CD8A and cancer: The results showed that, at E/T ratio of 10: 1 and 20: 1, the average killing activity of CIK cells against K562 cells were 7.38% and 19.79%, while the average killing activity of CD8+ CIK cells against K562 cells were 64.79% and 82.07%, respectively (Fig 6B), indicating CD8+ CIK cells have a stronger anti-cancer function than CIK cells (p<0.05).