Transgenic mice producing major histocompatibility complex class II molecules on thyroid cells do not develop...

Area of Science:

• Immunology
• Endocrinology
• Genetics

Background:

• Aberrant expression of major histocompatibility complex (MHC) class II molecules on thyrocytes is observed in autoimmune thyroid diseases.
• The precise role of this MHC class II expression in initiating autoimmune processes remains unclear.

Purpose of the Study:

• To investigate whether MHC class II expression on thyrocytes can induce autoimmune thyroid disease.
• To determine if aberrant MHC class II expression alone is sufficient to trigger thyroid autoimmunity.

Main Methods:

• Generation of transgenic mice with MHC class II gene expression under the control of the rat TSH receptor promoter.
• Confirmation of MHC class II expression in thyrocytes using immunofluorescence and flow cytometry.
• Assessment of thyroid histology, autoantibody production, thyroid hormone levels, and T cell proliferation in transgenic mice.

Main Results:

• Transgenic mice exhibited MHC class II expression on thyrocytes without developing thyroid abnormalities or autoantibodies.
• Serum free T(4) levels were slightly reduced, but no clinical hypothyroidism or hyperthyroidism was observed.
• Absence of thyroid lymphocytic infiltration and lack of autologous T cell proliferation upon stimulation with MHC class II-expressing thyrocytes.

Conclusions:

• Transgenic mice expressing MHC class II on thyrocytes do not develop autoimmune thyroid disease.
• Aberrant MHC class II expression on thyrocytes alone is not sufficient to induce thyroid autoimmunity.
• Further factors likely contribute to the pathogenesis of autoimmune thyroid diseases.