Serological and chemical studies of latent allotypes in the rabbit

Genetic data has shown that antigenic variants or allotypes of variable and constant regions of the heavy and light chains of immunoglobulins represent products of allelic structural genes. New findings in several animal systems have demonstrated the non-allelic behavior of immunoglobulin allotypes. In the present study we report the results of our efforts to confirm the presence of latent allotypes in rabbit sera. Varying amounts of latent allotypes for groups a and b markers were detected in 95% of all normal and immune sera tested. Several rabbits expressed high levels of latent a and b allotypes (in excess of 200 micrograms/ml of serum). By gel diffusion and radioimmune inhibition analysis, the latent b4 marker from one b6b6 rabbit, B240, was identical to the nominal b4 allotype. Also, the L chains bearing the latent b4 marker were isolated from B240 IgG and analyzed chemically by taking advantage of an acid-labile aspartic acid-proline bond at positions 109 and 110, which is unique for b4 and b9 kappa L chains.