Concentration of Long-Acting Thyroid Stimulator (LATS) by Subfractionation of γG Globulin from Graves' Disease Serum1

Abstract

The concentration of long-acting thyroid stimulator (LATS) present in the serum of patients with Graves' disease was increased 30–37 times over that of the original sera, by means of column chromatography. More than half the original LATS activity appeared in the first fraction obtained when serum was passed, initially, through a DEAE-Sephadex column. The protein contained therein was identified by immunoelectrophoresis as γG;, globulin. Biological activity of this material was specifically neutralized by anti-γG globulin serum and not by anti-γA or anti-γM serum. Further purification was achieved by passage through a carboxymethyl cellulose (CMC) column with a recovery in all fractions of 50% of the starting LATS activity. The bulk of the LATS activity, however, was concentrated in the slower-eluting fractions. Approximately half the total LATS activity in all the fractions (10% of the original serum activity) appeared in one of the slower-eluting fractions (C V). These slower-eluting fractions on immunoelectrophoresis, although forming a single γG precipitin are with anti-γG serum like the other fractions, were found to occupy a more cathodal position on the are than the fastereluting fractions.