Circulating T cells in sarcoidosis have an aberrantly activated phenotype that correlates with disease outcome

•Disease course in sarcoidosis is highly variable and unpredictable.•The discovery of biomarkers to predict long-term disease outcome can help clinical decision making.•Peripheral T cells differ between patients and controls in frequency and phenotype.•Aberrantly activated naïve and regulatory T cells correlate with worse long-term outcome in sarcoidosis.•Stimulated naïve and memory T cells show an altered cytokine profile in sarcoidosis.