CD4 and rectal cancer: But collectively, if the blood mtDNA status reflects the balance of advantageous immunity versus adverse inflammation in high-risk rectal cancer, tumour-targeting cytotoxic immune cells (CD3+CD8+CXCR4+) that are dependent on helper cells (CD3+CD4+Ki67+) sustained by a recruitment population (CD3+CD4+LAG-3+) [36, 37, 44] may hold fundamental functions in this context.