TRANSCRIPTION OF THYROID AUTOANTIGENS IN NON-EXPRESSING TISSUES

Reverse transcriptase- polymerase chain reaction (RT-PCR) enhances the probability of detecting rare transcripts in complex mixtures of mRNA . Using thyroid autoantigens and the controversy about the role of the TSH-receptor (TSH-R) in thyroid-associated ophthalmopathy as an examp le, this study demonstrates the problems of interpreting RT-PCR result s in typically non-expressing tissues resulting from the extremely hig h sensitivity of the method. Unexpected transcripts for thyroperoxidas e, thyroglobulin, TSH-R (exon 1-4. 354 bp), FSH-receptor, or insulin f ragments were demonstrated in a number of thyroid or orbit-derived as well as unrelated tissues or cell types. Unexpected transcripts were m ost prevalent in fibroblasts, irrespective of the tissue of origin and most likely caused by ectopic transcription. To establish a physiolog ical significance of rare transcripts such as the TSH-R in orbital tis sues, demonstration of the protein in addition to the positive RT-PCR results is needed.