Report of two cases of acute myelogenous leukemia immunized with autologous leukemia-derived hybrid cells

Reports that immunizations with leukemia-derived hybrid cells prolonged the survival of leukemic mice led us to attempt an analogous approach in two adult patients with acute myeloid leukemia (AML). Hybrid cells were prepared from the pretreatment marrows of the newly-diagnosed patients with D98OR cells, in the first case, and with KR12 cells, in the second case. (D98OR and KR12 cells are human cell-lines.) Hybrids formed with KR12 cells expressed HLA antigens of both parental sources and some of the clonal isolates expressed myeloid-associated determinants. The immunizations were performed during the first complete clinical remission; the patients were demonstrably immunocompetent. Positive delayed type hypersensitivity responses to both (X-irradiated) hybrid cells and to (X-irradiated) autologous pretreatment marrow were observed following the immunizations. Mixed lymphocyte reactions toward autologous marrow were positive in one of the patients. In both, relapse occurred approximately two months after the first immunization and eight months after first diagnosis. The first patient remained in complete remission for two and one-half years following reinduction chemotherapy; reinduction chemotherapy was unsuccessful in the second patient.