Figure 1.

Preferential recognition of posttranslationally modified peptides by T-cell clones from subjects with diabetes. A: Preferential recognition was confirmed by measuring the proliferative response of T-cell clones following stimulation with either modified peptide (white squares) or the corresponding unmodified peptide (black squares), as determined by [3H] thymidine incorporation. Data are represented as stimulation index (SI) values, calculated in triplicate by normalizing the proliferation of each clone based on [3H] thymidine incorporation in unstimulated wells. Horizontal lines represent means and error bars indicate SD. Each clone exhibited negligible proliferation (SI <3) in response to unmodified peptide and robust proliferation (SI >30) in response to modified peptide. B: T-cell clones specific for each modified epitope were also stained using tetramers loaded with modified peptide (each “E” indicates a glutamic acid modification at the indicated amino acid position and each “X” indicates a citrulline modification at the indicated amino acid position) or the corresponding unmodified version (wild-type peptide [WT]), and the mean fluorescence intensities of the staining were compared. Each clone was preferentially stained by modified peptide tetramers. Results shown are representative of T-cell clones isolated from multiple subjects with type 1 diabetes (n ≥ 2). FITC, fluorescein isothiocyanate; PE, phycoerythrin; Tmer, tetramer.