TISSUE DISTRIBUTION AND QUANTITATION OF A GENE EXPRESSING A 64-KDA ANTIGEN ASSOCIATED WITH THYROID-ASSOCIATED OPHTHALMOPATHY

We have developed a competitive reverse transcriptase-polymerase chain reaction (RT-PCR) assay for the quantitation of 1D mRNA, which encode s a 64-kDa protein associated with thyroid-associated ophthalmopathy, in preparations of total RNA from a variety of human tissues. This com petitive RT-PCR assay is based on coamplification of competing 1D cDNA internal control template (pGEM-1D') and target cDNA template. 1D-spe cific mRNA was quantified in 10 human tissues. The level of 1D transcr ipt expression in these tissues decreased in the following order: thyr oid (5 pg/mg total RNA) > eye muscle (3.2 pg/mg) > skeletal muscle (2. 4 pg/mg) > ovary (2 pg/mg) > cerebellum (0.4 pg/mg), kidney (0.33 pg/m g), pancreas (0.27 pg/mg), spleen (0.22 pg/mg), and thymus (0.19 pg/mu g) > retina (0.016 pg/mg). Graves' disease may be a multisystem autoi mmune disorder of the connective tissue and skeletal muscle (and thyro id) that is mainly localized in the orbit and skin. One mechanism for this localization may be increased expression of target autoantigens, of which the 64-bDa protein 1D is a candidate, in the involved tissues . The higher expression of the 1D molecule in thyroid and eye supports this hypothesis. (C) 1996 Academic Press, Inc.