A recent study published in the European Respiratory Journal has revealed new insights into the immune response in children suffering from recurrent respiratory tract infections (rRTIs). The study, which included 100 children under the age of 10, their families, and healthy healthcare professionals, found that serum antibody levels, typically used in immunodiagnostic testing, do not correlate with the severity of respiratory infections. Instead, the research highlights the critical role of salivary antibodies, particularly polyreactive immunoglobulin A (IgA), in determining infection severity and risk.
The study discovered that 28% of salivary antibodies exhibited polyreactivity, a significant contrast to only 2% in serum antibodies. Notably, higher levels of salivary polyreactive IgA were associated with a reduced risk of recurrent lower respiratory tract infections and the presence of multiple respiratory viruses. Furthermore, the abundance of Haemophilus influenzae, a common respiratory bacterium, was found to correlate with a higher symptom burden in these infections.
These findings underscore the importance of mucosal immunity, specifically in the respiratory tract, and suggest that salivary IgA levels and the presence of H. influenzae could serve as important biomarkers for assessing infection risk and severity in young children with rRTIs. This research may prompt a shift in how healthcare professionals approach the diagnosis and management of recurrent respiratory infections in paediatric patients.
