title: Development of autoreactive diabetogenic T cells in the thymus of NOD mice.
abstract: Type 1 diabetes results from destruction of pancreatic beta cells by beta cell-specific autoreactive T cells in the nonobese diabetic (NOD) mouse. Defects in thymic negative selection are thought to result in failure to delete potential beta cell-reactive T cells, contributing to the development of autoimmune diabetes. We investigated this possibility by comparing the deletion profile of double-positive (DP) thymocytes in NOD mice with diabetes-resistant strains of mice after anti-CD3 Ab treatment to trigger the TCR-mediated signaling pathway. We found that immature NOD CD4+CD8+ DP thymocytes have a lower activation threshold than C57BL/6 and Balb/c thymocytes. This was confirmed by showing that NOD DP thymocytes have a higher level of ERK and JNK phosphorylation. The low activation threshold of immature thymocytes resulted in rapid deletion of strongly activated immature DP thymocytes by negative selection, whereas weakly activated immature thymocytes differentiated more efficiently into CD69+CD3high DP thymocytes by positive selection. SP thymocytes, particularly CD4-CD8+ T cells that were efficiently generated from activated DP thymocytes, could induce severe insulitis and diabetes in NOD.scid mice. We conclude that the development of autoreactive diabetogenic T cells results from inordinate positive selection due to the low activation threshold of DP thymocytes in NOD mice.
authors.affiliation: Julia McFarlane Diabetes Research Centre, Faculty of Medicine, The University of Calgary, 3330 Hospital Drive N.W., Calgary, Alberta T2N 4N1 Canada.
authors.forename: Hyokjoon
authors.initials: H
authors.lastname: Kwon
authors.forename: Hee-Sook
authors.initials: HS
authors.lastname: Jun
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Conchi
authors.initials: C
authors.lastname: Mora
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Mariathasan
authors.forename: Pamela S
authors.initials: PS
authors.lastname: Ohashi
authors.forename: Richard A
authors.initials: RA
authors.lastname: Flavell
authors.forename: Ji-Won
authors.initials: JW
authors.lastname: Yoon
mesh_terms: D000818:Animals; D017209:Apoptosis; D002454:Cell Differentiation; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology* / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008213:Lymphocyte Activation; D051379:Mice; D016688:Mice, Inbred NOD; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism
chemical_list: D019014:fas Receptor; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases