Immunogenicity of recoded FIX constructs. Immunogenicity assessment of recoded FIX constructs by MAPPs assay and T-cell proliferation assay is shown. (A) Distinct presentation of FIX-derived peptides bound to MHC-II molecules by wild-type (WT) and recoded FIX constructs. The sequences of the FIX peptides presented by MoDCs and their amino acid positions are included in the side table. The figure shows the number of times each of the peptides were presented by MoDCs, colored differently for each donor source. (B) Potential immunogenicity of these peptides as suggested by CD4⁺ T-cell proliferation in assay. Data are shown as percentage of donors showing response to test antigens measured as stimulation above background (≥0.5% and 2 standard errors greater than background). Four control antigens, tuberculin-purified protein derivative (PPD), keyhole limpet hemocyanin (KLH), hemagglutinin (HA), and tetanus toxoid (TT), were included in the assay.