Final Activity Report Summary - CLM RECEPTOR FAMILY (CMRF35-like molecules: a novel receptor family involved in the control of myeloid cell function) The work has involved the study of novel receptors expressed by the white blood cells of the immune system. Receptors are small protein molecules that are present on the surface of white blood cells that enable the cells to interact with their environment. For instance they may allow the cells to detect bacteria or viruses that are present in the body. Other receptors allow fine tuning of the cell activation state by activating or inhibiting cell processes. We have shown that one of the receptors that we are studying is an activating receptor that activates the killing process in one type of white blood cell, known as a natural killer cell. Natural killer cells kill infected or tumour cells found in the body. The next step is to determine what this receptor binds to (a structure known as the receptor ligand) so that we know what it helps the white blood cells to recognize. This is an extremely difficult task, but we have developed a very stable and sensitive system that allows us to do this. We have already used this system to identify the ligands for a number of receptors expressed by natural killer cells, and have begun to use it to hunt the ligands of the novel receptors that we are studying. We have identified cells that express the ligands on the cell surface and are in the process of identifying precisely what the ligands are.