Immunology of hepatocellular carcinoma

Table 1 Summary of the status of various immune components in hepatocellular carcinoma

Immune component	Status in HCC	Ref.
Dendritic cells	Decreased antigen presentation, decreased numbers, impaired functions	[12,13]
Macrophages	Poor antigen presentation, activated Th2 immune responses, promoted Tregs	[17,18,20]
Myeloid-derived suppressor cells	Exerted suppressive functions through free radicals, arginase activity, and TGF-β	[21,22]
Neutrophils	Promoted angiogenesis through metalloproteinase-9	[24]
NK cells	Decreased numbers, low cytolytic activity	[26,28]
T lymphocytes	Decreased frequency, fewer Th1 cytokines, increased expression of inhibitory receptors	[36,37]
Tregs	Increased frequency, suppressed T-cell proliferation and IFN-γ secretion, inhibited NK cell responses	[42,48,86]
Th17 cells	Increased numbers, incompletely defined role, correlated with disease progression	[51,52]
NKT cells	Dual roles, increased frequency, promoted Th2 cytokines	[55,56]
Th1 cytokines	Decreased in tumor microenvironment, induced CD8+ T-cells	[59,61,87]
Th2 cytokines	Increased levels, correlation with tumor progression	[21]
Proinflammatory cytokines	Involved in pathogenesis of HCC	[65,69]
Anti-inflammatory cytokines	Increased in HCC, correlated with progression	[72,73,76]
Chemokine-receptor axis	Tumor progression and metastasis	[78,83,84]

HCC: Hepatocellular carcinoma; NK: Natural killer cells; Tregs: Regulatory T cells; Th17: T helper type 17; NKT: Natural killer T; TGF: Transforming growth factor; IFN: Interferon.