Figure 3. Lysis of hESCs, hiPSCs, hDPSCs and hMSCs by untreated and IL-2 treated NK cells is inhibited by anti-CD16 antibody treatment, however, the same treatment induced significant secretion of IFN-γ by the NK cells.

NK cells (1×10⁶/ml) were left untreated or treated with IL-2 (1000 units/ml), or anti-CD16 mAb (3µg/ml) or a combination of IL-2 (1000 units/ml) and anti-CD16 mAb (3µg/ml) for 12-24 hours before they were added to ⁵¹Cr labeled hESCs, hiPSCs, hDPSCs and hMSCs. NK cell cytotoxicities were determined using a standard 4 hour ⁵¹Cr release assay, and the lytic units 30/10⁶ cells were determined using inverse number of NK cells required to lyse 30% of hESCs (A), hiPSCs (D), hDPSCs (G) and hMSCs (J) ×100. NK cells were treated as described above and each NK sample at (1×10⁵/ml) were either cultured in the absence or presence of hESCs, hiPSCs, hDPSCs and hMSCs at an NK to stem cell ratio of 1∶1. After an overnight culture, supernatants were removed from the co-cultures and the levels of IFN-γ (B,E,H,K), and bFGF (C,F,I,L) secretion were determined using specific ELISAs. One of a minimum three representative experiments for each stem cell population is shown in this figure.