New research in the February 2007 issue of Nature Immunology reveals why the immune system remains in check and does not attack gut tissues despite being full of bacteria.
Previous work revealed microbial compounds are powerful inducers of immune responses, yet this poses a dilemma for the gut. Shannon Turley and colleagues sought to address this question. They identified specific cells found in regional lymph nodes that express proteins previously thought only to be expressed in highly specialized tissues or organs, such as the eye, gut or pancreas. The resident lymph node cells present these tissue-specific proteins to immune cells, thereby rendering them tolerant of and harmless toward the tissues expressing these proteins.
Importantly, these lymph node cells differ from conventional antigen-presenting cells that activate the immune system and are responsive to bacterial products. These findings identify another means by which the body protects itself against autoimmune attack.
Shannon J. Turley (Dana Farber Cancer Institute, Boston, MA, USA)
Additional comment on the paper:
Michael J. Bevan (University of Washington, Seattle, WA, USA)
Abstract available online.
(C) Nature Immunology press release.
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