title: Evidence that the V kappa III gene usage is nonstochastic in both adult and newborn peripheral B cells and that peripheral CD5+ adult B cells are oligoclonal.
abstract: There is evidence that in certain situations the expressed antibody repertoire is dominated by small subsets of V gene segments. They include fetal, CD5+, and autoantibody-forming B cells as well as low grade B cell malignancies. For instance, inside the V kappa III family of approximately 10 members, only 3 (humkv325, 328, and Vg) are used recurrently for autoantibody production. However, the significance of this recurrence is difficult to interpret without a clear vision of the actual repertoire in normal subjects. To address this, we have sequenced and compared two sets of rearranged V kappa III genes generated by cDNA PCR amplification from a normal newborn, a normal adult, and from CD5+ B cells of the same adult donor. The results show that: (a) only four V kappa III gene segments are used by neonatal and total adult B cells (humkv325, humkv328, Vg, and kv305), humkv325 being overexpressed in both repertoires; (b) there is no significant difference in terms of V kappa III gene usage between the adult and newborn repertoires; (c) regarding the junction regions, there is a favored use of the most 5' JK gene segments (Jk1-Jk2); approximately 20% of the newborn and adult junction sequences was characterized by one or two additional codons, most probably resulting from a nontemplate addition of nucleotides; (d) adult clones, in contrast to most newborn clones, show sequence divergences from prototype sequences with patterns which suggest antigen-driven diversity; (e) regarding the adult CD5+ B cell library, it is most probable that the 78 clones analyzed derived from no more than nine different VK-JK rearrangements. Humkv325 is used by at least six of them, and most of the expressed V genes were in exact or very near germline configuration. Collectively these results suggest that the expressed antibody V kappa III repertoire in the adult represents only a fraction of the potential genetic information and that it resembles the preimmune repertoire of the neonate. The data, which also suggest that the adult peripheral blood CD5+ B cell population may be dominated by a small number of B cell clones, are discussed with regards to the V kappa III usage in pathological situations.
authors.affiliation: Laboratoire d'Immunopathologie, Hôpital Central, Hôpitaux Universitaires, Strasbourg, France.
authors.forename: J C
authors.initials: JC
authors.lastname: Weber
authors.forename: G
authors.initials: G
authors.lastname: Blaison
authors.forename: T
authors.initials: T
authors.lastname: Martin
authors.forename: A M
authors.initials: AM
authors.lastname: Knapp
authors.forename: J L
authors.initials: JL
authors.lastname: Pasquali
mesh_terms: D000328:Adult; D000375:Aging / Q000235:genetics*; D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000235:genetics; D016175:B-Lymphocyte Subsets / Q000276:immunology; D001483:Base Sequence; D018956:CD5 Antigens; D002999:Clone Cells; D005312:Fetal Blood / Q000166:cytology / Q000276:immunology; D015723:Gene Library; D015322:Gene Rearrangement, B-Lymphocyte / Q000235:genetics*; D005803:Genes, Immunoglobulin / Q000235:genetics*; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D007145:Immunoglobulin kappa-Chains / Q000235:genetics*; D007231:Infant, Newborn; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid
chemical_list: D015703:Antigens, CD; D018956:CD5 Antigens; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D007145:Immunoglobulin kappa-Chains