Intercellular adhesion molecule

PDB 1iam EBI

Intercellular adhesion molecule (ICAM) refers to a group of proteins that are typically expressed on the surface of endothelial cells and cells of the immune system. These molecules play a crucial role in the immune response by facilitating the binding of leukocytes to endothelial cells, which is essential for leukocyte transmigration from the bloodstream to sites of inflammation or injury.

Types of ICAM[edit | edit source]

There are several types of intercellular adhesion molecules, including:

ICAM-1 (Intercellular adhesion molecule 1)
ICAM-2 (Intercellular adhesion molecule 2)
ICAM-3 (Intercellular adhesion molecule 3)
ICAM-4 (Intercellular adhesion molecule 4)
ICAM-5 (Intercellular adhesion molecule 5)

Structure[edit | edit source]

ICAMs are members of the immunoglobulin superfamily and are characterized by their immunoglobulin-like domains. These domains are responsible for the binding interactions with integrins, such as LFA-1 (lymphocyte function-associated antigen 1) and Mac-1 (macrophage-1 antigen).

Function[edit | edit source]

ICAMs are primarily involved in the immune response. They facilitate the adhesion of leukocytes to the endothelium, which is a critical step in the process of leukocyte extravasation. This process allows leukocytes to exit the bloodstream and migrate to sites of infection or injury. ICAMs also play a role in antigen presentation and the activation of T cells.

Clinical Significance[edit | edit source]

Dysregulation of ICAM expression has been implicated in various diseases, including inflammatory diseases, autoimmune disorders, and cancer. For example, overexpression of ICAM-1 has been observed in conditions such as rheumatoid arthritis and multiple sclerosis. Therapeutic strategies targeting ICAMs are being explored for the treatment of these diseases.