IL6 and infection: Among these proinflammatory cytokines, IL-6 may play an important role mediating severe disease caused by influenza virus infection, since increased levels of this cytokine correlate with infection with high virulent H1N1 strain in ferrets [48], severe infections of macaques with 1918 influenza virus [38] and pH1N1 virus [28], a fatal human case of pH1N1 [49] and with severe clinical manifestations in infected patients [50].