ITGAM and respiratory syncytial virus bronchiolitis: This is supported by clinical studies of children hospitalized with RSV bronchiolitis, which showed that neutrophils with upregulated CD11b were recoverable both from the airways by bronchiolar lavage and from peripheral circulation.9 Furthermore, neutrophils recovered from peripheral circulation of infants with RSV bronchiolitis have been shown to contain RSV mRNA.11 Viraemia due to RSV has not, to our knowledge, been observed clinically, which suggests that the virus causes symptoms because of its effects on the respiratory tract.