The therapeutic potential of PTX3 in aspergillosis is abrogated in FcRγ-deficient mice. (A) Periodic acid-Schiff–stained medial sections of lungs from C57BL/6 or FcRγ^−/− mice intranasally infected with 2 × 10⁷/20 μL viable, unopsonized Aspergillus fumigatus conidia and treated with 1 mg/kg/intranasally of PTX3 or saline for 5 consecutive days and assessed 1 day after the end of treatment. Note the presence of few infiltrates of inflammatory mononuclear cells scattered in an otherwise intact lung parenchyma in C57BL/6 mice as opposed to the abundant infiltration of inflammatory cells and signs of diffuse interstitial pneumonia in FcRγ^−/− mice and its amelioration by PTX3 treatment in C57BL/6 but not in FcRγ^−/− mice. Bars indicate magnification. (B) Colony forming units (mean ± SE, n = 6) in the lung and brain of C57BL/6 or FcRγ^−/− mice treated with PTX3 or saline.