Inhibition of syngeneic tumor growth in rats immunized with allogeneic skin grafts.

The growth of a transplantable tumor (KMT-17) in syngeneic Wistar King Aptekman/Mk (WKA) rats was inhibited by preimmunization with allogeneic normal cells from Donryu strain rats. The phenomenon is referred to as allogeneic cell immunity. A slight inhibition was observed in rats immunized with normal liver, spleen, kidney, embryonal cells, whole blood and white blood cells from allogeneic Donryu rats. A strong inhibition was observed in animals which had rejected allogeneic skin grafts, particularly from the Donryu and Kyoto rats. The inhibition was comparatively weak after immunization with skin grafts from the Long Evans, ACI, Buffalo, Ficsher, Sprague Dawley or Tokyo allogeneic rat strains. This immunizing effect was dependent on the viability of the grafts and was easily abrogated by low-dose irradiation. The mechanism of allogeneic cell immunity is considered to be a non-specific stimulation of the immunity against antigenic tumors in the syngeneic host