Natural killer cell mediated cytotoxicity against VERO target cells;: the suppressive effect of pentoxifylline

The K-562 cell line is widely known and used as a NK cell target. In this study we report that VERO (African green monkey kidney epithelial cell line) is an excellent target of the human NK cell cytotoxicity. Considerable cytotoxicity was observed in a 4 h 51Cr release assay with nonadherent and immunomagnetically separated CD56 + NK cells from PBMC. On the contrary, adding K-562 cells as cold target to the assay the cytotoxicity significantly decreased. Using a standard chromium-release assay the NK cell activity (NKCA) against VERO cells was investigated in a population of healthy volunteers (mean value of cytotoxicity was 26.6%) and compared with the values of cytotoxicity against K-562 target cells (32.6%). The difference was not significant (P > 0.05). The suppressive effect of PTX on in vitro NK cell activity was observed at concentration of 100 μg/ml using VERO target cells as well as K-562 cells. Our studies provide the first evidence that the NK cell activity is suppressed in vitro by PTX using VERO cells as NK target cells.