Growing Good-Guy Blood Cells in Culture

By Jan Suszkiw
June 29, 2000

A laboratory method for growing white blood cells called macrophages may bolster studies aimed at combating pathogens that exploit the immune systems of animals and humans.

Multiplying macrophages in culture avoids the standard practice of flushing them from fluids pumped into an animal’s lungs or peritoneal cavity, according to Neil Talbot, at the Agricultural Research Service’s Gene Evaluation and Mapping Laboratory at Beltsville, Md. The work was done with Joan Lunney, Max Paape and Mulumebet Worku of ARS’ Immunology and Disease Resistance Laboratory, also at Beltsville.

In humans and livestock such as pigs, the amoeba-like macrophages help eliminate dead cells, used proteins and other refuse. They also attack bacteria, viruses, fungi or other pathogenic organisms at infection sites. And by “wearing” a dead pathogen’s proteins, macrophages also mobilize the immune system's T-cells and antibody-producing B-cells.

But in pigs, one such pathogen--the virus that causes porcine reproductive and respiratory syndrome (PRRS)--actually infects macrophages to replicate itself. Only partially controlled by existing vaccines and other measures, the PRRS virus causes late-term abortion, stillbirths and other costly problems in pigs.

Talbot hopes veterinary researchers will find macrophage tissue-culturing useful in deciphering the virus's biological machinery. That might reveal weaknesses for finding new drug targets. It may also benefit medical researchers seeking alternatives to using human macrophages derived from cancers. Such cells differ in various ways from normal macrophages.

In published research, Talbot’s team overcame the problem of growing pig macrophages by first culturing precursor cells called monocytes from 10 drops of blood on a special layer of “feeder cells.” After several weeks, a bumper crop of hundreds of millions of mature macrophages is ready for storage or immediate research use. Importantly, macrophage culturing doesn't harm animal donors and yields cells similar to those found in the animals’ bodies.

ARS is the U.S. Department of Agriculture's principal research agency.

Scientific contact: Neil Talbot, ARS Gene Evaluation and Mapping Laboratory, Beltsville, Md., phone (301) 504-8216, fax (301) 504-8414, ntalbot@lpsi.barc.usda.gov.