The role of gene deletion in the immunoglobulin heavy chain switch

Abstract
We have examined the arrangement of the genes for the mouse heavy chain subclasses γ2b, γ2a and γ1 by the Southern hybridisation procedure. Evidence has been found for rearrangement involving the γ2b and γ2a CH genes in the DNA of cells making IgG2b andIgG2a respectively. The DNA of an IgG2b-secreting line lacks detectable Cγ1 gene, whilst the DNA of an IgG2a-secreting line lacks detectable Cγ1 and Cγ2b genes. The DNA of a cell line secreting IgA lacks detectable Cγ genes. These observations implicate deletion in the mechanism of the H-chain switch and allow a preliminary ordering of some of the CH genes in the mouse genome.