A Simple Protocol for the Screening and Preliminary Identification of Antibodies to Human IgA Using Unpurified Proteins in the Passive Haemagglutination Test

Experiments have shown that suitably diluted, unpurified IgA paraprotein sera can be substituted for chemically purified IgA proteins in the passive haemagglutination test for the detection of anti-IgA antibodies. The substitution of unpurified IgA paraprotein was made possible by the enhanced serological activity obtained by pre-heating the unpurified immunoglobulin preparations at 56 degrees C for 60 min. Using a small screening panel of suitably coated tanned red cells, various population groups were investigated for the presence of anti-IgA antibodies. Results were similar to those obtained by other workers using purified IgA preparations in the passive haemagglutination test.