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Updated: Aug 15, 2026
Isolation of Mouse Lung Dendritic Cells
Published on: November 22, 2011
CD4+ cells play a limited role in murine lung infection with Mycobacterium kansasii
Catharina W Wieland1, Sandrine Florquin, Jennie M Pater
1Laboratory of Experimental Internal Medicine, G2-132, Academic Medical Center, University of Amsterdam, The Netherlands. c.wieland@amc.uva.nl
Abstract:
Mycobacterium kansasii has emerged as an important nontuberculous mycobacterium that can cause severe infection in the immunocompromised host, especially in human immunodeficiency virus-infected patients. However, little is known about the pathogenesis of this infection. Because patients suffering from M. kansasii infection are severely compromised in their cellular immune response, we studied the course of infection in CD4+ cell knockout (KO) mice. Wild-type (WT) mice and CD4+ KO mice were infected with 10(5) cfu of M. kansasii. Although previously shown to be susceptible to Mycobacterium tuberculosis infection, CD4+ KO mice demonstrated no impairment in clearing infection with M. kansasii when compared with WT animals, despite reduced pulmonary inflammation (reduced granuloma formation and lymphocyte infiltration in the lungs). Pulmonary IFN-gamma levels and M. kansasii-induced IFN-gamma production by splenocytes from infected animals were reduced in CD4+ KO mice, confirming that these mice were defective in the M. kansasii-specific T helper cell type 1 immune response. Furthermore, mice deficient for IFN-gamma, IL-12p35, IL-12p40, or IL-18 also displayed a normal host defense against pulmonary infection with M. kansasii. These data suggest that CD4+ cells, IFN-gamma, and an intact T helper cell type 1 response play a limited role in protective immunity against pulmonary M. kansasii infection.
Insights
CD4+ cells and T helper type 1 responses play a limited role in clearing Mycobacterium kansasii lung infections. Even in knockout mice lacking these, infection clearance was normal, suggesting alternative immune mechanisms are key.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Nontuberculous mycobacteria, like Mycobacterium kansasii, cause severe infections, particularly in immunocompromised individuals.
- The exact mechanisms of M. kansasii pathogenesis remain poorly understood.
- Patients with M. kansasii infection often have compromised cellular immunity.
Purpose of the Study:
- To investigate the role of CD4+ T cells and T helper type 1 (Th1) immune responses in host defense against pulmonary Mycobacterium kansasii infection.
- To compare the course of M. kansasii infection in wild-type (WT) mice and CD4+ cell knockout (KO) mice.
Main Methods:
- Infection of WT and CD4+ KO mice with a standardized dose of M. kansasii.
- Assessment of bacterial clearance, pulmonary inflammation (granuloma formation, lymphocyte infiltration), and cytokine levels (IFN-gamma).
- Evaluation of host defense in mice deficient for key Th1-related cytokines (IFN-gamma, IL-12, IL-18).
Main Results:
- CD4+ KO mice showed no impairment in clearing M. kansasii pulmonary infection compared to WT mice.
- Pulmonary inflammation was reduced in CD4+ KO mice, indicating less granuloma formation and lymphocyte infiltration.
- Despite reduced IFN-gamma production in CD4+ KO mice, indicating a defective Th1 response, host defense remained intact.
- Mice deficient in IFN-gamma, IL-12, or IL-18 also exhibited normal host defense against M. kansasii.
Conclusions:
- CD4+ T cells and a functional T helper type 1 immune response play a minimal role in protective immunity against pulmonary Mycobacterium kansasii infection.
- Alternative immune mechanisms, independent of CD4+ T cells and Th1 cytokines, are crucial for controlling M. kansasii lung infections.
- Further research is needed to elucidate the specific immune pathways involved in M. kansasii clearance.
