The immunoglobulins derived from a V_H-C_H recombinant rabbit and its normal relatives-I. Measurements of heavy chain molecular weights and allotypes of colostral IgA

In addition to the a group of heavy chain allotypes, the IgG class of rabbit immunoglobulins has unique allelic allotypes (group d and group e) which correlate with single amino acid interchanges within the constant region of the γ chain. Family studies in several laboratories have demonstrated genetic linkage between the group a, d and e allotypes. In the cour]e of breeding studies, we obtained one rabbit which appeared to reflect a recombination event between group a and group e markers in the sire. We developed homozygous rabbits from the original sire (al, A14) and from the recombinant rabbit (a2,A14). In this report we compared the mol. wt of the heavy chains from the IgG produced by the two groups of homozygotes and found them to be indistinguishable by a method which could have detected a difference of 2500 daltons. We isolated colostral IgA from the recombinant rabbit and showed that it also had the a2 allotype present on the recombinant form of IgG.