Evidence for the overexpression of the VH4-34 (VH4.21) Ig gene segment in the normal adult human peripheral blood B cell repertoire.
The VH4-34 (VH4.21) gene has been repeatedly found to encode monoclonal anti-i/l cold agglutinins and is occasionally used by other autoantibodies with anti-DNA and rheumatoid factor specificity. To understand the basis for the frequent expression of the VH4-34 gene in autoimmunity, we prepared linker-based, amplified C mu and C gamma V gene (cDNA) libraries from the peripheral blood of two healthy adults (PBL-3 and PBL-4). The frequency of VH4 family gene-containing clones was determined with VH family-specific oligonucleotide probes, and by random sequencing we examined the frequency of VH4-34 gene expression among the VH4+ C mu clones. Collectively, these studies suggested that VH4-34 gene expression accounted for 7.8 and 10.3% of all IgM clones in the cDNA libraries of PBL-3 and PBL-4, respectively. In VH4 family-specific libraries prepared from genomic rearranged Ig DNA, the VH4-34 gene was also overrepresented relative to other VH4 family genes. In both the mu-cDNA as well as the rearranged Ig DNA libraries, the VH4-34-expressing clones were 95 to 100% homologous to the germline sequence and contained different CDR3 sequences. By contrast, the VH4-34-expressing C gamma clones showed somatic diversification from germline; in addition, the C gamma clones often had the same CDR3 sequences, suggesting that these clones were derived from either activated B cells or expanded, clonally related B cells. Multiparameter flow cytometric analysis of peripheral blood lymphocytes indicated that 3.2 to 6.2% of mu+CD20+ cells express the VH4-34-related Id 9G4. These current findings are relevant to the interpretation of restricted Ig gene usage reported in monoclonal cold agglutinin disease and other autoimmune disorders.
Kraj
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P
Department of Pathology, University of Pennsylvania School of Medicine, Philadelphia, USA.
Friedman
D F
DF
Stevenson
F
F
Silberstein
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LE
D000328:Adult; D000373:Agglutinins / Q000235:genetics; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000235:genetics; D015551:Autoimmunity / Q000235:genetics; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D003450:Cryoglobulins; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D015723:Gene Library; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D005803:Genes, Immunoglobulin; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007130:Immunoglobulin Idiotypes / Q000235:genetics; D007075:Immunoglobulin M / Q000235:genetics; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D000373:Agglutinins; D000911:Antibodies, Monoclonal; D003450:Cryoglobulins; D017931:DNA Primers; D018076:DNA, Complementary; D007143:Immunoglobulin Heavy Chains; D007130:Immunoglobulin Idiotypes; D007075:Immunoglobulin M; C029443:cold agglutinins