MLC-conditioned media stimulate an increase in Fc receptors on human macrophages.
Macrophage Fc receptors (FcR) are essential for antibody-dependent cellular cytotoxicity and for optimal phagocytosis of opsonized particulate antigens. Culture in the presence of conditioned medium from mixed leukocyte cultures (MLC-CM) resulted in a dose- and time-dependent increase (up to 10-fold) in FcR-dependent binding of 125I-labeled IgG1 to promyelocytic HL-60 cells, macrophage-like U-937 cells, and normal cultured human monocytes. FcR increase in HL-60 cells was blocked by cycloheximide (100 microM) and was accompanied by a slight decrease in binding affinity. Since cell volume did not change, the increase in FcR probably represents an increase in the surface density of FcR sites. MLC-CM prepared with or without serum were equally effective in augmenting FcR sites, whereas only serum-containing MLC-CM caused morphologic change of U-937 and HL-60 cells.
D000918:Antibody Specificity; D000920:Antibody-Dependent Cell Cytotoxicity; D001665:Binding Sites; D001692:Biological Transport; D003470:Culture Media; D006801:Humans; D007959:Lymphocyte Culture Test, Mixed; D008264:Macrophages / Q000276:immunology*; D011961:Receptors, Fc; D012397:Rosette Formation; D013997:Time Factors
D003470:Culture Media; D011961:Receptors, Fc