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Efficient responses to the different forms of fungi require different mechanisms of immunity. Dendritic cells (DCs) are uniquely able to decode the fungus-associated information and translate it in qualitatively different T helper (Th) immune responses, in vitro and in vivo. DCs sense fungi in a morphotype-specific manner, through the engagement of distinct recognition receptors ultimately affecting cytokine production and costimulation. Adoptive transfer of different types of DCs activates protective and non-protective Th cells as well as regulatory T cells and affects the outcome of the infections. DCs transfected with fungal RNA also restore antifungal resistance in hematopoietic transplantation. Thus, the remarkable functional plasticity of DCs in response to fungi can be exploited for the deliberate targeting of cells and pathways of cell-mediated immunity in response to fungal vaccines.

Dendritic cells (DCs) have a remarkable functional plasticity in response to conidia and hyphae of the fungus Aspergillus fumigatus. In the present study we sought to assess the capacity of DCs activated by live fungi or fungal RNA to generate antifungal immunity in vivo. We found that both human and murine DCs pulsed with live fungi or transfected with fungal RNA underwent functional maturation, as revealed by the up-regulated expression of histocompatibility class II antigen and costimulatory molecules and the production of interleukin 12 (IL-12) in response to conidia or conidial RNA and of IL-4/IL-10 in response to hyphae or hyphal RNA. DCs pulsed with conidia or transfected with conidial RNA activated antigen-specific, interferon gamma (IFN-gamma)-producing T lymphocytes in vitro and in vivo on adoptive transfer in mice otherwise susceptible to aspergillosis. TH1-dependent antifungal resistance could also be induced in mice receiving allogeneic bone marrow transplants and was associated with an accelerated recovery of myeloid and lymphoid cells. Because the efficacy of the infusion of DCs was superior to that obtained on the adoptive transfer of Aspergillus-specific T cells, these results indicate the vaccinating potential of DCs pulsed with Aspergillus conidia or conidial RNA in hematopoietic transplantation.