Ulrich Sack is the head of the diagnostic laboratory of the Institute of Clinical Immunology, Medical Faculty, University of Leipzig, Germany. After his Medical study at Leipzig University and a fellowship of the Alexander von Humboldt Society at the Clinical Research Groups of the Max Planck Society in Erlangen, he completed his qualification in Clinical Immunology. Since 2002 he has been holding a professorship at the Institute of Clinical Immunology, University of Leipzig, Germany. From 2008 to 2015 he supported the Translational Centre for Regenerative Medicine (TRM) at the University of Leipzig in the function of the Research Director. Furthermore, he was a group leader and advisor at the Fraunhofer Institute for Cell Therapy and Immunology from 2005 to 2015. He is involved in several networks of scientific experts. He has been the chair of the IFCC Working Group Flow Cytometry from 2011 to 2018, offering 16 flow cytometry courses in Europe, Asia, and South America, covering basic science, immunology, and hematology. As a technical assessor, he promotes ISO 15189, 17025, and 17043 accreditation. His scientific work focuses on cellular immunology, with a strong focus on immune function and flow cytometry. He published more than 300 research papers.