Development of an immunoassay for the detection of minute amounts of IgG-coated erythrocytes in whole blood and its application for the assessment of Fc-mediated clearance of anti-D-coated erythrocytes in vivo.
A rapid and sensitive immunoassay for the detection of minute quantities of IgG-coated erythrocytes in whole blood was developed. Washed red blood cells were incubated in two steps with anti-human IgG antiserum followed by 125I-labelled protein A. The assay was able to detect amounts of sensitized erythrocytes as small as 0.5 ml of packed erythrocytes in a total blood volume of 5 liters and hematocrit 40%. A linear relation between increasing amounts of IgG-coated red cells in whole blood and the binding of 125I-labelled protein A was obtained. We applied the technique on the assessment of the removal of IgG anti-D-coated erythrocytes from the circulation of test individuals. T1/2 for the elimination of approximately 4 ml packed red cells sensitized with 62 micrograms of anti-D in 14 normal subjects was 20 +/- 5 min (mean +/- SEM). A splenectomized person did not clear the injected cells from the circulation during the test period of 70 min. If a standard curve was constructed the total blood volume in the test subjects could be calculated. This value correlated well (r = 0.99) with the blood volume calculated from the height and weight of the test individuals.
Nilsson Ekdahl
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Department of Clinical Immunology and Transfusion Medicine, University Hospital, Uppsala, Sweden.
Lööf
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Nilsson
U R
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Nilsson
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B
D000328:Adult; D004912:Erythrocytes / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007141:Immunoglobulin Fc Fragments / Q000502:physiology; D007074:Immunoglobulin G / Q000032:analysis* / Q000378:metabolism; D007136:Immunoglobulins / Q000032:analysis* / Q000378:metabolism; D007518:Isoantibodies / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D018029:Rho(D) Immune Globulin; D013156:Splenectomy
D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007136:Immunoglobulins; D007518:Isoantibodies; D018029:Rho(D) Immune Globulin