Introduction: Catalase is an enzyme, which functions in the detoxification of hydrogen peroxide, and is one of the most important antioxidant enzymes in humans. It is responsible for protecting the cell from oxidative damage by reactive oxygen species. Catalase promotes growth of cells including T-cells, B-cells, myeloid leukemia cells, melanoma cells, mastocytoma cells, and normal and transformed fibroblast cells. Nevertheless, the role of this enzyme in thyroid pathologies is still not completely known, therefore the aim of the study was to assess the immunohistochemical expression of catalase in lesions of thyroid gland.
Methods: 22 patients with thyroid goiter were included in the study: 13 cases with non-toxic nodular goiter (NTNG) and 9 patients with Hashimotos thyroiditis (HT). Normal glands served as controls. For immunohistochemistry, mouse monoclonal antibodies against catalase were applied. The investigations were performed by the BrightVision method from Immunologic. The sections were counterstained with Mayers haematoxylin. The number of positively stained cells were counted and expressed as a mean value of at least 10 high power fields (400×).
Results: The expression of catalase in healthy thyroids was weak or focal. All cases of Hashimotos thyroiditis demonstrated higher expression of catalase in comparison with non-toxic nodular goiter and healthy thyroid gland. Positively stained cells were also detected in infiltrating lymphocytes and macrophages. Only 16% of NTNG demonstrated the immunoreactivity for catalase.
Conclusions: Results may suggest that increased expression of catalase in Hashimotos thyroiditis is implicated in the pathogenesis of this disorder. Nevertheless, the role of catalase in inflammation of thyroid is still not completely known and further studies in this matter should be continued.