Human papillomavirus 16-specific T cell responses in classic HPV-related vulvar intra-epithelial neoplasia. Determination of strongly immunogenic regions from E6 and E7 proteins

Abstract

Cell-mediated immunity directed against human papillomavirus 16 (HPV-16) antigens was studied in 16 patients affected with classic vulvar intra-epithelial neoplasia (VIN), also known as bowenoid papulosis (BP). Ten patients had blood lymphocyte proliferative T cell responses directed against E6/2 (14-34) and/or E6/4 (45-68) peptides, which were identified in the present study as immunodominant among HPV-16 E6 and E7 large peptides. Ex vivo enzyme-linked immunospot-interferon (IFN)-gamma assay was positive in three patients who had proliferative responses. Twelve months later, proliferative T cell responses remained detectable in only six women and the immunodominant antigens remained the E6/2 (14-34) and E6/4 (45-68) peptides. The latter large fragments of peptides contained many epitopes able to bind to at least seven human leucocyte antigen (HLA) class I molecules and were strong binders to seven HLA-DR class II molecules. In order to build a therapeutic anti-HPV-16 vaccine, E6/2 (14-34) and E6/4 (45-68) fragments thus appear to be good candidates to increase HPV-specific effector T lymphocyte responses and clear classic VIN (BP) disease lesions.