Thyrotrophin blocking antibodies in the sera of mothers with congenitally hypothyroid infants.
We examined IgG from 15 mothers of infants with congenital hypothyroidism for their ability to block TSH-stimulated iodine organification in vitro. Only one out of 15 of these IgGs exhibited TSH-blocking activity. This IgG could inhibit TSH action by 30-50%. It could not block radiolabelled TSH from binding to its receptor but did inhibit dibutyryl cyclic AMP stimulation of iodine organification implying a unique effect on post-receptor processes via a membrane binding site distant from the TSH binding site. Interestingly there was no evidence of autoimmune thyroid disease in the mother. These results suggest that the transplacental passage of TSH-blocking antibodies plays little, if any, role in the development of congenital hypothyroidism.
D000906:Antibodies / Q000502:physiology*; D001667:Binding, Competitive; D003409:Congenital Hypothyroidism; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000276:immunology*
D000906:Antibodies; D013972:Thyrotropin