Immunoactive products of placenta. IV. Impairment by placental cells and their products of CTL function at effector stage.

Trophoblast-enriched cell suspensions prepared by collagenase digestion from midterm murine placentae were found resistant to CTL-mediated lysis. Treatment of such cells by trypsin or neuraminidase rendered these cells susceptible to such lytic effectors. Collagenase-prepared cell suspensions could impair CTL action, whereas neuraminidase- or trypsin-treated cells did not retain this property. This effect was also observed with extracts. These results indicate that soluble factors (which we will characterize in another paper) released by trophoblast cells (in fact, spongiotrophoblast) can interfere in a dose-dependent fashion with the action of lytic effectors. We suggest that such active mechanisms are physiologic components of the placental barrier and might be defective in some cases of immunologic abortions.