Tregalizumab, a humanized IgG1-type monoclonal antibody targeting CD4, selectively activates regulatory T cells (Tregs) with suppressive functions in vitro and has potential applications in researching autoimmune diseases (due to inadequate Treg activity) and allergies [1] [2] [3].

Tregalizumab activates the suppressive function of regulatory T cells [1]. It diminishes the proliferation and cytokine secretion of isolated PBMCs stimulated with tetanus toxoid in a dose-dependent manner [1]. Tregalizumab treatment (0-30 µg/mL; 18 h) induces the downregulation of CD4 in T cells [2] and primarily instigates CD4 downregulation at sites of inflammation [2].