title: Anti-B cell autoantibodies encoded by VH 4-21 genes in human fetal spleen do not require in vivo somatic selection.
abstract: We isolated immunoglobulin (Ig) VH4 genes that were rearranged in the genomic DNA of 160 day human fetal spleen. Productively rearranged VH 4-21 genes were cloned into pRTM1, a human IgM expression vector. This allowed us to generate IgM kappa-expressing transfectomas by co-transfecting each of these constructs with pSVG-V kappa 3, an Ig kappa light-chain expression vector that has a variable region encoded Humkv325, a conserved V kappa gene that is frequently expressed early B cell ontogeny. We find that all transfectomas expressing IgM kappa encoded by VH 4-21 make IgM autoantibodies reactive with i, a linear poly-N-acetyllactosamine determinant present on neonatal red blood cells and a B cell-restricted isoform of the CD45 surface molecule. In contrast, a transfectoma expressing pSVG-V kappa 3 and pRTM1 containing a rearranged VH4-59 (V71-4) gene isolated from a chronic lymphocytic leukemia B cell population, designated WIL, produced IgM kappa antibodies that had no detectable anti-i binding activity. However, transfectomas expressing VH 4-21 fused onto the Ig heavy-chain third complementarity determining region (CDR3) of WIL are found to make anti-B cell autoantibodies with anti-i activity. These studies indicate that VH 4-21 genes rearranged in human fetal B cell ontogeny can encode anti-B cell autoantibodies with a binding specificity that does not require in vivo somatic selection.
authors: Sam and Rose Stein Institute for Research on Aging, Department of Medicine, University of California, San Diego, La Jolla 92093-0663.
authors: T B
authors: TB
authors: Parr
authors: T A
authors: TA
authors: Johnson
authors: L E
authors: LE
authors: Silberstein
authors: T J
authors: TJ
authors: Kipps
mesh_terms: D000373:Agglutinins; D000595:Amino Acid Sequence; D001323:Autoantibodies / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D003450:Cryoglobulins; D017931:DNA Primers / Q000737:chemistry; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D005803:Genes, Immunoglobulin; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013154:Spleen / Q000196:embryology; D014162:Transfection
chemical_list: D000373:Agglutinins; D001323:Autoantibodies; D003450:Cryoglobulins; D017931:DNA Primers; D007135:Immunoglobulin Variable Region; D011993:Recombinant Fusion Proteins; C029443:cold agglutinins