Monoclonal antibodies against the Fc fragment of IgA alpha-chain: preparation and clinical application.

Fragments of the heavy alpha-chain of IgA (IgA Fc alpha) were prepared and purified from the serum of patients with heavy chain disease. It was used to immunize BALB/c mice. The immunized mouse spleen cells were then fused with myeloma cells Sp2/O. Through successive recloning of the hybridoma cell lines by the limiting dilution method, four subclonal hybridoma cells (D2, E4, F5 and G10) capable of screening IgA Fc alpha were found. Intraperitoneal transplantation of these cells induced ascites in the BALB/c mice, from which four types of monoclonal antibodies (McAb-IgA Fc alpha) were obtained. The highest McAb titer was as high as 1:16348 by the hemagglutination inhibition (HAI) test. These McAb's reacted specifically with IgA Fc alpha, but not with IgG, IgM, IgD, kappa or lambda. Serum samples from 92 normal subjects and 73 patients with various diseases were tested for Ig genetic markers by means of HAI. The family trees of three positive cases were surveyed. Results showed that the McAb-IgA Fc alpha may be used to determine the genetic marker of IgA allotypes.