Cytotoxic CD4+ T cells decrease under primary chemoradiotherapy of HNSCC

Introduction Cytotoxic CD4+ T cells are known to play an important role in antitumour Immunity and are able to maintain tumour control after therapy. Peripheral total CD4+ T cells counts are diminished by conventional chemoradiotherapy (CRT) while regulatory CD4+ T cells are relatively increased. Until now, it is unclear how the protective subpopulation of CD4+ cytotoxic T cell behaves under the influence of CRT.