Expression and developmental regulation of the 5-HT transporter and MAO in mouse DCs. (A) CD11c⁺ CD86^- (immature DCs) or CD11c⁺ CD86⁺ (mature DCs) were purified by cell sorting from BMDC cultures or spleen cells. BMDCs were activated by overnight exposure to LPS (50 ng/mL) prior to sorting CD11c⁺ CD86⁺ (activated DCs). Gene expression for SERT, TPH-1 and TPH-2, MAO-A, and MAO-B was examined by RT-PCR. (B) Density gradient-enriched day 5 BMDCs were immunolabeled and analyzed by confocal microscopy. CD11c (mouse DC marker) and SERT were visualized with antibodies labeled with Alexa Fluor 488 (green; i) and Alexa Fluor 546 (red; ii), respectively. Nuclei were counterstained with TO-PRO-3 (blue). In the red, green, and blue overlay (iii), the yellow signal indicates regions of red/green overlap. The bright-field image (iv) includes a CD11c and SERT double-negative cell with lymphocytic morphology (arrowhead). Scale bar represents 10 μm. Data are representative of 2 independent experiments.