Interferon-gamma protects human thyroid epithelial cells against cell-mediated cytotoxicity

Area of Science:

• Immunology
• Endocrinology
• Cell Biology

Background:

• Interferons are known to modulate cell-mediated cytotoxicity.
• Autoimmune thyroid diseases involve complex immune dysregulation.
• The role of specific interferons in thyroid autoimmunity requires further elucidation.

Purpose of the Study:

• To investigate the effect of interferon-gamma (IFN-gamma) on various immunologically mediated cytotoxic reactions against human thyroid cells.
• To determine if IFN-gamma influences antibody-dependent cell-mediated cytotoxicity (ADCC), natural killer (NK) cell-mediated cytotoxicity, and autologous lymphocyte-mediated cytotoxicity (ALC) in the context of autoimmune thyroid disease.

Main Methods:

• Utilized a 51chromium release assay to measure cytotoxic reactions.
• Employed human thyroid cells as target cells, cultured with or without IFN-gamma.
• Assessed ADCC, NK cell-mediated cytotoxicity, and ALC using thyroid tissue, sera, and lymphocytes from patients with autoimmune thyroid disease and normal subjects.

Main Results:

• Culturing thyroid target cells with 1000 U/ml IFN-gamma reduced ADCC by 70% in patients with Hashimoto's thyroiditis.
• Pretreatment of thyroid target cells with 500-1000 U/ml IFN-gamma significantly decreased NK cell-mediated cytotoxicity and ALC.
• Demonstrated IFN-gamma's resistance-inducing effect on human epithelial cells against NK cell-mediated lysis for the first time.

Conclusions:

• IFN-gamma exhibits potent inhibitory effects on multiple cell-mediated cytotoxic mechanisms against human thyroid cells.
• These findings provide novel evidence for the impact of IFN-gamma on human epithelial cells, distinct from previous observations on other cell types.
• The study suggests a significant role for IFN-gamma in the pathogenesis and persistence of autoimmune thyroid diseases.