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 necess itating mechanical ventilation. At initiation of mechanical ventilation in 30 patients with RSV, production of interleukin (IL)-12 and IL-10 was measu red in 48-h peripheral blood cell cultures that were stimulated with lipopo lysaccharide and interferon-gamma. The ventilation index (VI)-an indicator of respiratory dysfunction that includes partial pressure of arterial CO,, 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 correlati on was found between the duration of mechanical ventilation and the product ion of IL-12 at admission (r = -.62; P < .001). This correlation was indepe ndent of VI, No correlation was found between IL-10 production and the dura tion of mechanical ventilation. It is hypothesized that low monocyte IL-12 response during initial RSV infection adversely affects clinical outcome of patients with severe RSV bronchiolitis.