摘要：SummaryMacrophages release a variety of extracellular vesicles (EVs). Here we describe a previously unreported class of EVs that are released from macrophages in response toEscherichia coliendotoxin, lipopolysaccharide (LPS), that we have named "macrolets" since they are extruded as large "droplets" released frommacrophages. Morphologically, macrolets are anuclear, bounded by a single lipid membrane and structurally dependent on an actin cytoskeleton. Macrolets are enriched in tetraspanins and separable on this basis from their parent macrophages. Macrolets are distinguished from classic exosomes by their larger size (10–30 μm), discoid shape, and the presence of organelles. Macrolets are rich in both interleukin 6 (IL-6) and interleukin 6 receptor (IL-6R),and are capable of trapping and killingE.coliin association with production of reactive oxygen species. Our observations offer insights into the mechanisms by which macrophage activities may be amplified in sites of infection, inflammation, and healing.Graphical AbstractDisplay OmittedHighlights•Macrolets, outsized extracellular vesicles, release from LPS-stimulated macrophages•Macrolets are rich in tetraspanin proteins such as CD81, CD63, and CD9•Macrolets capture and internalizeE. colibacteria within acidic compartments•Macrolets killE. coliby a mechanism associated with production of ROS and superoxideBiological Sciences; Immunology; Immune Response; Cell Biology; Specialized Functions of Cells
