Thymosin α 1 protects mice that received BM transplants from invasive aspergillosis. Mice that received BM transplants were intranasally infected with Aspergillus conidia a week after the BM infusion. Thymosin α 1 or the scrambled peptide (group 7) was given intraperitoneally daily beginning the day of the BM infusion, in concomitance with the infection and continuing for additional 3 days. Amphotericin B was given intraperitoneally for 3 days, in concomitance with the infection. (A) MST indicates median survival times (days), calculated from the beginning of the infection. The numbers refer to animals that died over total injected. The fungal growth was assessed at 1 (control) or 4 days after the last conidia inoculation. Bars indicate the standard errors. ^*P < .05, treated versus untreated mice. ^**P < .05, combined treatment versus each single treatment. (B-C) Periodic acid-Schiff-stained sections from lungs of infected mice that received BM transplants either untreated (panel B at 1 day after infection) or treated with thymosin α 1 (panel C at 4 days after infection). Numerous Aspergillus hyphae (arrows) infiltrating the lung parenchyma, with severe signs of bronchial wall damage and necrosis and scarce inflammatory cell recruitment are observed in the lungs of untreated mice, as opposed to that observed in thymosin-treated mice, whose lungs were characterized by healing infiltrates of inflammatory cells with no evidence of bronchial wall damage and fungal growth. Magnification × 400 in both panels.