Intercellular Adhesion Molecule 5 (ICAM-5)

ICAM-5, also called telencephalin, is the neuron-specific member of the ICAM family and its largest, carrying nine Ig-like domains. It is expressed exclusively in the mammalian telencephalon, where it localizes to somatodendritic membranes and regulates dendritic spine maturation, spine morphology and excitatory synapse formation through homophilic adhesion and heterophilic binding to LFA-1 on T cells and to beta-1 integrins. Neuronal activity and metalloproteinases release soluble ICAM-5, and elevated soluble telencephalin in cerebrospinal fluid has been reported in encephalitis and other inflammatory brain conditions, positioning it as a candidate neurological biomarker. Recombinant ICAM-5 supports studies of synapse development and neuroimmune adhesion.