Pulmonary immune responses against Aspergillus fumigatus are characterized by high frequencies of IL-17 producing T-cells

- Frequencies of Aspergillus-specific T-cells in peripheral blood and lung are similar.
- Pulmonary Aspergillus-specific T-cells display a Thelper17 cytokine profile.
- Aspergillus-specific T-cells in peripheral blood have a Th1 phenotype.
- Activation and ability to produce cytokines are equal in both compartments.

SummaryIn healthy individuals and in patients with invasive aspergillosis, Aspergillus-specific T-cells in peripheral blood display mainly a Thelper1 phenotype. Although in other fungal infections Thelper17 immunity is important, it was suggested that in aspergillus infection Thelper17 cells do not play a role or may even be detrimental.ObjectivesTo compare the cytokine profiles of Aspergillus-specific CD4+ T-cells in peripheral blood and in the lung. To investigate the Thelper phenotype at the primary location of A. fumigatus exposure.MethodsLung-derived T-cells and peripheral blood T-cells from COPD-patients were stimulated with overlapping peptides of 6 A. fumigatus proteins. Aspergillus-specific T-cells were identified on the basis of the activation marker CD154 and production of TNFα. In addition, production of the cytokines IFNγ, IL-17, IL-4 and IL-5 by the Aspergillus-specific T-cells was measured.ResultsThe majority of lung-derived Aspergillus-specific T-cells displayed a Thelper17 phenotype, and only low percentages of cells produced IFNγ. In contrast, in the peripheral blood of COPD patients Aspergillus-specific T-cells displayed a Thelper1 phenotype, similar as peripheral blood-derived Aspergillus-specific T-cells from healthy individuals.ConclusionsThese data demonstrate that in A. fumigatus infection, similar as in other fungal infections, Thelper17 cells may play a more important role in the immune response than was appreciated until now.