Distribution of subpopulations of dendritic cells in peripheral blood of patients treated with exogenous thyrotropin

BACKGROUND: Dendritic cells (DCs) play a major role as regulators of inflammatory events associated with thyroid pathology. The immunoregulatory function of DCs depends strongly on their subtype, as well as maturation and activation status. Numerous hormonal factors modulate the immune properties of DCs, however, little is known about effects exerted by the hypothalamus-pituitary-thyroid-axis. Recently, we have shown a direct regulatory influence of thyroid hormones (TH) on human DCs function. The aim of the present study was to analyze the effect of systemically administered thyrotropin (TSH) on human blood DCs ex vivo. METHODS: Blood samples for the cytometric analysis of peripheral blood plasmacytoid and myeloid DCs subtypes were collected from patients subjected to total thyroidectomy because of differentiated thyroid carcinoma at 2 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 plasmacytoid and myeloid DCs subtypes was performed by flow cytometry. RESULTS: Administration of TSH did not influence the percentage of plasmacytoid DCs in peripheral blood of study participants. Also the percentage of the two main myeloid DCs subpopulations – CD1c/BDCA1+ DCs and CD141/BDCA3+ DCs did not change significantly. TSH administration had no effect on the surface expression of CD86 – one of the major costimulatory molecules – neither in the whole peripheral blood mononuclear cell (PBMC) fraction nor in particular DCs subtypes. CONCLUSIONS: In the present study, we demonstrated no influence of systemic TSH administration on human peripheral blood DCs subtypes. These results are in accordance with our previous work suggesting the direct effect of TH on human DCs ex vivo.