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Infection and Immunity, February 1999, p. 879-884, Vol. 67, No. 2
Division of Pulmonary and Critical Care
Medicine, Department of Internal Medicine, University of Michigan
Medical School, Ann Arbor, Michigan 48109-0360,1
and
Pulmonary Section, Department of Veterans Affairs
Medical Center, Ann Arbor, Michigan 48105-23032
Received 14 September 1998/Returned for modification 22 October
1998/Accepted 4 November 1998
Effective host defense against Pneumocystis carinii
depends upon the integrated actions of inflammatory cells and mediators in the lungs. Using immunocompetent and immunosuppressed mice, our
laboratory has defined inflammatory changes in the lungs in response to
P. carinii. However, the essential molecules and mechanisms required for cellular recruitment and for host defense against P. carinii are undefined. We hypothesized that urokinase-type plasminogen activator (uPA), a protease intimately involved in inflammatory cell migration and activation, is required for clearance of P. carinii. To test this hypothesis in vivo, we compared
the intensity of P. carinii infection and inflammation in
the lungs of mice lacking the uPA gene (uPA knockout mice) and in the
lungs of wild-type mice. After intratracheal inoculation with P. carinii organisms, uPA knockout mice developed uniformly heavy
P. carinii pneumonia while wild-type mice cleared the
P. carinii inoculum. Bronchoalveolar lavage fluid from uPA
knockout mice contained significantly smaller numbers of cells than did
lavage fluid from wild-type mice. We conclude that deletion of the uPA
gene prevents the clearance of P. carinii and reduces
inflammatory cell recruitment. Therefore, uPA is an important
participant in the network of inflammatory events required for the
clearance of P. carinii, confirming an important role for
this molecule in pulmonary host defense against opportunistic pathogens.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Urokinase-Type Plasminogen Activator in
Inflammatory Cell Recruitment and Host Defense against
Pneumocystis carinii in Mice
*
Corresponding author. Mailing address: Pulmonary and
Critical Care Medicine (111G), Department of Veterans Affairs Medical Center, 2215 Fuller Rd., Ann Arbor, MI 48105-2303. Phone: (734) 761-7980. Fax: (734) 761-7843. E-mail: jamebeck{at}umich.edu.
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