Quantitative and functional analysis of PD-1 + NK cells in patients with autoimmune thyroid disease.
NK cells have an important role in innate immunity and in the regulation of immune response. The role of NK cells expressing the PD-1 regulatory receptor has not been explored in patients with autoimmune thyroid disease (AITD).To analyze the levels and function of PD-1 + NK cells in samples from AITD patients.Cases and controls, observational study.Hospital Universitario la Princesa, Spain.Forty patients with AITD, sixteen with Hashimoto thyroiditis (HT) and twenty-four with Graves’ disease (GD), and fifteen healthy controls.Multi-parametric flow cytometry analysis of peripheral blood NK cells. In vitro assays of cytotoxic activity of NK cells, and synthesis of cytokines.Main outcome measures. Levels and function of PD-1 + NK cells in blood samples from AITD patients and controls.Increased levels of NK cells and the CD56 dimPD-1 + subset were observed in GD patients. In HT, an enhanced expression of the regulatory receptors NKG2A and NKG2C by CD56 brightPD-1 + NK cells was detected. AITD patients showed an increased synthesis of IL-10 by CD56 brightPD-1 – NK cells, whereas CD56 dimPD-1 + cells from GD patients exhibited an enhanced production of IFN-γ. PD-1 + NK cells from patients with GD and HT showed an increased cytotoxic activity. Significant associations were observed in patients with GD or HT between the levels of PD-1 + NK cells and clinical laboratory parameters.The different abnormalities in NK cell subset levels, in the expression of PD-1 and its function in AITD patients’ further support the complex role of these cells in this pathogenesis.