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Activity of classical and alternative pathways of complement in preterm and small for gestational age infants
Insights
Low birth weight infants show impaired complement activity, particularly preterm infants. However, intrauterine growth restriction does not impact complement development, which progresses with gestational age.
Area of Science:
- Immunology
- Neonatology
- Pediatrics
Background:
- Complement system activity is crucial for immune defense.
- Low birth weight infants are at increased risk for infections due to immature immune systems.
- Understanding complement development in neonates is vital for assessing immune competence.
Purpose of the Study:
- To compare complement activity in low birth weight infants based on gestational age.
- To investigate the influence of birth weight and gestational age on complement development.
- To assess complement pathway function in appropriate for gestational age versus small for gestational age infants.
Main Methods:
- Assessed complement activity using CH50 and kinetics (tH50) for classical and alternative pathways.
- Measured levels of complement C3 and Factor B.
- Compared complement parameters between small for gestational age and appropriate for gestational age low birth weight infants, and adult controls.
Main Results:
- Small for gestational age infants exhibited significantly higher complement activity (CH50, tH50, C3, Factor B) than appropriate for gestational age infants.
- All measured complement parameters were significantly lower in low birth weight infants compared to adults.
- Complement levels correlated strongly with gestational age, with classical and alternative pathway activities showing similar developmental patterns.
Conclusions:
- Low birth weight infants, especially preterm infants, possess a significant deficit in complement activity.
- Complement factor levels increase progressively with gestational age.
- Intrauterine growth restriction does not impede complement system development, which is primarily driven by gestational age.
Abstract:
Complement activity was compared in 50 low birth weight infants divided into appropriate and small for gestational age groups; the influence of birth weight and gestational age on complement development was also investigated. CH50 and kinetics (tH50) of both classical and alternative pathway activity of complement, C3, and Factor B levels were significantly higher in small for gestational age infants (classical pathway CH50, 630 HU/ml +/- 184 SD; CP tH50, 77 min +/- 47; aternative pathway CH50, 44.8 HU/ml +/- 11.3; AP tH50, 56 min +/- 43; C3, 73.98 mg/dl +/- 12.68; and Factor B, 13.17 mg/dl +/- 3.67) than in weight-matched appropriate for gestational age infants (CP CH50, 523 HU/ml +/- 152; CP tH50, 105 min +/- 49; AP CH50, 38.8 HU/ml +/- 13; AP tH50, 90 min +/- 53; C3, 58.14 mg/dl +/- 9.43; and Factor B, 9.32 mg/dl +/- 1.73). Complement values were lower in low birth weight infants than in adult controls (P less than 0.001 in all cases). All complement parameters were mainly correlated with gestational age; CH50 values of the classical and alternative pathways were also highly correlated with each other (r = 0.64; P less than 0.001). Low birth weight infants, especially preterm infants, have an important defect of complement activity. Complement factors increase gradually during gestation and intrauterine growth retardation does not affect complement development. Classical and alternative complement pathway activities have a similar development pattern.