title: A novel approach to study variable heavy chain gene usage in response to the capsular polysaccharide of Neisseria meningitidis serogroup C.
abstract: The molecular mechanisms involved in the relatively poor immune response in the elderly are not clearly understood. Qualitative aspects of the immune response could be a possible explanation for the differential response to T-independent antigens in young adults and elderly. This study is directed towards elucidating the differential usage of variable heavy chain by young adult and elderly derived sequences in response to the capsular polysaccharide of Neisseria meningitidis serogroup C. We currently report findings of a preliminary study designed to test the feasibility of a novel approach to isolate antigen-specific B cells. Paramagnetic beads coated with an anti-idiotypic antibody, which mimics the capsular polysaccharide of N. meningitidis serogroup C, were used to select B cells. Analysis of the gene usage data indicates some unexpected differences in the use of variable chain heavy chain in the case of young adult versus elderly sequences. The elderly derived sequences use a more diverse array of V(H) gene families in contrast to the young adult sequences, where the V(H) gene family usage is restricted. Nearly half the young adult sequences utilize V(H)3-15 germline sequence while only 25% of the elderly sequences use this germline sequence. There were interesting differences in the types of JH chain and the composition and length of CDR3 utilized by the two groups. Together, these significant differences may contribute towards the poor immune response to T-independent antigens in the elderly. These data validate the techniques used for these studies and suggest that it is pertinent to use this approach towards future investigations to elucidate gene usage in response to an antigen.
authors.affiliation: Departments of Medicine and Pathology, Medical College of Ohio, 3055, Arlington Avenue, Toledo, OH 43614, USA.
authors.forename: Neeti
authors.initials: N
authors.lastname: Srivastava
authors.forename: S Louise
authors.initials: SL
authors.lastname: Smithson
authors.forename: M A Julie
authors.initials: MA
authors.lastname: Westerink
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D000907:Antibodies, Bacterial / Q000235:genetics*; D016667:Bacterial Capsules / Q000276:immunology*; D002874:Chromosome Mapping; D022801:Complementarity Determining Regions / Q000235:genetics; D016384:Consensus Sequence; D005803:Genes, Immunoglobulin; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007144:Immunoglobulin J-Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology; D018189:Immunomagnetic Separation / Q000379:methods*; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D009345:Neisseria meningitidis / Q000276:immunology*; D010802:Phylogeny; D010865:Pilot Projects; D017386:Sequence Homology, Amino Acid
chemical_list: D000907:Antibodies, Bacterial; D022801:Complementarity Determining Regions; D007143:Immunoglobulin Heavy Chains; D007144:Immunoglobulin J-Chains; D007135:Immunoglobulin Variable Region