THE THYROID CYTOTOXIC AUTOANTIBODY

Abstract

The thyroid cytotoxic autoantibody was found to be a 7S gamma globulin which required complement for lysis of human thyroid cells in culture. The evidence presented indicates that the autoantibody is the same as, or closely similar to, that which fixes complement with the microsomal antigen obtained from toxic human thyroid glands. It was shown to localize on the cytoplasm of unfixed sections of thyroid epithelium using Coons'' fluorescent antibody technique. The autoantibody apparently reacts in vitro with antigen present in the cell membrane. The antigen is lost from the cells within 2 or 3 days in culture. The clinical incidence was parallel to the incidence of microsomal complement fixing antibody. Only one of 15 mothers of cretins had cytotoxic autoantibody, in lowest titer. There was a high incidence in relatives of propositi with thyroid disease.