Although several immunoregulatory mechanisms and mediators are involved in host responses to PCM, such as IDO-1 production (16, 18, 19), TLRs, dectin-1, iNOS activation (39–42), and IL-10 and TGF-β secretion (43, 44), the involvement of MDSCs in the regulatory mechanisms that control pulmonary PCM has not yet been investigated. The gene discussed is IDO1; the disease is paracoccidioidomycosis.