Leonard H. Calabrese, DO, is Professor of Medicine and Vice Chair of the Department of Rheumatic and Immunologic Diseases at the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University. He is also Codirector of the Center for Vasculitis Care and Research, and he holds a joint appointment in the Department of Infectious Disease. Furthermore, Dr. Calabrese serves as Director of the R.J. Fasenmyer Center for Clinical Immunology at the Cleveland Clinic, specializing in diseases of the immune system, in particular, immunodeficiencies, including HIV. He has published extensively on the safety of biologic therapies for autoimmune diseases, including the epidemiology of opportunistic and viral infections.