Studies on the antigenicity of human thyroglobulin.

Human iodothyronine-binding auto-antisera were used to define a thyroxyl containing antigenic site on thyroglobulin. The peptide sequences flanking the thyroxyl residue are important antigenic determinants of this region and only one such thyroxyl seems to be exposed on the thyroglobulin molecule. Apparent specificity for binding of free thyroxine or triiodothyronine by these auto-antibodies does not necessarily imply the presence of either one or the other in the immunogen.