Expression of thyroid-related genes in human thymus

Thyroid. 1999 Feb;9(2):133-41. doi: 10.1089/thy.1999.9.133.


There are several thyroid antigens including human sodium iodide symporter (hNIS), thyrotropin receptor (TSH-R), thyroid peroxidase (TPO), and thyroglobulin (Tg) that have been considered to be thyroid-specific proteins involved in the pathogenesis of autoimmune thyroid diseases. We examined the expression of these thyroid-tolerance related genes in normal human thymus, the lymphoid organ responsible for the induction of central T-cell self. Reverse transcription-polymerase chain reaction (RT-PCR) amplifications were performed with 4 pairs of oligonucleotide primers specific for the hNIS, TSH-R, TPO, and Tg genes, respectively. Gene-specific transcripts were confirmed by Southern hybridization using digoxigenin-labeled internal oligonucleotide probes. To monitor cDNA integrity and quantity, all samples were coamplified with a pair of intron-spanning human beta-actin-specific oligonucleotide primers. Furthermore, using a highly sensitive immunostaining technique and antibodies specific for these 4 antigens, we examined whether NIS-, TSH-R-, TPO-, and Tg-specific immunoreactivity can be detected and localized in normal human thymus. RT-PCR and Southern hybridization revealed expression of each of these 4 thyroid-related genes in normal human thymus. In addition, immunohistochemical analysis of frozen tissue sections derived from normal human thymus showed marked immunoreactivity for NIS, TSH-R, and Tg as well as weaker staining for TPO. Control reactions using isotype matched nonimmune immunoglobulins were consistently negative. Taken together, our results suggest that NIS-, TSH-R-, TPO-, and Tg-RNA are present and actively processed to immunoreactive NIS-, TSH-R-, TPO-, and Tg-like protein in human thymus. These data support the concept that pre-T lymphocytes may be educated to recognize thyroid-related epitopes expressed in thymus, and, thus, to generate self-tolerance against these thyroid-related antigens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blotting, Southern
  • Carrier Proteins / analysis
  • Carrier Proteins / genetics*
  • Female
  • Gene Expression
  • Humans
  • Immunohistochemistry
  • Infant
  • Iodide Peroxidase / analysis
  • Iodide Peroxidase / genetics*
  • Male
  • Membrane Proteins / analysis
  • Membrane Proteins / genetics*
  • RNA / analysis
  • Receptors, Thyrotropin / analysis
  • Receptors, Thyrotropin / genetics*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Symporters*
  • Thymus Gland / chemistry*
  • Thyroglobulin / analysis
  • Thyroglobulin / genetics*
  • Thyroid Gland / chemistry*


  • Carrier Proteins
  • Membrane Proteins
  • Receptors, Thyrotropin
  • Symporters
  • sodium-iodide symporter
  • RNA
  • Thyroglobulin
  • Iodide Peroxidase