Magazine article Science News

Multiplied Immune Cells Combat HIV

Magazine article Science News

Multiplied Immune Cells Combat HIV

Article excerpt

Cytotoxic T lymphocytes, or CTLs, richly deserve their nickname--killer cells. CTLs spot cells that have been invaded by viruses and kill them off. They even target immune cells infected by HIV, the virus that causes AIDS. Some HIV-positive people who have avoided AIDS for years have strong CTL counts.

However, some scientists doubt that CTLs play a great role against HIV. HIV-specific CTLs lurk mostly in the bloodstream, they note, whereas HIV tends to invade lymph nodes. There, the virus infects an immune cell called the helper T cell, which directs a range of immune responses. Moreover, some researchers fear that CTLs revved up to kill HIV-infected helper T cells may run amok and destroy healthy helper T cells or allow mutating HIV to escape and reproduce. Both would pose risks to a compromised immune system.

Researchers now have evidence that CTLs indeed attack HIV in lymph tissue and seem to distinguish between healthy and infected helper T cells. To gauge CTLs' effect on HIV, researchers took CTLs from the blood of three HIV-positive people who were receiving antiviral treatment. Over an 8-week period, the scientists mass-produced the CTLs, marking some with a slight genetic difference for tracking purposes. The researchers then injected CTLs derived from each person back into that individual, a total of about 13 billion cells in five infusions at 2-week intervals.

The CTLs seemed to know where to go to fight HIV, says study coauthor Stanley R. Riddell, an immunologist at the Fred Hutchinson Cancer Research Center in Seattle. …

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