The study lays the groundwork for a way to determine when a relapse is about to occur, and could eventually lead to a treatment to prevent relapses. "Right now, there is no good blood test to evaluate when a person is going to have a flare-up," said senior author Larry Steinman, MD, professor of neurology and neurological sciences. "If we had one, we might be able to give them prophylactic preventive medication."

Steinman found that a protein called osteopontin was abundant in multiple sclerosis-affected brain tissue, but not in normal tissue. Since then, other groups have confirmed that osteopontin is elevated just prior to and during a relapse of the disease in M.S. patients. Although the protein had been known to play a role in bone growth, it was unclear why it would be associated with multiple sclerosis, which results when the immune system attacks the protective myelin sheath surrounding nerve cells.

Through mouse studies Steinman showed that osteopontin - produced by immune cells and brain cells - promotes the survival of the T cells that carry out the damaging attack on myelin; by increasing the number of these T cells, osteopontin increases their destructive potential. These results could be applicable to many other autoimmune diseases, including rheumatoid arthritis, type-1 diabetes and lupus. One of the ways that the immune response is muffled is that the activated T cells die in a process known as apoptosis. That is precisely what osteopontin seems to prevent. Osteopontin lets the T cells linger in the blood, ready to attack again.

Further study will determine whether thwarting osteopontin's effect yields new types of treatments for autoimmune diseases. "I think osteopontin will turn out to be important in a lot of processes, spanning autoimmunity to stem cells," said Steinman. "It's probably going to turn out to be a very basic growth factor."; Source: Stanford University Medical Center