NEW YORK (Reuters Health) - The abnormal immune response that leads to multiple sclerosis, or MS, is stronger in African Americans than in whites with the disease, new research indicates. This may partly explain why blacks often experience greater disability.

MS develops when myelin, the insulating tissue around neurons in the brain, is attacked by the body's own immune system. "The findings show that ethnic differences in multiple sclerosis extend to the immune response system, which plays a central role in multiple sclerosis," Dr. John R. Rinker, from Washington University School of Medicine in St. Louis, said in a statement.

The results, which appear in the medical journal Neurology, stem from a comparison of the immune responses seen in 66 African Americans with multiple sclerosis and in 132 whites with the disease.

The researchers found that levels of antibodies responsible for anti-myelin activity in the cerebrospinal fluid are higher in blacks than whites.

While this finding might help explain some of the racial differences seen with multiple sclerosis, it remains unclear why African Americans typically require help with walking earlier in the course of the disease.

Consistent with previous reports, the African American patients in the current study required assistance with walking sooner than did their white counterparts. However, the cerebrospinal antibody level was not related to earlier ambulatory assistance.

"It remains possible that genes are unevenly distributed between ethnic groups to account for different susceptibility to some diseases," Rinker noted. "In multiple sclerosis, recent genetic studies have begun to identify certain genes which may explain why African Americans experience more disability." However, exactly what these genes do remains unknown.

SOURCE: Neurology, July 3, 2007