How can the interferons be classified?

Interferon-alpha: type I interferon, produced by B cells, epithelial cells, monocytes, macrophages and DCs interferon-beta: type I interferon, produced by fibroblast interferon-gamma: type II interferon, produced by activated TH1 cells and NK cells, inhibits viral replication interferon-lambda: type III interferon, produced at epithelial and endothelial barriers to promote viral infection and healing