Table 1.

NK cells in immunity to pathogens.

Pathogen		Mechanism of action	References
Viruses	MCMV	TLR9 and MyD88 activation of DC-induced IFN-α and IL-12 production; this leads to NK cell IFN-γ production and cytotoxicity	[4, 5, 6••, 7••]
		Perforin and IFN-γ generation by NK cells limits viral replication in the spleen and liver	[8, 9]
		MCMV m157 binds Ly49H, induces NK cell IFN-γ, MIP-1α, MIP-1β, RANTES and ATAC, and controls MCMV in C57BL/6 mice	[17, 18, 19, 20•]
		NK cells mediate resistance in NZW mice by multiple gene products	[21]
		NK cells protect MA/My mice from infection; Ly49P recognizes H-2Dk-restricted ligand in MCMV-infected cells	[22•, 23•]
		KLRG1+ NK cells expand and contract in response to infection	[26]
	HCMV	NK cell IFN-γ, LTα/β and TNF induce IFN-β from infected cells and inhibit HCMV replication	[10]
		A truncated form of MICA escapes HCMV down-regulation and activates NK cell NKG2D	[13]
		CD94–NKG2C+ NK cells preferentially expand in response to infected fibroblasts	[25]
	Sendai virus	Viral infection induces IFN-α and MICB gene transcription; this leads to NK cell IFN-γ production	[11]
	Influenza A virus	Viral infection induces IFN-α and MICB gene transcription; this leads to NK cell IFN-γ production	[11]
	HIV	Neonatal NK cells suppress replication of CCR5-trophic viruses	[29]
		NK cells from viremic patients produce more IFN-γ and TNF-α than NK cells from aviremic patients	[30]
	MHV	NK cell recruited to the CNS after intracerebral MHV infection enhance survival and decrease viral titers	[33]
	Ebola virus	Injection of Ebola virus-like particles confers NK cell-mediated protection against Ebola virus infection in mice	[34]
Parasites	P. falciparum	Human NK cells produce IFN-γ in response to infected RBC	[36, 37•, 38•, 39]
		NK cells form stable conjugates with infected RBC	[39]
	P. berghei ANKA	Reduced pathogenesis in BALB/c mice maps to the NKC	[40]
	T. cruzi	NK cells enhance survival of infected C57BL/6 mice and reduce parasitemia	[42]
		NK cells directly lyse parasites	[41]
Bacteria	Shigella flexneri	NK cell IFN-γ controls infection	[43]
	M. tuberculosis	NK cells kill infected monocytes by a mechanism that involves NKp46 and NKG2D	[44]