title: CD4(+) T cell activation promotes the differential release of distinct populations of nanosized vesicles.
abstract: Many cell types release nanosized vesicles derived from endosomal compartments (exosomes) or the plasma membrane. Vesicles actively released by CD4(+) T cells have immune-modulatory characteristics. Using our recently developed high-resolution flow cytometry-based method for the analysis of individual nanosized vesicles, we here investigated how T cell receptor (TCR)-triggering and co-stimulatory signals influence the quantity and characteristics of nanosized vesicles released by CD4(+) T cells. We found that the number of released nanosized vesicles within the buoyant density range characteristic for exosomes (1.10-1.19 g/ml) was increased by TCR-triggering and that additional co-stimulatory signals had a potentiating effect on vesicle release. However, the increase in the number of released vesicles varied substantially between density fractions within the 1.10-1.19 g/ml range and was highest for the vesicle populations in 1.14 and 1.17 g/ml fractions. Heterogeneity was also observed within the individual density fractions. Based on lipid bilayer fluorescent labelling intensity and light scattering, 3 distinct vesicle subpopulations were identified. One vesicle subpopulation increased significantly more upon T cell activation than the other subpopulations, and this was dependent on high levels of co-stimulation. These data show that T cells release a heterogeneous population of nanosized vesicles and indicate that T cells differentially regulate the release of distinct vesicle subpopulations depending on their activation status.
authors.affiliation: Department of Biochemistry & Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht,, The Netherlands.
authors.forename: Els J
authors.initials: EJ
authors.lastname: van der Vlist
authors.forename: Ger J A
authors.initials: GJ
authors.lastname: Arkesteijn
authors.forename: Chris H A
authors.initials: CH
authors.lastname: van de Lest
authors.forename: Willem
authors.initials: W
authors.lastname: Stoorvogel
authors.forename: Esther N M
authors.initials: EN
authors.lastname: Nolte-'t Hoen
authors.forename: Marca H M
authors.initials: MH
authors.lastname: Wauben
keywords: NTA; T cells; exosomes; extracellular vesicles; flow cytometry; immune regulation; microparticles; microvesicles; nanosized vesicles