T Cells Fighting Infection Get Exhausted

T cells — immune cells battling a chronic viral infection — become exhausted, making them less effective over time, a U.S. study found.

Although the experiments were conducted in mice, the problem of T-cell exhaustion has also been identified in HIV, hepatitis B and hepatitis C infections in humans, as well as in some cancers, lead author E. John Wherry of The Wistar Institute in Philadelphia said.

Using a technique called gene-expression profiling, Wherry and colleagues identified 490 genes whose activity in T cells is altered during a chronic viral infection.

The study, published in the journal Immunity, found that at the end of two months, T cells contending with a chronic infection were sluggish metabolically, and immunologically unresponsive to stimulus.

We knew that T cells responding to chronic infections become progressively compromised in many of their functional properties, Wherry said in a statement. Put simply, the T cells become exhausted as time passes.