Macrophage suppression of T cell activation: A potential mechanism of peripheral tolerance

John T. Attwood, David H Munn

Research output: Contribution to journalReview articlepeer-review

20 Scopus citations


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 languageEnglish (US)
Pages (from-to)515-525
Number of pages11
JournalInternational Reviews of Immunology
Issue number5-6
StatePublished - 1999


  • Alveolar macrophages
  • Auto-reactive
  • Macrophages
  • Suppression
  • T Cells
  • Tolerance

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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