Multiple Sclerosis (MS) is a progressive disabling illness that affects nerve cells in the brain and spinal cord (Bernard). Under normal conditions an insulating sheath made of fatty myelin, which speeds the passage of nerve impulses, surrounds these nerve cells. In MS, this mye

lin sheath is inflamed or damaged, disrupting nerve impulses and leaving areas of scarring (sclerosis). The disruption of nerve signals within the brain and spinal cord causes a variety of symptoms that may affect vision, sensation, and body movements. These symptoms usually wax and wane through a series of relapses (episodes when symptoms suddenly get worse) alternating with remissions (periods of recovery, when symptoms improve). (Brunnscheiler) For many patients, a long history of MS attacks over several decades’ leads to slowly progressing disability, but for others the disability is more rapid and severe. MS is a life-long chronic disease diagnosed primarily in young adults who have a virtually normal life expectancy. Consequently, the economic, social, and medical costs associated with the disease are significant. Estimates place the annual costs of MS in the United States in excess of $2.5 billion. (Melvin) No one knows exactly how many people have MS. It is believed that, currently, there are approximately 250,000 to 350,000 people in the United States with MS diagnosed by a physician. (Boyden) This estimate suggests that approximately 200 new cases be diagnosed each week. Also, MS is the most common nerve disease to develop in young persons after birth, and it affects over 1 million young adults worldwide. Close relatives of a person with MS are 8 times more likely than average to develop the disease themselves, and children of a person with MS run 30 to 50 times the average risk. (Waxman) Most people experience their first symptoms of MS between the ages of 20 and 40, but a diagnosis is often delayed. This is due to both the transitory nature of the disease and the lack of a specific diagnostic test--specific symptoms and changes in the brain must develop before the diagnosis is confirmed. (Health Central) Although scientists have documented cases of MS in young children and elderly adults, symptoms rarely begin before age 15 or after age 60. Whites are more than twice as likely as other races to develop MS. In general, women are affected at almost twice the rate of men; however, among patients who develop the symptoms of MS at a later age, the gender ratio is more balanced. (Waxman) To understand what is happening when a person has MS, it is first necessary to know a little about how the healthy immune system works. The immune system -- a complex network of specialized cells and organs -- defends the body against attacks by "foreign" invaders such as bacteria, viruses, fungi, and parasites. It does this by seeking out and destroying the interlopers as they enter the body. Substances capable of triggering an immune response are called antigens. (Hofmann) The immune system displays both enormous diversity and extraordinary specificity. (Hofmann) It can recognize millions of distinctive foreign molecules and produce its own molecules and cells to match up with and counteract each of them. In order to have room for enough cells to match the millions of possible foreign invaders, the immune system stores just a few cells for each specific antigen. When an antigen appears, those few specifically matched cells are stimulated to multiply into a full-scale army. Later, to prevent this army from overextending, powerful mechanisms to suppress the immune response come into play. T-cells, so named because they are processed in the thymus, appear to play a particularly important role in MS. They travel widely and continuously throughout the body patrolling for foreign invaders. In order to recognize and respond to each specific antigen, each T cell's surface carries special receptor molecules for particular antigens. T cells contribute to the body's defenses in

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