Intercellular adhesion molecule 3 (ICAM3) also known as CD50 (Cluster of Differentiation 50), is a protein that in humans is encoded by the ICAM3 gene

Expression of soluble and cell surface ICAM-3 (s- and c-ICAM-3) is preferentially seen in the state of low activation of the immune system. Soluble forms of ICAM-1, VCAM-1, E-selectin, L-selectin, P-selectin and, more recently, ICAM-3 are known to exist in human serum and have elevated levels in numerous diseases. Elevated levels of sP-selectin and sICAM-3 in RA synovial fluids compared to OA may indicate inflammatory interactions between endothelial cells, leukocytes, and other synovial cells in the diseased joint.