Maternal cells in chorionic villi from placentae of normal and abnormal human pregnancies.

Problem: We asked if activated macrophages and CD4 positive T lymphocytes in placental chorionic villi with villitis were of maternal or fetal origin.

Method: We employed a double antibody immunocytochemical technique on placental sections from three normal and four abnormal pregnancies with small-for-gestational-age infants. All studied placentae were mismatched for the maternal-fetal HLA-DRw 52 antigen. Areas of immunopathology were identified by using a monoclonal antibody to a monomorphic determination on HLA-DR, and the origin of immunological cells in areas of immunopathology was identified by using a monoclonal antibody to a polymorphic determinant on HLA-DRw 52.

Results: We used a double antibody technique that employed monoclonal antibodies to HLA-DR and HLA-DRw 52 antigens and placentae that were mismatched for the maternal-fetal HLA-DRw 52 antigen. We found that the vast majority of immunological cells within villi with inflammation were of maternal origin. Quantitative studies showed that between 75 and 100% of the cells in normal as well as in abnormal pregnancies were of maternal origin, and that abnormal pregnancies had a significantly higher percentage of villi with maternal cellular infiltrates.

Conclusion: Our data show unequivocally that cells in areas of placental immunopathology are predominantly of maternal origin, and that abnormal pregnancies are associated with significantly more villi containing immunological cells of maternal origin.