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[Acute respiratory tract infections and mannose-binding lectin insufficiency in small children]
Anders Koch1, Mads Melbye, Per Sørensen
1Afdeling for epidemiologisk forskning, Statens Serum Institut, Artillerivej 5, DK-2300 København S. ako@ssi.dk
Introduction:
According to hospital-based studies, increased susceptibility to certain infections is associated with genotypes that cause low serum levels of the protein mannose-binding lectin (MBL). However, the contribution of MBL insufficiency to the incidence of common childhood infections on a population basis is unknown. To investigate the effect of MBL insufficiency on the risk of acute respiratory infections (ARI) in unselected children, we performed a prospective population-based study of ARI in young children in Sisimiut, Greenland.
Material And Methods:
An open cohort of children aged 0-2 years was formed in 1996, and followed up with weekly morbidity surveillance visits for a two-year period. Episodes of ARI were diagnosed on medical history and clinical examinations. MBL genotypes were determined from blood samples according to the presence of structural alleles and promoter alleles.
Results:
Altogether 294 children participated and 44 refused. Blood samples were taken from 252 participants. A 2.1-fold (95% confidence interval 1.4-3.1) increased risk of ARI was found in MBL-insufficient children compared with MBL-sufficient children (p < 0.001). The risk association was largely restricted to the period 6 to 17 months of age, whereas less or no effect could be shown in younger and older children.
Discussion:
These population-based data suggest that genetic factors such as MBL insufficiency play an important role in host defence, particularly during the vulnerable period of infancy between 6 and 17 months of age, when the adaptive immune system is immature.
Insights
Mannose-binding lectin (MBL) insufficiency significantly increases the risk of acute respiratory infections (ARI) in young children. This genetic factor is particularly impactful during infancy, from 6 to 17 months of age.
Area of Science:
- Immunology
- Genetics
- Pediatrics
Context:
- Low mannose-binding lectin (MBL) levels are linked to infection susceptibility.
- Population-level impact of MBL insufficiency on childhood infections remains unclear.
- Previous studies were hospital-based, limiting generalizability.
Purpose:
- To investigate the effect of MBL insufficiency on the incidence of acute respiratory infections (ARI) in a population of unselected children.
- To determine the role of genetic factors in host defense against common childhood infections.
Summary:
- A prospective, population-based study followed 294 children aged 0-2 years in Greenland.
- MBL genotypes were analyzed, and ARI episodes were monitored.
- MBL-insufficient children had a 2.1-fold increased risk of ARI, primarily between 6 and 17 months of age.
Impact:
- Genetic factors like MBL insufficiency are crucial for host defense in infants.
- Highlights the vulnerability of the immature adaptive immune system during early childhood.
- Provides population-based evidence for MBL's role in preventing common infections.