Studies on IgA class circulatory red cell antibodies--I. Preparation and identification of IgA class anti-A,anti-B.

To elucidate the role of IgA class alloantibodies in transfusion practice, anti-A,anti-B was prepared using pooled serum from healthy group O donors. IgG was removed by protein A and protein G, whilst IgM was extracted by concanavalin A and anti-human mu chain. The final preparation contained both IgA1 and IgA2; it had an IgA concentration similar to the original serum pool and an environment as near to normal as possible; the absence of IgG and IgM was confirmed by sensitive enzyme-linked antiglobulin tests, and extensive haemagglutination studies showed that anti-A,anti-B was the only red cell antibody present.