FACS analysis of T2 binding assay. (A) HLA-A2 surface expression on 1 × 10⁶ T2 cells without peptide (negative) and up-regulation of HLA-A2 expression after preincubation with the native peptide (FI = 1.1) and the heteroclitic peptide (FI = 2.4). (B) HLA-A2 surface expression on 1 × 10⁶ T2 cells without peptide (negative) and up-regulation of HLA-A2 expression after preincubation with the native peptide (FI = 0.2) and the heteroclitic peptide (FI = 2.7). The results are representative of at least 3 independent experiments performed on a total of 34 peptides.