CD17 is an intermediate glycosphingolipid from the metabolism of higher gangliosides that localizes to sphingolipid-sterol rafts. CD17 is detectable in monocytes, granulocytes, basophils, platelets, a subset of peripheral B cells (CD19+) and tonsil dendritic cells. It is rapidly down regulated on activated granulocytes and is upregulated on IL-2 activated T lymphocytes. CD17 binds to bacteria and may function in phagocytosis. VEGF-treated endothelial cells can produce CD17, which can then mediate signaling toward PECAM-1 expression and angiogenesis. Tumor necrosis factor ? ? (TNF? ?)-induced astrogliosis (astrocyte proliferation and glial fibrillary acidic protein (GFAP) upregulation) in response to neuro-inflammation (i.e. spinal cord injury) causes an increase in intracellular levels of CD17. Aberrant levels of glycosphingolipids are a feature of cancer cells and may influence integrin clustering and internalization.