Identification of a promiscuous HLA DR-restricted T-cell epitope derived from the inhibitor of apoptosis protein survivin.

The inhibitor of apoptosis protein survivin is a promising tumor-associated antigen specifically recognized by CD8+ cytotoxic effector T-lymphocytes (CTL). To improve current vaccines that aim to induce survivin-specific CTL, it is necessary to study the role of CD4+ T-helper (TH) and CD4+ T-regulatory (Treg) cells. Because both TH and Treg cells recognize antigens in the context of HLA-class II molecules, identification of HLA class II-associated peptide epitopes from survivin is required. Here, we analyzed T-cell responses against survivin using synthetic peptides predicted to serve as HLA-DR-restricted epitopes. Six peptides were shown to induce CD4+ T-cell responses, restricted by HLA-DR molecules. For one peptide epitope, SVN10, T-cell clones were demonstrated to be capable of recognizing naturally processed antigen. SVN10-specific T cells could be stimulated from the blood of healthy individuals and cancer patients with multiple HLA-DR genotypes. Thus the identified SVN10 epitope can be used to study the role of CD4+ TH and Treg cells in immune responses and possibly be included in a multivalent peptide vaccine against survivin.