New immunoglobulin IgG allotypes and haplotypes found in wild mice with monoclonal anti-allotope antibodies

Sera from 156 wild mice (Mus musculus L.) collected from parts of Eurasia, Nothern Africa, and the Americas were tested in solid-phase radioimmunoassays for reactivity with 20 monoclonal anti-allotope antibodies directed against gene products of the Igh-1, Igh-3, and Igh-4 loci. Most of the wild mice have Igh phenotypes similar to those of inbred strains or heterozygotes thereof, but frequently the wild mice showed unique combinations of allotypic determinants (allotypes) for a given immunoglobulin allele and unique combinations of allotypes on a given chromosome (haplotypes) not seen in inbred strains. We found new allotypes of the Igh-1 and Igh-4 loci. Mice from three regions (Poland, Taiwan, and Japan) possess combinations of allotypes indicating that recombination, gene conversion, or other gene duplication events have occurred in portions of the Igh constant region gene complex. Most interestingly, sera of three mice from Egypt possess immunoglobulin molecules appearing to result from an intragenic recombination event involving either Igh-1d or Igh-3d with Igh-1b. Two mice from Pakistan and one from Seychelles Island in the Indian Ocean also showed similar unusual phenotypes. These mice possess two CH2 IgH-1b and two CH2 Igh-1a/CH2 Igh-1d determinants, suggesting that these variant immunoglobulin arose from recombinations within the CH2 domain.