Related Experiment Video
Updated: Aug 9, 2026

A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity
Published on: August 9, 2017
Effects of aging on natural killer cell activity and activation by interleukin-2 and IFN-alpha
1Department of Microbiology and Immunology, Medical College of Pennsylvania, Philadelphia 19129.
Abstract:
To address the conflicting reports concerning both innate and lymphokine-inducible NK activity of elderly individuals, NK activity of peripheral blood mononuclear cells (PBMC) of 21 young (23 to 35 years old) and 43 elderly (65 to 100 years old) subjects was assessed using a 4-hr chromium release assay with K562 or Daudi cells as targets. Significantly higher innate NK cell activity was observed in elderly compared to young individuals (P < 0.001, Student t test). NK activity of both groups was enhanced to the same degree by IL-2. Although intermediate amounts of IFN-alpha (100-500 mu/10(6) cells) induced comparable maximal NK activity of both young and elderly subjects, young subjects responded better than elderly to low amounts of IFN-alpha (10 mu/10(6) cells), while higher amounts (10(3) mu/10(6) cells) reduced the NK activity of the elderly, but not young, to basal levels. IFN-alpha also expanded the range of target cells susceptible to NK activity. Untreated cells of neither young nor elderly showed activity against Daudi targets. Two-hour treatment with IFN-alpha resulted in significant activity against Daudi cells; however, this activity was significantly lower in the elderly compared to the young subjects.
Related Concept Videos
The Effect of Aging on Tissues
Cells of the Innate Immune Response
Phagocytes
Phagocytes police the peripheral tissues by removing cellular debris and responding to the invasion of foreign substances or pathogens. Many phagocytes attack and remove microorganisms even before lymphocytes detect them. The human body has two general...
Immune Surveillance by NK Cells and Phagocytes
Natural Killer Cells: The Fast Responders
NK cells are large granular lymphocytes found in the blood and lymphatic system. These...
T Cell Activation and Clonal Selection
Naive T cells that have not yet encountered an antigen express two primary CD...
T Cell Types and Functions
Th1 cells stimulate dendritic cells to express necessary co-stimulatory molecules on their surfaces for...
Cytotoxic T Cells-mediated Immune Response
Immunological surveillance is the ability of immune cells to monitor and eliminate infected cells with intracellular pathogens, neoplastically transformed cells, and cells with non-self antigens. Cytotoxic T cells and NK...

