Detection of thyroid-stimulating antibodies in thyroid diseases, employing rat thyroid fragment perifusion.

The technique of perifusing rat thyroid fragments was used to investigate the presence of thyroid-stimulating antibodies (TSAb) in the sera of 48 patients. Response to IgG was measured by determining the mean rate of release of T4 (R) during a 30-min perifusion and the secretion peak (Imax) by means of samples taken every 5 min. Values found to be above the mean + 2 SD of the control values of R or Imax were considered to be positive. TSAb were found in all the 17 patients with untreated Graves' disease (GD) and in the 2 treated with antithyroid drugs, but not in the 3 who had undergone surgery or 131I treatment or in the 2 on corticosteroid treatment. TSAb were also found in 2 out of 3 patients with untreated nodular toxic goiter (UNTG) and in 6 out of 8 with diffuse nontoxic goiter (DNG) but at lower levels. In the untreated GD group, R and Imax correlated significantly with the corresponding IgG concentrations (from 90 to 800 micrograms/ml), suggesting TSAb activity which can be compared from one patient to another. TSAb activity did not correlate with thyroid function tests in any group. In all the groups it induced an early secretion peak followed by a decreasing response throughout the stimulation period, as was previously found with 65 mIU/ml TSH. The specificity of this technique was verified by five different control methods: the perifusion technique was checked by using KRBG buffer alone; sera were studied from a group of healthy controls.(ABSTRACT TRUNCATED AT 250 WORDS)