Line of Defense

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Science  15 Sep 2000:
Vol. 289, Issue 5486, pp. 1841-1843
DOI: 10.1126/science.289.5486.1841f

The epithelial monolayer of the small intestine needs to be protected well against bacterial colonization and invasion. Specialized Paneth cells, located at the base of the small intestinal crypts of Lieberkühn, contain granules of preformed microbicidal polypeptides known as α-defensins or cryptdins. The Paneth-cell defensins are known to be secreted in response to cholinergic stimulation, but Ayabe et al. discovered that bacteria could stimulate Paneth cells directly to secrete these weapons. When they isolated crypt cells from mouse gut and incubated them with Salmonella typhimurium, Escherichia coli, or Staphylococcus aureus, up to 90% of the bacteria were killed, but only a third as many if cryptdin-negative mutants were used. They found that a wide variety of bacterial antigens stimulated Paneth cells to degranulate, and they concluded that common pattern recognition events triggered the exocytosis. — CA

Nature Immunol.1, 113 (2000).

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