Lymphokine-activated killer cells can discriminate CD34+ leukemia cells from normal hematopoietic progenitor cells

The ability of lymphokine-activated killer (LAK) cells to discriminate between CD34+ leukemia cells and hematopoietic progenitor cells was investigated. As effector cells, CD4(-)-LAK generated from a CD4- subset of allogeneic peripheral blood lymphocytes were used. The target cell samples were obtained from peripheral blood stem cell (PBSC) collections. Detection of residual tumor cells was performed using a polymerase chain reaction (PCR) technique for chimeric bcr/abl messenger RNA. When PBSC were obtained from patients with seminoma and lung cancer, treated with the CD4(-)-LAK for 12 h and the CD34+ cells were isolated, colony formation (CFU-GM) by these cells was preserved. When PBSC were obtained from a patient with PCR-positive acute lymphocytic leukemia and treated with the CD4(-)-LAK for 3 h, reexamination showed conversion to PCR negativity. Furthermore, when the CD34+ cells isolated from the negative converted PBSC were cultured, they still exhibited colony formation. These results suggest that the CD4(-)-LAK can kill the CD34+ leukemia cells, discriminating from the normal hematopoietic progenitors.