Natural killer cells contribute to the ability of the innate immune system to successfully defend against a constant onslaught of viral pathogens. They appear to be particularly important in the host defense against herpesviruses. In responding to viral infections, natural killer produce cytokines and chemokines that modulate the subsequent adaptive immune response. Dr. French’s work suggests that inappropriate or ineffectual natural killer cell responses during viral infections may contribute to the onset or pathogenesis of autoimmune musculoskeletal disorders. This project focuses on developing the tools to characterize natural killer cell functional responses in pediatric patients. An intended outcome is the development of new clinical tests to identify children at risk for recurrent herpesvirus infections or autoimmune musculoskeletal disorders..