memory T cell extravasation

Definition

Target type: biologicalprocess

The migration of a memory T cell from the blood vessels into the surrounding tissue. A memory T cell is a distinctly differentiated long-lived T cell that has the phenotype CD45RO-positive and CD127-positive. [CL:0000813, GOC:BHF]

Memory T cells, the guardians of long-term immunity, are primed to quickly respond to re-exposure to a specific antigen. This rapid response involves their efficient migration from the bloodstream into infected tissues, a process known as extravasation. Here's a detailed breakdown of the steps involved:

1. **Chemokine Sensing and Activation:** Memory T cells constantly patrol the bloodstream. Upon encountering an infection, they are alerted by chemokines, small signaling molecules released from infected cells and tissues. These chemokines bind to specific receptors on the surface of memory T cells, initiating a signaling cascade that primes them for extravasation.

2. **Adhesion and Rolling:** As the memory T cells approach the infected site, they encounter the vascular endothelium, the lining of blood vessels. Weak interactions between selectins (molecules on the surface of both the T cells and endothelial cells) cause the T cells to roll along the vessel wall.

3. **Firm Adhesion:** The rolling T cells encounter chemokines bound to the endothelial cell surface. This interaction strengthens the binding between integrins (another type of adhesion molecule on the T cell) and their ligands (ICAM-1 and VCAM-1) on the endothelium, leading to firm adhesion of the T cells to the vessel wall.

4. **Transmigration:** The firmly adhered T cells receive additional signals from chemokines and other cues that trigger them to squeeze through the tight junctions between endothelial cells. This process, called diapedesis, allows the memory T cells to exit the bloodstream and enter the infected tissue.

5. **Migration towards Antigen:** Once inside the infected tissue, memory T cells use a combination of chemokine gradients and antigen recognition to navigate towards the site of infection. They can detect even low levels of antigen, ensuring they reach the target site rapidly and effectively.

6. **Activation and Effector Function:** Upon encountering the antigen, memory T cells become fully activated. They release cytokines and cytotoxic molecules to eliminate infected cells and orchestrate the immune response.

This complex process of extravasation ensures that memory T cells are efficiently delivered to the site of infection, enabling them to mount a rapid and potent immune response to prevent disease.'
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Proteins (1)

Compounds (15)