Histopathology of SCA lungs after pneumococcal challenge. (A-D) H&E-stained lung sections at 18 hours after infection: control without infection (A); mock transplanted, infected, saline treated (B); SCA, infected, saline treated (C); and SCA infected receiving hydroxyurea (HU; D). Magnification: top row, ×4; bottom row, ×10. (E) Mean vascular lesion scores of SCA and mock-transplanted (Tx) mice receiving HU or saline therapy at 24 hours after challenge (n = 5/group). (F) Quantification of the signs of interstitial pneumonia determined by histologic examination of lung sections at 24 hours after infection (n = 5 mice/group; mean = 3.7 ± 0.5 for SCA saline, 2.6 ± 0.4 for SCA + HU; *P < .05 compared with SCA, †P < .05 compared with SCA+HU using Mann-Whitney).