Related Experiment Video

Updated: Apr 25, 2026

A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity
06:08

A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity

Published on: August 9, 2017

24.2K

NK cells kill mycobacteria directly by releasing perforin and granulysin

Chia-Chen Lu1, Ting-Shu Wu2, Ya-Jing Hsu3

  • 1Department of Respiratory Therapy, College of Medicine, Fu Jen Catholic University, Taipei, Taiwan;

Journal of Leukocyte Biology
|August 21, 2014
PubMed

Insights

Natural killer (NK) cells kill extracellular bacteria like Mycobacterium using perforin and granulysin. This mechanism, activated by specific receptors, offers a new defense against mycobacterial infections.

Area of Science:

  • Immunology
  • Microbiology
  • Cellular Biology

Background:

  • Natural killer (NK) cells are crucial for immunity against tumors and intracellular pathogens.
  • Mechanisms of NK cell cytotoxicity against extracellular bacteria, particularly mycobacteria, are not well understood.

Purpose of the Study:

  • To investigate how human NK cells kill extracellular bacterial pathogens, specifically Mycobacterium kansasii and Mycobacterium tuberculosis (M.tb).
  • To elucidate the molecular mechanisms and cellular pathways involved in NK cell-mediated killing of mycobacteria.

Main Methods:

  • Co-culture of human NK cells with Mycobacterium species.
  • Analysis of cytolytic protein expression (perforin, granulysin).
  • Assessment of cell-surface receptor activation (NKG2D/NCR) and intracellular signaling pathways (ERK, JNK, p38 MAPKs).

Main Results:

  • NK cell-mediated killing of mycobacteria is contact-dependent.
  • Perforin and granulysin are essential cytolytic proteins for this process.
  • Mycobacteria activate NKG2D/NCR receptors, leading to enhanced perforin and granulysin expression via ERK, JNK, and p38 MAPK signaling.

Conclusions:

  • NK cells employ similar cytotoxic mechanisms against mycobacteria as they do against tumor cells and intracellular pathogens.
  • This study reveals a novel role for NK cells, perforin, and granulysin in combating mycobacterial infections.
  • Identifies a potential alternative immune defense strategy against mycobacterial diseases.
Keywords:
NCRNKG2Dantibacterial activityinnate immunitytuberculosis

More Related Videos

A GPC3-targeting Bispecific Antibody, GPC3-S-Fab, with Potent Cytotoxicity11:13

A GPC3-targeting Bispecific Antibody, GPC3-S-Fab, with Potent Cytotoxicity

Published on: July 12, 2018

7.9K
A Colorimetric Assay that Specifically Measures Granzyme B Proteolytic Activity: Hydrolysis of Boc-Ala-Ala-Asp-S-Bzl05:20

A Colorimetric Assay that Specifically Measures Granzyme B Proteolytic Activity: Hydrolysis of Boc-Ala-Ala-Asp-S-Bzl

Published on: November 28, 2014

12.6K

Related Concept Videos

Cells of the Innate Immune Response01:28

Cells of the Innate Immune Response

The innate immune response is an immediate and non-specific response against pathogens, acting swiftly to prevent the spread of infections. The primary cells involved in this response are phagocytes and natural killer (NK) cells.
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...
8.3K
Cytotoxic T Cells-mediated Immune Response01:27

Cytotoxic T Cells-mediated Immune Response

Cytotoxic T cells are a vital component of the immune system. They have the remarkable ability to identify and target antigens on infected or abnormal cells. These antigens often originate from intracellular pathogens such as viruses or abnormal proteins cancer cells produce.
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...
7.0K
Immune Surveillance by NK Cells and Phagocytes01:25

Immune Surveillance by NK Cells and Phagocytes

Immune surveillance is an integral part of the innate immune system, involving the continuous monitoring of peripheral tissues to detect and respond to pathogens, infected cells, or cancerous cells. This surveillance is conducted primarily by natural killer (NK) cells and phagocytes, which employ distinct but complementary mechanisms to identify and eliminate threats.
Natural Killer Cells: The Fast Responders
NK cells are large granular lymphocytes found in the blood and lymphatic system. These...
7.2K
Immune Response Against Viral Pathogens01:29

Immune Response Against Viral Pathogens

The immune system's response to viral infections is a complex and coordinated process involving natural killer (NK) cells, T cell-mediated responses, and antibody-mediated responses.
NK Cells
NK cells are a crucial part of our innate immune system, acting as the first line of defense against viral infections. These cells can recognize and kill infected cells without prior exposure to the virus, effectively slowing down the spread of infection. Additionally, NK cells produce proinflammatory...
2.3K
Phagocytosis of Apoptotic Cells01:17

Phagocytosis of Apoptotic Cells

Cells undergoing apoptosis form apoptotic bodies that must be removed immediately to prevent inflammation, autoimmune diseases, and necrosis. Phagocytosis is carried out by professional phagocytes such as macrophages or  immature dendritic cells. Non-professional phagocytes such as  epithelial cells and fibroblasts also take part in this process; however, they are not as effective as professional phagocytes. 
Normal cells contain receptors that prevent them from being recognized...
3.9K
The Extrinsic Apoptotic Pathway01:17

The Extrinsic Apoptotic Pathway

The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...
6.1K