Clinical Experience with a Human Thyroid Cell Bioassary for Thyroid-Stimulating Immunoglobin *

Abstract

A sensitive, specific, and practical bioassay for thyroid-stimulating immunoglobulin (TSI) is now available for clinical use. Fifty-seven of 61 patients with untreated hyperthyroid Graves' disease were TSI positive (sensitivity, 93%). TSI was undetectable in all normal subjects and in patients with Hashimoto's thyroiditis (without concurrent Graves' ophthalmopathy), nontoxic goiter, and toxic nodular goiter (specificity, 100%). The prevalence of TSI in serum declined after therapy, particularly during methimazole or propylthiouracil treatment. TSI correlated well with relapse or remission after antithyroid drug therapy. All 12 patients who were TSI negative at the time of discontinuing antithyroid drug therapy remained in remission (average follow-up of 10 months). TSI values in Graves' disease correlated better with thyroid dysfunction than with ophthalmopathy. Prenatal TSI activity tended to be higher in mothers of infants who developed neonatal Graves' disease than in at-risk mothers who delivered normal infants. However, there was considerable overlap between the two groups.

Studies on Auto-Anti-idiotypic Thyroid-Stimulating Antibodies

“…The human thyroid cell bioassay was performed in hypot onic buffer (HB) (5.4 mM KCI, 0.44 m M K H ,P04, 0.34 m M Na;HPOj, 1.3 m CaCL, 0.5 mM M gS04, and I % glucose, pH 7.4) as described previously (15). Crude rabbit IgG preparations were pre pared by precipitation of globulins at 33% saturation of ammo nium sulfate.…”

Studies on multiple thyroid cell membrane-directed antibodies in Graves' disease.

“…The procedure for human thyroid cells followed in detail that described by Dr. B. Rapoport et al (10), to whom we are grateful for advice regarding the preparation of cells. The cells were obtained from one Graves' disease thyroid weighing 240 g and were used for TBI and TSAb assays as follows.…”

Thyroid Hormone Excess: Graves’ Disease

“…In vitro bioassays are based on the ability of patients serum to stimulate adenylate cyclase and produce cAMP from cultured hamster ovary cells transfected with human TSHR (CHO-R), 23 or rat thyroid cell strain (FRTL-5) 24 or human thyroid follicular cells 25 are used as a source for functional TSHR. CHO-R system is slightly more sensitive, and requires an easier culture condition than other systems.…”