title: Analysis of B cell selection in the germinal center reaction during a T-dependent antibody response at a single cell level.
abstract: The quasimonoclonal mouse is useful to examine B cell selection during T-dependent antibody (Ab) responses because of its limited B cell populations mainly expressing the knockin 17.2.25 V(H)-encoded H chain (V(H)T) paired with the lambda1 or lambda2 L chain. It has been reported that both two V(H)T/lambda1 and V(H)T/lambda2 B cell populations responded to a T-dependent antigen conjugated with a hapten p-nitrophenylacetyl (pNP), but only V(H)T/lambda2 B cells differentiated to secrete high affinity anti-pNP IgG Abs by acquiring a critical mutation (T313A) in the V(H)T. The V(H)T/lambda2 B cells may be more potent in migrating to the germinal centers (GCs) due to about 50-fold higher affinity for pNP than V(H)T/lambda1 B cells. Here, to uncover how V(H)T/lambda2 B cells were preferentially recruited for affinity maturation during the anti-pNP Ab response, we examined the L chain usage and mutation frequency of V(H)T(+) GC B cells at a single cell level. V(H)T/lambda2 B cells bearing the unmutated V(H)T gene were found in the GCs more frequently than V(H)T/lambda1 and mutated V(H)T/lambda2 counterparts in an early phase of the Ab response. In the course of the GC reaction, the number of V(H)T/lambda2 B cells that mutated their V(H)T genes preferentially expanded, and finally V(H)T/lambda2 B cells bearing the T313A mutation occupied V(H)T(+) GC B cell population. Thus, it is suggested that B cells with a higher affinity were selected not only for entry to the GCs but also in the affinity maturation process during a T-dependent Ab response.
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-Naka, Okayama 700-8530, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Okazawa
authors.forename: Masaki
authors.initials: M
authors.lastname: Magari
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kimoto
authors.forename: Emi
authors.initials: E
authors.lastname: Kouyama
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ohmori
authors.forename: Naoki
authors.initials: N
authors.lastname: Kanayama
mesh_terms: D000818:Animals; D000915:Antibody Affinity; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D002999:Clone Cells; D015328:Gene Rearrangement, B-Lymphocyte, Light Chain; D050438:Genes, Immunoglobulin Heavy Chain; D050439:Genes, Immunoglobulin Light Chain; D018858:Germinal Center / Q000166:cytology / Q000276:immunology*; D006241:Haptens; D007146:Immunoglobulin lambda-Chains / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D009596:Nitrophenols / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D005719:gamma-Globulins / Q000008:administration & dosage
chemical_list: D006241:Haptens; D007146:Immunoglobulin lambda-Chains; D009596:Nitrophenols; D005719:gamma-Globulins; C008642:4-nitrophenyl acetate