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Acute shift in immune response to microbial activators in very-low-birth-weight infants
M B Veber1, S Cunningham-Rundles, M Schulman
1Department of Pediatrics, New York Hospital, NY 10021.
Insights
Very-low-birth-weight infants show heightened initial immune responses to microbes but a significant decrease within two weeks. This early immune shift impacts infant immune development and defense post-birth.
Area of Science:
- Immunology
- Neonatal Research
- Microbiology
Background:
- The immune system of very-low-birth-weight (VLBW) infants (<1500g) is immature.
- Understanding early immune responses is crucial for neonatal health and host defense.
Purpose of the Study:
- To investigate in vitro lymphocyte activation in VLBW infants during the first two weeks of life.
- To compare VLBW infant immune responses to microbial pathogens and mitogens with adult and full-term infant controls.
Main Methods:
- Studied 23 VLBW infants on day 1 and 7 of those infants on day 14.
- Utilized normal adults (n=23) and cord blood (n=7) as controls.
- Assessed lymphocyte activation in vitro using microbial pathogens (Haemophilus influenzae, Staphylococcus epidermidis, Staphylococcal protein A) and phytohaemagglutinin (PHA).
Main Results:
- VLBW infants exhibited significantly higher lymphocyte responses to microbial pathogens on day 1 compared to controls.
- Responses to the T cell mitogen phytohaemagglutinin (PHA) were significantly lower in VLBW infants than in adult controls.
- A significant down-regulation of immune response was observed in VLBW infants between day 1 and day 14 post-birth.
Conclusions:
- VLBW infants display a unique early immune profile with heightened microbial responses but reduced mitogen responses.
- A notable down-regulation of immune function occurs within the first two weeks post-natally.
- This dynamic immune shift has critical implications for neonatal immune development and post-natal host defense strategies.
Abstract:
Investigation of lymphocyte activation in vitro to microbial pathogens was undertaken in very-low-birth-weight infants during the first 2 weeks of life. Twenty-three infants with birth weights less than 1500 g were studied on day 1. Normal adults (n = 23) and cord blood from seven full-term infants were used as controls. Longitudinal studies were also carried out on seven of the 23 infants 2 weeks following delivery. Results indicated that lymphocyte responses of very-low-birth-weight infants on day 1 of life were significantly greater than those of both adult controls and full-term infants, particularly to Haemophilus influenzae, Staphylococcus epidermidis and Staphylococcal protein A. In contrast, response to the T cell mitogen phytohaemagglutinin (PHA) was significantly less in very-low-birth-weight infants than in adult controls and full-term infants. The seven very-low-birth-weight infants studied showed a down-regulation of immune response in the 2 weeks following birth, such that responses on day 14 were significantly less than those on day 1 for the same activators. This shift in immune response appears to have important implications for the immune development and host defence in the post-natal period.