Cellular immune responses are a significant defence mechanism in human paracoccidioidomycosis (PCM), an endemic mycosis in Latin America; however, little is known about the role of dendritic cells (DCs) in human PCM. We investigated monocyte‐derived DCs from patients with treated (TP) and active PCM (AP) compared with healthy non‐PCM donors (CO). DCs from the TP group showed higher expression of HLA‐DR, CD86 and DC‐SIGN compared with CO, whereas AP showed similar expression to CO. Production of IL‐10 was downregulated by TNF‐α in all groups and lower levels were observed in untreated DCs from AP compared with CO. Conversely, IL‐12p40 was significantly upregulated in the DCs of the TP group. TNF‐α‐activated DCs from the CO group produced significantly lower levels of IL‐12p40 when differentiated from magnetic‐sorted monocytes (MACS) compared with adhered monocyte‐derived DCs. This comparison in the TP group revealed similar levels of IL‐12p40, suggesting a T cell–independent increase in the production of IL‐12p40. Higher expression of surface molecules with increased IL‐12p40 may indicate a better activation of DCs after the treatment of PCM. Our findings suggest that DCs may be crucial in the protective response to Paracoccidioides brasiliensis and that in vitro‐generated DCs might be useful in enhancing antifungal immunity, especially during active PCM.

We investigated the in vitro effects of two Paracoccidioides brasiliensis antigens on monocyte-derived dendritic cells (moDCs) from patients with paracoccidioidomycosis (PCM). MoDCs from patients with active or treated PCM and non-PCM subjects were generated, stimulated with TNF-α, and P. brasiliensis antigens, 43 kDa glycoprotein (gp43) and cell-free antigen (CFA), and analyzed by flow cytometry and enzyme-linked immunosorbent assays (ELISA). Our data revealed that patients with PCM had a high frequency of HLA-DR+ cells, but the treated group had more CD86+ cells with increased IL-12p40. Patients with active PCM had more CD80+ moDCs, and as a novel finding, large amounts of chemokine (C-C motif) ligand 18 (CCL18) in the supernatants from their in vitro moDC cultures. Both gp43- and CFA-stimulated moDCs from the patients with PCM successfully reverted the in vitro antigen-specific anergy, inducing a proliferative response. However, CFA-stimulated moDCs led to higher lymphoproliferation, with increased IFN-γ and TNF-α in the cells from the patients with active PCM compared with gp43. These original results combined with constant IL-10 and increased IL-12p40 levels suggest that a more complex antigen, such as CFA, may be a better inducer of the protective Th1 immune response than purified gp43 is, and a suitable target for future studies on anti-P. brasiliensis dendritic cell (DC)-based vaccines.