A new radiometric assay for the quantitation of surface-bound IgG on sensitized erythrocytes.
We have developed a sensitive, straightforward method for the quantitation of surface-bound IgG on sensitized erythrocytes. The assay is based on the consumption by sensitized cells of anti-IgG antiserum. The remaining anti-IgG is quantitated in a second incubation by precipitation with 125I-IgG in the presence of polyethylene glycol. Calibration curves for this assay were constructed using known amounts of unlabeled IgG. The method can be performed in microtitre plates and eliminates the use of purified anti-erythrocyte antibodies, or highly purified specific anti-IgG antisera. The results were completely consistent with those of immunofluorescence assays, but our method was much more sensitive, less than 500 molecules of IgG per cell being detected reproducibly. The technique is not laborious and takes much less time than previously described methods with similar sensitivity. As an example of the applicability of this test, the implications of ligand density for the detection by EA rosetting of Fc receptors on human monocytes are shown. The results suggest that a large variation exists in the affinity of the different types of Fc receptors for their ligands.
Van de Winkel
J G
JG
Department of Medicine, University Hospital Nijmegen, The Netherlands.
Tax
W J
WJ
Groeneveld
A
A
Tamboer
W P
WP
De Mulder
P H
PH
Capel
P J
PJ
D000818:Animals; D004306:Dose-Response Relationship, Immunologic; D004910:Erythrocyte Membrane / Q000032:analysis* / Q000276:immunology; D005470:Fluorometry / Q000379:methods; D006801:Humans; D007114:Immunization / Q000379:methods; D007074:Immunoglobulin G / Q000032:analysis* / Q000592:standards; D051379:Mice; D011874:Radiometry / Q000379:methods* / Q000592:standards; D011947:Receptors, Antigen, B-Cell / Q000032:analysis* / Q000592:standards; D012397:Rosette Formation / Q000379:methods
D007074:Immunoglobulin G; D011947:Receptors, Antigen, B-Cell