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Pneumocystis carinii infection in transgenic B cell-deficient mice
H Marcotte1, D Levesque, K Delanay
1Groupe de Recherche en Ecologie Buccale, Université Laval, Quebec, Canada.
Abstract:
Pneumocystis carinii is an important cause of pneumonia in immunocompromised hosts. Both cellular and humoral immunity seem important in resistance to this pathogen, but the specific role of each component is poorly understood. An outbreak of P. carinii pneumonia in transgenic B cell-deficient mice (muMT) was studied. Over 4 months, >50% of 41 muMT/muMT mice maintained in a sterile environment died of pneumonia. Some mice had concurrent infection with Pasteurella pneumotropica. Homozygous muMT/muMT mice had no detectable serum immunoglobulins, while their heterozygous muMT/+ counterparts had normal levels of IgM, IgG, and IgA and did not develop pneumonia. The infection was controlled by treating the mice with trimethoprim-sulfamethoxazole, and the pathogen was eliminated by cesarean rederivation. These observations suggest an important role for B cells in the host defense against P. carinii.
Insights
B cells play a crucial role in defending against Pneumocystis pneumonia in immunocompromised individuals. This study highlights their importance in host defense against this opportunistic pathogen.
Area of Science:
- Immunology
- Infectious Diseases
- Microbiology
Background:
- Pneumocystis pneumonia is a significant threat to immunocompromised individuals.
- The precise roles of cellular and humoral immunity in combating Pneumocystis carinii are not fully understood.
Purpose of the Study:
- To investigate the role of B cells in host defense against Pneumocystis carinii pneumonia.
- To assess the impact of B cell deficiency on susceptibility to P. carinii infection.
Main Methods:
- Utilized transgenic B cell-deficient mice (muMT/muMT) and their heterozygous counterparts (muMT/+) for infection studies.
- Monitored survival rates, presence of pneumonia, and serum immunoglobulin levels.
- Administered trimethoprim-sulfamethoxazole for treatment and employed cesarean rederivation for pathogen elimination.
Main Results:
- Over 50% of B cell-deficient muMT/muMT mice developed fatal Pneumocystis pneumonia within four months.
- Homozygous muMT/muMT mice lacked detectable serum immunoglobulins, unlike heterozygous controls with normal immunoglobulin levels.
- Concurrent Pasteurella pneumotropica infection was observed in some affected mice.
- Antibiotic treatment and cesarean rederivation successfully controlled and eliminated the pathogen.
Conclusions:
- B cells are essential for effective host defense against Pneumocystis carinii.
- The absence of B cells and serum immunoglobulins significantly increases susceptibility to Pneumocystis pneumonia.
- Further research into B cell-mediated immunity is warranted for understanding and treating opportunistic infections.