THYROID-STIMULATING ANTIBODY (TSAB) DETECTED IN SERA OF GRAVES PATIENTS USING HUMAN THYROID CELL-CULTURES

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 40  (3) , 532-539
Abstract
As a homologous system is required to evaluate the effect of thyroid-stimulating antibody (TSAb) present in the serum of Graves'' patients, primary cultures obtained from normal human thyroid gland were used and the stimulatory effect measured as an increase of c[cyclic]AMP intracellular levels. Monolayer cell cultures were stimulated by Ig[immunoglobulin]G purified from sera of Graves'' patients or control subjects and compared to the effect of bovine TSH [thyroid-stimulating hormone]. Bovine TSH produced a dose-dependent increase in cAMP intracellular levels between 0.05 mU [milliunits] and 2.5 mU/ml, reaching a maximal value after 30 min with higher doses. While normal IgG had no effect, IgG prepared from untreated patients with frank Graves'' disease elicited a significant increase in cAMP accumulation at a concentration between 0.05 and 0.5 mg/ml within 60 min in 13 of 14 patients. A longer incubation period showed no further increase in cAMP values, even if in 1 case a higher concentration (5.0 mg/ml) of Graves'' IgG had a delayed response. When the cAMP intracellular level modifications produced by Graves'' IgG preparations in thyroid cell cultures were compared to those evoked in thyroid slices, an identical percentage (93%) of positive cases was obtained, without a coincidence of negative cases. Using thyroid slices the cAMP intracellular increase above basal levels was higher, if considered as a percentage, but in cultured cells a very low IgG concentration was sufficient to detect the presence of TSAb. No correlation between the 2 assays was found. Normal human cultured thyroid cells appeared a more suitable substrate when compared to human thyroid slices for detecting the presence of TSAb in Graves'' disease and for studying its effect on thyroid cells. A 100% TSAb positivity was present in these Graves'' patient series only when both assays were used.