The hOCT1 mRNA expression was measured in PB LEU (n 5 66), PB PMNC (n 5 35), and PB MNC (n 5 33) from 66 healthy volunteers. Figure  1 summarizes these results and clearly shows a wide range of hOCT1 mRNA expression in total LEU as well as in PMNC and MNC. The hOCT1 mRNA expression was significantly higher in PMNC compared to MNC. Therefore, the total LEU hOCT1 mRNA expression was preferentially determined by the percentage of PMNC in the total LEU.