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Cutting edge: profound defect in T cell responses in TNF receptor-associated factor 2 dominant negative mice
Jennifer L Cannons1, Edward M Bertram, Tania H Watts
1Department of Immunology, University of Toronto, Toronto, Ontario, Canada.
Abstract:
TNFR-associated factor 2 (TRAF2) is an adapter protein that links several members of the TNFR family to downstream signaling pathways. Mice expressing a dominant negative form of TRAF2 in their lymphoid cells (TRAF2.DN mice) have a profound defect in T cell responses to allogeneic APC. In contrast, APC from wild-type or TRAF2.DN mice show an equivalent level of stimulation in a MLR. Ab production and class switch are unimpaired in TRAF2.DN mice. Thus, defects in the TRAF.DN mice appear to be limited to T cells. TRAF2.DN mice demonstrate an impaired T cell response to influenza virus, including decreased secondary expansion of IFN-gamma-secreting T cells as well as a decrease in CTL activity. CD4 T cell production of IL-2 was also dramatically impaired in TRAF2.DN mice. These studies suggest an essential role of TRAF2-linked receptors in secondary CD4 and CD8 T cell responses and have important implications for transplantation.
Insights
Tumor necrosis factor receptor-associated factor 2 (TRAF2) is crucial for T cell responses. TRAF2.DN mice show impaired T cell immunity, impacting adaptive immunity and viral responses, with implications for transplantation.
Area of Science:
- Immunology
- Molecular Biology
Background:
- TNFR-associated factor 2 (TRAF2) acts as an adapter protein, connecting TNFR family members to downstream signaling.
- TRAF2 is essential for various immune cell functions and signal transduction.
Purpose of the Study:
- To investigate the role of TRAF2 in T cell responses using a dominant-negative mouse model (TRAF2.DN).
- To elucidate the specific defects in T cell immunity caused by the absence of functional TRAF2.
Main Methods:
- Generation of mice expressing a dominant-negative form of TRAF2 in lymphoid cells (TRAF2.DN mice).
- Assessment of T cell responses, including mixed lymphocyte reactions (MLR), antibody production, and responses to viral infections.
- Analysis of T cell proliferation, cytokine production (IL-2, IFN-gamma), and cytotoxic T lymphocyte (CTL) activity.
Main Results:
- TRAF2.DN mice exhibited profound defects in T cell responses to allogeneic antigen-presenting cells (APCs).
- APC stimulation in MLR was equivalent between wild-type and TRAF2.DN mice, indicating T cell-specific defects.
- Impaired T cell responses to influenza virus, including reduced secondary expansion of IFN-gamma-secreting T cells and diminished CTL activity.
- Significantly impaired CD4 T cell production of IL-2 in TRAF2.DN mice.
Conclusions:
- TRAF2 plays an essential role in secondary CD4 and CD8 T cell responses.
- TRAF2-dependent signaling is critical for effective adaptive immunity against viral challenges.
- These findings have significant implications for understanding T cell function in transplantation immunology.