Deletion mapping of Ig VH gene segments expressed in human CD5 B cell lines. JH proximity is not the sole determinant of the restricted fetal VH gene repertoire.

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 CD5 B cell lines map > 500 kb from the cluster of JH segments. Two of the gene segments, positioned at approximately 850 kb (58p2) and approximately 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.

Expression of members of the immunoglobulin VH3 gene families is not restricted at the level of individual genes in human chronic lymphocytic leukemia.

Previous studies on the repertoire of Ig VH genes utilized in the malignant cells of chronic lymphocytic leukemia (CLL) have suggested a non-random expression pattern. In particular, individual genes from the VH1, VH5, and VH6 gene families have been frequently found in CLL. With regard to other VH gene families, including the large VH3 family which is expressed in greater than 50% of CLL cases, it is unknown whether CLL cells utilize either a broad or a restricted repertoire of VH genes. In the present paper, we analyzed the VH genes expressed in a collection of 11 CLL cases. The results of these experiments demonstrate that there is no apparent restriction in the usage of individual members of the VH3 gene families in CLL.