αCD20-IL-21 fusokine increases NK-cell mediated cytotoxicity of B-cell lymphomas in vitro. For A-C, human NK cells (used as effectors) isolated from peripheral blood were stimulated overnight with indicated Abs. Lymphoma cells (used as targets) were labeled with 51Cr for 2 hours, followed by coating with αCD20-IL-21 (0.01 µg/mL), or molar equivalent of the indicated proteins for 1 hour. Target cells and effector cells were then incubated for 4 hours at depicted ratios to determine release of 51Cr as a measure of percentage of cell lysis. Minimum and maximum release was determined by incubation of labeled target cells in culture media alone or media supplemented with 0.1% Triton X-100, respectively. Percentage of total cell lysis was determined using (sample-spontaneous/maximal-spontaneous) × 100 formula. Data are mean ± SD between triplicate wells. *P < .05, **P < .01, ***P < .001.
