Evidence that circulating lymphocytes act as vehicles or viraemia in measles.

Previously described giant multinucleated cells were observed in phytohaemagglutinin (PHA) cultures of leucocytes from blood samples of 17 (36%) out of 47 children with measles or undiagnosed fever in Ibadan. The giant cells were more readily seen in PHA cultures of purified lymphocyte preparations than in total leucocyte suspensions. It was concluded that the observation indicates in vivo infection of some blood lymphocytes of patients with measles and related infections by syncitium producing virus to manifest the giant cells seen in culture. The practical application of lymphocyte cultures to the laboratory diagnosis of measles is stressed and the concept of circulating lymphocytes contributing to the systemic spread of measles infection is highlighted.