Figure 3. T cell exosome biogenesis and externalization

(A.) Schematic representation of exosome biogenesis. Exosome biogenesis starts from internalization of membrane proteins and lipid complexes from the PM by endocytosis. Endocytotic vesicles are delivered to the early endosomes, which fuse with each other resulting in formation of late endosomes. Internal vesiculation of limiting membrane of late endosomes results in the formation of multivesicular bodies (MVB). MVB may gradually mature to lysosomes, were the degradation of their content occurs. However, in hematopoietic cells, MVB can fuse with the plasma membrane and release internal vesicles (exosomes) to the extracellular space. (B & C) Fusion of a MVB with the PM and exosome externalization in activated T cell. (C) Enlargement of the boxed area in (B). N- nucleus; m-mitochondria. Scale bars are 0.5 mm.