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

Abstract

Placental lesions of 71 women with documented recurrent spontaneous abortions of unknown etiology were evaluated using immunohistochemical staining. Placental tissue blocks (less than 12 weeks gestation) from prior pregnancy losses were obtained, recut, and analyzed utilizing monoclonal antibody to identify the trophoblast (cytokeratin 8/18) and natural killer (NK) cells (CD57) at the implantation site. The following features were evaluated: trophoblast invasion pattern; syncytium formation; vasculitis and thromboembolism of decidual vessels; decidual inflammation; decidual necrosis; 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 decidual tissue near the implantation site. Controls consisted of 20 healthy women with no history of recurrent pregnancy losses, who had their pregnancies electively terminated. Of the women studied, 29.6% demonstrated elevated CD57+ NK cells at the implantation site (P = 0.030), 54.1% had inadequate cytotrophoblast invasion depth (P = 0.000), 44.1% demonstrated inadequate syncytium formation (P = 0.004), and 33.9% presented thromboembolism in decidual vessels (P = 0.025). Some women with recurrent spontaneous abortions demonstrate abnormal placental lesions at the implantation site. Immunopathologic evaluation of the placental implantation site that terminated in a spontaneous abortion may reveal the immunopathogenesis of previous pregnancy losses.