Comparative study of four fluorescent probes for evaluation of natural killer cell cytotoxicity assays

Immunobiology. 2008;213(8):629-40. doi: 10.1016/j.imbio.2008.02.006. Epub 2008 Apr 28.

Abstract

Cytotoxicity is one of the major defence mechanisms against both virus-infected and tumor cells. Radioactive (51)chromium ((51)Cr) release assay is a "gold standard" for assessment of natural killer (NK) cytolytic activity in vitro. Several disadvantages of this assay led us to design alternative tools based on flow cytometry analysis. Four different fluorescent dyes, calcein acetoxymethyl ester (CAM), carboxyfluorescein succinimidyl ester (CFSE), Vybrant DiO (DiO) and MitoTracker Green (MTG) were tested for labeling of NK target K-562 cells. Target staining stability, spontaneous release of fluorochromes and subsequent accumulation in bystander unstained cells were measured using fluorimetry and flow cytometry. Healthy donor peripheral blood mononuclear cells and affinity column purified NK cells were used as effectors coincubated with target K-562 cells at different E:T ratios for 3h and 90 min, respectively. Fluorescent probe 7-amino-actinomycin D was used for live and dead cell discrimination. Bland-Altman statistical method was applied to measure true agreement for all CAM-(51)Cr, CFSE-(51)Cr, DiO-(51)Cr and MTG-(51)Cr pairs analyzed. Based on the data, none of the four proposed methods can be stated equivalent to the standard (51)Cr release assay. Considering linear relationships between data obtained with four fluorochromes and (51)Cr release assay as well as linear regression analysis with R(2)=0.9393 value for CAM-(51)Cr pair, we found the CAM assay to be the most closely related to the (51)Cr assay.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehydes*
  • Cell Separation
  • Chromium Radioisotopes
  • Cytotoxicity Tests, Immunologic
  • Cytotoxicity, Immunologic*
  • Dose-Response Relationship, Immunologic
  • Flow Cytometry
  • Fluoresceins*
  • Fluorescent Dyes*
  • Humans
  • K562 Cells
  • Killer Cells, Natural / cytology
  • Killer Cells, Natural / immunology
  • Killer Cells, Natural / metabolism
  • Staining and Labeling
  • Succinimides*

Substances

  • 5-(6)-carboxyfluorescein diacetate succinimidyl ester
  • Aldehydes
  • Chromium Radioisotopes
  • Fluoresceins
  • Fluorescent Dyes
  • Succinimides
  • mitotracker green FM
  • calcein AM