Immature Myeloid Cells in Respiratory Syncytial Virus Bronchioliltis

The investigators hypothesize that Respiratory Syncytial Virus (RSV) infection may influence the population of lung immature myeloid cells and dendritic cells in a way that will impair their ability to invoke an effective immune response and lead to prolonged inflammation, angiogenesis and scarring. This may lead in turn to disturbed lung function. Our aim is to determine the presence and phenotype of immature myeloid cells present in respiratory secretions of children with RSV bronchiolitis as compared to non-RSV bronchiolitis and healthy controls.