title: Parameters underlying distinct T cell-dependent polysaccharide-specific IgG responses to an intact gram-positive bacterium versus a soluble conjugate vaccine.
abstract: IgG anti-polysaccharide (PS) responses to both intact Streptococcus pneumoniae (Pn) and PS conjugate vaccines are dependent on CD4(+) T cells, B7-dependent costimulation, and CD40-CD40-ligand interactions. Nevertheless, the former response, in contrast to the latter, is mediated by an ICOS-independent, apoptosis-prone, extrafollicular pathway that fails to generate PS-specific memory. We show that pre-existing PS-specific Igs, the bacterial surface or particulation, selective recruitment of B cell subsets, or activation and recruitment of Pn protein-specific CD4(+) T cells do not account for the failure of Pn to generate PS-specific IgG memory. Rather, the data suggest that the critical factor may be the lack of covalent attachment of PS to protein in intact Pn, highlighting the potential importance of the physicochemical relationship of PS capsule with the underlying bacterial structure for in vivo induction of PS-specific Igs.
authors: Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
authors: Jesus
authors: J
authors: Colino
authors: Gouri
authors: G
authors: Chattopadhyay
authors: Goutam
authors: G
authors: Sen
authors: Quanyi
authors: Q
authors: Chen
authors: Andrew
authors: A
authors: Lees
authors: David H
authors: DH
authors: Canaday
authors: Anatoly
authors: A
authors: Rubtsov
authors: Raul
authors: R
authors: Torres
authors: Clifford M
authors: CM
authors: Snapper
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D006094:Gram-Positive Bacteria / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D007156:Immunologic Memory; D051379:Mice; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D013296:Streptococcus pneumoniae / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D011135:Polysaccharides, Bacterial; D018074:Vaccines, Conjugate