Adenosine receptor expression of human PDCs. Messenger RNA was extracted from highly purified PDCs (purity more than 96%) immediately after isolation or after overnight culture in the presence of IL-3 and CD40L. Profiles of A₁, A_2a, A_2b, and A₃ receptor expression were generated by RT-PCR. In addition to the expected 278 bp product for the A₁ receptor, a second transcript of 483 bp was amplified (arrows), which contained the expected A₁ receptor sequence with a 205 bp insert belonging to the intron between exons 5 and 6. One representative experiment of 6 is shown.