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Keywords:

  • endoscopy;
  • immunology;
  • inflammation;
  • lung disease;
  • sarcoidosis;
  • T cell

Abstract.  Darlington P, Haugom-Olsen H, von Sivers K, Wahlström J, Runold M, Svjatoha V, Porwit A, Eklund A, Grunewald J (Karolinska Institutet, Stockholm, Sweden). T-cell phenotypes in bronchoalveolar lavage fluid, blood and lymph nodes in pulmonary sarcoidosis – indication for an airborne antigen as the triggering factor in sarcoidosis. J Intern Med 2012; 272: 465–471.

Background.  An increased percentage of CD4+ T cells is usually observed in bronchoalveolar lavage fluid (BALF) from patients with sarcoidosis. In HLA-DRB1*03-positive patients, such T cells express the T-cell receptor (TCR) AV2S3+ gene segment. It is not known whether cells found in BALF reflect those in enlarged regional lymph nodes (LNs). Therefore, the aim of this study was to compare T-cell phenotypes in BALF, blood and mediastinal LNs.

Methods.  Fifteen patients underwent clinical investigation including bronchoscopy with bronchoalveolar lavage. Blood samples were drawn, and endoscopic ultrasound-guided fine-needle aspiration of enlarged mediastinal LNs was performed via the oesophagus. T cells from all three compartments were analysed by flow cytometry for markers of activity, differentiation and T regulatory function.

Results.  The CD4/CD8 ratio was significantly higher in BALF compared with regional LNs and was also significantly higher in LNs than in blood. The CD4+ T cells were recently activated and more differentiated in BALF than in blood and LNs. There was an accumulation of T regulatory cells (FOXP3+) in LNs and a correlation between high levels of FOXP3+ cells in BALF and in LNs. In HLA-DRB1*03-positive patients, TCR AV2S3+ CD4+ T cells were predominantly localized within BALF.

Conclusions.  The CD4+ T-cell phenotype in BALF indicates an active ongoing specific immune response primarily localized to the alveolar space.