METHIMAZOLE HAS NO DOSE-RELATED EFFECT ON THE SERUM CONCENTRATIONS OFSOLUBLE CLASS-I MAJOR HISTOCOMPATIBILITY COMPLEX ANTIGENS, SOLUBLE INTERLEUKIN-2 RECEPTOR, AND BETA(2)-MICROGLOBULIN IN PATIENTS WITH GRAVES-DISEASE

Soluble class I major histocompatibility antigens (sHLA), beta(2)-micr oglobulin (beta(2)-M), and soluble interleukin-2 receptor (sIL-2R), ar e secreted by B and T lymphocytes upon activation, and have been used as markers of immune activation in several diseases. Thirty-two Graves ' disease patients were randomly assigned to three methimazole (MMI) r egimens of treatment: (1) low-dose, starting with 45 mg/day, and lower ing the dose thereafter to maintain normal serum thyroid hormones; (2) MMI 160 mg/day + levothyroxine, and (3) MMI 30 mg/day + levothyroxine . Serum sHLA, beta(2)-M, sLL-2R, TSH receptor antibodies (TSH-R Ab), T -3, and free T-4 (fT(4)) were measured at diagnosis and at weeks 4, 12 , and 24 (end of treatment). Patients were followed-up after treatment for at least 24 weeks (24 to 89). At diagnosis, serum levels of sIL-2 R, beta(2)-M, sHLA, and TSH-R Ab were elevated. Serum sIL-2R, beta 2-M , sHLA, and TSH-R Ab decreased with treatment. No effect of the varyin g MMI regimens on these parameters was observed. Soluble IL-2R correla ted positively with T-3, fT(4), beta(2)-M, sHLA, and TSH-R Ab. Statist ically significant, but weak, correlations (r < 0.35) were observed be tween beta(2)-M, sHLA, and TSH-R Ab, between beta(2)-M, T-3, and fT(4) , and between TSH-R Ab and T-3. Recurrence rates were not associated e ither with the MMI regimen or any of the parameters studied, with the exception of elevated initial TSH-R Ab levels. Serum sHLA, beta(2)-M, and sIL-2R are increased in untreated Graves' disease, and decrease du ring treatment. No MMI dose-related differences were observed in these parameters, and in the recurrence rate. Unfortunately, sHLA, beta 2(M ), and sIL-2R were not useful predictors of prolonged remission after MMI treatment.