IFNA1 and infection: Interestingly, monocytes and macrophages from older individuals (65–89 years of age) produce similar amounts of IL-6 and IL-1β after in vitro infection with PR8 H1N1 compared to those from younger donors (20–30 years of age), yet type I IFN production, as well as the expression of IFN signaling molecules and IFN-stimulated genes were reduced [18].