title: Significance of C4d Immunostaining in Placental Chronic Intervillositis.
abstract: Deposition of the complement split product C4d is a phenomenon studied extensively as a marker for complement activation in antibody-mediated transplant rejection. C4d also is observed in placental disease processes including spontaneous abortion, infarct, and villitis of unknown origins. Massive chronic intervillositis is a rare placental abnormality associated with increased risk of growth restriction, fetal death, and recurrent fetal loss. In this study, we evaluated C4d immunostaining in placentas with accumulation of intervillous monocytes with and without villitis. Archived placentas from Kosair Children's Hospital (Louisville, KY) and Seattle Children's Hospital (Seattle, WA) were selected and divided into 4 groups, 16 cases of intervillositis with complicated pregnancy, 15 cases of uncomplicated intervillositis, 20 cases of complicated villitis, and 13 cases of uncomplicated villitis, all with varying degrees of monocytic cells in the intervillous space. Representative specimen blocks were immunohistochemically stained for C4d. The percentage of positive staining of the microvillous surface of the syncytiotrophoblast was scored by five pathologists, and the following consensus score was determined: 0  =  0% to 5%; 1  =  5% to 25%; 2  =  25% to 75%; and 3 ≥ 75%. C4d immunostain localized to the microvillous border of syncytiotrophoblast in many of the placentas. C4d staining was more strongly associated with intervillositis than with villitis (odds ratio: 6.3; confidence interval: 2.1-18.7; P  =  0.001).
authors.affiliation: 1 Department of Pathology, Kosair Children's Hospital, Louisville, KY 40202, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Bendon
authors.affiliation: 1 Department of Pathology, Kosair Children's Hospital, Louisville, KY 40202, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Coventry
authors.affiliation: 1 Department of Pathology, Kosair Children's Hospital, Louisville, KY 40202, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Thompson
authors.affiliation: 2 Department of Laboratories, Seattle Children's Hospital, Seattle, WA 98105, USA.
authors.forename: Erin R
authors.initials: ER
authors.lastname: Rudzinski
authors.affiliation: 2 Department of Laboratories, Seattle Children's Hospital, Seattle, WA 98105, USA.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Williams
authors.affiliation: 3 Core for Biomedical Statistics, Seattle Children's Research Institute, Seattle, WA 98101, USA.
authors.forename: Assaf P
authors.initials: AP
authors.lastname: Oron
mesh_terms: D002824:Chorionic Villi / Q000473:pathology; D003181:Complement C4 / Q000032:analysis / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D010922:Placenta Diseases / Q000473:pathology*; D011247:Pregnancy; D012189:Retrospective Studies
chemical_list: D003181:Complement C4
keywords: C4d immunostain; intervillositis; placenta