Leukapheresis is a medical procedure that separates white blood cells from the rest of the blood components. This process is often used to collect specific types of white blood cells, such as lymphocytes, for various treatments, including cancer therapies and stem cell transplants. During leukapheresis, blood is drawn from a patient, passed through a machine that filters out the white blood cells, and then returned to the body. This procedure can help manage certain medical conditions, such as leukemia or lymphoma, by reducing the number of abnormal white blood cells in the bloodstream.