Kinetics of in vitro natural killer activity against K562 cells as detected by flow cytometry

✍ Scribed by Loris Zamai; Adriana R. Mariani; Giorgio Zauli; Luigi Rodella; Rita Rezzani; Francesco A. Manzoli; Marco Vitale

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 158 KB
• Volume: 32
• Category: Article
• ISSN: 0196-4763
• DOI: 10.1002/(sici)1097-0320(19980801)32:4<280::aid-cyto4>3.0.co;2-m

✦ Synopsis

Natural killer (NK) cells bind to K562 tumor target cells in vitro and kill them. The binding and cytotoxic activities of NK cells are tightly related to each other: degranulation of the cytotoxic effector is the basis for target cell damage and a consequence of effector-target recognition and binding. However, the two phases of NK activity, binding and killing, have always been measured separately by various methodologies and under different experimental conditions, because of the lack of a comprehensive methodology able to measure both of them at one time. Here we describe the simultaneous measurement of the binding and killing activities against K562 of resting and cytokine (IL-2 or IL-12)-stimulated NK cells by flow cytometry. NK, K562 and conjugates can be identified and measured by flow cytometry on the basis of NK mAb staining and target cells autofluorescence (Binding Plot).

Within each population of the binding plot, killed targets can be identified and measured by their scatter characteristics (Cytotoxicity Plot). We show that i) the conjugate formation is enhanced in cytokinestimulated cells, even at relatively short co-incubation times; ii) the conjugate release is also accelerated by cytokines; iii) the conjugate release is always quicker than the induction of the morphological changes in the target cell that generate its modified scattering properties.