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Apoptosis induction by macrophage-derived reactive oxygen species in myelin-specific T cells requires cell-cell
1Department of Neurology, University of Rostock, Germany.
Abstract:
Apoptosis of autoreactive T cells has been recognized as an important mechanism of immune homeostasis in autoimmune PNS diseases. To examine whether T cells are induced to undergo apoptosis by macrophages (Mphi) via reactive oxygen species (ROS) neuritogenic P2-specific T line cells were exposed to peritoneal Mphi of Lewis rats in vitro. ROS production was stimulated by phorbol myristate acetate (PMA) and inhibited by catalase. Flow cytometric analysis of apoptosis as measured by TUNEL technique revealed that 5-15% of all P2-cells were apoptotic, if cultured alone. This percentage increased slightly, but did not exceed 20% when P2-cells were cocultivated with PMA-stimulated Mphi in a two-chamber culture plate separated by a cell-impermeable membrane. Direct cocultivation caused apoptotic cell death of more than 40% of P2-cells, which was completely abrogated by catalase. These results suggest a requirement for close cell-cell contact for apoptosis induction of T cells via Mphi-derived ROS. Thus Mphi may contribute to termination of inflammation in vivo through the release of highly reactive oxygen species that mediate apoptotic cell death of autoaggressive T lymphocytes.
Insights
Macrophages induce apoptosis in autoreactive T cells through reactive oxygen species (ROS) requiring close cell contact. This mechanism may help resolve autoimmune peripheral nervous system (PNS) diseases.
Area of Science:
- Immunology
- Neuroscience
- Cell Biology
Background:
- Apoptosis of autoreactive T cells is crucial for immune homeostasis in autoimmune peripheral nervous system (PNS) diseases.
- Macrophages (Mphi) are key immune cells involved in regulating T cell responses.
Purpose of the Study:
- To investigate if macrophages induce apoptosis in T cells via reactive oxygen species (ROS).
- To determine the role of cell-cell contact in macrophage-mediated T cell apoptosis.
Main Methods:
- Neuritogenic P2-specific T line cells were co-cultured with peritoneal macrophages from Lewis rats in vitro.
- Reactive oxygen species (ROS) production was stimulated using phorbol myristate acetate (PMA) and inhibited by catalase.
- Apoptosis was quantified using flow cytometry and the TUNEL technique.
Main Results:
- In vitro culture of T cells alone resulted in 5-15% apoptosis.
- Co-culturing T cells with PMA-stimulated macrophages in a separated system (cell-impermeable membrane) slightly increased apoptosis to <20%.
- Direct co-cultivation of T cells with stimulated macrophages led to >40% apoptotic cell death, which was blocked by catalase, indicating Mphi-derived ROS mediate apoptosis.
Conclusions:
- Close cell-cell contact is necessary for macrophages to induce T cell apoptosis via ROS.
- Macrophages may terminate autoimmune inflammation in vivo by inducing apoptotic cell death of autoaggressive T lymphocytes through ROS release.