Higher IgG index found in African Americans versus Caucasians with multiple sclerosis.
BACKGROUND
African Americans (AAs) experience greater disability from multiple sclerosis (MS) compared with Caucasian Americans (CAs). Interethnic immunologic differences in MS and their relationship to disease-related disability have not been described.


OBJECTIVE
To compare measures of CSF humoral immunity between AAs and CAs with MS.


METHODS
Using a case-control design, all AA MS patients with CSF immune studies at the Washington University MS center were compared with randomly selected CAs with MS. Two CA controls were selected for every AA case. Immunoglobulin G (IgG) index and synthesis rates, oligoclonal band positivity, white blood cell count, and CSF protein were compared between groups. Survival analysis was conducted to compare times to ambulatory assistance.


RESULTS
Sixty-six AA cases and 132 CA controls were identified. Measures of CSF humoral activity were all higher in the AA group. The mean IgG index of AAs was 1.35 (SD 0.62), and that of CAs was 1.05 (SD 0.55), for a mean difference of 0.30 (p = 0.001). The median IgG synthesis rate was also higher among AAs (13.55 vs 8.20 mg/day), for a median difference of 5.35 mg/day (p = 0.010). Survival analysis confirmed previous reports of earlier ambulatory assistance requirement among AAs. Despite differences in both humoral immune response and times to ambulatory assistance, Cox proportional hazards modeling did not show IgG index as predictive of earlier ambulatory assistance.


CONCLUSIONS
The CSF humoral immune response is more active among African Americans (AAs) than among Caucasian Americans (CAs) with multiple sclerosis. AAs also progress to ambulatory assistance earlier than CAs, but high immunoglobulin G index does not predict earlier progression to the disability endpoint.
Rinker
John R
JR
Department of Neurology and Neurosurgery, Washington University School of Medicine, St. Louis, MO, USA. rinkerj@neuro.wustl.edu
Trinkaus
Kathryn
K
Naismith
Robert T
RT
Cross
Anne H
AH
D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data*; D017668:Age of Onset; D016022:Case-Control Studies; D002556:Cerebrospinal Fluid Proteins / Q000032:analysis*; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000134:cerebrospinal fluid*; D007155:Immunologic Factors / Q000627:therapeutic use; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D007249:Inflammation; D053208:Kaplan-Meier Estimate; D007958:Leukocyte Count; D008297:Male; D008923:Missouri / Q000453:epidemiology; D009103:Multiple Sclerosis / Q000134:cerebrospinal fluid / Q000188:drug therapy / Q000453:epidemiology / Q000276:immunology*; D043025:Oligoclonal Bands / Q000134:cerebrospinal fluid; D009902:Optic Neuritis / Q000453:epidemiology / Q000209:etiology; D044465:White People / Q000706:statistics & numerical data*
D002556:Cerebrospinal Fluid Proteins; D007074:Immunoglobulin G; D007155:Immunologic Factors; D007166:Immunosuppressive Agents; D043025:Oligoclonal Bands