IL10 and viral infectious disease: In the context of cytokine production, T-helper type 1 (Th1) cells, which secrete IL-2, IFN-γ and lymphotoxin, have a major role in cellular immunity to intracellular pathogens, virus infections and cancers, whereas Th2 cells, which secrete IL-4, IL-5 and IL-10, play a predominant role in humoral immunity against extracellular parasites [41].