Psychoneuroimmunology and Natural Killer Cells: The Chromium-Release Whole-Blood Assay

Methods Mol Biol. 2018;1781:209-220. doi: 10.1007/978-1-4939-7828-1_12.


Natural killer (NK) cells are an essential component of innate immunity. These lymphocytes are also sensitive barometers of the effects of endogenous and exogenous stressors on the immune system. This chapter describes a chromium (51Cr)-release bioassay designed to measure to the target cell killing capacity of NK cells (NKCC). Key features of the cytotoxicity assay are that it is done with whole blood and that numbers of effector cells are determined for each sample by flow cytometry and lymphocyte count. Effector cells are defined as CD3-CD56+ lymphocytes. Target cells are the K562 erythroleukemia cell line. Killing capacity is defined as number of target cells killed per effector cell, at an effector cell/target cell ratio of 1:1 during a 4-h in vitro assay.

Keywords: Chromium-release assay; Flow cytometry; Innate immunity; K562 target cells; Lymphocytes; NK cells; NKCC; Natural killer cell cytotoxicity; Natural killer cells.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Biological Assay
  • CD56 Antigen / immunology
  • Case-Control Studies
  • Chromium / blood*
  • Chromium / immunology
  • Cytotoxicity Tests, Immunologic / methods*
  • Fatigue Syndrome, Chronic / blood
  • Fatigue Syndrome, Chronic / immunology*
  • Fatigue Syndrome, Chronic / pathology
  • Flow Cytometry
  • Humans
  • K562 Cells
  • Killer Cells, Natural / cytology
  • Killer Cells, Natural / immunology*
  • Persian Gulf Syndrome / blood
  • Persian Gulf Syndrome / immunology*
  • Persian Gulf Syndrome / pathology
  • Psychoneuroimmunology / methods*


  • CD56 Antigen
  • Chromium