FLOW CYTOMETRIC ANALYSIS OF NATURAL-KILLER-CELL FUNCTION AS A CLINICAL ASSAY

The Cr-51 release assay has been the method of choice in analyzing nat ural killer cell (NK) function. Previous FCM cytotoxicity assays of NK activity have had numerous disadvantages that discouraged clinicians from attempting to evaluate NK function by flow cytometry. We demonstr ate the effectiveness of using PKH-26, a stable membrane dye, to label the K562 target cells and propidium iodide intercalation into killed target cell DNA to determine the percentage of target cells killed by effector NK cells from the peripheral blood or bone marrow. This metho d compares favorably with the Cr-51 release assay and is quicker and e asier to perform. The percentage of cytotoxicity of NK cells (CD3(-)CD 56(+) and/or CD16(+)) from 10 normal subjects and 10 HIV-infected chil dren are reported to demonstrate the feasability of studying NK functi on in clinical populations by FCM. The potentiation of cytolysis by al pha-interferon and interleukin 2 in vitro was also compared between th ese two study groups. In addition, a patient whose leukemic blasts exp ressed CD56(+) was also studied for NK activity using this flow cytome tric assay. The benefits of using this flow cytometric approach to cli nically assess NK function are discussed. (C) 1994 Wiley-Liss, Inc.