Human mononuclear phagocyte-associated antigens: I. Identification and characterization

Rabbit antisera were produced against a lymphokine-activated human macrophage cell line, U937 (αU937), and human peritoneal macrophages (αPEMØ). After absorption with AB erythrocytes, pooled platelets, and B-lymphoblastoid cell lines, both antisera reacted by microcytotoxicity, indirect immunofluorescence (IF), and radioimmunoassay (RIA) with adherence-purified human peripheral blood monocytes, splenic and peritoneal macrophages, and leukemic myelomonoblasts. A panel of normal human T lymphocytes, B lymphocytes, and erythroid-myeloid or lymphoblastoid cell lines failed to react with both αU937 and αPEMØ. Although both heteroantisera reacted against polymorphonuclear leukocytes (PMNs), after absorption with PMNs specific reactivity against mononuclear phagocytes remained. Absorption of αU937 and αPEMØ with myelomonoblastic leukemia cells (AMML) removed IF and RIA activity against both PMNs and monocytes but not against splenic and peritoneal macrophages. In contrast, absorptions of both heteroantisera preparations with splenic macrophages abolished their IF and RIA reactivity not only to splenic and peritoneal macrophages but also to peripheral blood monocytes and leukemic myelomonoblasts. These results are consistent with (1) both antisera defining specific monocyte/macrophage-associated antigens(s) which are distinct from MHC-coded HLA-A,B,C, and DR antigens, and (2) expression of common monocyte/macrophage-associated antigen(s) and uniquely associated antigen(s) selectively expressed on tissue macrophages. These reagents will be useful in delineating human monocyte/macrophage differentiation as well as the immunological functions of mononuclear phagocytes.