Expression of 5-HTR by naive and activated T cells. T cells were negatively purified and activated with Con A or PMA plus ionomycin, and gene expression for 5-HTR subtype was examined by RT-PCR. (A) Primers for the type 1 and type 7 5-HTR families amplify a region with 1 exon; thus, both cDNA and RT-negative (RNA) samples are shown. (B) Gene expression of the 5-HT_2-6 receptor subfamilies. Comparable quantities of cDNA were ensured by amplification of GAPDH. Data are representative of 3 independent experiments.