Fig. 4.

Capacity for producing proinflammatory cytokines of serotonin (5-hydroxytryptamine, 5-HT)-treated dendritic cells (DC). (a,b) Monocytes were cultured with (closed square) or without 5-HT (open square) in addition to interleukin (IL)-4 and granulocyte–macrophage colony-stimulating factor (GM-CSF) for 6 days. Alternatively, monocytes were cultured in the presence of M-CSF alone for 6 days (hatched square). After washing, the cells (1 × 10⁶/ml) were stimulated with 100 ng/ml lipopolysaccharide (LPS) for 24 h. The cytokine concentrations of the culture supernatants were estimated by enzyme-linked immunosorbent assay (ELISA). The data are the means ± s.e.m. of four independent experiments with different donors.