Impact of cladribine therapy on changes in circulating dendritic cell subsets, T cells and B cells in patients with multiple sclerosis

Background: Cladribine causes sustained reduction in peripheral T and B cell populations while sparing other immune cells. We determined two populations of dendritic cells (DCs): namely CD1c(+)/CD19(-) (myeloid DCs) and CD303(+)/CD123(+) (plasmacytoid DCs), CD19(+) B lymphocytes, CD3(+) T lymphocytes and CD4(+) or CD8(+) subpopulations in patients with multiple sclerosis after cladribine therapy. Methods: We examined 50 patients with secondary progressive multiple sclerosis (SP MS) according to McDonalds et al's criteria, 2001 [15]. Blood samples were collected before the initiation of cladribine therapy and after 1st, 2nd, 3th, 4th and 5th courses of treatment DC subsets, T and B cells were analyzed by flow cytometry. Results: During cladribine treatment the myeloid DCs CD1c(+)/CD19(-) did not change (p = 0.73175), and the plasmacytoid DCs CD303(+)/CD123(+) significantly increased (p = 0.00034) which resulted in significant changes in the ratio of myeloid DCs to plasmacytoid DCs (p = 0.00273). During therapy, B lymphocyte CD19(+) significantly decreased (p = 0.00005) and significant changes in CD4(+) cells (p = 0.00191), changes in CD8(+) cells (p = 0.05760) and significant changes in CD3(+) (p = 0.01822) were found. Conclusions: We noticed significant trend to increase the CD303(+) circulating the dendritic cells. This population produces large amounts of IFN-alfa. We found significant and rapid decrease in B cells and CD4(+) Th cells. Our results suggest two possible ways of beneficial cladribine influence on immune system in MS. Induction of IFN-alfa producing cells and their predominance over BDCA-1(+) DCs, which are associated with cytotoxic response. Additionally, cladribine could influence two populations of lymphocytes: B cells and Th lymphocytes responsible for induction of immune response against myelin antigens. (C) 2013 Elsevier B.V. All rights reserved.