Rabbit 136 represented the first instance whereby more than two alleles for any immunoglobulin locus are detected phenotypically in a single animal. This was reported as the acquisition of the a2 and b6 markers in the animal nominally typed a1a3, b4b5 after intensive immunization. Follow-up studies indicate that another immunoglobulin marker, notably d11, also appeared in the postimmune serum. The d11 specificity was detected serologically by the hemagglutination-inhibition assay and chemically by analysis of the CNBr digestion products involving a strategic methionine.
This work was supported by grants from the United States Public Health Service (AI-07184), Belgian government (02021 and 02022), and from the Robert A. Welch Foundation (F-209).