Figure 3.

T1, S14, and OT-1 TCR transgenic animals exhibit a similar affinity threshold for negative selection. (A) Thymic selection properties of peptide variants specific for S14 TCR transgenic thymocytes were determined by FTOC. Positive and negative selection were assessed as in Fig. 1 D. (B) Binding of pMHC monomers (4A-H-2K^d [□], 4L-H-2K^d [▪], and 4H-H-2K^d [▿]) to thymocytes from S14 TCR transgenic mice at 37°C using the two-step photoaffinity labeling method. (C–E) Tetramer binding of threshold ligands to thymocytes from T1, S14, or OT-1 TCR transgenic mice at 37°C. (C) 4S-H-2K^d tetramers (•) applied to T1 thymocytes. (D) 4L-H-2K^d tetramers (♦) applied to S14 thymocytes. (E) SIITFEKL-K^b tetramers (▪) applied to OT-1 thymocytes. Tetramer concentrations resulting in half-maximal TCR saturation are indicated in each panel.