific antibody (but not with normal guinea pig serum) only on pulmonary macrophages. It was always absent from peritoneal macrophages. Proteins which precipitated in a non-specific fashion and were common to both pulmonary and peritoneal macrophages had molecular weights of 150,000–160,000, 70,000, and 32,000–40,0000. These proteins were detected with both the specific antiserum and normal guinea pig serum.