Immunopathology of the implantation site utilizing monoclonal antibodies to natural killer cells in women with recurrent pregnancy losses

PROBLEM: Placental lesions of 71 women with documented recurrent spontaneou s abortions of unknown etiology were evaluated using immunohistochemical st aining. METHOD OF STUDY: Placental tissue blocks (less than 12 weeks gestation) fro m prior pregnancy losses were obtained, recut, and analyzed utilizing monoc lonal antibody to identify the trophoblast (cytokeratin 8/18) and natural k iller (NK) cells (CD57) at the implantation site. The following features we re evaluated. trophoblast invasion pattern; syncytium formation; vasculitis and thromboembolism of decidual vessels; decidual inflammation; decidual n ecrosis; fibrin deposition at the decidual necrosis site; mononuclear-cell infiltration in villi and intervillous space. perivillous fibrin deposition ; trophoblast morphology; and quantitation of CD57+ NK cells within the dec idual tissue near the implantation site. Controls consisted of 20 healthy w omen with no history of recurrent pregnancy losses, who had their pregnanci es electively terminated. RESULTS: Of the women studied, 29.6% demonstrated elevated CD57 + NK cells at the implantation site (P=0.030), 54.1% had inadequate cytotrophoblast in vasion depth (P = 0.000), 44.1% demonstrated inadequate syncytium formation (P = 0.004), and 33.9'% presented thromboembolism in decidual vessels (P = 0.025). CONCLUSION: Some women with recurrrent spontaneous abortions demonstrate ab normal placental lesions at the implantation site. Immunopathologic evaluat ion of the placental implantation site that terminated in a spontaneous abo rtion may reveal the immunopathogenesis of previous pregnancy losses.