Macrophages (histiocytes) in various reactive and inflammatory conditions express different antigenic phenotypes.

The purpose of this study was to determine whether human tissue macrophages (M phi s) in various inflammatory/reactive conditions express different immunophenotypes. Using a large panel of monoclonal antibodies to monocyte/M phi-related antigens and a frozen-section immunoperoxidase technique, the following conditions were studied: granulomatous inflammation of unknown etiology, sarcoidosis, cat-scratch fever, toxoplasmosis, Gaucher's disease, and juvenile xanthogranulomas. The results show that there is immunophenotypic variation of the M phi s among the various inflammatory/reactive conditions. For example, the M phi s in cat-scratch fever are nearly unique in the expression of the "early inflammation" antigen identified by antibody 27E10, and the M phi s in juvenile xanthogranulomas, unlike those in most of the other conditions, lacked the antigen detected by antibody 25F9. The M phi s in Gaucher's disease differed from those in the other disorders by the combined absence of CD11b, CD14, G16/1, CD1a, CD25, and CD30. The inflammatory/reactive M phi s also exhibited differences from those in "normal" tissues, namely, a tendency toward acquisition of the antigens identified by antibodies Mac 387 and G16/1 and the more uniform expression of the "activation" antigens CD25, CD30, and CD71. The antigenic variations described here probably reflect differences in antigenic stimuli and M phi function. In addition to the possible biologic implications, this M phi immunophenotypic diversity may have practical diagnostic applications.