Cytotoxic cells directed against placental cells detected in human habitual abortions by an in vitro terminal labeling assay.

PROBLEM

From the clinical point of view, it has been proposed that an immunological imbalance between the mother and the fetus might exist in one of the mechanisms for human habitual abortion. However, in the definition of habitual abortion, we have no distinct immunological criteria for this clinical entity at the moment.

METHOD

We employed aborted placental cells as the target cells in an in vitro terminal labeling (IVTL) assay system, in which the cytotoxic activity of maternal peripheral blood mononuclear cells (PBMCs) against the placental cell was examined.

RESULTS

Our results showed that the cytotoxic activity of maternal PBMCs was significantly higher in the habitual aborters (the mean target cell destruction: %TCD = 34.9%, N = 14) than that in the women with a normal first trimester (the mean % TCD = 8.9%, N = 14, P < .01). The results from the IVTL assay did not correlate with other assays using paternal lymphocytes as the target cells. The surface marker analyses revealed that CD16+ cells, CD14+ cells, and CD5+ cells were involved in the cytotoxic response against the placental cells in various degrees among the cases.

CONCLUSIONS

The above evidence suggests that a variety of cytotoxic cells participate in the phenomenon of human habitual abortion.