eosinophil chemotaxis

Definition

Target type: biologicalprocess

The movement of an eosinophil in response to an external stimulus. [GOC:jid, PMID:11292027, PMID:12391252]

Eosinophil chemotaxis is a complex biological process that involves the directed migration of eosinophils, a type of white blood cell, towards a chemical stimulus. This process is crucial for the immune response, particularly in the context of allergic reactions and parasitic infections. Here's a breakdown of the key steps involved:

1. **Stimulus Release:** Eosinophil chemotaxis is initiated by the release of chemoattractants, chemical signals that attract eosinophils. These chemoattractants can be released by various cells, including mast cells, epithelial cells, and other immune cells. Some common eosinophil chemoattractants include:
- **Eosinophil chemotactic factor (ECF):** Released by mast cells and other immune cells, ECF is a potent attractant for eosinophils.
- **Leukotriene B4 (LTB4):** A lipid mediator produced by various cells, LTB4 is a strong chemoattractant for eosinophils.
- **Interleukin-5 (IL-5):** A cytokine produced by T lymphocytes and other cells, IL-5 plays a crucial role in eosinophil development and activation, indirectly contributing to chemotaxis.

2. **Eosinophil Activation:** Upon encountering chemoattractants, eosinophils become activated. This activation involves a cascade of intracellular signaling events that lead to changes in cell morphology and behavior.

3. **Chemotaxis Receptor Binding:** Eosinophils express specific receptors on their surface that recognize and bind to chemoattractants. These receptors, such as the chemokine receptor CCR3, initiate intracellular signaling pathways upon ligand binding.

4. **Signal Transduction:** The binding of chemoattractants to their receptors triggers a series of intracellular signaling events. These events involve second messenger molecules like cAMP and Ca2+, leading to activation of kinases and other signaling molecules.

5. **Actin Polymerization and Cell Polarization:** The signaling cascade results in the reorganization of the cytoskeleton, particularly the actin filaments. This reorganization leads to the formation of pseudopodia, finger-like projections that extend towards the source of the chemoattractant. The cell also polarizes, with the leading edge facing the chemoattractant and the trailing edge facing away.

6. **Directional Migration:** The formation of pseudopodia and cell polarization allows eosinophils to move directionally towards the chemoattractant. This movement involves a cycle of extension and retraction of pseudopodia, driven by the polymerization and depolymerization of actin filaments.

7. **Eosinophil Recruitment:** As eosinophils migrate towards the source of the chemoattractant, they accumulate at the site of inflammation or infection. This recruitment of eosinophils is essential for the immune response to allergic reactions and parasitic infections.

8. **Eosinophil Function:** Once at the site of action, eosinophils release a variety of cytotoxic and inflammatory mediators, such as:
- **Major basic protein (MBP):** A toxic protein that damages parasitic worms and other pathogens.
- **Eosinophil cationic protein (ECP):** A cytotoxic protein that kills parasites and contributes to tissue damage in allergic reactions.
- **Eosinophil peroxidase (EPO):** An enzyme that generates reactive oxygen species, which can be toxic to parasites and other pathogens.

The process of eosinophil chemotaxis is tightly regulated by a complex interplay of signaling molecules, receptors, and intracellular pathways. This intricate regulation ensures that eosinophils are recruited only when necessary and that their activation and effector functions are carefully controlled. This is crucial for maintaining immune homeostasis and preventing excessive inflammation and tissue damage.'
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Proteins (2)

Compounds (13)