title: Comparison of the Fc receptors for IgE on human lymphocytes and monocytes.
abstract: Fc receptors for IgE (Fc epsilon R) on human peripheral blood lymphocytes and monocytes and cultured lymphoblastoid and macrophage-like cell lines were compared with respect to: 1) binding affinity for radiolabeled IgE, 2) inhibition of IgE-specific rosette formation and inhibition of binding of radiolabeled IgE by an antiserum raised against Fc epsilon R isolated from a lymphoblastoid cell line, and 3) m.w. of radiolabeled cell surface proteins precipitated with the anti-Fc epsilon R serum. Scatchard analysis of 125I-IgE binding to lymphocytes, monocytes, and their corresponding cell lines showed biphasic binding curves with all cell types, from which 2 binding affinities were calculated to be KA = 6.2 +/- 1.1 and 2.0 +/- 0.5 x 10(7) M-1. The anti-Fc epsilon R serum inhibited both IgE rosette formation and binding of radiolabeled IgE by lymphocytes and monocytes but did not inhibit IgE rosettes formed by basophils. The inhibitory activity of the anti-Fc epsilon R serum could be absorbed with Fc epsilon R(+) but not with Fc epsilon R(-) cell lines. The anti-Fc epsilon R serum precipitated 2 peptides having m.w. of approximately 47,000 and 23,000 daltons from lysates of both cell surface-labeled lymphocyte and macrophage cell lines. These data indicate that Fc epsilon R on normal lymphocytes and monocytes, as well as on cultured lymphoblastoid and macrophage-like cells, are related structurally, since they share antigenic determinants, bind IgE with a similar affinity, and have similar m.w. However, they differ in all 3 parameters from Fc epsilon R on basophilic granulocytes.
mesh_terms: D000915:Antibody Affinity; D001667:Binding, Competitive; D011232:Chemical Precipitation; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology; D007139:Immunoglobulin epsilon-Chains / Q000276:immunology; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000276:immunology; D008875:Middle Aged; D009000:Monocytes / Q000378:metabolism*; D011961:Receptors, Fc; D017455:Receptors, IgE; D011971:Receptors, Immunologic; D012397:Rosette Formation; D014357:Trypsin / Q000494:pharmacology
chemical_list: D007106:Immune Sera; D007139:Immunoglobulin epsilon-Chains; D008565:Membrane Proteins; D011961:Receptors, Fc; D017455:Receptors, IgE; D011971:Receptors, Immunologic; D014357:Trypsin