Shared idiotypes among anti-albumin antibodies of different species

A system designed to detect plasma cells that produce antibodies directed at autologous idiotypic determinants of anti-human serum albumin (HSA) antibodies in rabbits was used to determine whether anti-HSA antibodies of horse, goat, swine and chicken origin were cross-reactive with rabbit antibodies of the same specificity. Fluorochrome-tagged anti-HSA preparations of these diverse species were used to stain splenic plasma cells of HSA-immunized rabbits and a similarly immunized chicken. The degree of idiotypic cross-reactivity, as detected by binding of anti-HSA antibodies to anti-idiotype within plasma cells of HSA-immunized animals, was sometimes equal to autologous staining. However chicken anti-HSA, the most phylogenetically distant idiotype examined, was demonstrably less cross-reactive than that obtained from the other species. Likewise, chicken plasma cells usually did not bind mammalian anti-HSA antibodies to an appreciable degree, as compared with autologous staining. These findings provide evidence for serologic and possibly structural similarities of antibodies of the same specificity from different species.