Figure 2.

Autocrine purinergic signaling maintains basal functions of resting T cells. A, Jurkat T cells were stained with the adenosine triphosphate (ATP) probe 2-2Zn(II) and basal ATP release or ATP release in response to T cell receptor/CD28 stimulation with anti-CD3/CD28–coated beads was recorded using fluorescence microscopy. Apyrase (10 U/mL) was added as a control to remove extracellular ATP (eATP) (×63 oil objective; nominal aperture, 1.4; scale bar, 5 µm) (see also Supplementary Videos 2 and 3). B, C, Jurkat cells were treated or not treated (control) with 100 µmol/L suramin for 10 minutes, stimulated with anti-CD3/CD28 antibody–coated beads, and stained with DHR123; then mitochondrial activity (reactive oxygen species production) and the percentage of cells interacting with beads were analyzed with flow cytometry. Cells attached to beads were identified by their increased side scatter (SSC) signal (B; see also Supplementary Figure 1B). The area under the curve in SSC-positive cells was used to quantify changes in the percentage of cells bound to beads. Cells with active mitochondria were identified by DHR123 staining, as shown in Supplementary Figure 1C. Means and standard deviations from different experiments (n = 6) are shown in C. *P < .05; †P < .001 (Student t test).