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Antibacterial activity in human amniotic fluid: dependence on divalent cations.
British Journal of Obstetrics and Gynaecology
|June 1, 1986
Summary
Human amniotic fluid contains antibacterial activity, with both high-molecular-weight (beta-lysin) and low-molecular-weight components. These components exhibit distinct biochemical properties and responses to various treatments, suggesting different antimicrobial mechanisms.
Area of Science:
- Microbiology
- Biochemistry
- Obstetrics
Background:
- Human amniotic fluid (HAF) plays a crucial role in fetal development and protection.
- The presence and nature of antibacterial factors in HAF are important for understanding intrauterine infection prevention.
- Previous studies have indicated antibacterial properties in HAF, but their biochemical characterization remains incomplete.
Purpose of the Study:
- To investigate and characterize the antibacterial activity present in human amniotic fluid.
- To differentiate between high-molecular-weight and low-molecular-weight antibacterial components.
- To elucidate the biochemical properties and metal ion dependencies of these antibacterial factors.
Main Methods:
- Collection of 34 human amniotic fluid samples from term gestations (37-41 weeks).
- Testing antibacterial activity against Bacillus subtilis.
- Differential treatment of antibacterial activity using chelating agents (EDTA, 1,10-phenanthroline, dithizone) and metal ion restoration (Mg2+, Ca2+, Zn2+, Mn2+, Co2+).
- Separation of low-molecular-weight components using acid-alcohol extraction.
Main Results:
- All amniotic fluid samples exhibited antibacterial activity against Bacillus subtilis.
- High-molecular-weight activity (beta-lysin) was sensitive to EDTA, suggesting a metalloenzyme or metal-dependent mechanism, and was restored by Mg2+, Ca2+, or Zn2+.
- Low-molecular-weight activity was sensitive to dithizone but not EDTA, and was restored by Mn2+, Co2+, or Zn2+.
- The biochemical profiles of high- and low-molecular-weight antibacterial activities differed significantly.
Conclusions:
- Human amniotic fluid possesses distinct high- and low-molecular-weight antibacterial components.
- The high-molecular-weight component (beta-lysin) shares biochemical similarities with serum beta-lysin.
- The low-molecular-weight component exhibits unique biochemical characteristics, distinct from the beta-lysin fraction.