Expansion of cytotoxic effectors with lytic activity against autologous blasts from acute myeloid leukaemia patients in complete haematological remission

Abstract

Summary. New therapeutic approaches are needed to improve the cure rates in acute myeloid leukaemia (AML). The present study was designed to investigate whether: (1) cytotoxic lymphocytes could be expanded from AML patients in complete remission; (2) their signal transduction machinery was preserved; (3) these cells were capable of producing cytokines involved in the cytolytic process; and (4) these cells showed cytotoxic activity against allogeneic and autologous blasts. By co-culturing blood mononuclear cells with feeder cells, we obtained an average 5á3-fold increase in the total cell number and a 35-fold increase in natural killer (NK) cells. Expression of the f chain and of tyrosine kinases of the Src and Syk-ZAP families involved in the triggering of NK functions was analysed on expanded cells. The results demonstrated a signal transduction apparatus preserved and quantitatively similar to that of normal donors. After phorbol myristate acetate and ionomicin stimulation, the ability of expanded cells to produce interferon c and tumour necrosis factor a was documented. Patients' expanded cells showed a cytotoxic activity against target lines and allogeneic blasts which was similar to that of normal donors. Puri®cation experiments indicated that the NK cell fraction was responsible for most of the lytic effect. More signi®cantly, these cells also exerted a lytic effect against autologous blasts that could be further enhanced following incubation with low-dose interleukin 2. These ®ndings document the possibility of expanding cytotoxic effectors with preserved signal transduction machinery and autologous killing capacity from AML patients in remission, and suggest a new potential immunotherapeutic strategy for the management of early disease recurrence or of residual disease.

Recognition of adult and pediatric acute lymphoblastic leukemia blasts by natural killer cells

“…This possibility is further supported by the results of the cytotoxic tests presented here, confirming the susceptibility of BCR-ABL + ALL cells to NK-mediated killing, and by the previously reported ability of autologous NK cells activated in a non-GMP setting to recognize and kill ALL blasts. 39 Further studies performed in compliance with GMP rules will address this point also in the autologous setting.…”

Cytotoxic effect of trans-cinnamaldehyde on human leukemia K562 cells

“…Despite major progress in treating hematologic malignancies, much work remains ahead. Some of these patients will eventually relapse due to the persistence of residual leukemic cells that escape the cytotoxic effects of therapy [21] . Occasionally, routine radiation and chemotherapy used to treat leukemia are both unable to eradicate the residual and metastatic leukemic cells.…”

Natural killer cell‐mediated lysis of freshly isolated human tumor cells

“…For example, activation signals through the DNAM-1 receptor seem to play an important role in the recognition of neuroblastomas and ovarian carcinomas, whereas signaling via NKG2D is important in the recognition of AML blasts. 48,60,61,66 Killing of the tumor types studied seem often not mediated solely via one receptor, but often seem to rely on a complex pattern of receptor-ligand engagements as demonstrated in several of the reviewed papers. The varying ligand profile of fresh tumor cells, even within specific tumor types, represents a hallmark of many tumors and highlights the importance of moving the focus from homogeneous cell lines to complex freshly isolated, nonpropagated, patient-derived tumor targets when studies relating to human immunotherapy are addressed.…”

“…48,[60][61][62][63][64][65][66][67] Although, in some cases hampered by technical difficulties, including monitoring the specific lysis of fresh tumor cells within heterogeneous patient-derived cell populations, recent reports have provided evidence for NK cell targeting of human AML, multiple myelomas, neuroblastomas, gastric cancers, renal cell carcinomas, colon carcinomas and ovarian carcinomas. Below, we briefly discuss the results from some of the more recently published studies.…”

“…60 One recently published study focusing on NK cell killing of primary AML blasts used NK cell lines with single KIR specificities for HLA Class I allotypes. This study nicely demonstrates NK cell recognition of freshly isolated primary AML blasts and indicates a beneficial role for KIR ligand mismatching in tumor cell killing.…”