Diapedesis

Definition

Diapedesis is the process by which leukocytes (white blood cells) move out of the bloodstream and into surrounding tissues, allowing them to reach sites of infection or injury. This movement is crucial for immune response and inflammation, enabling leukocytes to migrate to areas where they are needed to combat pathogens and facilitate tissue repair.

5 Must Know Facts For Your Next Test

1. Diapedesis is a critical step in the inflammatory response, allowing immune cells to exit blood vessels and enter tissues where they can address infections.
2. The process is facilitated by changes in the endothelium (the inner lining of blood vessels), which becomes more permeable during inflammation.
3. Adhesion molecules such as selectins and integrins play essential roles in the diapedesis process by helping leukocytes bind to endothelial cells.
4. Diapedesis is not only important for immune defense but also plays a role in tissue repair by allowing leukocytes to participate in wound healing.
5. Different types of leukocytes can perform diapedesis, including neutrophils, monocytes, and lymphocytes, each playing specific roles in immune responses.

Review Questions

• How does diapedesis contribute to the immune response during an infection?
  • Diapedesis allows leukocytes to leave the bloodstream and enter infected tissues where they can combat pathogens. When an infection occurs, signaling molecules attract leukocytes to the site. Through diapedesis, these immune cells migrate through the blood vessel walls, allowing them to effectively target and eliminate the infectious agents, thus playing a vital role in the overall immune response.
• Discuss the role of adhesion molecules in facilitating diapedesis and how they impact the inflammatory response.
  • Adhesion molecules, such as selectins and integrins, are critical for diapedesis as they mediate the binding of leukocytes to endothelial cells lining blood vessels. During inflammation, these molecules are upregulated, enhancing the ability of leukocytes to adhere to vessel walls before migrating into tissues. This interaction ensures that immune cells can quickly respond to inflammatory signals, thereby amplifying the body's defense mechanisms against infections or injuries.
• Evaluate how dysregulation of diapedesis might contribute to autoimmune diseases or chronic inflammatory conditions.
  • Dysregulation of diapedesis can lead to inappropriate or excessive leukocyte migration into tissues, contributing to autoimmune diseases and chronic inflammation. In autoimmune disorders, this malfunction can cause immune cells to target healthy tissues as if they were pathogens. Chronic inflammation may occur when there is persistent recruitment of leukocytes without resolution, leading to tissue damage and contributing to conditions like rheumatoid arthritis or inflammatory bowel disease. Understanding this dysregulation offers potential avenues for therapeutic intervention.

Related terms

Chemotaxis: The movement of cells toward or away from a chemical stimulus, often guiding leukocytes to sites of infection or inflammation.

Adhesion Molecules: Proteins on the surface of cells that help leukocytes adhere to blood vessel walls during diapedesis and facilitate their migration into tissues.

Inflammation: A localized physical condition characterized by redness, swelling, heat, and pain, often triggered by injury or infection, and involving diapedesis as leukocytes infiltrate affected tissues.