1984 Volume 75 Issue 1 Pages 32-42
It has been generally accepted that natural killer (NK) cells are responsible not only for various tumor cells in vitro, but also for the possible role in the resistance against growth of tumor cells in vivo.
This study was designed to demonstrate the human NK cell activity against cell lines dervied from malignant tumors of the urinary tract, and the effects of human interferon-β (IFN) on augmentation of NK cell activity.
Peripheral blood lymphocytes (PBL) from the buffy coat, obtained from healthy male volunteers, were separated by centrifugation on a Ficoll-Conray density gradient. IFN-treated and non-treated PBL were used as the effector cells. Different cell lines derived from carcinoma of the prostate and kindney were utilized as monolayer cells for immunoadsorption and target cells for a short-term 51Cr-release assay. K562 cells, well known for their high susceptibility to NK cell-mediated cytotoxicity, were used as the control. IFN-stimulated PBL were depleted of target-binding NK cells on various monolayrs and aliquots of nonaldherent PBL were assayed for their residual NK cell activity. The finally recoverd non-adherent PBL, after the third immunoadsorption, were cultured with IFN to examine the possibility of recruitment of NK cell activity.
The present study demonstrates the following: 5 different anchorage dependent cell lines used in this study were resistant to natural cytotoxicity; preincubation of monocyte-depleated PBL with IFN significantly increased NK cell activity against target cels as well as against K562 cells; and after almost complete loss of NK cell activity by immunoadsorption, appreciable NK cell activity was restored by the subsequent incubation with IFN. This result suggests that IFN promotes the differentiation of human pre-NK cells (immature NK cells) to the active NK cells (mature NK cells) and that there are several stages in the course of the maturation of NK cells.
