Antigen-specific multifunctional T-cells in sarcoidosis patients with Lofgren's syndrome.

Sarcoidosis is a granulomatous disease of unknown aetiology, mainly affecting the lungs. Recently, T-cell responses towards a specific mycobacterial protein, catalase-peroxidase (mKatG), were observed in sarcoidosis patients. Bronchoalveolar lavage (BAL) fluid and peripheral blood were obtained from a total of 23 sarcoidosis patients, of whom 13 had Löfgren's syndrome and lung accumulations of T-cell receptor AV2S3+ T-cells. Using six-colour flow cytometry in combination with intracellular cytokine staining, T-cell subsets were studied with regard to interferon (IFN)-γ, tumour necrosis factor (TNF) and interleukin-2 production, after stimulation with mKatG or Mycobacterium tuberculosis purified protein derivate (PPD). Stimulation with mKatG resulted in higher simultaneous IFN-γ and TNF production, but less single IFN-γ production, from total BAL fluid CD4+ T-cells of Löfgren's syndrome patients, when compared with non-Löfgren's patients. In contrast, PPD stimulation gave rise to largely similar cytokine responses in both patient subgroups. Furthermore, mKatG stimulated higher IFN-γ production in BAL fluid and blood AV2S3+ T-cells than AV2S3- T-cells, whereas the opposite was seen in BAL fluid with PPD stimulation. Our finding that patients with Löfgren's syndrome exhibited a more pronounced multifunctional cytokine profile (simultaneous IFN-γ and TNF production) towards the mycobacterial protein mKatG may help to explain the distinct disease presentation in this patient subgroup.