Spontaneous resorption in the CBA x DBA/2 model is attributed to NK cells, macrophages, and Th1-type cytokines. In vivo depletion of NK cells by anti-asialoGM1 Ab or macrophage depletion by silicon dioxide treatment reduced abortion rates, which could no longer be boosted by injecting TNF-alpha (which activates NK cells) or IFN-gamma (which activates macrophages). TNF-alpha + gamma-IFN coadministration aborted >80% of the embryos whether or not NK cells or macrophages had been depleted or estradiol + progesterone was injected to correct potential reduction in ovarian function by cytokines. The cytokines also aborted IRF1+/+ C57BL/6 but not IRF1-/- females pregnant by IRF1+/+ DBA/2. Both spontaneous and cytokine-boosted abortions in CBA x DBA/2 were blocked by Ab to fgl2 prothrombinase [corrected] expressed by cytokine-stimulated vascular endothelial cells and monocytes; in vivo Ab depletion of granulocytes also prevented TNF-alpha + IFN-gamma-induced abortions. Cytokine-triggered thrombotic/inflammatory processes in maternal uteroplacental blood vessels causes abortion.
