Subclasses of Human Immunoglobulin A Based on Differences in the Alpha Polypeptide Chains

Antiserum from goats immunized with heavy polypeptide chains from a gammaA-type myeloma globulin was absorbed with serum from patients with selective absence of immunoglobulin A (gammaA). The resulting reagents could be used for the classification of 58 gammaA-myeloma proteins into two distinct antigenic types, respectively called subclasses He and Le. These differences were shown to be related to the heavy (alpha) polypeptide chains and independent of the integrity of interchain disulfide bridges. The gammaA-immunoglobulin from normal serum appears to consist, for the most part, of molecules with Le subclass specificity.