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Is there an effect of immunoglobulins and G-CSF on neutrophil phagocytic activity in preterm infants?
1Institut für Tropenmedizin des Universitätsklinikums Tübingen, Germany.
Insights
Neutrophil phagocytosis of Group B Streptococcus (GBS) was impaired in preterm infants when using their own serum. Treatments like intravenous immunoglobulin and G-CSF did not significantly enhance this activity.
Area of Science:
- Neonatal immunology
- Infectious disease research
- Hematology
Background:
- Group B Streptococcus (GBS) is a leading cause of neonatal sepsis.
- Neutrophil phagocytosis is a critical defense mechanism against bacterial infections.
- Preterm infants exhibit altered immune responses, increasing their susceptibility to infections.
Purpose of the Study:
- To compare neutrophil phagocytic activity against GBS in preterm infants and adult controls.
- To investigate the effects of preterm infant serum, intravenous immunoglobulin (IVIG), and granulocyte colony-stimulating factor (G-CSF) on phagocytosis.
Main Methods:
- Acridine orange fluorescence whole blood assay used to quantify neutrophil phagocytosis of GBS.
- Comparison between ten healthy preterm infants (<32 weeks gestation) and adult controls.
- Evaluation of phagocytosis with adult serum, preterm infant serum, and supplemented preterm serum (IVIG, IgM-enriched immunoglobulin, G-CSF).
Main Results:
- No significant difference in GBS phagocytosis between preterm infants and adults when using adult serum.
- Significantly reduced phagocytosis in preterm infants when using pooled preterm infant serum (6% at 10 min, 18% at 30 min) compared to adults (32% at 10 min, 56% at 30 min).
- IVIG and IgM-enriched immunoglobulin did not significantly alter phagocytosis in preterm infants. G-CSF accelerated phagocytosis at 10 min but did not increase overall activity at 30 min.
Conclusions:
- Preterm infant serum significantly impairs neutrophil phagocytosis of GBS.
- The potential benefits of IVIG and G-CSF in neonatal sepsis may not be due to a direct, immediate enhancement of neutrophil phagocytic activity.
- Further research is needed to understand the mechanisms underlying impaired neonatal immunity to GBS.
Abstract:
The percentage of neutrophils phagocytosing group B streptococci (GBS) in vitro was determined in ten healthy preterm infants (< 32 weeks of gestation) and adult controls by using an acridine orange fluorescence whole blood assay. When GBS were opsonized with adult serum, no difference in phagocytic activity was found between both groups after 10 and 30 min (preterms: 40% and 68%, adults: 32% and 56%, respectively). Phagocytosis rates in preterm infants decreased significantly to 6% and 18% (at 10 and 30 min) when pool serum of preterm infants was used instead. Supplementation of the preterm serum with either intravenous immunoglobulin or IgM-enriched immunoglobulin did not change the results significantly. The addition of granulocyte colony-stimulating factor (G-CSF) accelerated phagocytosis significantly after 10 min, but did not increase the overall phagocytic activity after 30 min in either group. Hence the potential benefits of intravenous immunoglobulins and G-CSF in neonatal sepsis may not be attributable to an immediate increase in and direct effect on neutrophil phagocytic activity.