title: CD1a expression in psoriatic skin following treatment with propylthiouracil, an antithyroid thioureylene.
abstract: BACKGROUND
  The antithyroid thioureylenes, propylthiouracil (PTU) and methimazole (MMI), are effective in the treatment of patients with plaque psoriasis. The mechanism of action of the drugs in psoriasis is unknown. Since the drugs reduce circulating IL-12 levels in patients with Graves' hyperthyroidism, the effect of propylthiouracil on CD1a expression in psoriatic lesions was examined in biopsy samples of patients with plaque psoriasis. CD1a is a marker of differentiated skin antigen presenting cells (APC, Langerhans cells). Langerhans cells and skin monocyte/macrophages are the source of IL-12, a key cytokine involved in the events that lead to formation of the psoriatic plaque.
  
  
  METHODS
  Biopsy specimens were obtained from six patients with plaque psoriasis who were treated with 300 mg propylthiouracil (PTU) daily for three months. Clinical response to PTU as assessed by PASI scores, histological changes after treatment, and CD1a expression in lesional skin before and after treatment were studied.
  
  
  RESULTS
  Despite significant improvement in clinical and histological parameters the expression of CD1a staining cells in the epidermis did not decline with propylthiouracil treatment.
  
  
  CONCLUSIONS
  It appears that the beneficial effect of propylthiouracil in psoriasis is mediated by mechanisms other than by depletion of skin antigen-presenting cells.
authors.affiliation: Department of Medicine/Endocrinology, University of California, Irvine, USA. anelias@uci.edu
authors.forename: Alan N
authors.initials: AN
authors.lastname: Elias
authors.forename: Vandana S
authors.initials: VS
authors.lastname: Nanda
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Barr
mesh_terms: D000328:Adult; D018949:Antigens, CD1 / Q000187:drug effects* / Q000378:metabolism; D013956:Antithyroid Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001706:Biopsy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011441:Propylthiouracil / Q000494:pharmacology* / Q000627:therapeutic use; D011565:Psoriasis / Q000188:drug therapy* / Q000276:immunology
chemical_list: D018949:Antigens, CD1; D013956:Antithyroid Agents; C419393:CD1a antigen; D011441:Propylthiouracil