The formation of thyrotropin receptor (TSHR) antibodies in a Graves' animal model requires the N-terminal segment of the TSHR extracellular domain.
Immunization of AKR/N mice with murine fibroblasts, transfected with the TSH receptor (TSHR) and a murine major histocompatibility complex class II molecule having the same H-2k haplotype (but not either alone), induces immune thyroid disease with the humoral and histological features of human Graves', including the presence of two different TSHR antibodies (TSHRAbs): stimulating TSHRAbs, which cause hyperthyroidism; and TSH-binding-inhibiting immunoglobulins. The primary functional epitope for both types of antibodies in Graves' patients is on the N-terminal portion of the extracellular domain of the TSHR, residues 25 to 165; most require residues 90-165 to express TSHRAb activity, as evidenced in studies using chimeras of the TSHR and lutropin-choriogonadotropin receptor (LH-CGR). To evaluate the role of this region of the TSHR in the formation of Graves' TSHRAbs, we immunized AKR/N mice with fibroblasts transfected with three human TSHR chimeras with residues 9-165 (Mc1+2), 90-165 (Mc2), or 261-370 (Mc4) substituted by equivalent residues of the rat LH-CGR. Mice immunized with the Mc1+2 and Mc2 chimeras, with the N-terminal portion of the extracellular domain of the TSHR substituted by LH-CGR residues, did not develop TSHRAbs. Mice immunized with the Mc4 chimera, having a major portion of the C-terminal portion of the extracellular domain of the TSHR replaced by comparable LH-CGR residues, can develop TSHRAbs. The results suggest that the N-terminal segment of the TSHR extracellular domain is not only a critical functional epitope for Graves' TSHRAbs, but it is important also in their formation in a mouse model of Graves' disease.
Kikuoka
S
S
Department of Pediatrics, Chiba University School of Medicine, Japan.
Shimojo
N
N
Yamaguchi
K I
KI
Watanabe
Y
Y
Hoshioka
A
A
Hirai
A
A
Saito
Y
Y
Tahara
K
K
Kohn
L D
LD
Maruyama
N
N
Kohno
Y
Y
Niimi
H
H
D000818:Animals; D001323:Autoantibodies / Q000096:biosynthesis*; D001324:Autoantigens / Q000276:immunology; D004195:Disease Models, Animal; D006111:Graves Disease / Q000276:immunology*; D006183:H-2 Antigens / Q000032:analysis; D007114:Immunization; D007739:L Cells; D051379:Mice; D008806:Mice, Inbred AKR; D010446:Peptide Fragments / Q000276:immunology*; D051381:Rats; D011974:Receptors, LH / Q000235:genetics / Q000276:immunology; D011989:Receptors, Thyrotropin / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology; D014162:Transfection
D001323:Autoantibodies; D001324:Autoantigens; D006183:H-2 Antigens; D010446:Peptide Fragments; D011974:Receptors, LH; D011989:Receptors, Thyrotropin; D011993:Recombinant Fusion Proteins