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The gene for a T lymphocyte triggering factor from African trypanosomes
T Vaidya1, M Bakhiet, K L Hill
1Department of Biochemistry, University of Iowa, and the Howard Hughes Medical Institute, Iowa City, Iowa 52242, USA.
The Journal of Experimental Medicine
|August 4, 1997
Summary
African trypanosomes secrete a factor, T lymphocyte triggering factor (TLTF), that stimulates CD8+ T cells to produce interferon-gamma (IFN-gamma). This finding reveals a novel mechanism by which parasites manipulate the host immune response.
Area of Science:
- Immunology
- Parasitology
- Molecular Biology
Background:
- Interferon-gamma (IFN-gamma) is crucial for immune responses against viruses and protozoa.
- African trypanosome infections show elevated IFN-gamma levels that do not confer protection.
- African trypanosomes express T lymphocyte triggering factor (TLTF), which induces IFN-gamma production.
Purpose of the Study:
- To isolate the gene for TLTF.
- To characterize the function of recombinant TLTF in T cell activation.
- To determine the localization of TLTF within trypanosomes.
Main Methods:
- Gene isolation and cloning of TLTF.
- Recombinant TLTF production and in vitro T cell stimulation assays.
- TLTF-green fluorescent protein fusion for subcellular localization studies.
Main Results:
- The gene for TLTF was isolated.
- Recombinant TLTF specifically induced CD8+ T cells, but not CD4+ T cells, to secrete IFN-gamma.
- TLTF was localized to vesicles near the flagellar pocket in trypanosomes.
Conclusions:
- TLTF is a parasite-secreted factor that selectively activates CD8+ T cells to produce IFN-gamma.
- TLTF represents a new class of molecules, termed 'trypanokines', that modulate host immunity.
- These findings shed light on parasite strategies to manipulate the host immune system for survival.