African American patients with Multiple Sclerosis (MS) have higher proportions of CD19+ and CD20+ B-cell lineage cells in their cerebrospinal fluid than White MS patients

•We compared cell populations in CSF of African-American (AA) and White MS patients.•AA patients had a much higher percentage of B-lineage cells in CSF than White patients.•Other cell populations were not significantly different in AA and White patients. To compare proportions of B-cell lineage CD19+ and CD20+ cells in CSF of African-American (AA) and White (W) patients with MS. AA MS patients are more likely to have oligoclonal bands in CSF, higher IgG index in CSF, and higher circulating plasmablasts in blood than W MS patients. It is unknown whether the proportion of B-cells in CSF differs between AA and W patients in MS. Demographics, disease-related information, treatment history were retrospectively collected on patients with MS who self-identified as AA or W and underwent flow cytometry of CSF during diagnostic work-up. Proportion of B-lymphocytes, T-lymphocytes, NK cells, monocytes, and plasma cells were analyzed with flow cytometry. 20 AA and 56 W MS patients fulfilled our inclusion criteria. The groups had similar demographics, CSF cell counts, protein and glucose CSF concentrations, and oligoclonal band number. IgG index was higher in AA compared to W (1.08 vs. 0.85, p = 0.031). AA had higher proportions of CD19+ (5.46 % AA vs. 2.26 % W, p = 0.006) and CD20+ (4.64 % AA vs. 1.91 % W, p = 0.004) cells but did not significantly differ in proportion of CD4+, CD8+, CD38+ bright B-cells, NK cells and monocytes. B-cells are overrepresented in the CSF of African American patients with MS relative to Whites.