IL6 and influenza: For instance, enhanced infiltration of macrophages and neutrophils has been reported in mice infected with highly pathogenic strains of influenza such as 1918 H1N1 and H5N1, compared to low pathogenic strains, along with higher levels of proinflammatory cytokines and chemokines such as MCP-1, MIP-1a, IL-1a, IFN-y, and IL-6 [123].