Stimulation of humoral immunity to surface antigens of leukemic cells by interferon-containing serum

C57BL/6 mice were immunized by a single injection of L-1210 leukemia cells and (CBA×C57BL/6)F1 mice were immunized by a single injection of leukemia L-1210 and P-388 leukemia cells. For 8 days (including the day of immunization) the animals received daily intraperitoneal injections of 0.4 ml of allogeneic or syngeneic interferon-containing serum, whereas control animals received the same dose of normal serum from intact mice (the interferon-containing serum was obtained from (CBA×C57BL/6)F1 mice 24 h after intraperitoneal injection of 2 mg tilorone hydorchloride). Some samples of interferon-containing serum were dialyzed for 48 h against physiological saline. The serum interferon titer was 512–1500 units/ml. On the 9th–10th day after immunization the mouse sera were put through the microcytotoxic test against leukemia cells. Definite stimulation of the cytotoxic activity of sera of mice receiving the interferoncontaining serum was discovered. The syngeneic interferon-containing serum produced a stronger immunostimulant effect than the allogeneic serum.