02040nas a2200217   4500000000100000008004100001260001500042653001300057653002900070653003100099653002900130653001500159100002100174700002000195245011500215856007200330300001200402490000800414520138600422022001401808       2015                            d  c2015-02-0110aExosomes10afetal bovine serum (FBS)10aInterleukin 1beta (IL-1β)10aLipopolysaccharide (LPS)10aMacrophage1 aLida A. Beninson1 aMonika Fleshner00aExosomes in fetal bovine serum dampen primary macrophage IL-1β response to lipopolysaccharide (LPS) challenge  uhttps://www.sciencedirect.com/science/article/pii/S0165247814002387  a187-1920 v1633 aThis study identifies a previously unknown immunological function of exosomes present in fetal bovine serum (FBS). Exosomes are small (40–100nm), biologically active nanoparticles released from cells that associate with a variety of proteins and miRNA. Exosomes are present in nearly all biological fluids, including FBS, a common supplement to cell culture media. While there are a growing number of studies examining cellular responses to exosomes, there is no assessment of how FBS exosomes impact cellular responses to immunological challenges. Our results demonstrate that primary macrophages from Fisher 344 rats cultured with lipopolysaccharide (LPS) in the presence of FBS exosomes exhibit a dose-dependent reduction in IL-1β compared to macrophages cultured in medium supplemented with exosome-depleted FBS. The addition of fetal bovine exosomes also reduced macrophage tumor necrosis factor-alpha (TNF-α) and IL-6, but not IL-10, monocyte chemotactic factor-1 (MCP-1), nitric oxide (NO), or lactose dehydrogenase (LDH) response to LPS. The selectivity of exosomal impact on macrophage IL-1β and pro-inflammatory protein responses may implicate the potential role of exosome-inflammasome interactions. These findings suggest that researchers should consider the immunological influence of FBS exosomes, particularly on IL-1β activity, when studying cells in culture.  a0165-2478