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[Incidence of circulating immune complexes in pediatric diseases. Comparative study with adults]
Insights
This study found circulating immune complexes in 32.6% of children with various diseases. Viral hepatitis and sepsis showed the highest prevalence of these immune complexes.
Area of Science:
- Pediatric Immunology
- Clinical Chemistry
Background:
- Circulating immune complexes (CICs) are implicated in various autoimmune and infectious diseases.
- Understanding CICs in pediatric populations is crucial for diagnosing and managing childhood illnesses.
Purpose of the Study:
- To investigate the prevalence and composition of CICs in a cohort of children with diverse diseases.
- To compare CIC findings in children with adult populations and explore potential pathogenetic mechanisms.
Main Methods:
- Polyethylene glycol (PEG) precipitation assay was used to detect CICs in 312 children (1 month–14 years).
- Immunodiffusion was employed to determine the immunoglobulin (IgG, IgM, IgA) and complement (C3, C4) components of identified CICs.
Main Results:
- Overall, 32.6% of children had detectable CICs.
- Highest CIC prevalence was observed in viral hepatitis (90%), sepsis (80.7%), collagen diseases (76.4%), and Schonlein-Henoch purpura (57.1%).
- IgG and IgM were the most common immunoglobulin components, with IgA noted in hepatitis cases. C4 and C3 were the predominant complement factors.
Conclusions:
- Circulating immune complexes are present in a significant proportion of children with various diseases, with varying frequencies depending on the underlying condition.
- While autoimmune diseases are less common in children, CICs appear to have a similar frequency to adults, suggesting potentially different pathogenetic roles.
- The clinical significance of CICs in children remains unclear, with possibilities including mere markers, mediators of tissue damage, or modulators of immune cell function.
Abstract:
Circulating immune complexes were studied using 3.5% polyethyleneglycol precipitation in 312 children with various diseases whose ages ranged from 1 month to 14 years. One hundred and one patients (32.6%) were positive and the groups with the highest percentage were those with viral hepatitis (90%), sepsis (80.7%), collagen diseases (76.4%) and Schonlein-Henoch purpura (57.1%). We found immune complexes less frequently in idiopathic thrombocytopenic purpura than in published series of adult cases, possibly due to the fact that the diseases in children is due to a different pathogenetic mechanism. The composition of the immune complexes was tested by 1% agarose immunodiffusion against a panel of antisera. IgG and IgM were found most frequently, and IgA was very uncommon except in some cases of hepatitis. C4 was the most frequently found complement component, followed by C3. Important differences between the various diseases studied were noted. Our results are very similar to those previously published by other authors. Whereas serum autoantibodies and autoimmune diseases are less common in children than in adults, circulating immune complexes seem to have a similar frequency in children to that already reported for adults. It is difficult to assess the significance of circulating immune complexes. They might be (a) a mere "marker" of no pathogenic significance (b) a mechanism of tissue damage by intravascular deposition, or (c) they might interfere with the cell membrane receptors of macrophages, producing a defect in phagocytosis. However, we were unable to demonstrate an increased number of infections in these patients.