CD31+ T cells represent a functionally distinct vascular T cell phenotype

In contrast to CD3+/CD31− cells, CD3+/CD31+ cells aid in endothelial repair and revascularization. There are limited data regarding the functional differences between circulating CD3+/CD31+ and CD3+/CD31− cells that may contribute to their divergent cardiovascular effects. The aim of the present study was to characterize functional differences between CD3+/CD31+ and CD3+/CD31− cells. To address this aim, migratory capacity, proangiogenic cytokine release and apoptotic susceptibility of CD3+/CD31+ and CD3+/CD31− cells were determined. Human CD3+/CD31+ and CD3+/CD31−cells from peripheral blood were isolated using magnetic-activated cell sorting. CD3+/CD31+ cells demonstrated significantly higher (∼60%) migratory capacity to the chemokines SDF-1α (655 ± 99 vs. 273 ± 54 AU) and VEGF (618 ± 99 vs. 259 ± 57 AU) vs. CD3+/CD31− cells. Release of angiogenic cytokines G-CSF, interleukin-8 and matrix metallopeptidase-9 were all ∼100% higher (P < 0.05) in CD3+/CD31+ than CD3+/CD31− cells. CD3+/CD31+ cells exhibited significantly higher intracellular concentrations of active caspase-3 (2.61 ± 0.60 vs. 0.34 ± 0.09 ng/mL) and cytochrome-c (21.8 ± 1.4 vs. 13.7 ± 1.0 ng/mL). In summary, CD3+/CD31+ cells have greater migratory and angiogenic cytokine release capacity, but are more susceptible to apoptosis compared with CD3+/CD31− cells. Enhanced migratory capacity and angiogenic cytokine release may contribute to the vasculogenic properties of this unique T cell subpopulation.