“…It has lost almost all its thyroid stimulating activity while retaining the ability to stimulate retroorbital tissues. EPS can compete with TSH for receptor sites in these tissues and if ophthalmogenic immunoglobulins (0-Ig) are added this enhances the attachment of EPS (Bolonkin et al 1975). Winand & Kohn are of the opinion that 0-Igs are antibodies which react both with EPS and part of the TSH receptor.…”