Abstract Macrophage antigens were studied on 12 macrophage cell lines and variant clones, as well as on 11 other lines representative of a variety of hematopoietic lineages, to determine the relation of surface antigen expression to cell differentiation, maturation, and function. Biosynthetic labeling followed by immunoprecipitation with monoclonal antibodies and gel electrophoresis showed that Mac-1 polypeptides of 95,000 and 170,000 Mr and the Mac-2 polypeptide of 32,000 Mr were found in lysates of mature macrophage lines but not in other lines, including myeloid or immature leukemias. The Mac-3 antigen was found in large amounts in all macrophage lines and to lesser degrees in some myeloid and B lymphoid lines. The Mr of Mac-3 varied from 100,000 to 170,000, perhaps due to differential glycosylation. Analysis of Mac-1 and Mac-2 antigens by flow cytometry showed expression on all macrophage lines. Similarly, all three Mac antigens were detected in high amounts on macrophage lines by 125l-labeled antibody binding. Mac-1 and Mac-2 were not routinely seen on other hematopoietic lines, but Mac-3 was expressed in variably low amounts on some lines of myeloid and B cell lineage. These results with macrophage lines and variants exclude a simple relationship between Mac differentiation antigens and certain macrophage characteristics (5' nucleotidase, cytotoxic capacities, antibody-dependent phagocytosis, and production of oxygen radicals). Mac-1 and Mac-3 but not Mac-2 could be induced in the M1 myeloblast line by corticosteroid, lipopolysaccharide, and several conditioned media containing myeloid colony-stimulating activity. These agents are known to induce a number of other macrophage markers in M1, e.g., Fc and C receptors, phagocytosis, and lysozome production. Therefore, it appears Mac-2 antigen is not required for expression of these characteristics. The levels of Mac-1 and Mac-3 in M1 cells increased slowly over 6 days of stimulation, approaching those found on mature macrophage lines. Although anti-Mac-1 does not block the detection of Mac-3 antigen on induced M1 cells, the presence of anti-Mac-1 antibody during induction partially blocked the appearance of Mac-3 antigen. Thus, the surface structure associated with Mac-1 antigen appears to be involved in differentiation of macrophages.

Ralph, P., Ho, M. K., Litcofsky, P. B., & Springer, T. A. (1983). Expression and induction in vitro of macrophage differentiation antigens on murine cell lines. The Journal of Immunology, 130(1), 108–114.