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Murine malaria is exacerbated by CTLA-4 blockade
Thomas Jacobs1, Sebastian E B Graefe, Sonja Niknafs
1Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany. tjacobs@bni.uni-hamburg.de
Journal of Immunology (Baltimore, Md. : 1950)
|August 24, 2002
Summary
Cytolytic T lymphocyte-associated antigen-4 (CTLA-4) normally limits T cell responses. Blocking CTLA-4 in malaria models worsened disease, suggesting its protective role against immune pathology.
Area of Science:
- Immunology
- Parasitology
- Pathology
Background:
- Cytolytic T lymphocyte-associated antigen-4 (CTLA-4) is a key negative regulator of T cell activation.
- CTLA-4 expression increases on activated T cells during Plasmodium berghei infection in mice.
Purpose of the Study:
- To investigate the role of CTLA-4 in experimental blood-stage malaria.
- To determine if CTLA-4 blockade exacerbates malaria-induced pathology.
Main Methods:
- Kinetic analysis of CTLA-4 expression on CD4+ T cells in infected mice.
- In vivo blockade of CTLA-4 using a specific monoclonal antibody (mAb).
- Histological examination of brain tissues and assessment of T cell responses.
Main Results:
- CTLA-4 expression peaked on day 9 post-infection, with nearly 10% of splenic CD4+ T cells expressing it.
- CTLA-4 blockade led to neurological signs of cerebral malaria and premature death.
- Anti-CTLA-4 treatment reversed CD4+ T cell loss and restored suppressed T cell responses.
Conclusions:
- CTLA-4 expression acts as a crucial mechanism to prevent immune pathology by limiting T cell activation during malaria.
- Failure to down-regulate T cell activation, potentially due to impaired CTLA-4 function, contributes to cerebral malaria development.