Abstract
The mechanisms of induction and maintenance of tolerance in self-reactive T cells in the periphery are poorly understood. Current models assume that successful T cell activation only occurs if ligation of the T cell receptor (signal 1) by antigen presenting cells (APCs) is accompanied by a costimulatory signal (signal 2), and that signal 1 in the absence of signal 2 is either ignored or is tolerizing. However, there is also evidence for the existence of macrophages (Mφ) capable of suppressing T cell activation both in vitro and in vivo. The possibility of a more actively induced tolerance exists, in which the Mφ itself responds to T cell-mediated signals in a tolerogenic fashion. This would help to resolve the paradox that tissue Mφ, which act as scavengers of self-antigen, can also act as professional APCs. The ability of tissue macrophages to actively suppress T cells would further underscore the importance of the innate immune system in regulating adaptive immune responses.
Original language | English (US) |
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Pages (from-to) | 515-525 |
Number of pages | 11 |
Journal | International Reviews of Immunology |
Volume | 18 |
Issue number | 5-6 |
DOIs | |
State | Published - 1999 |
Keywords
- Alveolar macrophages
- Auto-reactive
- Macrophages
- Suppression
- T Cells
- Tolerance
ASJC Scopus subject areas
- Immunology and Allergy
- Immunology