[Expression of perforin in cord blood NK cells after IL-2/IL-15 stimulation and its relation with cytotoxicity].

This study was aimed to investigate the expression level of perforin in cord blood NK cells and the relation of perforin expression after IL-2, IL-15 stimulation to cytotoxicity of NK cells. NK cells were isolated from cord blood MNC by depleting CD3(+) cells and then enriching CD56(+) cells using immunomagnetic separation (CD3 and CD56 cell isolation kit, autoMACS, miltenyi). The purity was analysed by flow cytometry. According to the different combination of cytokines, there were two groups: group A (IL-2) and group B (IL-2 + IL-15). The cytotoxicity and perforin expression rate of fresh and different cultured CB-NK cells against K562/Jurkat cell lines were estimated by LDH release test (cytotoxic 96 non-radioactive cytotoxicity assay). The results showed that the purity of NK cells after separation was more than 90%. The cytotoxicity towards both tumor lines in group B was higher than that in group A (p < 0.05), and cytotoxicity in group A was higher than that of fresh NK cells (p < 0.05). Perforin expression rate of group A (84.55%) was higher than that of fresh NK cells (67.21%) (p < 0.05), and there was no significant difference between group A and B (84.55% versus 87.22%) Cytotoxic activity of CB-NK cells was positively correlated with perforin expression rate (r = 0.886, p < 0.05). It is concluded that IL-2 can enhance cytotoxicity of CB/BM-NK cells by increasing the perforin expression.