Intercellular adhesion molecules (ICAMs) are type I transmem brane glycoproteins, which contain 2-9 immunoglobulin-like C2-type domains, and bind to lymphocyte function- associated antigen-1 (LFA-1, also known as a L/ ß 2 or CD11a/CD18). ICAM-3 (CD50) is broadly expressed on leukocytes, endothelial cells, and Langerhans cells. ICAM-3 is the most important ligand for LFA-1 in the initiation of the immune response because the expression of ICAM-1 (CD54) and ICAM-2 (CD102) on resting leukocytes is very low or not at all. Previous studies suggest that ICAM-3 acts as a biologically significant molecule playing a role in HIV-1 transcription and replication, particularly in resting CD4 + T cells. It has been suggested that dendritic cell-specific ICAM grabbing nonintegrin (DC-SIGN, CD209), a C-type lectin of macrophages and DCs, is an additional ligand of ICAM-3. The interaction of DC-SIGN with ICAM-3 establishes initial contact between dendritic cells and resting T-cells during antigen presentation.Synonyms: CDw50, ICAM-3, ICAM-R, Intercellular adhesion molecule 3