Allotypes of the a series and their variants in rabbit immunoglobulins.

Six allotypic specificities of the a series are found on rabbit immunoglobulins: a1, a2 and a3 are found both in domestic and wild rabbits Oryctolagus cuniculus; a100, a101 and a102 seem to be present only in wild rabbits. Each of these specificities is a family of variants always present together in a given serum. These variants can be studied through the cross-reactivities detected between the patterns of the a series. The results of studies of cross-reactivities between a1, a3 and the two specificities a100, and a102 and also the cross-reactivity between a2 and a minor variant of the a1 specificity suggested a hypothetical scheme. This hypothesis attempts to take into account the evolution of the specificities of the a series and their variants. This hypothesis also postulates the existence of a set of closely linked genes which control the synthesis of the variants of a given specificity. One could suppose that primordial allelic genes might have appeared from an ancestor gene. By duplication each allele would have led to the appearance of a set of genes coding for a given specificity. These genes might have evolved through mutations and recombinations. In wild rabbits, the observation of an allotype which seems to result from a recombination between the group of genes coding for the a2 variants and the group of genes coding for a3 variants argues in favors of the genetic recombination mechanism.