In contrast to the other immunosuppressive DMTs discussed in this review that associate with lymphopenia, natalizumab treatment leads to a considerable increase in peripheral blood of CD4+ and CD8+ T cells, CD19+ B cells, and NK cells in the peripheral blood, due to elevated release or impaired homing of lymphocytes, including the CD34+ progenitor cells subpopulation, from or to the bone marrow and secondary lymphoid tissues, respectively [50, 51]. Here, CD4 is linked to lymphopenia.