Inhibition of endogenous 5-HT synthesis impairs T-cell proliferation ex vivo. Splenic CD3+ T cells were negatively enriched from C57BL/6 mice pretreated with PCPA or saline. (A) Basal 5-HT released from naive T cells isolated from saline- (□) or PCPA-treated mice (▪) after overnight culture with IL-2 (10 IU/mL). Dashed line indicates background 5-HT resulting from complete media alone. Data are mean ± 1 SD from triplicate results (n = 2, *P < .01). (B) T cells from saline- or PCPA-treated mice were incubated for 48 hours with plate-bound anti-CD3 mAb (5 μg/mL). Data are the mean proliferation ± 1 SE from 6 independent assays, performed in triplicate (*P < .05). (C) T-cell proliferation in the presence of exogenous 5-HT (1 μM) or the 5-HT7 receptor agonist, AS19 (1 μM). Data are mean ± 1 SD from 1 representative experiment (n = 3) performed in triplicate (*P < .05).
