Extraction of leukemia associated antigen (LAA) and active specific immunization with LAA in acute leukemia.

Leukemia associated antigen (LAA) was prepared from leukemia cells, using hypotonic lysis and low frequency sonications, followed by diethylaminoethyl (DEAE) cellulose column chromatography. Four protein peaks were eluted by stepwise introduction of increased concentration of NaCl solutions. With running on polyacrylamide gel electrophoresis (PAGE), unique bands which were not present in extracts of remission bone marrow, appeared in eluates of higher mol NaCl solution. These eluates produced positive blastogenic response when incubated with autologous remission lymphocytes. Active specific immunization with pooled allogeneic LAA was performed in 14 adult AML patients in complete remission. Immunization was done weekly for 3 weeks and immunological studies (measurement of in vitro lymphocyte blastogenic responses and delayed hypersensitivity skin reactions) were done weekly for 5 weeks. Twelve out of 14 patients showed increased blastogenic responses to LAA after immunization, and 9 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). The increase of blastogenic responses 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. Increased skin test reactivity to LAA after immunization was seen in 7 out of 14 patients. Those patients with an initially weak reaction showed increased reactivity after immunization. There was no correlation between blastogenic responses and skin test reactivity.