CD8A and neoplasm: Ott et al. further theorised that the unexpected preponderance of CD4+ over CD8+ T cell responses could have been due to (1) a relative paucity of the cross-presenting dendritic cell subset within tumours, which led to more efficient priming of CD4+ relative to CD8+ T cells, and (2) the relatively higher promiscuity of MHC II-restricted epitopes due to more relaxed binding requirements compared with MHC I-restricted epitopes [39].