Histologic and immunologic study of uterine biopsy tissue of women with incipient abortion.

Biopsy specimens taken from the region of the placental bed were examined for the presence of phloxinophilic granulated mononuclear cells in women with a history of recurrent miscarriage and who would eventually miscarry a current pregnancy. They were compared with biopsy specimens from women with intact pregnancies presenting for elective termination of pregnancy and those with "missed abortion." Cells with large cytoplasmic granules (greater than or equal to 1 micron) were abundant in the group of ongoing pregnancies whereas cells with smaller granules (less than 1 micron) that were similar to large granular lymphocytes were more abundant relative to cells with large granules in the biopsy specimens from failing pregnancies. Immunosuppressive activity was tested in the supernatants of cultured biopsy samples of each group and found to be significantly lower in the incipient miscarriage group. These findings could represent alterations associated with the process of miscarriage, such as inflammation, or there may be deficient suppressor cell activity at the fetomaternal interface as the reason for "rejection" of the early embryo.