David W. Horohov, PhD, is a professor and the William Robert Mills Chair in Equine Immunology in the Department of Veterinary Science at the University of Kentucky's Gluck Equine Research Center. His research program focuses on identifying and characterizing cytokines (messenger molecules" by which cells of the immune system signal and instruct one another) and their role in protective and pathologic (disease-causing) immune responses. He's particularly interested in the effect of age on immune responses in the horse.""avid W. Horohov