Undereducated immune cells get aggressive with HIV

Scientists uncover a mechanism that may explain some resistance to the AIDS virus

A new study suggests that a lack of education allows some people who have been infected with HIV to keep the virus in check.

Not education in the traditional sense; this inadequate schooling takes place in the thymus, where immune cells are taught to distinguish friendly cells from invaders.

People with one version of a protein called HLA-B*5701 have immune cells that never fully learn this task. A new study published online May 5 in Nature shows how these uneducated cells help keep HIV down. The discovery may one day be helpful in designing vaccines against HIV and other viruses.

An unusual ability crops up in people who have the special protein: Their immune systems are much better at latching on to the proteins of HIV and other viruses, reports a team of researchers led by Arup Chakraborty of MIT and Bruce Walker of the Ragon Institute in Charlestown, Mass. This ability to get a death grip on viral proteins, even when the virus mutates and changes its appearance, comes from immune cells that haven’t learned to recognize the body’s own proteins, the team found.

Immune cells called T cells are born in the bone marrow and then travel to the thymus, where they encounter and learn to recognize the body’s own proteins. Only T cells that ignore the body’s own components while reacting to foreign proteins graduate from the thymus to become part of the army of immune cells that fight infection throughout the body, Chakraborty says. His team found that during their education, T cells from people with HLA-B*5701 see fewer bits of the body’s own proteins. As a result, once the T cells leave the thymus, they think they see foreigners everywhere.

That can be a problem because these undereducated T cells sometimes mistake normal body proteins for invaders and attack, causing autoimmune diseases such as psoriasis and creating hypersensitivity to some drugs. But these aggressive, undereducated T cells are also better at attacking HIV.

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

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