Provided herein are placental perfusate, placental perfusate cells, placenta-derived intermediate natural killer cells, combined natural killer cells from placenta and umbilical cord blood, and combinations thereof. Also provided herein are compositions comprising the same, and methods of using placental perfusate, placental perfusate cells, placenta-derived intermediate natural killer cells, and combined natural killer cells and combinations thereof, to suppress the growth or proliferation of tumor cells, cancer cells, and the like, and to treat individuals having tumor cells. Also provided herein are methods of treating an individual having a tumor or graft-versus-host disease with placental perfusate, placental perfusate-derived cells, natural killer cells from placenta, e.g., from placental perfusate, and/or combined natural killer cells comprising natural killer cells from placenta, e.g., from placental perfusate, and umbilical cord blood.