Monoclonal antibody to an alveolar macrophage surface antigen in hamsters.

A conventionally produced antibody specific for hamster lung macrophages was prepared by immunizing guinea pigs with lung macrophages from LSH (inbred) hamsters. Specificity was achieved by absorbing the resulting serum with hamster blood cells and peritoneal macrophages. This antibody was used to precipitate antigen from detergent lysates of hamster lung macrophages. To produce monoclonal antibodies, F1 hybrids of Balb C X C57Bl6 mice were immunized with these immunoprecipitates. Fusion of splenic lymphocytes from these mice with NS-1 myeloma cells produced 4 hybrid cell lines. Subcloning yielded 18 lines producing antibody reacting only with lung macrophages, and 2 lines secreting nonreactive antibody. Screening used lung and peritoneal macrophages and an ELISA assay. Using gel electrophoresis and lysates of 125I-labeled lung macrophages, all 18 lines reacted with the same antigen, a protein of 102,000 daltons. Subclasses of these monoclonal antibodies included IgG2b kappa and IgG1 kappa. Quantitative ELISA assays showed that the antibody reacted with lung macrophages of LSH and LVG (outbred) hamsters, but not with hamster resident peritoneal macrophages, spleen cells, or bone marrow cells. The antibody did not cross-react with lung or resident peritoneal macrophages from mice, rats, or guinea pigs. By flow cytometry, no reaction was detected with resident, thioglycollate-elicited, or BCG-stimulated peritoneal macrophages. When frozen sections of lung and other organs were examined by indirect immunofluorescence and immunoperoxidase methods, only alveolar macrophages were stained.