αCD20-IL-21 fusokine induces NK-cell activation and cytotoxic function. For A-D, freshly isolated human NK cells and Raji cells were cocultured at a 1:1 ratio in the presence of αCD20-IL-21 (1 µg/mL), or equimolar concentration of IL-21, or αCD20-IgG1. Flow cytometric analysis of NK cell activation markers (A) CD16, (B) CD69, and degranulation marker (C) CD107a is shown. (D) IFNγ levels in cell supernatant measured via ELISA. (E) Analysis of serum IFNγ levels in CD20-Tg Balb/c mice engrafted with A20-hCD20 tumors treated with αCD20-IL-21 fusokine, αCD20-IgG1, and/or IL-21 or control IgG. Each circle represents an individual mouse, with the horizontal line representing mean value. Data are mean ± SD. *P < .05, **P < .01, ***P < .001.