Biased VH gene usage in early lineage human B cells: evidence for preferential Ig gene rearrangement in the absence of selection.
Certain VH genes are predominantly expressed in mature B cells. We hypothesized that several, mutually nonexclusive VH-dependent mechanisms operating at distinct stages during B cell development may be responsible for overrepresentation of these VH genes. In the present study, we have assessed whether one of the mechanisms involves preferential rearrangement at the pro-B cell stage. The frequency of individual VH4 and VH3 genes in rearrangement libraries from FACS-purified human CD34+/CD19+ pro-B and CD34-/CD19+ pre-B cells was assessed. The in-frame and out-of-frame rearrangements from both cell populations were analyzed using a high resolution PAGE system. The frequencies of individual VH gene segments among out-of-frame rearrangements from pro-B cells were determined, because these frequencies should reflect only processes before the translation of the mu-heavy chain and should not be biased by selection mechanisms. Our results demonstrate that, at the pro-B cell stage, the V4-34, V4-39, and V4-59 gene segments are the most frequently rearranged VH4 family genes, and the V3-23 and V3-30 gene segments are the most frequently rearranged VH3 family genes. This finding suggests that the predominant expression of these VH genes in peripheral mature B cells is determined to a significant degree by their preferential rearrangement during V-DJ recombination.
Rao
S P
SP
Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
Riggs
J M
JM
Friedman
D F
DF
Scully
M S
MS
LeBien
T W
TW
Silberstein
L E
LE
D000328:Adult; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D019070:Cell Lineage / Q000235:genetics / Q000276:immunology; D005333:Fetus; D005787:Gene Frequency / Q000276:immunology; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D005803:Genes, Immunoglobulin; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D008099:Liver / Q000276:immunology / Q000378:metabolism; D005810:Multigene Family / Q000276:immunology; D016364:Reading Frames / Q000235:genetics / Q000276:immunology; D013234:Stem Cells / Q000276:immunology / Q000378:metabolism
D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region