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Cytofluorometric analysis of lymphocyte subsets in thyroid aspirates from patients with autonomously functioning
A Farsetti1, A Pontecorvi, I Antonozzi
1Dipartimento di Medicina Sperimentale, Università La Sapienza, Roma, Italy.
Insights
Immune cell imbalances, specifically a CD8+ T cell increase in thyroid tissue, characterize autonomously functioning thyroid nodules (AFTN). This finding, not seen in peripheral blood or cold thyroid nodules (CTN), correlates with elevated thyroid hormones.
Area of Science:
- Immunology
- Endocrinology
- Thyroid Research
Background:
- Autonomously functioning thyroid nodules (AFTN) are common endocrine disorders.
- The role of intrathyroidal immune cells in AFTN pathogenesis is not fully understood.
- Previous studies have not extensively characterized lymphocyte subsets within thyroid tissue in AFTN.
Purpose of the Study:
- To investigate and characterize lymphocyte subsets within thyroid tissue of patients with AFTN compared to cold thyroid nodules (CTN).
- To determine if observed lymphocyte subset alterations in AFTN are specific to the thyroid gland.
- To explore potential correlations between intrathyroidal lymphocyte distribution and thyroid hormone levels.
Main Methods:
- A microscale method utilizing two-colour dye immunolabelling and flow sorting cytofluorometry.
- Analysis of lymphocyte subsets (CD4+, CD8+) in thyroid tissue specimens obtained via fine-needle aspiration (FNA).
- Comparison of lymphocyte subsets in thyroid tissue and peripheral blood from AFTN and CTN patients.
Main Results:
- A significant inversion of the CD4+/CD8+ lymphocyte ratio was observed in the thyroid tissue of AFTN patients, characterized by an increase in CD8+ cells.
- This abnormal lymphocyte distribution was specific to the thyroid tissue and not detected in the peripheral blood of AFTN patients.
- Patients with CTN showed normal lymphocyte subset distribution in both thyroid tissue and peripheral blood.
- A negative correlation was found between the decreased intrathyroidal CD4+/CD8+ ratio and elevated plasma thyroid hormone levels in AFTN patients.
Conclusions:
- Intrathyroidal immune dysregulation, specifically an increase in CD8+ T cells, is a feature of autonomously functioning thyroid nodules.
- The observed immunological abnormalities are localized to the thyroid gland in AFTN.
- The FNA-based microscale method offers a potential tool for routine characterization of the immune microenvironment in thyroid disorders.
Abstract:
A microscale method, based on two-colour dye immunolabelling and flow sorting cytofluorometry, was used to characterize lymphocyte subsets in thyroid tissue specimens obtained by fine-needle aspiration (FNA) in 21 patients with autonomously functioning thyroid nodule (AFTN) and five patients with cold thyroid nodule (CTN). Inversion of the ratio between CD4+ and CD8+ lymphocytes, due to a relative increase of CD8+ cells, was found among intrathyroidal lymphocytes in AFTN patients. The abnormal lymphocyte subset distribution was not observed in the peripheral blood of the same group of patients. In patients with CTN the lymphocyte subset distribution was normal, both in the thyroid and in the peripheral blood. In AFTN patients, a significant correlation was observed between the decrease of intrathyroidal CD4+/CD8+ ratio and the increase of plasma thyroid hormone levels. Whether the immunological abnormalities found in AFTN could play a pathogenetic role in the clinical presentation and outcome of the disease remains to be established. The FNA-applied micromethod used in this study could be extended as a routine investigation to characterize the immunogenic substrate of thyroid disorders.