Identification of HLA restriction patterns of CD4⁺ and CD8⁺ responses against NY-ESO-1_51-62. Patient BMT47's CD4⁺ and CD8⁺ T cells stimulated with peptide NY-ESO-1_51-62 were tested in ELISPOT assays against partially matched allogeneic EBV-B cells pulsed with the same peptide. Patient BMT47 expressed the following alleles: HLA-A32 homozygous, HLA-B27 homozygous, HLA-CW01/HLA-CW02 for class I molecules, and HLA-DR01/HLA-DR04, HLA-DP03/HLA-DP04, and HLA-DQ03/HLA-DQ05 for class II molecules. The allele(s) the EBV lines were partially matched for are shown. Minus signs indicate completely mismatched targets and “auto” indicates autologous EBV-B cell targets. Only HLA-DQ5–expressing EBV-B cell lines were capable of presenting NY-ESO-1_51-62 to the CD4⁺ T-cell line (A), whereas the CD8⁺ response against the same peptide was clearly restricted by HLA-B27 (B). Black bars indicate specific responses against the NY-ESO-1 peptides whereas white bars show background responses against control peptides MAGEA3 271-279 for CD8⁺ and NY-CO-58 151-180 for CD4⁺ (mean spot numbers of duplicate experiments). Error bars indicate SEM.