On the Immunological Nature of the Long Acting Thyroid Stimulator1

Abstract

A series of experiments is reported designed to test the hypothesis that the long acting thyroid stimulator (LATS) of Graves'' disease has antibody function. It was not possible to transfer LATS activity to new immunoglobulin G (IgG) molecules in a dialysis bath or bound to cellulose, thus supporting the idea that LATS is an Integral part of the IgG molecule. LATS was consistently removed from serum by a thyroid microsomal fraction and eluted from the microsomes under conditions appropriate for dissociation of antigen-antibody complexes. The eluted material contained a much larger quantity of LATS in proportion to its IgG content than the original serum. These findings were consistent with the hypothesis that LATS is an antibody. However, mixtures of LATS-containing serum and thyroid microsomes did not fix complement.