Table 1.

Immunoregulatory functions of IFN-λs

Subtype	Target cell	Effect and possible mechanism	Overall impression	References
λ1	pDC	increase the expression of the homing molecules CCR7 and CD62L; upregulate co-stimulatory molecules CD80 and ICOS-L, and reduce stimulation of IL-10, IL-13, and IFN-γ production from allogeneic T cells	contribute to pDC activity and prolong pDC survival	58, 59
λ1, λ2	mDC (without LPS)	induce partial maturation of DCs; high levels of major MHC class I and MHC class II; express CCR7; low levels of costimulatory molecules, and retained phagocytic ability	induce partial maturation of mDCs	62
λ1, λ2	mDC	profoundly inhibit the generation of Th2 and Th17 responses; enhance Th1 polarization, and augment IL-12 secretion	promote mDC maturation	60, 61
λ1	CD4+ T cell	alter the Th1/Th2 development of naive human T cells; diminish the development of Th2 cells and lower the secretion of IL-13, and induce CD3+ T cell apoptosis	inhibit Th2, promote Th1, and induce apoptosis	60, 64, 73
λ1, λ2	Treg	IL-2-dependent proliferation of CD4+CD25+Foxp3+ T cells	induce proliferation of Treg	62
λ3	CD8+ T cell	increase CTL killing activity, and enhance antigen-specific cytolytic degranulation	promote killing activity	65, 66
λ1, λ2/3	NK	do not enhance NK cytotoxic activity and chemotaxis directly	no direct influence on NK	67, 68, 74
λ1	PBMC	elevate chemokines mRNA levels of CXCL9, CXCL10, and CXCL11, and upregulate IL-6, IL-8, and IL-10	activate PBMC	70, 71
λ1	monocyte	upregulate IL-6, IL-8, and IL-10; change morphology, and more motile	activate monocyte	71
λ1	macrophage	upregulate IL-6, IL-8, and IL-10; increase TLR-induced IL-12p40 production, and upregulate IFN-γR1	activate macrophage	35, 71
λ2/3	B cell	enhance TLR7 on B cells	unclear	75