Table 1.

Relationship between different immune cell subsets and colorectal cancer prognosis

Type of immune cell	Canonical function	Role in colorectal cancer	Ref.
CD8+ T cells	Production of cytokines (including IFN-γ) and cytotoxic molecules	High numbers of CD8+ T cells in the invasive margin correlate with favourable prognosis.	[56]
RORγT+IL-17+ T cells	Production of IL-17, which recruits inflammatory cells such as neutrophils	Associated with poor prognosis, especially in combination with low levels of Th1 cells (Tbet+IRF1+ IL12Rβ2+STAT4+)	[31]
Regulatory T (Treg) cells	Regulation and suppression of effector T cell responses, production of IL-10 and TGF-β.	High density of CD3+FOXP3+ Tregs associated with improved disease-free survival.	[11]
Effector Treg cells	Regulation of T cell responses, production of cytokines	CD3+FOXP3+Blimp-1+ associated with increased disease-free survival.	[72]
Macrophages	Phagocytic cells with pro- or anti-inflammatory properties, recruit T cells, neutrophils	Associated with favourable prognosis at the invasive margin.	[51]
Neutrophils	Phagocytosis of infected, damaged or dying cells, including tumours	Conflicting results, but a high ratio of neutrophils:CD8+T cells associated with poor prognosis.	[21-23,86]
Dendritic cells	Antigen presenting cells	Mature tumour-infiltrating (S100+CD83+) dendritic cells associated with improved prognosis.	[87]

Blimp-1: B lymphocyte-induced maturation protein 1; FOXP3: Forkhead box protein 3; IFN-γ: Interferon-gamma; TGF-β: Transforming growth factor-beta; Treg: Regulatory T cell.