Variant strain of rabbits lacking immunoglobulin kappa polypeptide chain

The antibody molecule consists of heavy and light polypeptide chains 1 . The light chains are shared by all immunoglobulin classes and they can be divided into two types, κ and λ. The great majority (up to 95%) of rabbit IgG molecules possess the κ type. This polypeptide chain, like many others, shows genetic polymorphism called allotypy 2–5 ; the b locus of the rabbit determines allotypes which exist in four allelic forms, namely b4, 5, 6 and 9. They are inherited in Mendelian fashion as codominant genes 3,4 and they have been correlated with amino acid sequences in the constant part of the κ chain, although some authors could associate amino acid differences in the variable part of this chain with certain b locus allotypes 4–7 . The allotypes of the λ chain are determined by an independent c locus (specificities c7 and 21). They do not show Mendelian segregation, at least in our rabbit colony, although they do in certain strains 4,8 .