Relapse of acute myeloblastic leukemia lasting for four years. Production by leukemic cells of colony-stimulating activity and non-production of leukemia-associated inhibitor.

A 36-year-old woman with acute myeloblastic leukemia (M2) achieved complete remission in Feb. 1973, after ten weeks of chemotherapy with rubidomycin-cytosine arabinoside. She received weekly immunotherapy with bacillus Calmette-Guerin and allogeneic non-irradiated blast cells and monthly chemotherapy with thioguanine-cytosine arabinoside as maintenance. The bone marrow remained normocellular for 20 months. A first relapse occurred after this period. A second remission was achieved by seven courses of different cytostatic combinations. A second relapse, refractory to all cytostatic combinations tried, occurred in June 1976. She was thereafter in relapse until her death in July 1980. Autopsy showed extensive leukemic infiltration in bone marrow, liver, spleen, pericardium, stomach, and lymph nodes. Cytochemistry, surface markers, the capacity to stimulate lymphocytes, the in vitro growth pattern (colony-forming unit culture) of bone marrow and biochemical analyses did not give any remarkable results. In contrast, the peripheral blood cells produced a normal amount of colony-stimulating activity, which is significantly more than that produced by the blood from other leukemia patients. In liquid culture, the peripheral blood cells from this patient also seemed to live longer and mature more than cells from other leukemia patients. Finally, the peripheral leukemic cells from this patient seemed to produce far less leukemia-associated stem cell inhibitor than cells from other leukemia patients. The normal colony-stimulating activity production by leukemic cells and the absence of leukemia-associated stem cell inhibitor may therefore explain the long survival of this patient in relapse.