Figure 4.

Influence of ERAP1 polymorphism on the HLA-B*51 peptidome. Comparison of the HLA-B*51:01 ligands from the transfectant cell line 721.221-B*51 (N: 1,271 peptides) expressing the Hap1/Hap8 variants of ERAP1 (blue), with the B*51:08 ligands from LCL BCH-30 (N: 624 peptides) expressing the Hap10 variant (red). The comparisons involve (A) peptide length distribution, (B) percent of peptides with Pro2 or Ala2, (C) Percent residue frequencies at P1 among peptides with Pro2 (upper panel) or Ala2 (lower panel), (D) percent of peptides with P1 residues showing low or intermediate+high susceptibility to ERAP1 trimming among peptides with Pro2 (upper panel) or Ala2 (lower panel), (E) theoretical affinity of B*51:01 and B*51:08 ligands for their respective B*51 subtypes, with the medians indicated by bars. The statistical significance of the changes is indicated by the p-values, as estimated by the χ² (A–D) or Mann–Whitney tests (E). These data were originally published in reference (103).