NK Cell-Mediated Cytotoxicity Assay

Natural killer cells (10⁵ cells per well) were incubated with NB target cells at ratios of 1:1, 3:1, and 5:1, respectively, for 4 h in 96-well plates with the 200 µl medium per well. NK-mediated cytotoxicity was analyzed by lactate dehydrogenase assay kits (Roche, Mannheim, Germany). The procedures of the assay were followed according to the manufacturer as previously described (28 (link)). Briefly, the culture medium was collected after treatment for the assay. The reaction underwent in the dark for 30 min before measurement. Changes in the absorbance were measured at 492 nm by a multiplate reader (Dynex, UK). Results were expressed as the percentage of control. Also, evaluation of the CD107a was performed to detect the degranulation capability of NKs as described in the Section “Immunophenotyping Tests.”