Figure 2.

Proposed mechanism of action of daclizumab and effects on key immune cell populations.

Notes: (A) IL-2 binds with higher affinity to the heterotrimeric IL-2R complex composed of CD25, CD122, and CD132 than to the heterodimeric intermediate-affinity IL-2R composed of the CD122 and CD132 subunits.⁷⁹ (B) Daclizumab binds to CD25 and prevents formation of the high-affinity receptor complex, which increases the availability of IL-2 to bind and signal through the intermediate-affinity receptor complex.⁵⁵,⁸⁴,⁸⁵ (C) Blockade of CD25 has effects on several different immune cell populations in patients with MS, most notably proinflammatory, activated T lymphocytes, CD56^bright NK cells, and T_REG cells.⁴⁰,⁴¹,⁵⁴,⁸⁶–⁸⁹,¹⁰⁷,¹⁵⁹

Abbreviations: IL-2R, interleukin 2 receptor; IL-2, interleukin 2; MS, multiple sclerosis; Tact, activated T cell; NK, natural killer; T_REG, regulatory T cell.