Transplantation immunity and the suppression of spleen colony formation by immunization with murine leukemia virus preparations (Friend)

Mice were immunized with tissue‐cultured or formalin‐inactivated murine leukemia virus preparations and challenged with active virus or with the virus‐induced leukemic cells from established tissue culture lines. Although the virus obtained from the tissue‐culture system had a low leukemogenic potential, its immunizing capacity was equal to that of the inactivated leukemic spleen filtrate virus. All preparations afforded protection against challenge with virus as well as with cells. Transplantation immunity was further demonstrated by the marked inhibition of spleen colony formation by the leukemic cells in preimmunized lethally irradiated mice.