IL10 and viral infectious disease: The increased IL-10 level in acute viral infection could mean that IL-10 is a causative mediator in virus provoked exacerbation (triggered by IFN-gamma), and that the generation of IL-10 is a response to a greater degree of pre-existing airway inflammation in individuals predisposed to virus, especially to RV, induced exacerbations, and serve to promote tolerance [17, 33].