DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.48120#0076
58 Molecular and Cell Biology of Autoantibodies and Autoimmunity
Characterisation of an Autoantigen in Graves’ Hyperthyroidism
A. F. Mulcahy and A. G. Diamond
Medical Molecular Biology Group, Medical School, University of Newcastle-Upon-Tyne,
Framlington Place, Newcastle-Upon-Tyne, NE2 4HH, UK
Graves’ Hyperthyroidism is an autoimmune condition in which antibodies
are produced against several thyroid components. At least three autoantigens have
been described in human thyroid; thyroid stimulating hormone receptor (TSH-R),
thyroglobulin (Tg) and thyroid peroxidase (TPO). Of these, only the Tg and TPO
autoantigens have been well characterised.
To further identify autoantigens involved in Graves’ Hyperthyroidism a
cDNA library was constructed in the Ag/77 vector from thyroid polyA+ RNA
from a Graves’ Hyperthyroidism patient who had not received anti-thyroid
drugs prior to surgery. The cDNA library was screened with a serum from a dif-
ferent Graves’ patient. One strongly positive clone, TM17.1, from this screening
has been studied further. TM17.1 has been tested for reactivity with a limited
number of sera and was found to be positive with other Graves’ sera, but
negative with two Hashimoto’s sera and control sera. The clone contains a
3.7 kb cDNA insert with a single internal EcoR 1 site producing fragments of 3 kb
and 0.7 kb. Northern blot analysis of thyroid RNA showed that both fragments
identify RNA approximately 3.7 kb in length, consistent with the clone containing
a single cDNA species of, or near, full length. This RNA was not present in B
lymphoblastoid cell lines. Southern blot analysis of human genomic DNA using
the 3 kb and 0.7 kb EcoR 1 fragments produced few bands, implying that the
clone was a product of a single gene or a low copy number family. The 0.7 kb frag-
ment has been sequenced and shows no significant homology with entries in the
Genbank database (Release 55). Therefore, TM17.1 is neither of the known
thyroid-specific antigens (Tg, TPO). It shows no homology with the recently de-
scribed 70 kDa autoantigen with TSH-binding properties (Chan et al., J. Biol.
Chem. 264:3651, 1989) nor a second autoantigen encoding a protein related to the
mitochondrial solute carrier protein (L. D. Kohn; personal communication).
Further work is in progress on the extent of antibody reactivity in patient
groups and the tissue distribution of the antigen, the complete sequence deter-
mination and whether T-lymphocyte reactivity to the protein can be detected in
this disease.
Characterisation of an Autoantigen in Graves’ Hyperthyroidism
A. F. Mulcahy and A. G. Diamond
Medical Molecular Biology Group, Medical School, University of Newcastle-Upon-Tyne,
Framlington Place, Newcastle-Upon-Tyne, NE2 4HH, UK
Graves’ Hyperthyroidism is an autoimmune condition in which antibodies
are produced against several thyroid components. At least three autoantigens have
been described in human thyroid; thyroid stimulating hormone receptor (TSH-R),
thyroglobulin (Tg) and thyroid peroxidase (TPO). Of these, only the Tg and TPO
autoantigens have been well characterised.
To further identify autoantigens involved in Graves’ Hyperthyroidism a
cDNA library was constructed in the Ag/77 vector from thyroid polyA+ RNA
from a Graves’ Hyperthyroidism patient who had not received anti-thyroid
drugs prior to surgery. The cDNA library was screened with a serum from a dif-
ferent Graves’ patient. One strongly positive clone, TM17.1, from this screening
has been studied further. TM17.1 has been tested for reactivity with a limited
number of sera and was found to be positive with other Graves’ sera, but
negative with two Hashimoto’s sera and control sera. The clone contains a
3.7 kb cDNA insert with a single internal EcoR 1 site producing fragments of 3 kb
and 0.7 kb. Northern blot analysis of thyroid RNA showed that both fragments
identify RNA approximately 3.7 kb in length, consistent with the clone containing
a single cDNA species of, or near, full length. This RNA was not present in B
lymphoblastoid cell lines. Southern blot analysis of human genomic DNA using
the 3 kb and 0.7 kb EcoR 1 fragments produced few bands, implying that the
clone was a product of a single gene or a low copy number family. The 0.7 kb frag-
ment has been sequenced and shows no significant homology with entries in the
Genbank database (Release 55). Therefore, TM17.1 is neither of the known
thyroid-specific antigens (Tg, TPO). It shows no homology with the recently de-
scribed 70 kDa autoantigen with TSH-binding properties (Chan et al., J. Biol.
Chem. 264:3651, 1989) nor a second autoantigen encoding a protein related to the
mitochondrial solute carrier protein (L. D. Kohn; personal communication).
Further work is in progress on the extent of antibody reactivity in patient
groups and the tissue distribution of the antigen, the complete sequence deter-
mination and whether T-lymphocyte reactivity to the protein can be detected in
this disease.