Efficient responses to the fungus require a complex network of immunological mechanisms. Together with alveolar macrophages and neutrophils, which constitute a primary line of innate cellular defence against A. fumigatus,1,2 the crucial role of the adaptive immunity has been extensively demonstrated.3 Indeed, besides the well-characterized protective role of T helper type 1 (Th1) lymphocytes,4–7 the newly described regulatory T cells and interleukin-17 (IL-17) -producing cells (Th17) represent important mediators of the inflammatory and anti-inflammatory

signaling pathway host responses against A. fumigatus.8 However, dendritic cells (DCs) also play a fundamental function in initiating and modulating the specific immune responses upon recognition of A. fumigatus.5,9,10 After internalization of A. fumigatus conidia, DCs mature and acquire the capacity to polarize

naive T cells and, in turn, to promote a protective response.9 In keeping with these findings, in vivo results on the migration of lung DCs into lymphoid organs, where they drive an appropriate T-cell response to fungal antigens,11 have brought DCs centre stage as promising targets for intervention in immunotherapy and fungal vaccine development.12 In addition, it is important FK228 ic50 to consider several studies that have recently pointed to DCs and type I interferons (IFNs) as special players in the immune response tailored to combat tumours and infections.13–15 Indeed, although the anti-microbial properties of these cytokines have not been fully characterized yet, type I IFNs represent important immunomodulators of the innate, as well as the adaptive, arm of the immune system. Type I IFN can promote

the differentiation of human blood monocytes into DCs and contribute to their maturation.16,17 This leads to the generation of DCs able to stimulate a primary human antibody response, a Th1 proliferation,18 and a cross-priming of CD8 T cells against viral antigens.19 In addition, one crucial outcome of type I IFN-induced effects is the ability to directly stimulate IFN-γ production in natural killer and T cells,20–22 which in turn promotes the development of a cell-mediated immune response. Based on these immunoregulatory properties, in this work the expression and the Molecular motor capacity of type I IFN, namely IFN-β, to modulate the T-cell polarizing capacity of A. fumigatus-infected DCs was investigated in an attempt to evaluate the effects induced by this cytokine on anti-fungal immunity. Although the phagocytosis of the fungus was not affected by IFN-β treatment, the maturation induced by A. fumigatus infection was enhanced in IFN-β-primed DCs, as evaluated by analysing the immunophenotype and the release of pro-inflammatory and regulatory cytokines. Accordingly, IFN-β endowed DCs with potent Th1 polarizing capacity because an enhanced IFN-γ production in T cells co-cultured with A. fumigatus-infected DCs was observed in the presence of IFN-β.