High anti-PLAC1 antibody levels in idiopathic infertile patients with repeated unexplained implantation failure

Introduction: Unexplained infertility is a diagnosis of exclusion since no pathogenetic mechanisms have been discovered in this setting. PLAC1 (Placenta-specific1), a trophoblast-specific gene, encodes for a protein that is highly expressed inhumanplacenta, localizing primarily to the differentiated syncytiotrophoblast. Recent studies showed that PLAC1 is immunogenic since it was found to elicit a spontaneous antibody response in cancer patients. This study aimed to determine the levels of anti-PLAC1 in infertile women affected by idiopathic sterility, and with a history of unexplained implantation failure after IVF cycles, as compared to fertile women Materials and Methods: Serum samples were drawn from 21 idiopathic infertile patients with a history of repeated unexplained implantation failure after IVF-ET (infertile group) and from 81 fertile control women (control group). Anti-PLAC1 antibody levels were determined by ELISA test. Results: We demonstrated that infertile womens’ mean (and standard deviation) optical densities (ODs) fromELISA test ranked significantly higher than controls (0.27 0.2 vs 0.13 0.1 respectively; Mann-Whitney test p 0.0009). Conclusions: Anti-PLAC1 antibodies could represent a biomarker associated with idiopathic sterility and with high probability of repeated implantation failure after ovarian stimulation and IVF-ET, greatly improving the diagnostic work up of infertile couples