This is a lymphocyte that has been infected by the Epstein-Barr Virus (EBV) or Cytomegalovirus (CMV) in infectious mononucleosis and is referred to as a "Downy cell". Downy cells may be classified as types I, II, or III. This is a type I Downy cell.
Review Date 3/10/2022
Updated by: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.