Antibody Linked to MS Significantly Higher in Spinal Fluid of Blacks
Antibody Linked to MS Significantly Higher in Spinal Fluid of Blacks
Description
An antibody frequently used as a diagnostic marker for multiple
sclerosis (MS) is present at greater levels in the cerebrospinal
fluid of blacks with MS than Caucasians with the disease.
Newswise — An antibody frequently used as a diagnostic marker for
multiple sclerosis (MS) is present at greater levels in the
cerebrospinal fluid of blacks with MS than Caucasians with the disease.
The findings suggest that genetic differences among ethnic groups
contribute to changes in the immune system, affecting susceptibility
to MS. And they add another piece to a tantalizing but stubborn
puzzle: Why do blacks get MS less often than other ethnic groups but
suffer more serious symptoms when they develop the disease?
“These antibodies are indicators of inflammation, but we don’t yet
understand how inflammation is linked to prognosis,” says first
author John R. Rinker II, M.D., who did the work as a fellow at
Washington University School of Medicine in St. Louis and is now
assistant professor of neurology at the University of Alabama at
Birmingham. “No one really understands yet why inflammation levels
differ from one MS patient to the next.”
The new study measured cerebrospinal fluid levels of IgG, an immune
system antibody. Rinker and others have previously linked greater IgG
to more aggressive MS in the general patient population. But that
same link could not be reestablished in the new study, which assessed
disease severity by comparing the time from MS diagnosis to when the
patient first needed assistance walking. Black patients needed help
walking sooner — an average of nine years after diagnosis versus 17
years for Caucasians — but on a case-by-case basis, scientists
couldn’t use greater IgG to predict an earlier need for assistance in
walking.
“It may be that we haven’t yet focused on the right disease
characteristic or milestone in our search for factors that correlate
with spinal inflammation,” says Rinker. “I’m hoping to expand the
search for correlations in follow-up studies.”
The results are published in the July 3 issue of Neurology.
Epidemiologists estimate that 400,000 people in the United States
have MS. Symptoms, which often strike in episodic bursts, include
bladder and bowel dysfunction, memory problems, fatigue, dizziness,
depression, difficulty walking, numbness, pain and vision problems.
The disease is more common among Caucasians than any other group and
affects two to three times as many women as men.
Research has shown that genetic factors contribute to MS risk but are
not the sole determining factor. Scientists believe MS is likely
triggered by a bacterial or viral infection. The infection causes an
abnormal response in the immune system that misdirects the body’s
defenses against myelin, a protective sheath that surrounds many
nerve cells.
To help clinch a diagnosis of MS, clinicians often test the spinal
fluid for elevated levels of IgG. Since everyone makes IgG as a part
of normal immune function, scientists have to assess cerebrospinal
IgG levels using an index that also factors in the amount of IgG in
the patient’s blood and the integrity of the blood-brain barrier,
which limits access to the brain.
“High IgG levels in a healthy person’s bloodstream can cause this
antibody to seep over into the cerebrospinal fluid, so a high level
of spinal IgG isn’t by itself very revealing,” explains senior author
Anne Cross, M.D., professor of neurology and head of the
neuroimmunology section. “What’s different in MS patients is that
they make IgG in the central nervous system. We can determine that
this is the case by using the IgG index.”
Working at the John L. Trotter MS Center at Washington University,
Rinker analyzed samples from 66 black patients with MS and 132
Caucasians with the disease. According to the index, blacks’ IgG
levels were 29 percent higher.
Study coauthor Rob Naismith, M.D., and others have previously shown
that while blacks develop MS less frequently, the consequences are
often more serious.
“Lower access to care and to medication may contribute to this
effect, but apart from those potential contributing factors, African
Americans with MS still seem to have more aggressive forms and suffer
more disability,” Cross says.
