B-1a, B-1b and B-2 B cells display unique VHDJH repertoires formed at different stages of ontogeny and under different selection pressures.
Analyses of VHDJH rearrangements isolated from murine peritoneal B-1a cells (CD5+, IgMhi, B220lo), peritoneal B-1b cells (CD5-, IgMhi, B220lo), and conventional splenic B cells provide evidence that a unique repertoire of VH regions is displayed by each of these B-cell subsets. The B-1a subset is characterized by a low N-region diversity, by a high frequency of sequence homologies in the VH-D and D-JH junctions, and by a limited exonuclease nibbling of the terminals of the joining gene segments. Through expansion in ageing mice, B-1a clones with these properties are favoured. B-1b cells are similar to conventional B-2 cells with respect to N-region diversity, but are unique in terms of D gene expression. Thus, while most murine pre-B and B cells preferentially use DSP and DFL gene segments in a given reading frame (RF1), B-1b cells frequently express D genes in another reading frame (RF2). Together, these findings provide structural evidence for a model where B-1a, B-1b and B-2 cells are produced by separate progenitors that are active at different stages of ontogeny.
Tornberg
U C
UC
Department of Cell and Molecular Biology, University of Umeå, Sweden.
Holmberg
D
D
D000375:Aging / Q000276:immunology; D000818:Animals; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D001483:Base Sequence; D002454:Cell Differentiation; D002999:Clone Cells; D005434:Flow Cytometry; D015322:Gene Rearrangement, B-Lymphocyte; D005803:Genes, Immunoglobulin / Q000235:genetics*; D014644:Genetic Variation; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010529:Peritoneal Cavity / Q000166:cytology; D016364:Reading Frames; D012641:Selection, Genetic; D013154:Spleen / Q000166:cytology; D013234:Stem Cells / Q000276:immunology
D007143:Immunoglobulin Heavy Chains