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Mediators of Inflammation
Volume 2008, Article ID 239740, 6 pages
http://dx.doi.org/10.1155/2008/239740
Research Article

Lymphotoxin- š¯›¼ Plays Only a Minor Role in Host Resistance to Respiratory Infection with Virulent Type A Francisella tularensis in Mice

1National Research Council Canada, Institute for Biological Sciences, 100 Sussex Drive, Room 3100, Ottawa, ON, Canada K1A 0R6
2Basic Medical College of Zhengzhou University, 100 Science Road, Zhengzhou, Henan 450001, China

Received 4 June 2008; Accepted 24 July 2008

Academic Editor: V. L. Petricevich

Copyright © 2008 Deng Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This study examined the role of lymphotoxin (LT)- š¯›¼ in host defense against airborne infection with Francisella tularensis, a gram-negative facultative intracellular bacterium and the causative agent of tularemia. Following a low-dose aerosol infection with the highly virulent type A strain of F. tularensis, mice deficient in LT š¯›¼ (LT š¯›¼ −/−) consistently harbored approximately 10-fold fewer bacteria in their spleens at day 2 and 10-fold more bacteria in their lungs at day 4 than LT š¯›¼ +/+ mice. However, the mortality and median time to death were indistinguishable between the two mouse strains. In addition, the inflammatory responses to the infection, as reflected by the cytokine levels and leukocyte influx in the bronchoalveolar lavage fluid and histopathological analysis, were generally similar between LT š¯›¼ −/− and LT š¯›¼ +/+ mice. These data suggest that although LT š¯›¼ does not contribute significantly to the resistance and host responses of mice to airborne type A F. tularensis infection, it does play a subtle role in the multiplication/dissemination of F. tularensis.