Abstract
Demyelination during multiple sclerosis (MS) can be associated with B-cells that can produce au-toreactive antibodies and can be localized in specialized lymphoid follicles within the central nervous system. Using multicolor flow cytometry, it was found out that the relative number of peripheral blood CD19+ B cells in patients with MS (n = 25) was significantly higher (p = 0.005) when compared with the healthy volunteers (n = 27, 17.88 % (12.88, 25.15) and 11.77 % (9.52, 15.26), respectively). To identify the distinct B lymphocytes subsets we studied coexpression of IgD and CD38, IgD and CD27, as well as CD5 and CD27. It was shown that in patients with MS the relative number of IgDdimCD38low "naive" and IgDlow memory subsets was significantly decreased due to the increased proportion of activated IgDdimCD38dim B lymphocytes. Furthermore, the relative content of B cells with the IgDdimCD27low phenotype was significantly increased (p < 0.001), while the percentages of the other subsets purified on the co-expression of IgD and CD27 were significantly reduced. A detailed analysis of B cells and follicular T-helpers - Th subset that affects the maturation and differentiation of B lymphocytes - could have a significant impact on the current understanding of the causes and pathogenesis of MS, as well as could develop the new approaches to the therapy of this disease.