FIG. 2.

Histology of P. carinii infection. Lungs of wild-type mice inoculated with P. carinii demonstrated perivascular and peribronchiolar mononuclear cell infiltrates (arrow) (A) but no P. carinii organisms (C). Lungs of uPA knockout mice inoculated with P. carinii demonstrated markedly reduced mononuclear cell inflammation but contained alveolar exudate indicative of P. carinii infection (arrows) (B), confirmed by the presence of P. carinii organisms (arrowheads) (D). (A and B) H&E stain; magnification, ×200. (C and D) Gomori methenamine silver stain; magnification, ×400.