A Man appears free of HIV after stem cell transplant

A 42-year-old HIV patient with leukemia appears to have no detectable HIV in his blood and no symptoms after a stem cell transplant from a donor carrying a gene mutation that confers natural resistance to the virus that causes AIDS, according to a report published Wednesday in the New England Journal of Medicine.

The case was first reported in November, and the new report is the first official publication of the case in a medical journal. Hutter and a team of medical professionals performed the stem cell transplant on the patient, an American living in Germany, to treat the man's leukemia, not the HIV itself.

However, the team deliberately chose a compatible donor who has a naturally occurring gene mutation that confers resistance to HIV. The mutation cripples a receptor known as CCR5, which is normally found on the surface of T cells, the type of immune system cells attacked by HIV.The mutation is known as CCR5 delta32 and is found in 1 percent to 3 percent of white populations of European descent.

HIV uses the CCR5 as a co-receptor (in addition to CD4 receptors) to latch on to and ultimately destroy immune system cells. Since the virus can't gain a foothold on cells that lack CCR5, people who have the mutation have natural protection. (There are other, less common HIV strains that use different co-receptors.)

People who inherit one copy of CCR5 delta32 take longer to get sick or develop AIDS if infected with HIV. People with two copies (one from each parent) may not become infected at all. The stem cell donor had two copies.