Serum ICAM‐1 concentrations in patients with psoriasis treated with antithyroid thioureylenes

Summary Serum concentrations of intercellular adhesion molecule-1 (ICAM-1), a marker of early T-cell activation were measured in 14 patients with stable plaque psoriasis who received treatment for 8 weeks with the antithyroid thioureylenes, propylthiouracil (PTU) or methimazole (MMI) which have been previously shown to produce significant improvement in such patients. Baseline serum concentrations of ICAM-1 were significantly higher in the patients with psoriasis compared with normal control volunteers. Following therapy with either PTU (300 mg daily) or MMI (40 mg daily) serum ICAM-1 concentrations did not decline significantly. Since ICAM-1 expression on vascular endothelium increases in active psoriasis, and is postulated to promote T-cell migration to and retention at these sites, it is hypothesized that the beneficial therapeutic effects of thioureylenes in psoriasis occur distal to the events that lead to lymphocyte migration to vascular structures in the dermis.