Harvest of white blood cells.

Harvest of white blood cells 

Although white blood cells are critical to the body's defense against disease, they are normally present only at low levels. Scientists who study the role of these cells in immunity must kill animals, or repeatedly draw blood from them, to obtain material for the research. Now a U.S. Department of Agriculture (USDA) researcher has developed a hollow sphere that can be implanted under the skin to collect white blood cells continuously for weeks without harming the animal.

The new collector is a plastic sphere with membrane-covered holes and two attached tubes. When it is implanted, white blood cells invade the area in response to the irritation. These cells then send chemical signals through the blood to recruit more of the migratory cells, which continue to enter the sphere. The scientists collect the cells by flushing a salt solution through the tubes that extend from the sphere to outside the animal's skin. In a day, the sphere collects millions of white blood cells, says the device's developer, Phillip H. Klesius of the USDA Parasite Research Laboratory in Auburn, Ala. It would take at least several days to collect as many cells by bleeding an animal.

Klesius implanted the device, 1.5 inches in diameter, beneath the underbelly skin of 20 cattle to collect cells for his own immunological research. "The best thing about this method is that the animal does not seem to miss the cells removed," Klesius says. He speculates that there may someday be a clinical need for such a device. For example, some current experimental procedures take blood from patients, treat the white blood cells with chemicals or radiation and then return them to the body (SN: 4/13/85, p. 229).