The immunolocalization of bcl-2 at the maternal-fetal interface in healthy and failing pregnancies

Abstract

Programmed cell death by apoptosis occurs in both fetal and maternal tissues during early pregnancy. To investigate a role for apoptosis at the maternal-fetal interface, we have immunolocalized the bcl-2 protein in formalin-fixed decidual and placental tissue collected from women undergoing surgical termination of pregnancy (n = 22), from women undergoing a sporadic miscarriage (n = 16) and from women with a history of recurrent pregnancy loss (more than three consecutive pregnancy losses; n = 22) undergoing a further miscarriage. In all three groups, bcl-2+ cells were found in aggregates and dispersed in the stroma, and immunoreactivity was observed in glandular epithelium. Double immunostaining revealed that a majority of stromal bcl-2+ cells were CD56+ large granular lymphocytes. A computerized image analysis revealed no significant differences in percentage area of bcl-2 or CD56+ immunostaining. Significantly more biopsies from the surgical termination group (4/10) had > 20% positive immunostaining for CD56 compared with 0% in the other two groups combined (0/20; P < 0.05). Bcl-2 immunoreactivity was observed in the villi syncytiotrophoblast, and staining intensity was consistently greater in the surgical termination group. The possible roles of bcl-2 at the maternal-fetal interface are discussed.