title: Precursor frequencies of T-cells reactive to insulin in recent onset type 1 diabetes mellitus.
abstract: T-cell mediated autoimmune beta-cell destruction is an important component of type 1 diabetes (T1D) and insulin is a critical antigen recognized by autoreactive T-cells. The aim of this study was to investigate the precursor frequency of insulin reactive T-cells in type 1 diabetes. We studied 19 T1D patients, 12 age-matching non-diabetic healthy siblings and 12 non-diabetic healthy parents. Limiting dilution analysis (LDA) was performed to insulin and tetanus toxoid (TT). A progressive decrease in the number of negative cultures at increasing cell concentrations that is represented by a low goodness-of-fit (GoF, low Chi-square), was seen with the TT response in all three groups; precursor frequencies and GoF were similar in patients, siblings, and parents. Reactivity to insulin, however, showed low precursor frequencies in patients and siblings and the LDA to insulin demonstrated dramatic decreases in the number of positive cultures at higher cell concentrations leading to a high GoF in patients and siblings compared to parents. This saw-toothed pattern of reactivity to insulin is indicative of multiple hit kinetics and implies that the response is regulated. Consequently the precursor frequency of insulin autoreactive cells in patients and their siblings is probably much higher than calculated.
authors.affiliation: Department of Medicine, Division of Metabolism, Endocrinology, and Nutrition, University of Washington and Department of Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA.
authors.forename: Ramachandra G
authors.initials: RG
authors.lastname: Naik
authors.forename: Cora
authors.initials: C
authors.lastname: Beckers
authors.forename: Rino
authors.initials: R
authors.lastname: Wentwoord
authors.forename: Arlette
authors.initials: A
authors.lastname: Frenken
authors.forename: Gaby
authors.initials: G
authors.lastname: Duinkerken
authors.forename: Barbara
authors.initials: B
authors.lastname: Brooks-Worrell
authors.forename: Nanette C
authors.initials: NC
authors.lastname: Schloot
authors.forename: Jerry P
authors.initials: JP
authors.lastname: Palmer
authors.forename: Bart O
authors.initials: BO
authors.lastname: Roep
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology*; D006801:Humans; D007223:Infant; D007328:Insulin / Q000276:immunology*; D007700:Kinetics; D013601:T-Lymphocytes / Q000276:immunology*; D013745:Tetanus Toxoid / Q000276:immunology
chemical_list: D007328:Insulin; D013745:Tetanus Toxoid