Lending support to a controversial theory of how the immune system works, researchers have found that injured or dying cells release uric acid, which then stimulates the activity of key immune cells.
Biologists have long described the immune system as something that distinguishes self from nonself, attacking invaders such as infectious microbes but not the body's own tissues. Some investigators have argued that this paradigm is flawed–after all, the human body safely provides a home for many microbes (SN: 5/31/03, p. 344: Gut Check)–and have proposed alternative theories. For example, Polly Matzinger, an immunologist at the National Institutes of Health in Bethesda, Md., suggests that the immune system reacts to microbes only after infected or injured cells have released danger signals.
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