Identification of an allotypic IgA in cattle serum.
Alloimmunization of cattle revealed a polymorphism carried on a serum antigen displayed beta-electrophoretic mobility. A genetic test indicated that the antigen is inherited in a Mendelian manner, as product of a dominant allele at an autosomal locus. By immunochemical investigation the allotypic determinant was found to be located on IgA: there were in fact no differences between the peptidic map of the molecule carrying the allotypic determinant and that of IgA from positive sera. Moreover the peptidic map of IgA from sera lacking of the allotype resulted lacking of an anodic peptide, thus suggesting that the polymorphism is indeed due to such a peptide.