Serologic Specificity of Human Anti.IgA and its Significance in Transfusion

By G. N. VYAS, L. HOLMDAHL, H. A. PERKINS AND H. H. FUDENBERG H UMAN ANTIBODIES to human gamma globulins are generally detected by agglutination of red cells coated with IgG, most often in the form of incomplete anti-Rh antiserum;’ normal and myeloma IgG proteins coated by bisdiazotized benzidine and chrornic chloride have also been used.2” These passive hernagglutination methods are applied to genetic typing of human immunoglobulins.14 Human anti-IgA antibodies are detected by passive hemagglutination using IgA paraproteins.5 This paper presents for the first time a detailed serologic system for the detection and characterization of anti-IgA antibodies in human sera. A dichotomy of two types of serologic specificities was observed: a) the class specific (reacting with all IgA coats) detected only in the sera of persons lacking IgA and, b) limited specificity (reacting with one or two of the IgA coats) detected in sera of persons with normal levels of IgA. Immunochemical studies suggest that most of these antibodies are of the IgG class. Preliminary evidence indicated the clinical significance of anti-IgA antibodies because of their association with anaphylactoid and urticarial transfusion reactions.6’7 Further evidence supporting this association is presented here. The frequency of anti-IgA antibodies in other clinical conditions related to blood transfusion is