NY-ESO-1 encodes DRB1*0401-restricted epitopes recognized by melanoma-reactive CD4+ T cells

The NY-ESO-1 gene is expressed by a range of human tumors and encodes HLA-A2-restricted melanoma peptides recognized by CD8+ CTLs. Here we report that the NY-ESO-1 gene also encodes two overlapping, but non-cross-reactive, HLA-DRB1*0401-presented peptides that are recognized by CD4+ T cells. The NY-ESO-1_119-143 peptide was able to induce specific CD4+ T cells in vitro from both an HLA-DRB1*0401⁺ normal donor and an HLA-DRB1*0401⁺ patient with melanoma. Bulk and cloned CD4+ T cells produced IFN-γ specifically in response to, and also lysed, T2.DR4 cells pulsed with peptide NY-ESO-1_119-143 and the autologous tumor cell line, but not a DRB1*0401⁺ melanoma cell line that does not express NY-ESO-1. Interestingly, the NY-ESO_119-143 peptide contains two overlapping putative 'core' epitopes recognized by non-cross-reactive anti-NY-ESO-1_119-143 CD4+ T-cell clones. Taken together, these data support the use of this novel DR4-restricted tumor peptide, NY-ESO-1_119-143, or its two 'sub-epitopes' in immunotherapeutic trials designed to generate or enhance specific CD4+ T-cell responses against tumors expressing NY-ESO-1 in vivo.