Incidence and risk factors of anti-HLA immunization after pregnancy Emeline Masson a,b,⇑ , Chrystelle Vidal c , Marina Deschamps a , Severine Bongain c , Chantal Thevenin b , Isabelle Dupont b , Didier Rietmulher d , Fabienne Pouthier e , Gilbert Mongaillard f , Jacqueline Chabod b , Christophe Ferrand a , Pierre Tiberghien a,b , Jean-Michel Rebibou a,g a UMR 1098, Inserm, Université de Franche-Comté, Etablissement Français du Sang BFC, IFR 133, Besançon, France b Laboratoire d’Immunogénétique, Établissement Français du Sang BFC, Besançon, France c CICBT 506 (Centre d’Investigation Clinique et Biothérapies), Centre Hospitalier Universitaire, Besançon, France d Service de Gynécologie Obstétrique, Centre Hospitalier Universitaire, Besançon, France e Banque de Sang Placentaire, Établissement Français du Sang BFC, Besançon, France f Centre de Ressources Biologiques, Centre Hospitalier Universitaire, Dijon, France g Service de Néphrologie, Centre Hospitalier Universitaire, Dijon, France article info Article history: Received 10 August 2012 Accepted 10 April 2013 Available online 27 April 2013 abstract Pregnancy is the only natural source of anti-HLA immunization. The exact frequency of this immuniza- tion remains undetermined as prior studies either used methods with a low sensitivity or were per- formed late after delivery. We present here the first study on women at delivery evaluating anti-HLA immunization by Luminex. We also attempted to isolate factors influencing immunization, such as soluble HLA-G (sHLA-G) levels and genetic polymorphisms. With Luminex, anti-HLA immunization was observed in 54.4% of the women. As expected, immuniza- tion frequency increased with the number of children, reaching 74% in women with >2 deliveries. Among immunized women, strong cytotoxic Ab (as detected by Complement Dependent Cytotoxicity) were asso- ciated with a lower level of sHLA-G. None of the studied polymorphisms influenced immunization rate in the whole cohort. Among 94 first pregnant women with no history of miscarriage, the -174 IL-6 gene pro- moter mutation (G/C) appeared more frequently in non immunized women (69% vs. 45% in immunized ones, p = 0.02). Lastly, the occurrence of a miscarriage before the first live delivery significantly decreased immunization. These results may help to understand mechanisms of pregnancy induced immunization. They also have an impact in the management of previous pregnant women requiring organ or hematopoietic stem cell transplantation. Ó 2013 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved. 1. Introduction Anti-HLA antibodies (Ab) are a major player in transplantation immunology, for their role in hyperacute, acute and chronic rejec- tion [1–3]. The development of such Ab occurs after allogeneic con- tact, by transplantation, transfusion, and mainly pregnancy for women. Most women on a transplant waiting list today have had pregnancies, which has become the first sensitizing event after the decrease of transfusions for patients awaiting kidney trans- plantation. The impact of pregnancy on the incidence of anti-HLA immunization is poorly explored: most of the data were obtained using the standard complement dependent cytotoxicity assay (CDC), with an incidence of 18–30% [4–6]. Two recent studies [7,8] used the sensitive flow cytometry method (Luminex); the incidence of immunization found is higher (24% [8] and 42.5% [7]), but these studies focused on blood donors, for whom preg- nancy happened many years (with a mean of 14) before testing, therefore failing to detect immunization which have faded in time, but can still have a significant clinical impact in a subsequent transplantation setting [9]. The first aim of our work was to study the incidence of anti- HLA immunization using the most sensitive method available (Luminex), on sera collected just after delivery, as well as 90 days later. 0198-8859/$36.00 - see front matter Ó 2013 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.humimm.2013.04.025 Abbreviations: Ab, antibody; Ag, antigen; BAFF, B cell Activating Factor; CDC, complement dependent cytotoxicity; CRP, C-reactive Protein; DTT, dithiothreitol; HLA, human leukocyte antigen; IL-6, interleukine 6; sHLA-G, soluble HLA-G; TLR4, toll-like receptor 4. ⇑ Corresponding author. Present Address: Laboratoire d’Immunogénétique et Histocompatibilité, Hôpital Saint-Louis, 1 Avenue Claude Vellefaux, 75010 PARIS, France. Fax: +33 142494449. E-mail address: emeline.masson@sls.aphp.fr (E. Masson). Human Immunology 74 (2013) 946–951 Contents lists available at SciVerse ScienceDirect www.ashi-hla.org journal homepage: www.elsevier.com/locate/humimm