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Serum haemolytic classical and alternative pathways of complement in infancy: age-related changes
V P Ferriani1, J E Barbosa, I F de Carvalho
1Department of Paediatrics, Faculty of Medicine of Riberão Preto, University of São Paulo, Brazil.
Insights
Complement
Area of Science:
- Immunology
- Pediatric Medicine
Background:
- The complement system is crucial for innate immunity.
- Understanding complement activity in infants is vital for assessing immune function.
Purpose of the Study:
- To evaluate the maturation of complement hemolytic activity in healthy children from birth to 2 years.
- To establish normal reference ranges for complement pathways in pediatric populations.
Main Methods:
- Kinetic method used to determine the time (t 1/2) for 50% red blood cell lysis.
- Assessed both classical and alternative complement pathways.
- Studied serum samples from healthy neonates and children aged 1-24 months.
Main Results:
- Lowest complement activity observed in neonates for both pathways.
- Classical pathway reached adult levels by 1-3 months; alternative pathway by 13 months.
- Classical pathway activity exceeded adult levels in children aged 7-24 months.
Conclusions:
- Complement pathways exhibit distinct maturation patterns in early childhood.
- Established normal t 1/2 ranges for pediatric complement activity.
- Provides essential reference data for pediatric immunology and clinical practice.
Abstract:
The haemolytic activity of complement was evaluated in the serum of healthy children from birth to 2 years of age using the kinetic method for the determination of the time needed to lyse 50% of target red cells (t 1/2). No sex-linked differences were observed in any of the age groups studied and the lowest lytic activity levels for both complement pathways were detected in neonates. The two pathways, however, showed different maturation patterns, i.e., lytic activity levels similar to those of adults were reached between the 1st and 3rd month of life (classical pathway) and around the 13th month (alternative pathway). In the age group of 7 to 24 months, the lytic activity of the classical pathway was higher than in adults. The present data permitted us to establish normal ranges of t 1/2 values for the classical and alternative pathways in serum of healthy neonates and children aged 1 to 24 months.