Reposted from New Scientist:
http://www.newscientist.com/channel/health/mg19426094.400?DCMP=NLC-nletter&nsref=mg19426094.400

IMAGINE having a spare copy of your immune system on ice, ready to replace your existing one should you fall victim to AIDS, an autoimmune disease, or have to undergo extensive chemotherapy for cancer.

An Anglo-American company called Lifeforce has received permission from the US Food and Drug Administration to do just that. The firm collects 480-millilitre samples of blood from healthy individuals, extracts the white blood cells and stores them as an insurance policy against future disease. The service comes at a price, though: around $800 for taking the initial sample then $25 per month for storing the cells at -196 °C. "That sample would have the complete repertoire of all your white blood cells," says Del DelaRonde, co-founder of Lifeforce in Newport, UK.

By taking some of the stored cells and exposing them to natural growth factors such as interleukin-2, whole new armies of white blood cells could be grown in the lab and reinfused into the patient. Many people with cancer undergo similar "adoptive" therapies using immune cells extracted before they have chemo- or radiotherapy, which can destroy immune cells. But there is a risk that the cells won't work optimally because of previous cancer damage, DelaRonde says. "Instead, we can send them their 'pristine' system from 25 years ago."
"Whole new armies of white blood cells could be grown in the lab and reinfused into the patient"

In the case of HIV, which progressively destroys immune cells, the process could be repeated perhaps once a year, by multiplying up and re-storing fractions of the samples.

"These things might be possible," says Francois Villinger of Emory University School of Medicine in Atlanta, Georgia. He previously showed that the progression of SIV infection, the monkey equivalent of HIV, could be delayed in macaques by using a similar approach. Whether it will work in humans is unknown, he says.

Also, some types of white blood cell, such as macrophages, may not survive freezing as well as others, meaning there may be a limit to the number of cells you could regenerate from the samples.

Last month, Lifeforce also won permission to expand its UK operations.

From issue 2609 of New Scientist magazine, 23 June 2007, page 8