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Concentrations of main serum opsonins in early infancy
V Drossou1, F Kanakoudi, E Diamanti
1Department of Neonatology, Aristotle University of Thessaloniki, Greece.
Insights
Serum opsonin levels in infants, including immunoglobulins and complement proteins, mature over the first six months. Gestational age significantly influences these levels, impacting immune development in newborns and infants.
Area of Science:
- Pediatrics
- Immunology
- Neonatology
Background:
- Opsonins are crucial for innate immunity, mediating pathogen clearance.
- Reference values for neonatal and infant opsonins are essential for assessing immune status.
- Immune system development varies significantly in preterm and term infants.
Purpose of the Study:
- To establish reference values for key serum opsonins in infants from birth to six months.
- To investigate the impact of gestational age on opsonin concentrations during early infancy.
- To analyze the transplacental transfer of immunoglobulins.
Main Methods:
- Serial measurement of serum immunoglobulins (IgG, IgA, IgM), IgG subclasses, C3, C4, and fibronectin.
- Rate nephelometry used for quantitative analysis.
- Study included 566 neonates (26-41 weeks gestational age), maternal samples, and adult controls.
Main Results:
- Opsonin concentrations at birth were lower than adult values, reaching adult levels by 3-6 months.
- Gestational age significantly affected IgG, IgG subclasses, C3, C4 (up to 3 months), and fibronectin (up to 1 month).
- IgA and IgM levels were not impacted by gestational age; higher neonatal IgM warrants reevaluation for intrauterine infection criteria.
Conclusions:
- Infant opsonin levels mature postnatally and are influenced by gestational age.
- Preferential active transplacental transport of IgG subclasses (IgG1>IgG3>IgG2>IgG4) was observed.
- Established reference ranges aid in evaluating infant immune function and diagnosing infections.
Abstract:
The evolution of the main serum opsonins in neonates and infants of varying gestational age was investigated to provide reference values for these opsonins in early infancy. Serum concentrations of immunoglobulins, IgG subclasses, C3, C4 and fibronectin were serially measured from birth until the age of 6 months in term and preterm infants. Measurements were performed by rate nephelometry. Five hundred and sixty six neonates (gestational age 26-41 weeks) were examined at birth, 233 at 1 month, 218 at 3 months, and 147 at 6 months, respectively. The same measurements were performed in 54 pairs of neonatal/maternal samples and in 230 apparently healthy adults. Gestational age had a significant impact on serum IgG, IgG subclasses, C3 and C4 up till the third month, and on fibronectin until the first month. No such impact was observed for IgA and IgM. Sixteen per cent of the neonates had IgM concentrations higher than 0.2 g/l at birth, suggesting that the critical concentration of serum IgM at birth for suspected intrauterine infection should be reconsidered. Concentrations of all opsonins at birth were significantly lower than adult reference values. They only approached or even reached adult values by the third or the sixth month. Data from analysis of the neonatal and the corresponding maternal sera indicate that there is a preferential active transplacental transport of IgG subclasses in the order of IgG1, IgG3, IgG2 and IgG4. These results show that concentrations of immunoglobulins, C3, C4 and fibronectin undergo changes during the first months of life, depending not only on the infants' postnatal age but also on gestational age.