Thyroid microsomal antigen in Graves' thyroid is not different from that in normal thyroid.
Differences from normal in microsomal antigen (M-Ag) may be involved in the development of autoimmune thyroid disease. We compared the M-Ag in Graves' thyroid immunologically and biochemically to that in normal thyroid. The concentration of M-Ag, measured with an enzyme-linked immunosorbent assay, was significantly greater in the Graves' microsomes than in normal microsomes. Binding of a patient's microsomal antibody to Graves' microsomes was completely inhibited when the serum was first incubated with normal thyroid microsomes. Sodium dodecylsulfate-polyacrylamide gel electrophoresis and Western blotting were done with a monoclonal antibody to denatured M-Ag. In both Graves' and normal thyroids, M-Ag existed as 107-, 101-, and 95-kDa peptides. After incubation with V8 protease, the residual antigenic peptide had a molecular weight of less than 60,000 and after incubation with trypsin, 95- and 87-kDa peptides and several smaller antigenic peptides were found. There were no significant differences in the pattern of normal and Graves' microsomes after digestion. Two-dimensional gel electrophoresis of Graves' microsomes showed that the isoelectric point for the 107-kDa peptide was at pH 7.2; that for the 101-kDa peptide was at pH 6.2, and that for the 95-kDa peptide was at 6.5. These values were not different from those observed for normal microsomes. These results indicate that M-Ag in Graves' thyroid does not differ from that in normal thyroid, and that microsomal antibodies in autoimmune thyroid disease probably do no arise from differences in the antigen.
Hamada
N
N
Thyroid Study Unit, Sumire Hospital, Osaka Social Welfare Foundation, Japan.
Degroot
L J
LJ
Portmann
L
L
Yamakawa
J
J
Noh
J
J
Okamoto
Y
Y
Ohno
M
M
Ito
K
K
Morii
H
H
D001324:Autoantigens / Q000737:chemistry* / Q000187:drug effects / Q000276:immunology; D015153:Blotting, Western; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006111:Graves Disease / Q000276:immunology*; D006801:Humans; D007453:Iodide Peroxidase; D033862:Iron-Binding Proteins; D007526:Isoelectric Point; D008861:Microsomes / Q000276:immunology; D013961:Thyroid Gland / Q000276:immunology*; D014357:Trypsin / Q000494:pharmacology
D001324:Autoantigens; D033862:Iron-Binding Proteins; C056658:TPO protein, human; D007453:Iodide Peroxidase; D014357:Trypsin