Basilea rabbit immunoglobulins: detection and characterization by specific alloantiserum.

Evidence is provided for the existence of the Fbbas (Basilea) gene product (allotype). Specific antisera were raised by immunization of rabbits that did not possess the Basilea genes. With the help of these antisera, the Basilea allotype was detected in sera from rabbits, homozygous and heterozygous with respect to Basilea gene. The Basilea gene is expressed on a very low proportion of immunoglobulin molecules. The isoelectric point of the Basilea light chains is distinct from that of the lambda-light chains (peaks at pH 4.7 and 5.5, respectively). Sera from a large proportion of Ab9-positive rabbits of the Basel Institute for Immunology that were heterozygous at the Ab locus reacted with the anti-Basilea serum, even though they could no possess the Basilea gene at the Ab locus. Sera from Ab9-positive rabbits from Toronto were Basilea-negative. It was suggested that Ab9 and Basilea allotypes are controlled at closely linked loci. Ab9 haplotype prevalent in the Basel animal colony, possesses both Ab9 and Basilea genes, whereas the corresponding Toronto haplotype has only the Ab9, but not Basilea gene. The formation of the Basilea genotype was attributed to a crossing over, during which the Ab9 and Basilea genes separated.