Relationship between exophthalmogenic and thyroid-stimulating immunoglobulins in Graves' endocrine ophthalmopathy

The effects of globulins from patients with Graves' infiltrative retrobulbar ophthalmopathy on the TSH binding inhibitory (TBIA) and stimulatory (TBSA) activities was examined utilising human thyroid Harderian gland (guinea-pig) plasma membranes in the TSh receptor assay. The changes of inhibitory and stimulatory activities of these globulins were observed following the preliminary incubation with human thyroid and Harderian gland plasma membranes. According to our data the TSh binding inhibitory activity of the globulins cases after saturating the samples with both thyroid and Harderian cell membranes. Whereas, their TSH-binding stimulatory activity ceases only after incubation with Harderian membrane. The TBSA of the samples after incubation with thyroid membrane increases significantly as compared to the values before incubation. We presume that the effects of the thyroid stimulating IgG (TSI) and the exophthalmogenic IgG (O-IgG) on the retrobulbar tissue are contradictory. It seems so the O-IgG is in some circumstances inhibited by TSI. Their TSH-binding inhibitory and stimulatory activities may depend on their quantitative ratio.