The immune response to the alpha 1-6 epitope of dextran is determined by a gene linked to the IgCH locus.

There is a marked strain variability in the immune response against the alpha 1-6 epitope of dextran B512. Responsiveness was independent of the H-2 genotype of the strains but completely determined by the IgCH allotypes of the strains. Thus, IgCHb and IgCHj allotypes characteristic of C57BL and CBA strains, respectively, determined high responsiveness, whereas strains possessing all other allotypes studied were low responders. Backcross analysis indicated that a gene(s) determined responsiveness and that this gene was linked to allotypes of the IgCH locus. F1 hybrids between high and low responder strains always gave a response, but the number of plaque-forming cells was approximately half of that obtained in the high responder strains.