Ethnic Differences in MS Evident in Antibody-secreting Cells in Blood, US Study Suggests
People with multiple sclerosis (MS) who self-identify black African or Latin American have a higher number of disease-associated antibody-secreting cells in their blood compared to those who identify as Caucasian, a U.S. study reports.
This difference may account for disparities related to ethnicity in MS prognosis, and may point to distinct underlying mechanisms linked to MS progression.
The study, “Black African and Latino/a identity correlates with increased plasmablasts in MS,” was published in the journal Neurology: Neuroimmunology & Neuroinflammation.
A person’s ethnic origin is an important factor in MS. Patients who identify as either black African or Latin American are likely to experience more severe disease — more and larger brain lesions, faster “brain and retinal degeneration” — than are those who identify as white.
The reason for this disparity is not understood, as no reports cite a direct underlying biological mechanism related to such ethno-based clinical disparity.
Analyses of medical records from patients of different ethnicities note differences in types of immune cells that secrete antibodies — normally present to fight infections. Specifically, elevated levels of antibody-secreting cells (ASCs) have been found in the space around the spinal cord among African-American MS patients compared to Caucasian patients, and this difference has been linked to the deterioration of nerve cells.
Two types of ASCs are plasma cells and immature plasma cells, known as plasmablasts. These cells appear to be important drivers of both the inflammatory and neurodegenerative aspects of MS.
To determine if the poorer prognosis based on ethnic origin can be explained by the numbers of ASCs, a team of researchers at Weill Cornell Medicine in New York collected blood samples from 74 people with relapsing-remitting MS (RRMS) from both black African/Latin American and Caucasian patient groups to determine the numbers of plasmablasts and maturing plasma cells.
An additional 24 age- and ethnic-matched healthy donors (without MS) served as control group.
Of the 74 MS patients analyzed, 39 self-identified as black African or Latin American, while 35 patients identified as Caucasians. In the control group, 11 said they were black African or Latin American, and 13 white.
A total of 54 of the MS patients (27 from each ethnic group) were being treatment with Tysabri (natalizumab, marketed by Biogen), while the remaining 20 were not under treatment.
The team first compared the number of ASCs from MS patients on Tysabri, as this treatment may influence the results. Researchers found significantly different levels, with black African/Latin American patients on average exhibiting higher levels of total ASCs compared with white patients. The subtypes of ASCs associated with inflammation in MS were also enriched in the black African/Latin American group over the Caucasian group.
Analysis was then extended to MS patients who were not using Tysabri. Of these, 60% were treatment-naive, while the others were off therapy for at least two months. In a similar fashion, the team found a higher number of ASCs in black African/Latin American MS patients compared to Caucasians.
In contrast to these findings in patients, no differences in ASC frequency were found among healthy controls. Regardless of ethnic origin, ASCs numbers were the same in healthy individuals.
Overall, “the enhanced peripheral blood plasmablast signature revealed among Black African or Latin American subjects with MS points to distinct underlying mechanisms associated with MS immunopathogenesis,” the researchers wrote. “This dysregulation may contribute to the disease disparity experienced by patient populations of Black African or Latin American ethno-ancestry.”
They believe that “understanding what mediates these differences may be key to unlocking major advancements in diagnostics and therapy, both for MS and other maladies.”
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