Background: Neutrophils are the predominant cell in the lung inflammatory infiltrate of infants with respiratory syncytial virus (RSV) bronchiolitis. Although it has previously been shown that neutrophils from both blood and bronchoalveolar lavage (BAL) are activated, little is understood about their role in response to RSV infection. This study investigated whether RSV proteins and mRNA are present in neutrophils from blood and BAL of infected infants.
Methods: We obtained blood and BAL samples from 20 infants with severe RSV bronchiolitis and 8 healthy control infants. Neutrophil RSV F, G, and N proteins, RSV N genomic RNA, and messenger RNA (mRNA) were quantified.
Results: RSV proteins were found in BAL and blood neutrophils in infants with RSV disease but not in neutrophils from healthy infants. BAL and blood neutrophils from infants with RSV disease, but not those from healthy infants, expressed RSV N genomic RNA, indicating uptake of whole virus; 17 of 20 BAL and 8 of 9 blood neutrophils from patients expressed RSV N mRNA.
Conclusions: This work shows, for the first time, the presence of RSV proteins and mRNA transcripts within BAL and blood neutrophils from infants with severe RSV bronchiolitis.