Test Details: CD56 (NCAM, neural cell adhesion molecule) is a transmembrane glycoprotein of the immunoglobulin family that serves as an adhesive molecule and is ubiquitously expressed in the nervous system in isoforms ranging from 120-180 kDa. CD56 is found on T cells and NK cells, and is involved in cell migration, axonal growth, pathfinding and synaptic plasticity. Polysialic modification results in reduction of CD56-mediated cell adhesion. CD56 is expressed on most neuroectodermal derived cell lines, tissues and neoplasms. Diseases associated with CD56 dysfunction include rabies and blastic plasmacytoid dendritic cell neoplasms.