Human mononuclear phagocyte-associated antigens. III. Relationship of cell surface antigen phenotype between cultured monocytes and tissue macrophages.

In order to determine the correlation between the in vitro model of monocyte differentiation and its in vivo counterparts, cell surface phenotypes of monocytes in culture and mature tissue macrophages were analyzed using monoclonal antibodies, M1/70, TA-1 anti-HLA-DR, and a heteroantisera prepared to macrophage cell line U937. Following 7 days in culture the reactivity of monocytes with M1/70 diminished from 70 +/- 9% to 31 +/- 8%. Similarly, the reactivity to TA-1 dropped from 88 +/- 8% to 23 +/- 7% and for anti-DR, from 79 +/- 5% to 41 +/- 16%. Reactivity with anti-U937 remained unchanged. This altered phenotype of cultured monocytes was found to approximate that of resident splenic macrophages (MO). In addition, freshly isolated monocytes and peritoneal exudate MO (PEMO) were found to be functionally similar in their inability to phagocytize via the C receptors. These results suggest that PEMO arriving recently into the peritoneal cavity from peripheral blood may be midway in transition between monocytes and mature MO, and that the phenotype and functional changes attributed to monocytes in culture may reflect changes that occur in vivo in the transition to tissue MO.