Interspecific distribution of allotypic mink (Mustela vison) IgG antigens

The antigenic specificities of six (1--6) IgG allotypes of the domestic mink were tested in the sera of closely related species of Mustelidae family and distant mammalian species. It was found that allotypes 1 and 5 are ancient. Their antigenic specificities were established not only in Mustelidae, but also in other taxonomic orders of mammals. Allotypes 3 and 2 are phylogenetically younger; they were detected only in Mustelidae. Allotypes 4 and 6 appear to be unique to the domestic mink. The instantaneous evolutionary emergence of complex allotypes 4 and 6 is difficult to explain by a rapid accumulation of gene point mutations during phylogenesis. Activation in the domestic mink of those immunoglobulin genes, which are silent or poorly expressed in closely related Mustelidae, is suggested as a more plausible explanation.