CD4 and cancer: Other variations of this strategy were attempts to isolate and expand tumour-reactive CD4+ T cells from patient tumour-infiltrating lymphocytes (TILs) using tumour-derived antigens with major histocompatibility complex (MHC) II-restricted epitopes and then re-infusing them as a form of ACT [19, 20], or more recently, by engineering autologous CD4+ T cells from cancer patients to express synthetic chimaeric antigen receptors that recognise antigenic epitopes on tumour cells.