title: Blood SC5b-9 complement levels increase at parturition during term and preterm labor.
abstract: We explored the hypothesis that complement, an innate and adaptive immune effector, is active in the plasma of parturient women and is deposited on fetal membranes collected after delivery. A cross-sectional study was designed to evaluate complement activity at parturition. Pregnant women (n = 97) between 15 and 41 years of age were enrolled in a hospital protocol during the perinatal period to assess both SC5b-9 complement activity in blood and complement deposition on fetal membranes during parturition. Soluble SC5b-9 complement activity in plasma fractions was measured using a standard enzyme-linked immunosorbent assay (ELISA) that included specific anti-complement antibodies. Complement deposition on membranes was analyzed using immuno-dot blots and immunohistochemistry. Soluble SC5b-9 complement complex levels were increased in the plasma of women during term labor (TL; median 3361; range 1726-5670 ng/mL), preterm labor (PL; median 2958; range 1552-7092 ng/mL), and preterm premature rupture of membranes (PPROM; median 2272; range 167-6540 ng/mL) compared with pregnant women who were not in labor (P; median 1384; range 174-4570 ng/mL; P < 0.001, Kruskal-Wallis test). Active complement, as assessed by the C9 neo-antigen in C5b-9 complexes, was deposited on fetal membranes, with no difference between term and preterm delivery. The deposition of active complement on fetal membranes was confirmed by immunohistochemistry. Women who underwent non-labor-indicated Cesarean sections did not exhibit complement deposition. Soluble SC5b-9 complement complex levels increased in the plasma of women during parturition, and complement C5b-9 complexes were deposited on fetal membranes.
authors: Departamento de Infectología e Inmunología Perinatal, Instituto Nacional de Perinatologia (INPer), Mexico. Electronic address: enriquesc2020@terra.com.mx.
authors: Enrique
authors: E
authors: Segura-Cervantes
authors: Escuela Superior de Medicina, IPN, Mexico. Electronic address: javiermancilla@hotmail.com.
authors: Javier
authors: J
authors: Mancilla-Ramirez
authors: División Académica de Ciencias de la Salud, UJAT, Mexico. Electronic address: Drluiszurita@gmedico.com.
authors: Luis
authors: L
authors: Zurita
authors: Departmento de Biología Celular, INPer, Mexico. Electronic address: yuriparedes@hotmail.com.
authors: Yuriria
authors: Y
authors: Paredes
authors: Unidad de Investigación Clínica, INP, Mexico. Electronic address: arredondo.joseluis@gmail.com.
authors: José Luis
authors: JL
authors: Arredondo
authors: Departamento de Infectología e Inmunología Perinatal, Instituto Nacional de Perinatologia (INPer), Mexico. Electronic address: NGalindoSevilla@hotmail.com.
authors: Norma
authors: N
authors: Galindo-Sevilla
mesh_terms: D000328:Adult; D015938:Complement Membrane Attack Complex / Q000378:metabolism*; D003430:Cross-Sectional Studies; D005321:Extraembryonic Membranes / Q000378:metabolism; D005260:Female; D006801:Humans; D036801:Parturition / Q000097:blood*; D011247:Pregnancy; D047928:Premature Birth / Q000097:blood*
chemical_list: D015938:Complement Membrane Attack Complex; C047610:SC5b-9 protein complex
keywords: Complement; Fetal membranes; Labor; Parturition; Pregnancy