TY - JOUR
T1 - Identification of thyroid blocking antibodies and receptor epitopes in autoimmune hypothyroidism by affinity purification using synthetic TSH receptor peptides
AU - Bryant, William P.
AU - Bergert, Elizabeth R.
AU - Morris, John C.
N1 - Funding Information:
This research was supported by National Institutes of Health Grant DK 42008 and by the Mayo Foundation.
PY - 1995
Y1 - 1995
N2 - To examine the interaction of immunoglobulins from patients with newly diagnosed hypothyroidism with the TSH receptor (TSHr), we tested protein-A purified IgG in an ELISA assay with a series of peptides representing the entire extracellular domain (ECD) of human TSHr. Antibodies bound, on average, 4.1 peptides (range 0-16) per patient, and antibodies from 26 of 30 patients (86.6% demonstrated binding to at least one peptide. Six of the 20-mer peptides (61, 151, 181, 301, 361, 376) were most frequently recognized. These were used to construct affinity columns and separate IgGs from 10 patients into bound and unbound fractions. All fractions were tested for their ability to stimulate and inhibit cAMP generation in FRTL-5 cells. Inhibitory IgGs were purified from 9 patients (90% suggesting that the incidence of blocking antibodies (TBAb) in autoimmune hypothyroidism is higher than previously reported. 7 of 10 patients had antibodies that recognized peptide 361 further supporting the importance of this epitope in TBAb binding. Anti-microsomal and anti-thyroglobulin antibodies did not co-purify with inhibitory antibodies, and were always in the unbound fractions. We found no correlation between the pattern of antibody binding or bioactivity with clinical manifestations of hypothyroidism. Conclusions: (1) The majority of patients with autoimmune hypothyroidism have antibodies against the TSHr-ECD that recognized linear epitopes. Most have antibodies directed at more that one site and the pattern is quite heterogeneous. (2) Six sites (noted above) are most frequently recognized. (3) Inhibitory antibodies are distinct from anti-microsomal and anti-thyroglobulin antibodies.
AB - To examine the interaction of immunoglobulins from patients with newly diagnosed hypothyroidism with the TSH receptor (TSHr), we tested protein-A purified IgG in an ELISA assay with a series of peptides representing the entire extracellular domain (ECD) of human TSHr. Antibodies bound, on average, 4.1 peptides (range 0-16) per patient, and antibodies from 26 of 30 patients (86.6% demonstrated binding to at least one peptide. Six of the 20-mer peptides (61, 151, 181, 301, 361, 376) were most frequently recognized. These were used to construct affinity columns and separate IgGs from 10 patients into bound and unbound fractions. All fractions were tested for their ability to stimulate and inhibit cAMP generation in FRTL-5 cells. Inhibitory IgGs were purified from 9 patients (90% suggesting that the incidence of blocking antibodies (TBAb) in autoimmune hypothyroidism is higher than previously reported. 7 of 10 patients had antibodies that recognized peptide 361 further supporting the importance of this epitope in TBAb binding. Anti-microsomal and anti-thyroglobulin antibodies did not co-purify with inhibitory antibodies, and were always in the unbound fractions. We found no correlation between the pattern of antibody binding or bioactivity with clinical manifestations of hypothyroidism. Conclusions: (1) The majority of patients with autoimmune hypothyroidism have antibodies against the TSHr-ECD that recognized linear epitopes. Most have antibodies directed at more that one site and the pattern is quite heterogeneous. (2) Six sites (noted above) are most frequently recognized. (3) Inhibitory antibodies are distinct from anti-microsomal and anti-thyroglobulin antibodies.
KW - Autoantibodies
KW - Autoimmune hypothyroidism
KW - TSH receptor
KW - Thyroid blocking antibodies
KW - Thyroid stimulating antibodies
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U2 - 10.3109/08916939508995302
DO - 10.3109/08916939508995302
M3 - Article
C2 - 8722576
AN - SCOPUS:0029549668
SN - 0891-6934
VL - 22
SP - 69
EP - 79
JO - Autoimmunity
JF - Autoimmunity
IS - 2
ER -