Aim 1 is to prepare natural and recombinant trophoblast Kunitz domain protein-1 (TKDP-1) and the other Kunitz domain proteins identified in trophoblast. In Aim 2, the inhibitory properties, including specificities, of these proteins will be tested against granzymes purified from activated mouse, human, and sheep lymphocytes. In Aim 3, the ability of TKDP-1 to protect tumor cells targeted by natural killer and cytotoxic lymphocytes will be assessed in a series of experiments that measure the release of cytoplasmic and nuclear contents. Aim 4 will examine the processing of TKDP-1 during its biosynthesis in trophoblast, and particularly whether the repeats serve to anchor the inhibitor at the surface of the trophoblast.