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

Chronic myeloid leukemia and allogeneic natural killer cells: a surprising dialogue

Chronic myeloid leukemia (CML) is a clonal multilineage myeloproliferative disease of stem cell origin characterized by the presence of the Bcr/Abl oncoprotein, a constitutively active tyrosine kinase. The actual treatment of CML patients in chronic phase is the specific abl kinase inhibitor imatinib mesylate that induces 90% of cytogenetic responses in early-phase patients. However, resistance in long-term treated patients occurs and the allogeneic stem cell transplantation remains the only curative treatment in resistant patients. Despite recent reports outlining the role of allogeneic natural killer (NK) cells as potent antileukemic effectors, the mechanisms controlling the leukemic target recognition and lysis by activated NK cells have not been well identified. The authors' experimental data obtained on appropriate cellular models identify diverse mechanisms that could explain the increased NK-cell susceptibility of Bcr/Abl targets to NK-mediated lysis. They further delineate unexpected effects of the inhibition of the tyrosine kinase activity on the cross-talk between NK and CML leukemic cells. The consequences of such discoveries are discussed in the context of combined treatments with antikinases as well as adoptive cellular therapy approaches in myeloid leukemia patients.

Expression of bcr-abl mRNA in individual chronic myelogenous leukaemia cells as determined by in situ amplification

We present the results of a novel method developed for evaluation of in situ amplification, a molecular genetic method at the cellular level. Reverse transcription polymerase chain reaction (RT-PCR) was used to study bcr-abl transcript levels in individual cells from patients with chronic myelogenous leukaemia (CML). After hybridizing a fluorochrome-labelled probe to the cell-bound RT-PCR product, bcr-abl mRNA-positive cells were determined using image analysis. A dilution series of bcr-abl-positive BV173 into normal cells showed a good correlation between expected and actual values. In 25 CML samples, the percentage of in situ PCR-positive cells showed an excellent correlation with cytogenetic results (r = 0.94, P < 0.0001), interphase fluorescence in situ hybridization (FISH) (r = 0.95, P = 0.001) and hypermetaphase FISH (r = 0.81, P < 0.001). The fluorescence intensity was higher in residual CML cells after interferon (IFN) treatment than in newly diagnosed patients (P = 0.004), and was highest in late-stage CML resistant to IFN therapy and lowest in CML blast crisis (P = 0.001). Mean fluorescence values correlated with bcr-abl protein levels, as determined by Western blot analysis (r = 0.62). Laser scanning cytometry allowing automated analysis of large numbers of cells confirmed the results. Thus, fluorescence in situ PCR provides a novel and quantitative approach for monitoring tumour load and bcr-abl transcript levels in CML.

Timing of effective natural killer cell collection in cancer patients after high dose chemotherapy, compared to peripheral blood stem cell collection

Natural killer (NK) and lymphokine-activated killer (LAK) activities in patients with seminoma were determined, and the timing of effective NK cell collection was evaluated, compared to autologous peripheral blood stem cell (PBSC) collection. After chemotherapy, patients were injected with granulocyte-colony stimulating factor (G-CSF). CD56 cells decreased in parallel with white blood cells and then were restored. After discontinuing the G-CSF, the CD56 cells increased and reached peak 3-5 days after PBSC collection. The peak showed higher levels than those at premedication. Recovery-peripheral blood lymphocytes (PBL) which were obtained 4 days after PBSC collection showed higher NK and LAK activities than the PBL obtained before chemotherapy (Before-PBL). They exhibited a high expression of CD2, CD18, CD29, and CD49d. Furthermore, the LAK cells generated from the Recovery-PBL could acquire 9.6 folds of killer unit compared with the Before-PBL-LAK. These results suggest that, in order to obtain large numbers of NK cells, Recovery-PBL collection may be more advantageous than PBL collection in no relation with the chemotherapy.