Abstract
Synthesis of the heavy immunoglobulin chain is controlled by two genes, one being in control of the variable, the second in control of the constant portion of the chain (1-3). Elucidation of the relation between the genes for constant and variable portions of the heavy chain and of the mechanism of assembly are crucial for an analysis of the generation of antibody diversity.
Structural and genetic studies of the heavy chain can be greatly facilitated by reagents for the identification of genetic markers of the constant and variable chain segments. Allotypic specificities provide such markers: the Fd, variable portion is characterized by three specificities A1, A2, A3, controlled at the Aa locus by three respective alleles (4, 5). The constant, Fc portion of the gamma chain is characterized by two groups of allotypic specificities, Ad and Ae (3, 6, 7). Within each group two specificites, controlled by two allelic genes, have been described. All three loci, Aa, Ad and Ae are closely linked with each other. Recombinants have been observed, both between Aa and Ad (8) and between Aa and Ae loci (9).
So far, only limited population studies on the genetics of the Aa allotypes have been reported (10, 11) and even less information is available on the Fc gamma specificities (Ad and Ae). Since we were in possession of a rather unique collection of rabbit sera which represented a random-bred, panmictic and unselected population, it was decided to use this collection in the present study. We concentrated on the specificities controlled at the Aa and Ae loci and intended to answer the following questions: (a) Can the genes within each group or “locus” be regarded as true alleles?
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