Vol. 278, No. 13, Issue of March 28, 2003, pp. 10963-10972, 2003 | Richard Wubbolts, Rachel S. Leckie, Peter T. M. Veenhuizen, Guenter Schwarzmann, Wiebke Mobiuss, Joerg Hoernschemeyer, Jan-Willem Slot, Hans J. Geuze, and Willem Stoorvogel
This study investigates the protein and lipid compositions of highly purified human B cell-derived exosomes, which are 60–100 nm membrane vesicles secreted from multivesicular bodies (MVBs). Mass spectrometric analysis revealed the presence of major histocompatibility complex (MHC) class I and II, heat shock proteins, integrin α4, CD45, moesin, tubulin, actin, Gα2, and other proteins. The α4-integrin may direct B cell-derived exosomes to follicular dendritic cells, which are potential target cells. Clathrin, heat shock cognate 70, and heat shock protein 90 are involved in protein sorting at MVBs. Exosomes are enriched in cholesterol, sphingomyelin, and ganglioside GM3, lipids typically found in detergent-resistant membranes. Most exosome-associated proteins, including MHC class II and tetraspanins, are insoluble in CHAPS-containing buffers, suggesting their incorporation into detergent-resistant membrane domains. These findings suggest that the incorporation of membrane proteins into tetraspanin networks and detergent-resistant membranes may be crucial for their sorting into MVB internal vesicles. The study also highlights the role of exosomes in immune responses and their potential as intercellular communication vehicles.This study investigates the protein and lipid compositions of highly purified human B cell-derived exosomes, which are 60–100 nm membrane vesicles secreted from multivesicular bodies (MVBs). Mass spectrometric analysis revealed the presence of major histocompatibility complex (MHC) class I and II, heat shock proteins, integrin α4, CD45, moesin, tubulin, actin, Gα2, and other proteins. The α4-integrin may direct B cell-derived exosomes to follicular dendritic cells, which are potential target cells. Clathrin, heat shock cognate 70, and heat shock protein 90 are involved in protein sorting at MVBs. Exosomes are enriched in cholesterol, sphingomyelin, and ganglioside GM3, lipids typically found in detergent-resistant membranes. Most exosome-associated proteins, including MHC class II and tetraspanins, are insoluble in CHAPS-containing buffers, suggesting their incorporation into detergent-resistant membrane domains. These findings suggest that the incorporation of membrane proteins into tetraspanin networks and detergent-resistant membranes may be crucial for their sorting into MVB internal vesicles. The study also highlights the role of exosomes in immune responses and their potential as intercellular communication vehicles.