Serologic Studies on Cells of Graffi Virus-Induced Myeloid Leukemia in Mice

Sera of mice resistant to isologous inocula of Graffi virus-induced myeloid leukemias reacted in vitro with cells of leukemias having the same viral origin. Specific humoral antibodies were detected by the indirect fluorescent-antibody and cytotoxic tests. Antibody activity was removed by absorption of the immune sera with Graffi leukemia cells. Normal spleen and lymph node cells and cells of a spontaneous AKR leukemia did not absorb the activity directed against Graffi leukemia cells. The immune sera possessed virus-neutralizing capacity as indicated by the inactivation of a virus-containing, cell-free leukemia filtrate. Formation of antibodies reacting with leukemia cells was also induced by inoculation of adult mice both with active and formalin-treated preparations of the Graffi virus. Whether the specific antigen of the leukemia cells could represent an antigen present in the virus is discussed.