title: Postvaricella purpura fulminans caused by acquired protein s deficiency resulting from antiprotein s antibodies: search for the epitopes.
abstract: Postvaricella purpura fulminans is a rare disease in children that is probably caused by an acquired protein S deficiency resulting from antiprotein S antibodies. The epitope of these antibodies is unknown. A 5-year-old girl is described with postvaricella purpura fulminans and an acquired protein S deficiency. In this patient and in her 3-year-old sister with uncomplicated varicella, the concentrations of antiprotein S antibodies were measured and followed with enzyme-linked immunosorbent assay techniques. The epitope of the antiprotein S antibodies was studied using miniprotein S, a recombinant variant of protein S that consists of the first 242 amino acids of protein S, lacking the sex hormone binding globulin-like domain. In the patient's plasma, concentrations of free protein S antigen and total protein S antigen reached normal levels in 4 months and 5 weeks, respectively. The concentrations of the antiprotein S antibodies decreased to 25% of the initial level in the course of 5 months. In the sister, antiprotein S antibodies were present as well, but the concentrations were lower than those in the patient. Most of the antiprotein S antibodies were directed against the first 242 amino acids of protein S. After varicella, a heterozygous autoantibody response may develop that may result in severe acquired protein S deficiency leading to purpura fulminans. Epitopes of these antiprotein S antibodies are situated on both the first 242 amino acids of protein S and the sex hormone binding globulin-like domain.
authors.affiliation: Department of Pediatrics (Pediatric Hematology), Emma Children's Hospital AMC, Amsterdam, The Netherlands. c.h.vanommen@amc.uva.nl
authors.forename: C Heleen
authors.initials: CH
authors.lastname: van Ommen
authors.forename: Merel
authors.initials: M
authors.lastname: van Wijnen
authors.forename: Flip G
authors.initials: FG
authors.lastname: de Groot
authors.forename: Chantal M A M
authors.initials: CM
authors.lastname: van der Horst
authors.forename: Marjolein
authors.initials: M
authors.lastname: Peters
mesh_terms: D001323:Autoantibodies / Q000276:immunology*; D001780:Blood Coagulation Tests; D002644:Chickenpox / Q000150:complications*; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology*; D005260:Female; D006801:Humans; D011695:IgA Vasculitis / Q000209:etiology* / Q000276:immunology; D008297:Male; D011446:Prospective Studies; D017293:Protein S / Q000276:immunology*; D018455:Protein S Deficiency / Q000150:complications*
chemical_list: D001323:Autoantibodies; D000939:Epitopes; D017293:Protein S