Peripheral blood cytokine responses and disease severity in respiratory syncytial virus bronchiolitis

The role of cellular immunity in disease severity in respiratory syncytial virus (RSV) bronchiolitis is largely unknown. This study investigated the association between disease severity and systemic cytokine responses in hospitalized ventilated and nonventilated RSV bronchiolitis patients. In whole blood cultures stimulated with phytohaemagglutinin (PHA), lymphoproliferative responses and interferon (IFN)‐γ and interleukin (IL)‐4 production during acute illness were measured. In addition, plasma cytokines were measured. Measurements were repeated in the convalescent phase, 3–4 weeks after admission. Fifty patients were included. The median age in ventilaled patients was significantly lower than in nonventilated patients (1 versus 4 months, p