MS researchers find missing immune link.

MS Researchers find missing immune link

New research shows that people with multiple sclerosis (MS) have immune cells that react with myelin basic protein, a key component of the protective sheaths surrounding nerve fibers in the brain and spinal cord. The finding raises the possibility that researchers may one day devise better treatment strategies for patients with this neurologic disease.

Other researchers had previously implicated myelin basic protein in the development of a neurologic disease in mice. They discovered that injecting healthy mice with the protein caused the mice to develop a central nervous system disorder similar to MS. Although the connection between myelin basic protein and the MS-like disease in mice was clear, researchers were unable to implicate the protein and the immune system in the development of human MS.

Now, Mark Allegretta, Subramaniam Sriram and their colleagues at the University of Vermont in Burlington report in the Feb. 9 SCIENCE that their clones of certain immune cells caled T-lymphocytes (T-cells) obtained from the blood of MS patients indeed react to myelin basic protein. Scientists believe these T-cells proliferate in response to the protein and release substances that damage myelin. This, in turn, short-circuits electrical messages sent from the central nervous system to the rest of the body.

Other research teams had sought such activated T-cells in the blood of MS patients but failed because their methods weren't sensitive enough to find the few T-cells that respond to myelin basic protein, Allegretta says. Rather than example all T-cells in the blood, the Vermont team studied those that had undergone a genetic mutation -- often a sign of recent cell division. Focusing on this subset narrowed the search, because T-cells are believed to divide in response to myelin basic protein.

When they exposed the mutant cells to myelin basic protein in the laboratory, the researchers observed that cell division began in 11 of 258 cells derived from the blood of five of the six MS patients in their study. This suggests that these T-cells react to the protein in the body as well, they say. In contrast, none of the T-cells taken from healthy controls responded to the protein.

The new findings may help point the wayto a therapy specifically designed to block the body's immune response to myelin basic protein, comments David A. Hafler at Harvard Medical School in Boston. Such a treatment, if given early in the course of the disease, might halt the progressive myelin destruction and prevent the disabling symptoms of MS, he says.