Isolation of early immunoglobulin lambda-like gene transcripts in human fetal liver.
In an attempt to identify early events of human Ig gene expression, we have screened a human fetal liver cDNA library (less than 90 days of gestation) with C mu-, C gamma-, C kappa-, C lambda-specific probes and we report the characterization of two clones, F lambda 1 and F lambda 8, that hybridized with a human C lambda gene. These two clones, which are only 85% homologous to the functional C lambda genes, were shown to be additional nonallelic members of the 14.1/16.1 C lambda-like family. Using pulsed field gel electrophoresis these three C lambda-like genes were shown to be present on a 200-kb DNA fragment, defining a cluster distinct from that of the C lambda one. F lambda 1 and F lambda 8 contained an identical C lambda-like region, and differed from each other by a splicing event which joins a J lambda-like to the C lambda-like exon in the F lambda 1 clone in the absence of any rearrangement. Homologies observed between F lambda 1 and the mouse lambda 5 gene suggest that this human clone may contain the exon 2 and 3 equivalents of lambda 5. Since lambda 5 is selectively expressed in pre-B cells, our proposal is also supported by the early expression of this clone, together with the presence of full-length mu and gamma transcripts and the absence of functional Ig light chain transcripts. The presence of one nucleotide deletion in the C region of F lambda 1 conferring it a pseudogene status, the actual lambda 5 equivalent might be either one of the 14.1 or 16.1 human C lambda-like genes, the function of which is so far unknown.
Schiff
C
C
Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, Marseille, France.
Milili
M
M
Fougereau
M
M
D004247:DNA / Q000032:analysis; D004586:Electrophoresis; D005091:Exons; D005333:Fetus / Q000276:immunology*; D015321:Gene Rearrangement; D005803:Genes, Immunoglobulin; D006684:HLA-DR Antigens / Q000235:genetics; D006801:Humans; D007146:Immunoglobulin lambda-Chains / Q000235:genetics*; D008099:Liver / Q000276:immunology*; D008970:Molecular Weight; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D006684:HLA-DR Antigens; D007146:Immunoglobulin lambda-Chains; D004247:DNA