title: Selection of individual VH genes occurs at the pro-B to pre-B cell transition.
abstract: B cells are subjected to selection at multiple checkpoints during their development. The selection of Ab H chains is difficult to study because of the large diversity of the CDR3. To study the selection of individual Ab H chain V region genes (V(H)), we performed CDR3 spectratyping of ∼ 75-300 rearrangements per individual V(H) in C57BL6/J mice. We measured the fraction of rearrangements that were in-frame in B cell DNA. We demonstrate that individual V(H)s have different fractions of in-frame rearrangements (IF fractions) ranging from 10 to 90% and that these IF fractions are reproducible in different mice. For most V(H)s, the IF fraction in pro-B cells approximated 33% and then shifted to the nearly final (mature) B cell value by the cycling pre-B cell stage. The frequency of high in-frame (IF) V(H) usage increased in cycling pre-B cells compared with that in pro-B cells, whereas this did not occur for low IF V(H)s. The IF fraction did not shift as much in BCR-expressing B cells and was minimally affected by L chain usage for most V(H). High IF clan II/III V(H)s share more positively charged CDR2 sequences, whereas high IF clan I J558 CDR2 sequences are diverse. These data indicate that individual V(H)s are subjected to differential selection, that V(H) IF fraction is mainly established through pre-BCR-mediated selection, that it may operate differently in clan I versus II/III V(H)s, and that it has a lasting influence on the Ab repertoire.
authors: Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors: Wenzhao
authors: W
authors: Meng
authors: Lenka
authors: L
authors: Yunk
authors: Li-San
authors: LS
authors: Wang
authors: Avinash
authors: A
authors: Maganty
authors: Emily
authors: E
authors: Xue
authors: Philip L
authors: PL
authors: Cohen
authors: Robert A
authors: RA
authors: Eisenberg
authors: Martin G
authors: MG
authors: Weigert
authors: Stephane J C
authors: SJ
authors: Mancini
authors: Eline T Luning
authors: ET
authors: Prak
mesh_terms: D000818:Animals; D022801:Complementarity Determining Regions / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D004247:DNA / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D051379:Mice; D054448:Precursor Cells, B-Lymphoid / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D051562:Proto-Oncogene Proteins c-bcr / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D027041:Somatic Hypermutation, Immunoglobulin / Q000502:physiology*
chemical_list: D022801:Complementarity Determining Regions; D004247:DNA; C496614:Bcr protein, mouse; D051562:Proto-Oncogene Proteins c-bcr