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Defective serum opsonization activity in children aged 6-48 months having acute purulent otitis media
1Department of Pediatrics, Hacettepe University Faculty of Medicine, Ankara, Turkey.
Insights
Children with acute purulent otitis media often have defective serum opsonization, a key immune function. This finding highlights the importance of mannan-binding lectin (MBL) in early childhood immunity.
Area of Science:
- Immunology
- Pediatrics
Background:
- Serum opsonization facilitates the clearance of pathogens by immune cells.
- Defective opsonization is a risk factor for recurrent infections, particularly in young children.
- Mannan-binding lectin (MBL) is a crucial serum opsonin involved in innate immunity.
Purpose of the Study:
- To investigate serum opsonization capacity in infants and young children with acute purulent otitis media.
- To compare opsonization levels between patients and age-matched healthy controls.
- To explore the role of opsonization defects in recurrent purulent otitis media.
Main Methods:
- Yeast (Saccharomyces) opsonization assay using electronic counting of unphagocytosed particles.
- Assessment of polymorphonuclear leukocyte (PMN) uptake of yeast particles in patient and control sera.
- Measurement of CH50 and serum immunoglobulin levels.
Main Results:
- A significant proportion of children (13.7%) with acute purulent otitis media exhibited defective serum opsonization, despite normal CH50 and immunoglobulin levels.
- Children with a history of recurrent purulent otitis media showed a higher prevalence of opsonization defects (21.8%).
- The prevalence of defective opsonization was significantly higher in patients compared to healthy controls (2.9%).
Conclusions:
- Defective serum opsonization is prevalent in children with acute purulent otitis media and recurrent infections.
- These findings support the critical role of mannan-binding lectin (MBL) in host defense during early childhood.
- Opsonization defects may contribute to the susceptibility to infections when the antibody repertoire is still developing.
Abstract:
Serum opsonization of yeast (Saccharomyces) was investigated in 51 patients whose ages were between six and 48 months (median 15 months) with acute purulent otitis media and in an age-matched control group (median 13 months). Opsonization was assessed by measuring yeast particle uptake in an assay based on an electronic count of the unphagocytosed particles in serum by polymorphonuclear leukocytes. Despite normal levels of CH50 and serum immunoglobulins, a defective opsonization was determined in 13.7 percent of the patients (7 in 51). The corresponding figure was 2.9 percent in 103 healthy controls (p < 0.001). On the other hand, 218 percent (5 in 23) of the children having a history of recurrent purulent otitis media showed defective opsonization (p < 0.001). Previously, the presence of an opsonization defect has been linked to low levels of mannan binding lectin (MBL), a calcium dependent serum lectin that acts as an opsonin. Therefore, our findings indirectly support the idea that MBL has an important role as host defense, particularly in the earlier period of life when the antibody repertoire is restricted.