<i>In vitro</i> effect of natalizumab (NTZ) on VLA-4 expression on pDCs after 6 days of culture of PBMCs in the presence of antigen-specific stimulus (PPD) in NTZ-treated MS patients at different time-points (baseline, at 48 hours, and at 3 months).

<p>In vitro, VLA-4 expression on the surface of pDCs was greatly enhanced at day 6 with/without PPD, while NTZ was able to down-modulate it in NTZ-treated MS patients. <i>In vitro</i>, we observed that the enhanced expression of VLA-4 on pDCs was diminished in NTZ-treated MS patients more markedly after 3 months of therapy and that their pDCs were more sensitive <i>in vitro</i> to the VLA-4 down-modulating effects of NTZ after therapy. Isotypic IgG4 control is marked in red.