CD4 and esophageal squamous cell carcinoma: Seven types of immune cells [naïve CD4+ T cells, activated memory CD4+ T cells, follicular helper T cells, resting natural killer (NK) cells, M0 macrophages, M1 macrophages and activated dendritic cells] were more abundant in ESCC tissues than in normal tissues, whereas 6 types of immune cells (naïve B cells, resting memory CD4+ T cells, gamma delta T cells, M2 macrophages, resting dendritic cells and resting mast cells) were more abundant in normal tissues.