Deletion mapping of Ig VH gene segments expressed in human cds b cell lines: JH proximity is not the sole determinant of the restricted fetal VH gene repertoire

Abstract

VH gene segments expressed in a panel of monoclonal human CD5 B cell lines have been positioned on the IgH locus by deletion mapping. The analysis yielded a relative order of VH fragments of the VH2, VH4, VH5, and VH6 gene families that was consistent with, and provided a further refinement of existing maps of the human IgH locus. We demonstrate that four of six VH gene segments expressed in the CDS B cell lines map >500 kb from the cluster of JH segments. Two of the gene segments, positioned at ∼850 kb (58p2) and ∼500 kb (1-9III) from the JH segments, respectively, belong to the previously identified small cohort of second trimester fetal VH gene segments. The data show that JH proximity is not the sole determinant of restricted VH gene utilization in early human ontogeny.