Immunological studies on LATS-immunoglobulin by the reaction with staphylococcal protein A.

Abstract

The reaction of LATS [long acting thyroid stimulator] [human] activity with staphylococcal protein A, a protein binding with the Fc part of human IgG(1) [immunoglobulin G(1)], IgG(2) and IgG(4), was examined. When IgG(1), IgG(2) and IgG(4) subclasses were removed from LATS positive sera or LATS-IgG fractions by affinity chromatography on protein A-Sepharose, LATS activity decreased. Almost all LATS activity was found in the fraction that reacted with Protein A. LATS probably expresses a very distinct IgG G structure; LATS activity is apparently mainly distributed in the fraction containing IgG(1), IgG(2) and IgG(4) in LATS positive serum.