Figure 1.

Heightened ASM activity during naive CD4⁺ T-cell activation and proliferation. (a–d) Naive CD4⁺ T cells (CD4⁺CD45RA⁺) were stimulated with anti-CD3/CD28 antibody-coated beads in the presence of l-carnitine (1 mM), amitriptyline (5 μM), or imipramine (20 μM) for different times as indicated, ceramide production was measured by TLC (a), expression of CD25 (b) and CD69 (c) at 48 h, or CFSE (d) at 72 h were determined by FACS (fluorescence-activated cell sorting ). (e–h) Anti-CD3/CD28 antibody-coated beads activated naive CD4⁺ T cells were treated with various concentrations of imipramine (0.2, 2, and 20 μM) for different times, followed by TLC measurement of ceramide production (e), and FACS analysis of T-cell activation (f) and CD25 at 48 h (g), or CFSE (h) expression at 72 h. Data are representative of three to six independent experiments