Probing VH gene-family utilization in human peripheral B cells by in situ hybridization.
Recent studies on the genomic organization of the human Ig VH locus have revealed the presence of an important proportion of VH pseudogenes and a high degree of interspersion among VH gene-family members. The mechanisms of selection of VH genes expressed by differentiating B cells remain to be elucidated. We have made use of RNA-RNA in situ hybridization to probe the repertoire of VH gene-families assembled in peripheral B cells of normal adults. Cells were in vitro activated with mitogens and then hybridized to [35S]-labeled anti-sense RNA probes specific for C mu and C gamma genes, and for the six known human VH gene-families. We found that the numbers of cells expressing C mu and C gamma mRNA were similar to the total numbers of cells expressing members of the six VH gene-families. Therefore, the six known VH gene-families represent essentially the human VH locus. We also found that expression of VH gene-families does not closely correlate with their relative genomic complexity. This apparently biased expression may suggest that in some VH gene-families the ratio of pseudogenes/functional genes is particularly high, and/or that regulatory mechanisms play a major role in shaping the available VH gene repertoire in differentiating B cells.
Zouali
M
M
Unité d'Immunogénétique Cellulaire, Institut Pasteur, Paris, France.
Theze
J
J
D000918:Antibody Specificity; D001345:Autoradiography; D001402:B-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D006801:Humans; D006825:Hybridomas; D007132:Immunoglobulin Isotypes / Q000032:analysis; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D015347:RNA Probes; D014158:Transcription, Genetic
D007132:Immunoglobulin Isotypes; D007135:Immunoglobulin Variable Region; D015347:RNA Probes