Complex role for the immune system in initiation and progression of pancreatic cancer

Table 1 Major functions of the innate immune cells in both inflammation and cancer

Inflammatory cell	Immune function	Role in cancer
Neutrophil	Secretion of cytokines/chemokines to modulate other cells in the immune response	Maintenance of pro-angiogenic phenotype[242]
	Release of cytotoxic granules	Suppression of anti-tumor immunity[243]
	Phagocytosis	Promotion of metastasis[244]
Mast cell	Release of cytotoxic granules	Suppression of anti-tumor immunity[245]
	Enhancement of immune cell recruitment	Stimulation of angiogenesis[152]
	Permeabilization of blood vessels	Direct stimulation of cancer cell growth[246]
		Secretion of mitogenic factors[157]
Macrophage	Phagocytosis
	Promotion of T-lymphocyte activation
M1	Initiation of immune cell response
	Antigen presentation
M2	Wound repair
	Immunosuppression
	Tissue remodeling
	Resolution of immune response
TAM		Secretion of Arginase-1[19]
		Support of Treg activation[247,248]
		Promotion of angiogenesis[16]
		Enhancement of tumor metastasis[17]
MDSC	Suppression of NKC and T-lymphocyte activation	Production of ROS[22]
		Secretion of peroxynitrite[23]
		Secretion of Arginase-1[24,25]
		Induction of Treg[26]
		Depletion of cysteine[27]
NKC	Release of cytotoxic granules	Tumor cytotoxicity[28]
DC	Antigen presentation

TAM: Tumor-associated macrophage; MDSC: Myeloid-derived suppressor cell; NKC: Natural killer cell; DC: Dendritic cells.