FD_AA scores of 12 AA substitutions in HLA-DPB1. Shown are 12 AA substitutions in ten polymorphic residues of HLA-DPB1, along with their FD_AA scores as determined previously.³²  Statistical comparison between the FD_AA scores of 7 nonconservative AA substitutions with peptide-binding characteristics (filled circles), and 5 other AA substitutions (filled squares) was performed by the nonparametric Mann-Whitney U test. **P = .0025.