Human mononuclear phagocyte differentiation antigens. I. Patterns of antigenic expression on the surface of human monocytes and macrophages defined by monoclonal antibodies.

Abstract Six newly developed monoclonal antibodies recognizing antigenic determinants expressed on the surface of human mononuclear phagocytes (MoPh) were applied to the antigenic analysis of this cell lineage. Antibody binding was detected by indirect immunofluorescence in conventional microscopy and flow microfluorometry. Through additive experiments, competitive blocking experiments and differences in the distribution histograms of immunofluorescence, evidence was obtained that each antibody detected a distinct antigenic determinant. Different increases in the amount of each antigen and in the frequency of positive cells were found on fluid or tissue macrophages when compared to blood monocytes. The six reagents could be placed in three general groups based on certain similar characteristics in their patterns of antigen expression. The reagents MϕP-9, MϕS-1, and MϕS-39 reacted with antigens found at high densities on up to 94% of phagocyte cells in purified blood monocyte preparations and on the vast majority of fluid or tissue macrophages. The reagent MϕP-15 recognized an antigen expressed at intermediate density on an average of 70% of blood monocytes and at greater density on almost all fluid and tissue macrophages. The reagents MϕP-7 and MϕR-17 detected antigens that were present at very low densities on 36% or less of blood monocytes but in larger quantities on almost all fluid or tissue macrophages; small amounts of these two antigens were also identified on a subpopulation of T cell blasts but not on resting T cells. The distribution and characteristics of the antigens recognized by the latter three reagents suggest they appear in sequence on the more mature members of the lineage MoPh and that their pattern of expression on blood monocytes defines three subsets.