The mechanisms involved in this immunosuppression are still not fully understood but seem to be related to the unbalanced production of suppressor cytokines (IL-10 and TGF-β) and membrane-bound inhibitory mediators (CTLA-4 and PD-1), suggesting an essential role for regulatory T cells (Tregs) in the development and control of PCM (17–20). This evidence concerns the gene CTLA4 and paracoccidioidomycosis.