Table 1.

Main characteristics of human IFN system (un update).

IFN	Members	Main Cellular Source	Receptor	Receptor Expression
Type I IFN	IFNα1/13, IFNα2,IFNα4, IFNα5, IFNα6, IFNα7, IFNα8, IFNα10, IFNα14, IFNα16,IFNα17, IFNα21	pDCs, fibroblasts, macrophages	IFNA receptor R1 and R2	Ubiquitous expression
	IFNβ
	IFNε
	IFNκ
	IFNω
Type II IFN	IFNγ	Natural killer cells,natural killer T cells, Th1 CD4, CD8 cytotoxic T lymphocytes	IFNG receptor R1and R2	Ubiquitous expression
Type III IFN	IFNλ1, IFNλ2, IFNλ3, IFNλ4	Epithelial cells, hepatocytes, pDCs, myeloid DCs and macrophages	IFNL receptor R1	Expressed preferentially by epithelial cells
			IL10 receptor R2	Ubiquitous expression