Active specific immunization with allogeneic leukemia associated antigens or irradiated allogeneic leukemia cells in acute leukemia

Active‐specific immunization was performed in 26 adult patients with acute leukemia in remission. Fifteen patients, 14 acute myelogenous leukemia (AML) and one acute lymphocytic leukemia (ALL), received pooled allogeneic leukemia associated antigens (LAA) and 11 patients, eight AML and three ALL, received pooled irradiated allogeneic leukemia cells. LAA were prepared from leukemia cells, using hypotonic lysis and low frequency sonication, followed by discontinuous polyacrylamid gel electrophoresis or diethylaminoethyl column chromatography. Immunization was done weekly for three weeks and immunological studies (measurement of in vitro lymphocyte blastogenic responses and delayed hypersensitivity skin test reactions) were done weekly for five weeks. Among the patients who were immunized with LAA, 11 out of 15 showed increased blastogenic responses to LAA after immunization, and eight out of 10 studied showed increased blastogenic responses to irradiated autologous leukemia cells. Significant increases in blastogenic responses to both LAA and autologous leukemia cells were noticed on day 22 (p < 0.05). Among the patients who were immunized with irradiated allogeneic leukemia cells, three out of eight evaluated showed increased blastogenic responses to LAA and five out of seven evaluated showed increased blastogenic responses to autologous leukemia cells. On day 22, significant increases of blastogenic responses to autologous cells (p < 0.05), but not to LAA, were noticed. There was no increased blastogenic response noted to nonspecific mitogens or to the specific mitogenic antigen Streptolysin‐O after active‐specific immunization. The increase of blastogenic responses to LAA or autologous cells seems to be higher among the patients whose length of remission was over 12 months at the time of immunization. There was no overall significant difference between blastogenic responses in autologous serum or pooled AB(+) serum, although there were some differences in individual cases. Increased skin test reactivity to LAA after immunization was seen in seven out of 14 patients who received LAA, and four out of eight evaluated patients who received allogeneic leukemia cells. Those patients with an initially weak reaction showed increased reactivity after immunization. There was no correlation between blastogenic responses and skin test reactivity.