Lecture Notes: Blood Vessel Endothelium and Leukocyte Interaction

Key Points

• Endothelial Expression at Infection Sites:

  • Blood vessel endothelium at infection sites expresses specific molecules such as P-selectin and ISA-lectin.

• Leukocyte Ligands:

  • Leukocytes, including neutrophils, express ligands for selectins.
  • These ligands are in the form of sialylated Lewis X (s-Le^x) carbohydrates.

• Selectin and Ligand Interaction:

  • The binding between endothelial selectins and s-Le^x on leukocytes is weak.
  • This weak binding is insufficient to hold the cell against the blood flow.
  • As a result, leukocytes roll along the blood vessel wall.
  • This rolling involves making and breaking multiple interactions with the selectins.

Important Concepts

• Selectins:

  • Molecules expressed on the endothelium at infection sites.

• Sialyl Lewis X (s-Le^x):

  • Carbohydrate ligands on leukocytes that bind to endothelial selectins.

• Leukocyte Rolling:

  • The process where leukocytes roll along the blood vessel wall due to weak and transient interactions between selectins and their ligands.