CD48 binds to heparan sulfate on the surface of epithelial cells.

CD48 is a member of the immunoglobulin superfamily whose cell surface expression is strikingly up-regulated on the surface of Epstein-Barr virus-infected B cells. To date, no ligand for human CD48 has been characterized. In this study, we show that human recombinant CD48 binds to the glycosaminoglycan heparan sulfate on the surface of human epithelial cells. We have produced a monoclonal antibody (615) against epithelial cell surfaces that blocks this binding and show that it too recognizes heparan sulfate. The specific epitope on heparan sulfate that is recognized by the antibody and is involved in binding is also expressed in vivo on the basolateral surfaces of mucosal epithelium and lamina propria.