Depletion of IL-4 in B10.A (genetically susceptible mice) led to increased lung fungal load, while the in vivo depletion of endogenous IL-4 in a PCM model at C57BL/6 (intermediate sensitivity to P. brasiliensis) was less severe and was associated with increased production of TNF-α and IL-12 and with decreased secretion of IL-4 and IL-5. The gene discussed is IL4; the disease is paracoccidioidomycosis.