Cellular immunity in subacute thyroiditis: a new perspective through neopterin

Area of Science:

• Immunology
• Endocrinology
• Pathogenesis of Thyroid Disorders

Background:

• Subacute thyroiditis (SAT) is an inflammatory thyroid condition often linked to viral infections and human leukocyte antigen (HLA)-B*35.
• Cellular immunity plays a significant role in SAT pathogenesis.
• Neopterin, a marker of cellular immunity, is produced by activated monocytes/macrophages stimulated by interferon gamma (IFN-γ).

Purpose of the Study:

• To investigate serum neopterin levels as an indicator of cellular immunity in patients with subacute thyroiditis.
• To compare neopterin levels between SAT patients during the active thyrotoxic phase and healthy controls.

Main Methods:

• Serum neopterin levels were measured in 15 SAT patients and 16 healthy controls.
• Thyroid function tests and classical inflammatory markers (erythrocyte sedimentation rate, C-reactive protein) were assessed.
• Cellular immunity markers and their relationship with neopterin were analyzed.

Main Results:

• SAT patients exhibited significantly altered thyroid functions and elevated classical inflammatory markers.
• Contrary to expectations, serum neopterin levels were significantly lower in SAT patients compared to healthy controls.
• Increased CD8+ T cells were observed in thyroid tissue of SAT patients.

Conclusions:

• The observed low serum neopterin levels in SAT patients may be associated with the interplay between HLA-B*35, major histocompatibility complex class I, and CD8+ T cell antigen presentation, leading to cytokine imbalance.
• Neopterin offers distinct information compared to conventional acute-phase response indicators in SAT.
• Further research is warranted to elucidate the precise mechanisms underlying neopterin dynamics in SAT.