Mast cell activation and leukotriene secretion in wheezing infants. Relation to respiratory syncytial virus and outcome.

The persistence of wheezing after early wheezing episodes in infancy may be related to the virus involved and to the type of inflammation during the initial wheezing. The role of mast cell activation and leukotriene secretion in wheezing, and the relation to outcome, is not known. Our objective was to study markers of mast cell activation and leukotriene secretion from wheezing infants, and the relation to respiratory syncytial virus (RSV) infection and persistent wheezing. Urinary 9alpha,11beta-PGF(2), a marker of mast cell activation, and urinary leukotriene E4 were measured in 106 infants hospitalized for wheezing during their first year of life. Results were related to the presence of RSV infection and the persistence of wheezing at follow-up 20 months later. Levels of 9alpha,11beta-PGF(2) were higher in infants positive for RSV than in those with RSV negative wheezing, but both groups had higher levels than controls. Leukotriene E4 levels were higher in wheezing infants than in controls. Urinary 9alpha,11beta-PGF(2) levels were higher in infants with transient compared with persistent wheezing. We found a positive correlation between 9alpha,11beta-PGF(2) and leukotriene E4, strongest in infants with RSV negative disease and in infants with persistent wheezing. The results suggest that mast cells play an important role in infant wheezing, and may be a major source of leukotriene secretion in these infants. Mast cell activation and leukotriene secretion were not associated with persistent wheezing.