Endocrine Abstracts

Introduction: Dendritic cells (DCs) are considered as main regulators of immune system. Functional properties of DCs depend on their subtype, maturation status, interaction with other immune cells as well as environmental factors including hormones. Recently, we have shown a direct, independent of TSH, regulatory influence of thyroid hormones on human DCs function. The aim of the present study was to analyze ex vivo the effect of systemically administered TSH on human peripheral blood immmune cell populations, potentially interacting with DCs and modulating their function.

Methods: Blood samples for the flow cytometry analysis of peripheral blood plasmacytoid and myeloid DC subtypes were collected from patients thyroidectomized because of differentiated thyroid cancer at two consecutive time points: i) directly before the commencement of TSH administration and ii) 5 days after first TSH injection. The whole blood quantitative and phenotypic analysis of immune cell populations was performed by flow cytometry.

Results: As previously shown, systemic administration of TSH did not influence the percentage and maturation status of plasmacytoid and myeloid DCs in peripheral blood of thyroidectomized patients. Interestingly, we observed a significant increase of CD16 positive PBMCs. This difference was dependent specifically on natural killer (NK) cells whereas the CD16+ monocyte fraction did not change after TSH administration.

Conclusions: In the present study, the systemic TSH administration resulted in the specific increase of CD16+ NK cells fraction in peripheral blood of thyroidectomized patients. These results are of great importance for the understanding of endocrine-immune regulatory network in humans.