Enhancement of the activity of thyroid-stimulating antibodies by anti-human IgG antibodies in vitro.
In an attempt to determine whether or not anti-human IgG antibodies could influence the activity of thyroid-stimulating antibodies (TSAb), we investigated the effects of anti-human Fc antibody (anti-Fc antibody) and IgG from rheumatoid arthritis patients (RA-IgG) on TSAb activity using FRTL-5 cells. It was found that these anti-human IgG antibodies enhanced the TSAb activity in vitro. FRTL-5 cells were first incubated with Graves' disease IgG for 30 min at 37 degrees C, then washed and incubated in Hanks' balanced salt solution with anti-human IgG antibodies for 60 min at 4 degrees C, and then for a further 120 min at 37 degrees C. The level of cAMP accumulated in the medium was determined by RIA. Anti-Fc antibody significantly augmented the cAMP formation stimulated by 16 out of 24 Graves' IgGs, whereas anti-F(ab')2 antibody did not potentiate cAMP accumulation. Three of five RA-IgGs, which are usually defined as specific antibodies for the Fc fragment of human IgG, mimicked these stimulatory effects. Protein A also potentiated the cAMP formation stimulated by Graves' IgGs. Furthermore, there was a significant correlation between the TSAb titres of these Graves' IgGs and the potentiating effects of anti-Fc antibody (r = 0.495, P less than 0.05, n = 21). These results suggest that the interaction of TSH receptor antibody with anti-human IgG antibodies might modulate thyroid function in Graves' disease.
Saito
T
T
Third Department of Internal Medicine, University of Yamanashi Medical School, Japan.
Shimura
H
H
Endo
T
T
Onaya
T
T
D000888:Antibodies, Anti-Idiotypic / Q000494:pharmacology*; D001172:Arthritis, Rheumatoid / Q000276:immunology; D001323:Autoantibodies / Q000378:metabolism*; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006111:Graves Disease / Q000276:immunology; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D018828:Immunoglobulins, Thyroid-Stimulating; D066298:In Vitro Techniques; D013205:Staphylococcal Protein A / Q000494:pharmacology
D000888:Antibodies, Anti-Idiotypic; D001323:Autoantibodies; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D018828:Immunoglobulins, Thyroid-Stimulating; D013205:Staphylococcal Protein A; D000242:Cyclic AMP