inflammatory response to antigenic stimulus

Definition

Target type: biologicalprocess

An inflammatory response to an antigenic stimulus, which can be include any number of T cell or B cell epitopes. [GOC:add, ISBN:0781735149]

The inflammatory response to antigenic stimulus is a complex and highly regulated process that involves the coordinated action of various immune cells, mediators, and tissues. It is initiated upon recognition of foreign antigens by immune cells, primarily antigen-presenting cells (APCs) like macrophages, dendritic cells, and B cells. Here's a breakdown of the process:

**1. Antigen Recognition and Presentation:**

* APCs engulf and process the antigen, breaking it down into smaller peptides.
* These peptides are presented on the surface of the APC in association with major histocompatibility complex (MHC) molecules, MHC class II for T helper cells and MHC class I for cytotoxic T lymphocytes (CTLs).

**2. Activation of T Lymphocytes:**

* Antigen-MHC complexes on APCs interact with specific T cell receptors (TCRs) on T helper cells (Th cells), triggering their activation.
* Th cells differentiate into various subtypes like Th1, Th2, and Th17, each producing distinct cytokines that orchestrate different aspects of the immune response.

**3. Activation of B Lymphocytes:**

* Th cells, particularly Th2, secrete cytokines that activate B lymphocytes.
* B cells differentiate into plasma cells, which produce antibodies specific for the antigen.

**4. Recruitment of Immune Cells:**

* Cytokines released by APCs and activated T cells, such as TNF-α, IL-1, and IL-6, act as chemoattractants, attracting neutrophils, macrophages, and other immune cells to the site of inflammation.

**5. Vasodilation and Increased Vascular Permeability:**

* Inflammatory mediators like histamine and prostaglandins cause vasodilation, widening blood vessels and increasing blood flow to the inflamed area.
* They also increase vascular permeability, allowing fluid and immune cells to leak out of the bloodstream into the tissue.

**6. Phagocytosis and Clearance of Pathogens:**

* Neutrophils and macrophages, attracted to the site by chemotaxis, engulf and destroy pathogens through phagocytosis.

**7. Tissue Repair and Resolution of Inflammation:**

* Once the infection is cleared, anti-inflammatory cytokines like IL-10 and TGF-β suppress the inflammatory response, promoting tissue repair and restoring homeostasis.

**Key Features of Inflammatory Response:**

* **Specificity:** Immune cells are highly specific in their recognition of antigens, targeting specific pathogens and foreign molecules.
* **Amplification:** The initial encounter with an antigen triggers a cascade of events, amplifying the response and mobilizing a larger army of immune cells.
* **Memory:** Once an antigen has been encountered, the immune system retains memory of that antigen, enabling a faster and more robust response upon subsequent exposure.'
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