CD4 and cancer: Previous studies have suggested that this population may act as a reservoir/precursor of CD4+CD25+FoxP3+ Tregs; thus, this reduction may assist in the reduced levels of Tregs present in our treated tumours.27 Importantly, Treg cells also contribute to the production of immunoregulatory cytokines, such as IL-10.37 IL-10 is an immune-suppressing anti-inflammatory cytokine and is upregulated in many cancer models.