The human immune system is a nearly perfect defense mechanism. It protects the body from disease-causing bacteria, viruses, and other pathogens. It detects nascent tumors and eradicates them. It cleans up cellular debris at the site of injury or infection.
To perform its myriad functions, the immune system must, above all, differentiate between self and non-self — a remarkable selective ability that allows it to detect and disable harmful agents while sparing the body’s own tissues.
If the immune system fails to make this distinction, it can mistakenly launch an assault against the body, causing autoimmune disorders.
Researchers have known the general principle underlying this selective ability for some time, but exactly how immune cells learn to distinguish friend from foe has remained less well understood.
Now, a new study led by researchers at Harvard Medical School identifies a new mechanism that explains how the body’s most powerful immune troops — T cells — learn to tell self and non-self apart.
The work, conducted mainly in mice, was published online June 16 in Cell and is scheduled to appear in the July 7 print issue.
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