Prevention of spontaneous leukemia in AKR mice by passive immunization and type specificity of this protection.

AKR mice were given sc injections of goat antiviral immune globulin from birth through 14 or 31 days of age. Although the shorter immunization schedule greatly reduced expression of spontaneous leukemia, the longer immunization period was required for essentially complete prevention of leukemia. Immune globulin with a high neutralization titer for ecotropic virus provided this protection, whereas antibody with a high neutralization titer for murine xenotropic virus did not.