http://www.appliedradiology.com RSS Feed on Applied Radiologyhttp://www.appliedradiology.com//Issues/2003/06/Supplements/Development-of-cell-surface-protein-targeted-CT-and-MR-contrast-agents.aspxAlthough nonspecific contrast agents have appreciably improved computed tomography (CT) and magnetic resonance imaging (MRI), specific tissue enhancement represents the next logical progression of improved patient care. Specific targeting of cell-surface proteins has been exploited for the delivery of chemotherapeutic agents and for many types of nuclear medicine studies, but cellular targeting of contrast agents has met with only limited success. This article reports the development of CT and MRI contrast agents specific for cell-surface proteins, accomplished through adaptation of an existing immunoliposome system used for the delivery of chemotherapy to breast tumors. We chose to develop contrast agents specific toward three cell-surface proteins, namely Fas ligand, Fc receptor, and CD5. Fas ligand, which is expressed on immune-privileged cells, binds to the Fas receptor present on T cells and induces apoptosis. The Fc receptor is specific for the terminal constant region of the immunoglobulin molecule, which is utilized by the reticuloendothelial system to bind immunoglobulins. Finally, CD5 is a signal transduction molecule that modulates signaling through the T cell or B cell receptors. We demonstrate specific in vitro enhancement of testicular tissue through Fas ligand targeting, and enhancement of the reticulo-endothelial system (RES) through Fc receptor and CD5 targeting.Wednesday, 11 Jun 2003 15:39:42 GMT