Human macrophages express tyrosine hydroxylase and aromatic amino acid decarboxylase. Quantitative RT-PCR (A) detected mRNA for tyrosine hydroxylase (TH) and aromatic amino acid decarboxylase (AADC) in monocyte derived macrophages (MDM) isolated from four different donors. Representative amplification curves from a single donor (A) are shown for TH, AADC (red curves) and the housekeeping gene β-actin (red curves). Amplification curves for the positive control (Total Human brain RNA, blue curves) and the negative control (cDNA negative samples, green curves) are also shown (A). Western blot analysis of MDM lysate from donors 1, 2, 3 and 4) (B) showed expression of TH (approximately 62 kDA) and AADC (approximately 50 kDA) in all donors examined.