Related Experiment Video

Updated: Oct 18, 2026

Evaluation of Caspase Activation to Assess Innate Immune Cell Death
10:23

Evaluation of Caspase Activation to Assess Innate Immune Cell Death

Published on: January 20, 2023

Early activation of caspases during T lymphocyte stimulation results in selective substrate cleavage in nonapoptotic

A Alam1, L Y Cohen, S Aouad

  • 1Laboratoire d'Immunologie, Institut de Recherches Cliniques de Montréal, Montréal, Québec H2W 1R7, Canada.

The Journal of Experimental Medicine
|December 22, 1999
PubMed

Insights

T cell activation triggers caspase processing in viable lymphocytes, impacting proliferation and MHC class II expression. This caspase activity is a physiological response involved in early lymphocyte activation steps.

Area of Science:

  • Immunology
  • Cell Biology
  • Biochemistry

Background:

  • T cell receptor (TCR) triggering in T lymphocytes can induce apoptosis via caspase activation.
  • Caspase-3 cleavage has been observed during T cell stimulation without apoptosis, but its physiological role is unclear.

Purpose of the Study:

  • To investigate the role and physiological relevance of caspase activation during T cell activation.
  • To determine the specific caspases involved and their substrates in non-apoptotic T cell stimulation.

Main Methods:

  • Inhibition of caspases using benzyloxycarbonyl (Cbz)-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD).
  • Assessment of T cell proliferation, MHC class II expression, and blastic transformation.
  • Detection of caspase processing and activation in intact cells using fluorescent substrates.
  • Analysis of caspase involvement in different T cell subsets and B lymphocytes.
  • Investigation of upstream pathways involving death receptors and caspase-8.

Main Results:

  • zVAD inhibited T cell proliferation, MHC class II expression, and blastic transformation.
  • T cell activation selectively processed and activated downstream caspases (caspase-3, -6, -7), but not caspase-1, -2, or -4.
  • Caspase-3 processing occurred in various T cell subsets and activated B lymphocytes.
  • The pathway involved death receptors and caspase-8, but not caspase-9.
  • Specific substrates like PARP, lamin B, and Wee1 kinase were processed, while DFF45 and RFC140 were not.
  • Caspase and substrate processing occurred in non-apoptotic lymphocytes.

Conclusions:

  • Caspase activation is an early, physiological response in viable, stimulated lymphocytes.
  • This caspase activity appears to be involved in the early stages of lymphocyte activation.
  • The findings clarify the role of caspases beyond apoptosis in T cell signaling.

More Related Videos

Measuring Caspase Activity Using a Fluorometric Assay or Flow Cytometry05:29

Measuring Caspase Activity Using a Fluorometric Assay or Flow Cytometry

Published on: March 24, 2023

Lighting Up the Pathways to Caspase Activation Using Bimolecular Fluorescence Complementation08:47

Lighting Up the Pathways to Caspase Activation Using Bimolecular Fluorescence Complementation

Published on: March 5, 2018

Related Concept Videos

Caspases01:24

Caspases

Caspase, a family of cysteine proteases, serve as effectors in apoptosis. The ced3 gene in C.elegans was first identified to be involved in apoptosis. This gene encodes the ced-3 caspase that is similar to the interleukin-1-beta converting enzyme or ICE in mammals. In addition to apoptosis, caspases also function in the inflammatory response. Inflammatory caspases are essential in activating pro-inflammatory cytokines that recruit immune cells and block the replication of pathogens inside cells.
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...
The Intrinsic Apoptotic Pathway01:31

The Intrinsic Apoptotic Pathway

Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...
Apoptosis01:30

Apoptosis

Apoptosis is a combination of two Greek words, 'apo' and 'ptosis,' meaning separation and falling off, respectively. Hippocrates used this word to describe gangrene, which was caused due to bandaging of fractured bones. Apoptosis was distinguished from necrosis in 1970 when John Kerr reported observations of morphological changes occurring during apoptosis. During one experiment, he observed that the disruption of blood supply to the liver tissue resulted in a size reduction of the tissue.
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...
Autophagic Cell Death01:18

Autophagic Cell Death

Christian de Duve discovered “autophagy,” a process in which cellular components are engulfed by membrane-bound organelles called autophagosomes. The autophagosomes then fuse with lysosomes to digest the enclosed contents. Autophagy is generally activated in cells to prevent cell death. However, cell death is triggered when the damage is beyond repair.
Autophagy and Apoptosis
Autophagy can activate apoptosis. In normal conditions, the autophagy activating protein Beclin-1 and pro-apoptotic...