Systemic eosinophil response induced by respiratory syncytial virus

Area of Science:

• Immunology
• Pediatrics
• Virology

Background:

• Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract disease (LRTD) in infants.
• Eosinophils are implicated in LRTD pathogenesis, with inflammation potentially altering granulocyte function.

Purpose of the Study:

• To investigate the activation status of eosinophils in infants with RSV-induced LRTD by analyzing surface marker expression.
• To compare eosinophil activation markers between RSV patients and healthy controls.

Main Methods:

• Analysis of eosinophil surface markers (CD11b, A17, A27, IL-5Ralpha) in 51 infants with RSV LRTD and 10 controls.
• Eosinophils were examined at admission and 6 weeks post-infection, with and without in vitro stimulation (fMLP).

Main Results:

• RSV patients exhibited higher eosinophil CD11b expression compared to controls.
• Priming markers (A17, A27) showed increased expression on stimulated eosinophils from RSV patients, suggesting in vivo priming.
• Interleukin-5 receptor alpha (IL-5Ralpha) expression was down-regulated in RSV patients.
• CD11b remained elevated at follow-up, while other markers normalized.

Conclusions:

• Infants with RSV LRTD have activated peripheral blood eosinophils compared to controls.
• This eosinophil activation state is only partially reversible during convalescence.
• Findings suggest a persistent inflammatory signature in eosinophils following RSV infection.