ST. PAUL, MN -- Differences in immune systems have been found in African Americans with multiple sclerosis (MS) compared to Caucasians, possibly offering a clue why African Americans experience more disability with MS than Caucasians, according to a study published in the July 3, 2007, issue of Neurology, the medical journal of the American Academy of Neurology.

For the study, researchers compared levels of antibodies in the cerebrospinal fluid of 66 African Americans to 132 Caucasians with MS.

The study found antibody levels in the cerebrospinal fluid of African Americans with MS were 29 percent higher than levels found in affected Caucasians.

The findings show that ethnic differences in MS extend to the immune response system, which plays a central role in MS, said study author John R. Rinker, MD, with the Washington University School of Medicine in St. Louis, MO, and member of the American Academy of Neurology.

Rinker says the reason for this biological difference is unknown, but may be related to differences in genetic background.

It remains possible that genes are unevenly distributed between ethnic groups to account for different susceptibility to some diseases, said Rinker. In MS, recent genetic studies have begun to identify certain genes which may explain why African Americans experience more disability, but the products of these genes and the mechanism of their effects remain unknown.

The study found that African Americans had MS for an average of nine years before needing a cane, walker, or wheelchair, compared to an average of 17 years for Caucasians. However, Rinker says the higher values of antibodies in African Americans did not predict an earlier need for help walking.