EFFECT OF PROPYLTHIOURACIL AND METHIMAZOLE ON SERUM LEVELS OF INTERLEUKIN-2 RECEPTORS IN PATIENTS WITH PSORIASIS

Background. We have previously reported clinical improvement in patien ts with psoriasis who received orally administered antithyroid thioure ylenes, propylthiouracil (PTU), and methimazole (MMI). The antithyroid drugs are believed to exert immunomodulatory effects based on the res ults of studies in patients with Graves' disease, the only disease in which they are clinically used. The potential of these drugs to mediat e clinical improvement in patients with psoriasis by reducing expressi on of the interleukin-2 receptor (IL2R), a marker of early T and B cel l activation, was addressed in the present study. Methods. Baseline se rum concentrations Of IL2R were measured by an enzyme-linked immunosor bant assay (ELISA) in 15 patients with stable plaque psoriasis and in the same patients after 8 weeks of oral therapy with either 300 mg of propylthiouracil (n=7) or 40 mg methimazole (n=8) given daily. Baselin e values were compared with normal controls. Results. Serum IL2R conce ntrations in the psoriatic patients were significantly higher than in normal controls. After treatment with PTU or MMI, IL2R serum concentra tions were not significantly reduced either in the group as a whole or separately in the PTU and MMI treated patients. Conclusions. Since el evated serum concentrations Of IL2R often reflect T and B cell activat ion, and elevated IL2R serum levels are seen in several autoimmune dis eases, it is speculated that the beneficial effect of thioureylenes in patients with psoriasis is mediated by some mechanism(s) other than r eduction Of IL2R expression in activated lymphocytes.