Polyreactive Salivary Antibodies Linked to Recurrent RTI Severity

FRIDAY, Aug. 16, 2024 (HealthDay News) -- For children with recurrent respiratory tract infections (rRTIs), serum antibody levels are not associated with respiratory disease severity, but salivary polyreactive immunoglobulin (Ig)A and Haemophilus influenzae are associated with severity, according to a study published online Aug. 8 in the European Respiratory Journal.

Mischa H. Koenen, from the University Medical Center Utrecht in the Netherlands, and colleagues conducted a prospective cohort study including 100 children aged younger than 10 years with rRTIs, their family members, and healthy health care professionals to examine antibody responses in saliva and their interplay with respiratory microbiota in relation to RTI severity and burden.

The researchers observed no association between serum antibody levels and RTI severity. Overall, 28 and 2 percent of salivary and serum antibodies, respectively, displayed polyreactivity. There was a negative association seen for salivary polyreactive IgA with recurrent lower RTIs (adjusted odds ratio, 0.80) and detection of multiple respiratory viruses (adjusted odds ratio, 0.76). There was a positive association seen for abundance of Haemophilus influenzae with RTI symptom burden (regression coefficient, 0.07).

"Our findings indicate a pivotal role for polyreactive antibodies and the respiratory microbiota in the occurrence and severity of RTI symptoms in children with rRTIs," the authors write. "Understanding local mucosal immunity dynamics is an essential step towards the early identification of children at risk of significant RTI burden."

One author received funding from Seqirus; another author disclosed ties to several pharmaceutical companies.

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