IgH gene rearrangements on the unexpressed allele in rabbit B cells.
VDJ genes are assembled in two sequential DNA recombination steps, rearrangement of D and J(H) gene segments followed by rearrangement of a V(H) gene segment. In mouse and human, VDJ gene rearrangements occur in a regulated step in which D rearranges to J(H) on both alleles before V(H) rearranges to DJ. To determine how VDJ gene rearrangements are regulated in the rabbit, we studied the IgH gene rearrangements in rabbit B cells by examining the gene rearrangement on the unexpressed allele in rabbit hybridomas. By Southern blot analysis with probes from the J(H) and 3'V(H)1 regions, we found that approximately 50% of the hybridomas had DJ gene rearrangements on the unexpressed allele, whereas the remaining 50% did not rearrange either J(H) or V(H) genes. Unexpectedly, we found a VD gene rearrangement on the unexpressed allele of a rabbit B cell line, so we PCR-amplified the VD gene rearrangements from splenocyte DNA and found a few VD gene rearrangements in normal B cells as well. The data taken together show that IgH gene rearrangements in rabbit B cells are regulated differently than those in the mouse, and we hypothesize that in some B cells, VDJ gene rearrangements proceed through a VD intermediate rather than through a DJ intermediate.
Tunyaplin
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Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA.
Knight
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KL
D000483:Alleles; D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology*; D001483:Base Sequence; D015870:Gene Expression; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D006801:Humans; D006825:Hybridomas; D051379:Mice; D008969:Molecular Sequence Data; D011817:Rabbits / Q000235:genetics / Q000276:immunology*; D015183:Restriction Mapping