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In the present study the migration of human monocytes towards the supernatants of five different human myeloid leukemic cell lines, four different human lymphatic leukemic cell lines and blasts derived from three different patients with acute myeloid leukemia (AML) was studied and the role of monocyte chemoattractant protein (MCP)-1 was established with an ELISA assay. Large differences in migration of monocytes towards the leukemic cell supernatants were shown (variation of approximately 10 to 150% compared to positive control), but high amounts of monocyte migration was always restricted to myeloid leukemic cells (cell lines or patient blasts). MCP-1 turned out to play a major role in the migration, firstly since there was a direct correlation between the amount of migration and the concentration of MCP-1 in the supernatants, and secondly since the addition of anti-hMCP-1 was able to inhibit migration to background level in all cases. Cytotoxicity experiments with a MTT test using MCP-1-stimulated monocytes against two human myeloid leukemic cell lines showed no increase in cell death compared to unstimulated monocytes. It is concluded that monocyte migration towards leukemic cells is restricted to the myeloid lineage and is regulated by MCP-1, which is produced in different amounts by the leukemic cells. Besides, MCP-1 does not increase the direct toxic effects of monocytes on leukemic cells. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the effect of hyperthermia on hematopoietic progenitors from six chronic myeloid leukemia (CML) bone marrow (BM) samples at diagnosis and four peripheral blood stem cell (PBSC) samples from CML patients after stem cell mobilisation. CD34-positive cells, isolated from these samples, were incubated for 2 h at 37, 42 or 43 degrees C and were plated in the colony-forming unit granulocyte-macrophage (CFU-GM) and the long-term culture initiating cell (LTCIC) assay. To evaluate purging, individual colonies from these assays were analyzed for the presence of the bcr-abl gene with interphase fluorescence in situ hybridization (FISH) and/or RT-PCR. BM samples showed a significant higher sensitivity both at the CFU-GM and LTCIC level, after treatment at 42 degrees C, as compared to the control BM samples obtained from healthy volunteers. The four BM samples of CML patients with a low leukocyte number at diagnosis harbored a mixture of bcr-abl-negative and positive colonies and an increase in the percentage of bcr-abl-negative colonies was observed in all cases. CML patients with a high leukocyte count at diagnosis, however, showed only bcr-abl-positive progenitors even after hyperthermia. PBSCs showed a significant higher sensitivity at the LTCIC level but not at the CFU-GM level, after treatment at 42 degrees C, as compared to the control PBSC samples obtained from nonhematologic cancer patients. Molecular analysis of individual colonies demonstrated an increase of bcr-abl-negative progenitors after thermic treatment in two out of three samples. When comparing both stem cell sources, PBSCs showed a decreased thermic sensitivity as compared to the BM samples at the CFU-GM level, whereas at the LTCIC level an increased thermic sensitivity was observed, both for the controls and the CML samples. In conclusion, both for BM and PBSCs samples, CML progenitors are more sensitive to hyperthermia than control cells, especially at the LTCIC level. In agreement with these results, an increase of bcr-abl-negative progenitors in six out of seven samples could be demonstrated either at the CFU-GM level, LTCIC level or both. Hyperthermia should be explored further as a possible purging modality in CML. [ABSTRACT FROM AUTHOR]

In this study we compared interphase fluorescence in situ hybridization (I-FISH) with reverse transcription polymerase chain reaction (RT-PCR) for the molecular analysis of hematopoietic colonies derived from patients with chronic myeloid leukemia (CML). Molecular analysis of individual colonies is often performed to monitor purging efficacy in CML. We harvested individual colony-forming unit granulocyte-macrophage (CFU-GM) colonies. One half was analyzed with I-FISH, for the presence of bcr-abl fusion gene. The other half was analyzed with RT-PCR for the presence of the bcr-abl mRNA. We wanted to address the following questions: (1) is the bcr-abl gene always expressed in CFU-GM colonies and (2) which technique has to be preferred to analyze individual CFU-GM colonies? In total, 133 colonies, derived from six CML patients, could be analyzed both with I-FISH and RT-PCR. We found a positive correlation in 89% of the cases: 118 colonies showed the same results with both techniques. However, 15 of the 106 I-FISH-positive colonies were negative in the RT-PCR. Serial analysis of the cDNA derived from 22 colonies showed in each round of amplification 21-29% RT-PCR-negative but I-FISH-positive colonies. However, all I-FISH-positive colonies showed at least one positive RT-PCR, either in the first, second or third round of amplification. These results indicate that the bcr-abl gene is probably always transcriptionally active in CFU-GM colonies. Reliable analysis with RT-PCR is possible but likely to generate false negative results. We conclude that: (1) I-FISH offers a reliable alternative to RT-PCR for analyzing individual hematopoietic colonies and (2) results obtained with RT-PCR should only be interpreted with caution. [ABSTRACT FROM AUTHOR]