Figure 1 Analysis of leukocyte and lymphocyte cell numbers in peripheral blood (PB)

Serial cross-sectional analysis showed that the total numbers of white blood cells (WBC) in the PB of natalizumab-treated patients with multiple sclerosis (MS) at study entry (MS Nat) were within normal limits (A). There was a nonsignificant (ns) decrease in WBC numbers between the entry time point, 6 months (MS Nat 6 months), and 14 months (MS Nat 14 months) after cessation of natalizumab therapy (A). The number of CD4+ T cells (B), CD8+ T cells (C), and CD19+ B cells (D) significantly increased 14 months after discontinuation of natalizumab therapy, whereas the number of CD138+ plasma cells did not change (E). CD4:CD8 T cell ratios in the PB were normal at all three time points (F). Longitudinal analysis of leukocyte and lymphocyte cell numbers showed a significant decrease of WBC between study entry and month 14 (G). After an initial decrease at 6 months after cessation of natalizumab, there was an increase of CD4+ T cells in the PB 14 months after study entry (H). The number of CD8+ T cells did not change over the 14-month study period, but there was an initial significant decrease 6 months after cessation of natalizumab (I).