title: The induction of carrier-specific helper cell tolerance in presensitized rats.
abstract: Lewis rats rendered tolerant to sheep IgG (SGG) show a markedly reduced antibody response to the 2,4,6-trinitrophenyl (TNP) hapten when later challenged with TNP-SGG. We have previously shown that this effect is due to functional unresponsiveness in the carrier SGG-specific helper T cell population. In this paper we demonstrate that induced helper cell tolerance is also maintained through a secondary immunogenic challenge. Furthermore, rats which are primed to the carrier SGG prior to tolerance induction also show a markedly reduced anti-TNP response upon secondary immunogenic challenge with TNP-SGG. The ability to specifically suppress a secondary response in this manner was found to be relatively long lasting, since rats showed reduced responsiveness when the secondary challenge was delayed for up to 4 weeks after tolerance induction. In addition, rats primed to the hapten (TNP) prior to carrier (SGG) tolerance induction also showed a marked reduction in anti-TNP antibody following challenge with TNP-SGG. These findings imply that helper cell tolerance can be induced in rats even after priming of carrier-specific (SGG) helper cells, or hapten-specific (TNP) B cells. These results parallel our other published findings that IgE responses in presensitized rats can be overcome by helper cell tolerance.
mesh_terms: D000818:Animals; D000917:Antibody Formation; D000921:Antibody-Producing Cells; D000941:Antigens; D007108:Immune Tolerance; D007074:Immunoglobulin G; D007156:Immunologic Memory; D051381:Rats; D011917:Rats, Inbred Lew; D012756:Sheep / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D014301:Trinitrobenzenes / Q000276:immunology
chemical_list: D000941:Antigens; D007074:Immunoglobulin G; D014301:Trinitrobenzenes