Blood SC5b-9 complement levels increase at parturition during term and preterm labor

Area of Science:

• Immunology
• Perinatal Medicine
• Complement System Biology

Background:

• The complement system is a crucial part of innate and adaptive immunity.
• Its role during parturition and on fetal membranes is not fully understood.

Purpose of the Study:

• To investigate the hypothesis that complement is active in the plasma of parturient women.
• To determine if complement is deposited on fetal membranes after delivery.

Main Methods:

• Cross-sectional study of 97 pregnant women.
• Measurement of soluble SC5b-9 complement activity in plasma using ELISA.
• Analysis of complement deposition on fetal membranes via immuno-dot blots and immunohistochemistry.

Main Results:

• Soluble SC5b-9 complement complex levels were significantly increased in women during term labor, preterm labor, and preterm premature rupture of membranes compared to non-laboring pregnant women.
• Active complement (C5b-9 complexes) was deposited on fetal membranes in laboring women, confirmed by immunohistochemistry.
• Complement deposition on fetal membranes was not observed in women undergoing non-labor-indicated Cesarean sections.

Conclusions:

• Complement is activated in the plasma of women during parturition.
• Active complement complexes are deposited on fetal membranes during labor.
• These findings suggest a role for the complement system in the processes of human parturition.