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. © 2012 Els J.
van der Vlist, E. J., Arkesteijn, G. J. A., van de Lest, C. H. A., Stoorvogel, W., Hoen, E. N. M. N. t., & Wauben, M. H. M. (2012). CD4+ T cell activation promotes the differential release of distinct populations of nanosized vesicles. Journal of Extracellular Vesicles, 1(1). https://doi.org/10.3402/jev.v1i0.18364