Background: We have previously reported clinical improvement in patients with psoriasis who received orally administered antithyroid thioureylenes, propylthiouracil (PTU), and methimazole (MMI). The antithyroid drugs are believed to exert immunomodulatory effects based on the results of studies in patients with Graves' disease, the only disease in which they are clinically used. The potential of these drugs to mediate clinical improvement in patients with psoriasis by reducing expression of the interleukin-2 receptor (IL2R), a marker of early T and B cell activation, was addressed in the present study.
Methods: Baseline serum concentrations of IL2R were measured by an enzyme-linked immunosorbant 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. Baseline values were compared with normal controls.
Results: Serum IL2R concentrations in the psoriatic patients were significantly higher than in normal controls. After treatment with PTU or MMI, IL2R serum concentrations were not significantly reduced either in the group as a whole or separately in the PTU and MMI treated patients.
Conclusions: Since elevated serum concentrations of IL2R often reflect T and B cell activation, and elevated IL2R serum levels are seen in several autoimmune diseases, it is speculated that the beneficial effect of thioureylenes in patients with psoriasis is mediated by some mechanism(s) other than reduction of IL2R expression in activated lymphocytes.