Interferon production in adults with respiratory syncytial viral infection.

Respiratory syncytial virus may cause repeated infections and appreciable illness in adults as well as children. Factors associated with immunity and recovery are poorly understood. We studied 37 adults with natural respiratory syncytial viral illness and eight experimentally infected volunteers for nasal interferon production. Their response was compared to that of 25 adults with influenza. Interferon was detected in only six of those with natural respiratory syncytial virus and in none of those with experimental infection. The quantities of interferon were low (geometric mean, 6 U/mL) and did not appear to affect viral shedding. In contrast, 24 of influenza patients produced interferon and in greater quantities (geometric mean, 116 U/mL). This suggests that interferon is not involved in recovery from respiratory syncytial viral infection and might indicate a lack of a local cell-mediated response that could relate to the often prolonged course and shedding observed with respiratory syncytial virus.