Genetic control of murine IgD structural heterogeneity.

Murine B lymphocytes express two native forms of surface IgD: IgDI consists of two delta heavy chains and two light chains; IgDII consists of one heavy chain and one light chain. The relative amounts of IgDI and IgDII present on spleen cells were found to vary significantly among different strains of mice. Genetic evidence demonstrated that the IgDI/IgDII ratio is linked to the Igh-5 allotype. (The delta heavy chain is the product of the Igh-5 locus). Mice bearing the Igh-5e allotype have a low ratio, and mice bearing the Igh-5a or Igh-5b allotype have a high ratio. The Igh-5 locus and the gene controlling the IgDI/IgDII ratio appear to map to the region between the Igh-6 and Igh-V loci.