Antigenic alterations in autoimmune thyroid diseases. Observations and hypotheses

Area of Science:

• Endocrinology
• Immunology
• Cell Biology

Background:

• Hashimoto's thyroiditis (HT) and Graves' disease (GD) are autoimmune thyroid disorders with distinct pathobiologic mechanisms.
• Understanding the cellular and molecular changes in HT and GD is crucial for defining their pathogenesis.

Purpose of the Study:

• To investigate the pathobiologic changes in thyroid tissue associated with Hashimoto's thyroiditis (HT) and Graves' disease (GD).
• To explore the expression of intermediate filaments, immune markers, and lectin binding in normal, hyperplastic, and diseased thyroid tissues.

Main Methods:

• Immunohistochemical analysis using antibodies against cytokeratin, vimentin, B-lymphocyte marker (LN-2), T-lymphocyte marker (UCHL-1), and HLA-DR.
• Application of biotinylated Helix pomatia lectin to paraffin-embedded thyroid tissue sections.
• Utilized the avidin-biotin-peroxidase complex method for detection.

Main Results:

• Cytokeratin expression was elevated in injured (HT) and hyperplastic (GD) thyroid tissue, unlike resting or hyperplastic epithelium.
• Vimentin was found in proliferating thyrocytes and basal portions of resting cells.
• HLA-DR and Helix pomatia lectin binding (N-acetyl-alpha-D-galactosamine) were observed in injured and hyperplastic tissues.
• T-lymphocytes (UCHL-1) infiltrated both HT and GD tissues, while B-lymphocytes (LN-2) were associated with lymphoid follicles.

Conclusions:

• T-cells appear to play a role in both HT and GD, but inflammation may not be the initiating factor.
• A shift in intermediate filament synthesis correlates with the expression of HLA-DR and N-acetyl-alpha-D-galactosamine in thyroid epithelium.
• Hypothesize that cytokeratins may influence gene activity related to Class II histocompatibility antigens and glycoprotein expression in HT and GD.