Cancer-specific T helper shared and neo-epitopes uncovered by expression of the MHC class II master regulator CIITA

CIITA transfection of murine and human cancer cells resulted in the expression of the MHC class II loading machinery and presentation of peptides. Mass spectrometric analysis of MHC class II eluted peptides resulted in the identification of novel immunogenic CD4-specific epitopes in known shared antigens, and epitopes containing non-synonymous mutations. Neo-epitopes in MC38 were found to be relevant antigens in therapeutic vaccination and 'helped' CD8-specific responses in tumor-bearing mice. Several databases were established to help identify presented mutations in MC38 and CT26.