basophil activation involved in immune response

Definition

Target type: biologicalprocess

A change in morphology and behavior of a basophil resulting from exposure to a cytokine, chemokine, soluble factor, or to (at least in mammals) an antigen which the basophil has specifically bound via IgE bound to Fc-epsilonRI receptors, leading to the initiation or perpetuation of an immune response. [GOC:add, ISBN:0781735149]

Basophils are granulocytes that play a crucial role in allergic reactions and other immune responses. Their activation is a complex process involving multiple signaling pathways and mediators. Here's a detailed description of basophil activation:

1. **Antigen Recognition:** Basophils express high-affinity IgE receptors (FcεRI) on their surface. When an allergen or antigen binds to IgE molecules already attached to FcεRI, it triggers the activation cascade.

2. **Signal Transduction:** Binding of the antigen to IgE-FcεRI complex initiates a cascade of intracellular signaling events. This involves the phosphorylation of tyrosine residues on various signaling proteins, including Lyn, Syk, and PLCγ.

3. **Calcium Influx:** The activation of PLCγ leads to the production of inositol trisphosphate (IP3) and diacylglycerol (DAG). IP3 triggers the release of calcium ions (Ca2+) from intracellular stores, leading to a rise in cytosolic Ca2+ concentration.

4. **Mediator Release:** Increased intracellular Ca2+ activates various signaling pathways, culminating in the release of pre-formed mediators stored in basophil granules. These mediators include:
* **Histamine:** A potent vasoactive amine that causes vasodilation, increased vascular permeability, and smooth muscle contraction.
* **Heparin:** An anticoagulant that prevents blood clotting.
* **Leukotrienes:** Lipid mediators that contribute to bronchoconstriction, vascular permeability, and chemotaxis of other immune cells.
* **Cytokines:** Proteins like IL-4, IL-13, and TNF-α that contribute to the development of allergic inflammation and the activation of other immune cells.

5. **Degranulation:** The process of releasing the pre-formed mediators is called degranulation. Basophils release these mediators in response to various stimuli, including allergens, parasites, and certain bacterial products.

6. **Late-Phase Response:** Basophil activation also triggers the synthesis and release of new mediators, including lipid mediators like prostaglandins and cytokines. These mediators contribute to the late-phase allergic response, which occurs several hours after the initial antigen exposure and can be characterized by prolonged inflammation.

7. **Amplification of Immune Response:** Basophils play a crucial role in amplifying the immune response by recruiting other immune cells, such as eosinophils and mast cells, to the site of inflammation. They also contribute to the development of allergic inflammation and the production of IgE antibodies.

In summary, basophil activation is a complex process that involves antigen recognition, signal transduction, calcium influx, mediator release, and the amplification of immune responses. Basophils are key players in allergic reactions and other immune responses, contributing to the development of inflammation and the recruitment of other immune cells.'
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Proteins (3)

Compounds (10)