Monocyte interleukin-12 production is inversely related to duration of respiratory failure in respiratory syncytial virus bronchiolitis

The correlation of clinical and immunological parameters with the duration of respiratory failure was investigated to identify factors determining the clinical outcome of respiratory syncytial virus (RSV) bronchiolitis necessitating mechanical ventilation. At initiation of mechanical ventilation in 30 patients with RSV, production of interleukin (IL)-12 and IL-10 was measured in 48-h peripheral blood cell cultures that were stimulated with lipopolysaccharide and interferon-γ. The ventilation index (VI)an indicator of respiratory dysfunction that includes partial pressure of arterial CO₂, peak airway pressure, and respiratory rate- correlated with the duration of mechanical ventilation (r = .47; P = .013). Age was not associated with the duration of mechanical ventilation. A highly significant inverse correlation was found between the duration of mechanical ventilation and the production of IL-12 at admission (r= -.62; P < .001). This correlation was independent of VI. No correlation was found between IL- 10 production and the duration of mechanical ventilation. It is hypothesized that low monocyte IL-12 response during initial RSV infection adversely affects clinical out come of patients with severe RSV bronchiolitis.