To compare proportions of B-cell lineage CD19+ and CD20+ cells in CSF of African-Americans (AA) and White (W) patients with MS.

Demographics, disease-related information, and treatment history were retrospectively collected on patients with neurologist-diagnosed MS who self-identified as AA or W, received care at NYU MS Care Center, and underwent flow cytometry of CSF during diagnostic work-up. Lymphocyte subsets (B-lymphocytes, T-lymphocytes, NK cells), monocytes and plasma cells were analyzed with flow cytometry (BD FACSCanto™ and FACSCanto™ II Cell Analyzers).

20 AA and 57 W MS patients fulfilled inclusion criteria. The groups had similar age at lumbar puncture, sex ratio, CSF cell counts, protein and glucose CSF concentrations, and oligoclonal band number. IgG index was higher in AA compared to W (1.08 v 0.87, p=0.044). With respect to mononuclear cell counts in CSF, AA had higher proportions of CD19+ (5.45% AA v. 2.27% W, p=0.0061) and CD20+ (5.00% AA v. 1.95% W, p=0.0046) cells, but did not significantly differ in proportion of CD4+, CD8+, CD38+ bright B-cells, NK cells and monocytes. Sensitivity analyses that excluded all patients on disease-modifying therapy at the time of lumbar puncture (n=8) yielded similar conclusions.

B-cells are overrepresented in the CSF of African American patients with MS relative to Whites. Whether this finding bears on the increased severity of MS disease course in AA patients warrants investigation.