title: Understanding thymus-independent antigen-induced reduction of thymus-dependent immune responses.
abstract: Deficiencies in immune responses against polysaccharides can have direct consequences for patients, and therefore, a better understanding of these immune reactions is crucial. We have studied the immune response against the polysaccharide dextran B512 (Dx). Administration of immunogenic doses of thymus-independent (TI) Dx reduces the immunoglobulin G1 response to later challenges with a thymus-dependent (TD) form of Dx. We investigated if this suppression is a general phenomenon caused not only by Dx but also by other TI antigens, and examined possible mechanisms contributing to this unresponsiveness. We show that clonal exhaustion is not involved in modulating subsequent responses, nor is signalling via FcgammaRIIB or other antibody mediated pathways. The reduced TD response is not an exclusive Dx phenomenon; it is also induced by TI antigen oxazolone (Ox). However, responses against the hapten dinitrophenyl (DNP) are not affected, indicating that the TI priming negative effect is not a general process. This may be explained by the restricted immune response to both Dx and Ox, in contrast to the unrestricted DNP response. Our conclusion from these experiments is that the underlying mechanism for the TI-induced reduction of latter TD responses is a property of the TI activation itself.
authors.affiliation: Department of Immunology, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden. karin.lindroth@imun.su.se
authors.forename: Karin
authors.initials: K
authors.lastname: Lindroth
authors.forename: Elena Fernández
authors.initials: EF
authors.lastname: Mastache
authors.forename: Izaura
authors.initials: I
authors.lastname: Roos
authors.forename: Africa González
authors.initials: AG
authors.lastname: Fernández
authors.forename: Carmen
authors.initials: C
authors.lastname: Fernández
mesh_terms: D000818:Animals; D000941:Antigens / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D001402:B-Lymphocytes / Q000276:immunology*; D003911:Dextrans / Q000276:immunology / Q000494:pharmacology*; D004136:Dinitrobenzenes / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006241:Haptens / Q000494:pharmacology; D006825:Hybridomas; D007074:Immunoglobulin G / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010081:Oxazolone / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000941:Antigens; D003911:Dextrans; D004136:Dinitrobenzenes; D006241:Haptens; D007074:Immunoglobulin G; D010081:Oxazolone