SOLUBLE INTERLEUKIN-2 RECEPTOR IS A THYROID HORMONE-DEPENDENT EARLY-RESPONSE MARKER IN THE TREATMENT OF THYROTOXICOSIS

Thyrotoxic patients exhibit increased levels of immune activation mole cules (soluble interleukin-2 receptor [sIL-2R], intercellular adhesion molecule-1 [ICAM-1], and endothelial-leukocyte adhesion molecule-1 [E LAM-1]) in serum, although the clinical significance of these measurem ents remains unclear, In a randomized ii-week study, we have recently shown that in the treatment of hyperthyroidism, the combination of cho lestyramine and methimazole (MMI) resulted in faster lowering of serum thyroid-hormone levels than did MMI alone, Stored serial serum sample s from patients participating in this randomized treatment trial were analyzed for sIL-2R, soluble ICAM-1 (sICAM-1), and soluble ELAM-1 (sEL AM-1), The levels of all three molecules were elevated in patients wit h hyperthyroidism, Although the levels of sICAM-1 and sELAM-1 remained elevated through the 4-week follow-up period in both groups of patien ts, the sIL-2R levels (normal levels, 1.0 to 4.2 ng/ml) decreased sign ificantly in the 10 patients who received cholestyramine in addition t o MMI (week 0, 14.2 +/- 1.5 ng/ml; week 2, 10.8 +/- 1.2 ng/ml; week 4, 8.9 +/- 1.5 ng/ml). In eight patients who received MMI alone, sIL-2R decreased less rapidly (week 0, 12.3 +/- 1.4 ng/ml; week 2, 12.3 +/- 1 .3 ng/ml; week 4, 10.9 +/- 1.3 ng/ml), sICAM-1 and sELAM-1 were elevat ed at baseline but did not decrease during therapy, In the former grou p, free thyroxine and free triiodothyronine decreased faster, These da ta show that levels of sIL-2R in serum, but not those of sICAM-1 and s ELAM-1, mag be of clinical use in the early follow-up evaluation of me dically treated patients.