Paracoccidioidomycosis (PCM) occurs in two distinct forms, the acute or juvenile form (JF), and the chronic or adult form (AF). To clarify the basis of this dichotomy, specific IgG subclasses, IgA and IgE anti-gp43 were measured by enzyme-linked immunosorbent assay, in patients with different forms of PCM. Serum levels of tumor necrosis factor-alpha, interleukin (IL)-6, IL-8, macrophage inflammatory protein (MIP)-1alpha and transforming growth factor (TGF)-beta were also quantified. We show here that JF patients have significantly higher titers of IgE antibodies against gp43, an immunodominant antigen specific for Paracoccidioides brasiliensis, than do patients with the unifocal adult form (UF-AF, isolated lesions). Patients with the multifocal adult form (MF-AF, lesions in more than one organ) also produced elevated levels of anti-P. brasiliensis IgE. Furthermore, specific IgE levels were correlated with IgG4, IgA and eosinophilia. Patients with JF showed eosinophilia and increased levels of TGF-beta, a switching factor for IgA. These results indicate a T helper (Th)-2 pattern of cytokine expression in both the JF and the MF-AF of PCM. On the other hand, patients with UF-AF had a significantly lower production of specific IgE, IgG4 and IgA than was seen in the other patient groups.