Characterisation of natural killer cells and CD56+ T-cells in sarcoidosis patients

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Abstract
The aim of the current study was to investigate the frequency, phenotype and functional activity of natural killer (NK) cells and CD56+ T-cells in the bronchoalveolar lavage fluid and peripheral blood of patients with pulmonary sarcoidosis when compared with healthy volunteers, using staining with a panel of monoclonal antibodies followed by flow cytometry.The results revealed that the majority of the lung NK cell subpopulation expressed CD56bright. In contrast, there was a predominant CD56dimsubset in the blood of both patients and healthy controls. Most lung NK cells expressed C-type lectin-like human leukocyte antigen (HLA)-E-specific inhibitory receptor (i.e.CD94/NKG2A), but only a few lung NK cells expressed killer cell immunoglobulin-like inhibitory receptors specific for HLA-A, -B or -C molecules. In addition, a significantly increased number of CD56+ T-cells were observed in the blood of patients when compared with controls. Uponin vitrostimulation, both lung NK and CD56+ T-cells produced considerable amounts of interferon-γ and tumour necrosis factor-α.Thus, in the lungs of patients with pulmonary sarcoidosis, a distinct phenotype of natural killer cells with the capacity to produce cytokines and actively participate in the T-helper 1-like inflammatory response associated with sarcoidosis was identified.