Kinetics of changes in lymphocyte sub-populations in mouse lungs after intrapulmonary infection with M. bovis (Bacillus Calmette-Guerin) and identity of cells responsible for IFNgamma responses.
Saxena-RK; Weissman-D; Saxena-QB; Simpson-J; Lewis-DM
Clin Exp Allergy 2002 Jun; 128(3):405-410
Gamma interferon (IFN) plays a key role in host defense against pulmonary mycobacterial infections. A variety of lymphocyte subsets may participate in producing pulmonary IFN responses, but their relative contributions after mycobacterial infection have not been clearly elucidated. To address this question, C57Bl/6 female mice were infected by intrapulmonary instillation of 2·5 104 BCG (Mycobacterium bovis Bacillus Calmette-Guerin). Lymphocyte populations in lung interstitium were examined at different time points after the infection. BCG load in lungs peaked between 4 and 6 weeks post-infection and declined to very low levels by the 12th week of infection. Recovery of lung interstitial lymphocytes doubled by 4-6 weeks after infection and declined thereafter. Flow cytometric analysis of the lung-derived lymphocytes revealed that about 5% of the these cells made IFN in control mice, and this baseline IFN production involved T (CD3+NK1.1), NK (CD3NK1.1+) and NKT (CD3+NK1.1+) cells. As the BCG lung infection peaked, the total number of CD3+ T cells in the lungs increased threefold at 5-6 weeks post-infection. There was a marked increase (sixfold) in the number of T cells secreting IFN 5-6 weeks post-infection. Some increase was also noted in the NKT cells making IFN, but the numbers of NK cells making IFN in BCG-infected lungs remained unaltered. Our results suggest that whereas NK and NKT cells contribute to baseline IFN secretion in control lungs, expansion in the IFN-producing T-cell population was essentially responsible for the augmented response seen in lungs of BCG-infected mice.
Pulmonary-disorders; Pulmonary-function; Lymphocytes; Animal-studies; Laboratory-animals; Cell-cultures; Cell-morphology; Microorganisms
Dr; Daniel M. Lewis, Analytical Services Branch, HELD, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA
Disease and Injury: Infectious Diseases
Clinical and Experimental Allergy