Biomedical subjects

K Lechner

Publications and source records attributed to K Lechner.

At least 91 records · Page 5Linked to original sources

PubMed1999

The mast cell as site of tissue-type plasminogen activator expression and fibrinolysis.

Recent data suggest that mast cells (MC) and their products (heparin, proteases) are involved in the regulation of coagulation and fibrino(geno)lysis. The key enzyme of fibrinolysis, plasmin, derives from its inactive progenitor, plasminogen, through catalytic action of plasminogen activators (PAs). In most cell systems, however, PAs are neutralized by plasminogen activator inhibitors (PAIs). We report that human tissue MC as well as the MC line HMC-1 constitutively produce, express, and release tissue-type plasminogen activator (tPA) without producing inhibitory PAIs. As assessed by Northern blotting, highly enriched lung MC (>98% pure) as well as HMC-1 expressed tPA mRNA, but did not express mRNA for PAI-1, PAI-2, or PAI-3. The tPA protein was detectable in MC-conditioned medium by Western blotting and immunoassay, and the MC agonist stem cell factor (c-Kit ligand) was found to promote the release of tPA from MC. In addition, MC-conditioned medium induced fibrin-independent plasmin generation as well as clot lysis in vitro. These observations raise the possibility that MC play an important role in endogenous fibrinolysis.

Cell Line↗

PubMed1999

Hyperfibrinolysis in a case of myelodysplastic syndrome with leukemic spread of mast cells.

Mast cells (MC) are multipotent hemopoietic effector cells producing diverse mediators like histamine, heparin, or tissue type plasminogen activator. We report a 75-year-old male patient with myelodysplastic syndrome (MDS) of recent onset (3 months' history) associated with a massive leukemic spread of immature tryptase+ MC (tentative term: myelomastocytic leukemia). The patient presented with pancytopenia, bleeding, hypofibrinogenemia, and an increased cellular tryptase level. Moreover, an excessive elevation of plasmin-antiplasmin complexes (9,200 ng/ml; normal range: 10-150), an elevated D-dimer, and an increase in thrombin-antithrombin III complexes were found. The identity of the circulating MC was confirmed by immunophenotyping (CD117/c-kit+, CD123/IL-3R alpha-, CD11b/C3biR-), biochemical analysis (cellular ratio [ng:ng] of tryptase to histamine >1), and electron microscopy. Bone marrow (bm) examination showed trilineage dysplasia (17% blasts), 30% diffusely scattered MC, and a complex karyotype. No dense, compact MC infiltrates (mastocytosis) were detectable in bm sections. Despite hyperfibrinolysis and mediator syndrome (flushing, headache), the patient received remission induction polychemotherapy (DAV) followed by two cycles of consolidation with intermediate dose ARA-C (2 x 1 g/m2/day on days 1, 3, and 5). He entered complete remission after the first chemotherapy cycle without evidence of recurring MDS. Moreover, in response to chemotherapy, the hyperfibrinolysis and mediator syndrome resolved, and the circulating c-kit+ MC disappeared. We suggest consideration of polychemotherapy as a therapeutic option in patients with high-risk MDS of recent onset, even in the case of MC lineage involvement.

Aged↗

PubMed1999

The lung resistance protein (LRP) predicts poor outcome in acute myeloid leukemia.

To determine the clinical significance of the lung resistance protein (LRP) in acute myeloid leukemia (AML), we have studied LRP expression of leukemic blasts and its association with clinical outcome in patients with de novo AML. LRP expression of leukemic blasts was determined by immunocytochemistry by means of monoclonal antibody LRP-56. LRP expression at diagnosis was detected in 31 out of 86 (36%) patients and correlated with white blood cell count (p = 0.01). The complete remission rate of induction chemotherapy was 72% for all treated patients (n = 82). The complete remission rate was 81% for patients without LRP expression but only 55% for patients with LRP expression (p = 0.01). Overall survival and disease-free survival were estimated according to Kaplan-Meier in 82 and 59 patients, respectively. At a median follow-up of 16 months, median overall survival was 17 months for LRP-negative patients but only 8 months for LRP-positive patients (p = 0.006). Disease-free survival was 9 months for LRP-negative patients and 6 months for LRP-positive patients (p = 0.078). Thus LRP predicts for poor outcome indicating that the LRP gene is a clinically relevant drug resistance gene in AML.

Adolescent↗

PubMed1999

MRP expression in acute myeloid leukemia. An update.

To determine the clinical significance of the multidrug resistance protein (MRP) in patients with de novo AML, we have studied MRP expression of leukemic cells at diagnosis and its association with clinical outcome in 127 patients. MRP expression was determined by immunocytochemistry by means of monoclonal antibodies QCRL-1/QCRL-3. MRP expression was low, intermediate and high in 30%, 46% and 24% of the patients, respectively. MRP expression was independent of age and sex of the patients, white blood cell count, FAB subtype, serum lactate dehydrogenase levels and karyotype aberrations. MRP expression had no impact no response to induction chemotherapy. The complete remission rates were 75%, 70% and 64% for patients with low, intermediate and high expression, respectively. Patients with intermediate or high MRP expression showed a trend toward shorter overall survival (p = 0.09) as compared to patients with low MRP expression. MRP does not predict for response to induction chemotherapy but intermediate or high MRP expression might be associated with shorter overall survival of the patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1999

Effect of high-dose melphalan and peripheral blood stem cell transplantation on renal function in patients with multiple myeloma and renal insufficiency: a case report and review of the literature.

Multiple myeloma with IgG-lambda monoclonal gammopathy and severe renal impairment with light-chain deposit disease was diagnosed in a 51-year-old man. Following conventional therapy with VAD (vincristine, adriamycin, dexamethasone) a partial remission was achieved. Peripheral blood stem cells (PBSC) were then collected following mobilization with cyclophosphamide and recombinant human granulocyte colony-stimulating factor and enriched for CD34-positive cells by immunoaffinity column. Fourteen months after diagnosis high-dose melphalan was given, followed by infusion of CD34-positive PBSC. Aside from mild oral mucositis and trigonitis, high-dose therapy was tolerated well. After he underwent PBSC transplantation his renal function improved, and the patient has been in in continuous complete remission for 1 year. Thus, high-dose chemotherapy can be safely administered to patients with multiple myeloma and severe renal impairment. Our findings confirm previous reports summarized in the current presentation.

Antineoplastic Agents, Alkylating↗

PubMed1999

Granulocyte colony-stimulating factor-supported combined immunosuppressive therapy (antilymphocyte globulin, cyclosporine, and methylprednisolone) in patients with aplastic anemia: tolerability, efficacy, and changes in the progenitor cell compartment.

Neutropenic infections are the major cause of morbidity and mortality in the treatment of aplastic anemia (AA) with antilymphocyte globulin (ALG), cyclosporin A (CSA), and methylprednisolone (MP). Recent data suggest a beneficial effect of administering G-CSF as an adjunct to immunosuppression. We have treated 11 consecutive patients with AA using a combined immunosuppressive regimen including ALG, CSA, and MP plus G-CSF at a dose of 5 microg/kg/day until neutropoietic recovery. In addition to measuring routine hematological parameters we have performed serial determinations of reticulocyte counts and in vitro progenitor cell cultures before and after therapy in order to assess their predictive value for treatment response and to determine the impact of therapy on early hematopoiesis. One patient died on day 34 of neutropenic septicemia. At 1 year, 81% of patients showed response to treatment. The median time to ANC values >0.5 and >1.0 x 10(9)/l were 19 and 35 days, respectively. Reticulocyte counts started to recover after 6 weeks, and transfusion independence was observed on day 52 for red blood cell transfusions and on day 53 for platelet concentrates. All patients with detectable colony formation in peripheral blood achieved a complete hematological remission, as compared with only one of five patients without progenitor cell growth. Although normal ranges were rarely achieved, there was a small but definitive improvement in progenitor cell numbers as compared with baseline values in most patients. Our results confirm the good tolerability and high efficacy of this G-CSF-supported combined immunosuppressive therapy for AA. Detectable colony growth at diagnosis seems to predict a high chance for complete hematological response.

Adult↗

PubMed1999

Successful treatment with arsenic trioxide of a patient with ATRA-resistant relapse of acute promyelocytic leukemia.

Arsenic trioxide has recently been introduced as a promising new agent to treat refractory acute promyelocytic leukemia (APL). In the present study, arsenic trioxide was given intravenously for 42 days to a 56-year-old female patient suffering from chemotherapy/ATRA-resistant APL, with 43% APL blasts in the bone marrow and elevated D-dimers. During the first days of arsenic trioxide treatment a rapid decrease in the D-dimers was seen (normal values reached until day 7), together with a slight decrease in peripheral blood leukocytes. This initial coagulation response was followed by a second phase of hematological response (starting on days 15-20) characterized by leukocytosis, occurrence of myeloid progenitor cells in the peripheral blood, and a decrease in bone marrow blasts (<1% on days 28 and 36). Finally, the patient entered complete hematological and cytogenetic remission, although the PML-RAR alpha fusion product was still detectable by PCR. These data confirm the therapeutic value of arsenic trioxide in relapsed/resistant APL.

Antineoplastic Agents↗

PubMed1999

Massive disseminated intravascular coagulation and hyperfibrinolysis in alveolar rhabdomyosarcoma: case report and review of the literature.

A 68-year-old woman presented with profuse hemorrhage and other signs suggesting an acute leukemia. Histologic and cytogenetic evaluation of her bone marrow revealed alveolar rhabdomyosarcoma as the underlying cause of massive disseminated intravascular coagulation and hyperfibrinolysis. A review of the literature reveals that coagulopathy appears to be a common feature of alveolar rhabdomyosarcoma.

Aged↗

PubMed1999

Hematopoietic donor chimerism and graft-versus-myeloma effect in relapse of multiple myeloma after allogeneic bone marrow transplantation.

A large group of patients relapsing after allogeneic bone marrow transplantation (BMT) have obtained remission after infusion of leukocytes from their original donor, suggesting a graft-versus-myeloma effect. However, side effects such as graft-versus-host disease and myelosuppression are severe, and sometimes fatal, complications of this therapeutic approach. Previously we demonstrated that patients with leukemia who lack donor hematopoiesis in relapse after BMT experience severe and lasting aplasia after infusion of donor leukocytes. In two patients - one with extramedullary and one with marrow relapse after a sex-mismatched transplantation - we analyzed hematopoietic chimerism by cell sorting and bone marrow cultures. CD34-positive cells, CD4-CD8-positive cells, committed progenitors, and LTC-IC were of donor origin, as demonstrated by two-color fluorescence in situ hybridization (FISH). Additionally, in relapse complete donor T-cell chimerism was seen. In contrast, plasma cells were of recipient origin in the patient who had a relapse in the bone marrow. Both patients were treated with infusions of donor leukocytes from their original donor. Neither patient suffered myelosuppression, and one achieved a stable complete remission.

Adult↗

PubMed1999

Clinical significance of lupus anticoagulants in children.

OBJECTIVES: To determine the spectrum of associated clinical manifestations and time course of lupus anticoagulants (LA) in children. STUDY DESIGN: Retrospective study of 95 consecutive children (46 boys and 47 girls), with a median age of 5.3 years (range, 1.7 to 17.1 years), diagnosed with presence of LA at a hemostasis referral center; 83 were followed up over a median of 2.9 years (range, 6 weeks to 21.6 years). RESULTS: At diagnosis, 80 of 95 (84%) children were free of symptoms, and presence of LA was found incidentally. Nine children (10%) had bleeding symptoms, 5 (5%) had thrombotic events, and 1 had systemic lupus erythematosus. Among the patients with bleeding, 5 had transient severe hypoprothrombinemia after adenovirus infections, and 3 had thrombocytopenia. None of the children who were initially free of symptoms had bleeding, thrombotic complications, or autoimmune disease subsequently. At follow-up, 48 of 83 (58%) patients had normal activated partial thromboplastin time values after 1.9 years (5 weeks to 19.1 years). Thirty-two (38%) still had activated partial thromboplastin time elevations but did not fulfill all criteria for presence of LA after 3.2 years (7.4 months to 9.3 years). Three (4%) patients, who had presented with thrombosis, had persistent positive LA, anti-cardiolipin, and antinuclear antibodies after 1.4, 2.8, and 7.5 years, respectively. One of these had recurrent thrombosis. CONCLUSIONS: In most children the presence of LA did not lead to clinical complications and was transient. Bleeding occurred with additional hypoprothrombinemia or thrombocytopenia. Thrombosis was rare and strongly associated with persistently positive LA.

Adolescent↗

PubMed1999

Mast cells are augmented in deep vein thrombosis and express a profibrinolytic phenotype.

A number of recent data suggest that mast cells (MC) and their products are involved in the pathophysiology of thrombosis. In the current study, we have evaluated the number, distribution, and phenotype of MC in patients with deep vein thrombosis of the lower limb (DVT) (n = 15). Contralateral nonthrombosed limb veins served as control (CO). MC were examined by Giemsa staining and by immunohistochemistry using antibodies against tryptase, chymase, tissue-type plasminogen activator (tPA), urokinase (uPA), urokinase receptor (uPAR), and plasminogen activator inhibitors (PAI-1, PAI-2). We found an increase in the number of tryptase-positive MC in DVT compared with CO (DVT: 9.1+/-1.0 v CO: 4.7+/-0.6 MC/mm2, P < .05). Most of these MC appeared to accumulate in the adventitia of the thrombosed veins, in vicinity of the vasa vasorum. In both DVT and CO, MC reacted with monoclonal antibodies to c-kit, tryptase, and chymase. MC also stained positive for tPA and urokinase receptor, but did not express detectable PAI-1 or PAI-2. As compared with CO, a decreased proportion of MC in DVT was found to stain positive for chymase and tPA. Together, our results show that MC increase in number in DVT and express a profibrinolytic phenotype. We hypothesize that MC and MC-derived profibrinolytic molecules play a role in the pathophysiology of DVT.

Aged↗

PubMed1999

Interleukin-10 inhibits burst-forming unit-erythroid growth by suppression of endogenous granulocyte-macrophage colony-stimulating factor production from T cells.

Numerous cytokines released from accessory cells have been shown to exert either stimulatory or inhibitory growth signals on burst-forming unit-erythroid (BFU-E) growth. Because of its cytokine synthesis-inhibiting effects on T cells and monocytes, interleukin-10 (IL-10) may be a potential candidate for indirectly affecting erythropoiesis. We investigated the effects of IL-10 on BFU-E growth from normal human peripheral blood mononuclear cells (PBMC) using a clonogenic progenitor cell assay. The addition of recombinant human IL-10 to cultures containing recombinant human erythropoietin suppressed BFU-E growth in a dose-dependent manner (by 55.2%, range 47.3-63.3%, p < 0.01, at 10 ng/mL). In contrast, no inhibitory effect of IL-10 was seen when cultivating highly enriched CD34+ cells. BFU-E growth from PBMC also was markedly suppressed in the presence of a neutralizing anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) antibody (by 48.7%, range 32.9-61.2% inhibition,p < 0.01), but not by neutralizing antibodies against granulocyte colony-stimulating factor and interleukin-3. This suggests a stimulatory role of endogenously released GM-CSF on BFU-E formation. Also, the addition of exogenous GM-CSF completely restored IL-10-induced suppression of BFU-E growth. To determine the cellular source of GM-CSF production, we analyzed GM-CSF levels in suspension cultures containing PBMC that were either depleted of monocytes or T cells. Monocyte-depleted PBMC showed spontaneous production of increasing amounts of GM-CSF on days 3, 5, and 7, respectively, which could be suppressed by IL-10, whereas GM-CSF levels did not increase in cultures containing T-cell-depleted PBMC. Our data indicate that IL-10 inhibits the growth of erythroid progenitor cells in vitro, most likely by suppression of endogenous GM-CSF production from T cells.

Cells, Cultured↗

PubMed1999

Immunophenotypic characterization of human bone marrow endosteal cells.

In order to determine the relationship between bone marrow (bm) endosteal cells (EDC) and hemopoietic progenitors, we have analyzed the immunophenotype of EDC using various antibodies (Ab) against mesenchymal antigens. The Ab were applied on paraffin sections of normal bm (iliac crest, n=17; talus, n=1; phalanx, n=1), myeloregenerative bm (after chemotherapy), and hematologic disorders (acute myeloid leukemia (AML), n=8; chronic myeloid leukemia (CML), n=6; myelodysplastic syndromes (MDS), n=14; severe aplastic anemia (SAA), n=4; essential thrombocythemia (ET), n=2; idiopathic (primary) osteomyelo-fibrosis (IMF), n=1; polycythemia vera (PV), n=1). In normal bm, EDC were found to react with Ab against vimentin, tenascin, alpha-smooth muscle actin, osteocalcin, CD51, and CD56, but did not react with Ab against CD3, CD15, CD20, CD34, CD45, CD68, or CD117. An identical phenotype of EDC was found in AML, MDS, SAA, ET, IMF, PV, myeloregenerative bm, and peripheral bones lacking active hemopoiesis (talus, phalanx). In patients with CML, EDC reacted with Ab to CD51, but did not react with Ab to CD56. Based on their unique antigen profile, EDC were enriched from normal bm by enzyme digestion and cell sorting. However, these enriched cells (CD56+, CD45-, CD34-) did not give rise to hemopoietic cells under the culture conditions used, i.e. in the presence of the growth factors IGF-1, bFGF, SCF, IL-3, and GM-CSF Together, our data do not support the hypothesis that EDC are totipotent mesenchymal progenitors giving rise to hemopoietic cells.

Antigens, CD↗

PubMed1999

Expression of homing receptors and related molecules on human mast cells and basophils: a comparative analysis using multi-color flow cytometry and toluidine blue/immunofluorescence staining techniques.

Mast cells (MC) and blood basophils (Ba) are multifunctional effector cells of the immune system and accumulate in areas of ongoing disease. However, despite of similar morphology, MC and Ba differ from each other in terms of cell surface receptor expression, mediator content, and tissue distribution. In order to gain new insights into mechanisms and molecules responsible for the distribution and accumulation of MC and Ba, we have investigated expression of homing receptors on primary human MC (lung, n=28; uterus, n=17), Ba (healthy donors, n=64), the mast cell line HMC-1, and the basophil line KU-812. Expression of cell surface antigens on MC and Ba was analyzed by mAb and indirect immunofluorescence staining techniques. In addition to previous findings, Ba were found to react with mAb against the selectin-ligands sLe(x) (CD15s) and PSGL-1 (CD162), L-selectin (CD62L), beta7-integrin, the 'matrix-receptor' neurothelin (CD147), platelet-endothelial cell tetraspan antigen-3 (PETA-3=CD151), and BST-1 (CD157). Novel antigens detectable on MC (lung and uterus) were CD147, CD151, CD157 and CD49c (VLA-3alpha). By contrast, MC were not recognized by mAb to sLe(x), PSGL-1, L-selectin, or beta7 integrin. No reactivity of Ba or MC with mAb to syndecan-1 (CD138), VE-cadherin (CD144), MUC18/MCAM (CD146), MGC-24 (CD164), or ALCAM (CD166) was found. The cell lines HMC-1 and KU-812 expressed a similar profile of antigens when compared to primary cells. In summary, Ba and MC express a unique profile of homing molecules. Apparently, Ba differ from MC in expression of recognition receptors relevant for binding to endothelium and consecutive transmigration.

Antibodies, Monoclonal↗

PubMed1999

Low transplant-related mortality in patients receiving unrelated donor marrow grafts for leukemia.

Transplantation with unrelated donor (UD) marrow has been shown to potentially cure patients with leukemia. Between January 1991 and April 1998, 54 patients with leukemia have received an UD BMT at our institution. Five patients received their UD BMT as a second transplant after a preceding autologous or syngeneic BMT and were excluded from further analysis. Forty-nine patients with leukemia (acute leukemia n = 26; CML n = 23) and a median age of 36 years (range 19-51) were analyzed. For conditioning, all patients received a combination of fractionated TBI and CY. GVHD prophylaxis consisted of MTX and CsA in all patients. As of 30 April 1998, 27 of 49 (55%) patients survive after a median observation time of 18 months. The probability of overall survival for standard risk and high risk patients is 54% and 31% (P = 0.05). Probability of transplant-related mortality (TRM) is 27%, 24% in standard risk and 31% in high risk patients (P = 0.44). Patients younger than 40 years (n = 33) had a similar TRM as patients 40 years and older (n = 16). The probability of relapse is 41% for the whole group, 29% for standard risk and 55% for high risk pts (P<0.05). Our data confirm that UD BMT is an effective treatment for patients with leukemia. TRM is almost similar to related sibling BMT, most probably due to improvements in HLA typing technology, conditioning regimen and supportive patient care.

Adult↗

PubMed1999

Post-transplant acute myeloid leukemia (PT-AML).

Acute myeloid leukemia following organ transplantation (PT-AML) is a rare event with only a few published cases in the literature. We present three patients who developed AML (FAB M1, M5, M4) after renal, double lung or liver transplantation. Molecular analysis detected a t(9;11) in one patient and documented the recipient origin of AML in a second patient. All patients were treated with chemotherapy. Immunosuppression was reduced to cyclosporin A (CsA) and prednisone in two patients and to prednisone alone in one patient. Two patients achieved a complete remission (CR), with a remission duration of 4.6 months in one patient, the other patient died from septicemia after 15.2 months in CR. One patient was refractory to chemotherapy and died from septicemia. This report together with the documented cases in the literature suggests that PT-AML (1) develops after a median interval of 5 years after transplantation with variable latency (range, <1-17 years); (2) is heterogeneous with respect to FAB classification; (3) shows chromosomal and molecular changes typical of therapy-related AML (t-AML: -7, +8, 11q23, inv16, t(15;17)); (4) standard chemotherapy is feasible after reduction of immunosuppression and produces a CR rate of 56% with a median remission duration of 4.6 months and an overall survival of 2.6 months; (5) the major complications are early death (25%), gram-negative septicemia, progressive disease or relapse. This review provides diagnostic and therapeutic experiences and guidelines for the management of this increasing group of post-transplant patients.

Acute Disease↗

PubMed1999

Monitoring of minimal residual leukemia in patients with MLL-AF9 positive acute myeloid leukemia by RT-PCR.

Twenty-seven patients with AML and MLL gene rearrangement were analyzed by a reverse transcriptase polymerase chain reaction (RT-PCR) for the MLL-AF9 translocation. The MLL-AF9 fusion transcript was detected in six patients. In five patients, the breakpoint of the AF9 gene was located within the recently described site A; in one patient, a novel breakpoint (AF9 site D) mapped to a position 377 bp 3' of site A. Five patients could be serially monitored for a period of 4-23 months. Two patients became two-step PCR negative in bone marrow and peripheral blood. Molecular remission was achieved rapidly after one cycle of induction chemotherapy. Both patients are in continuous complete remission (CR) at 22 and 15 months, respectively. Two patients who had achieved hematological CR did not become PCR negative and MLL-AF9 fusion transcripts were detectable in all samples after induction and consolidation chemotherapy. One patient relapsed 5 months after achieving CR. The other patient received allogeneic bone marrow transplantation from an HLA-identical sibling 2 months after achieving hematological CR and became PCR negative 4 weeks after transplantation. In the fifth patient, hematological CR could not be achieved with two cycles of intensive induction chemotherapy, and MLL-AF9 transcripts were present in all samples tested. Our data indicate that MLL-AF9 RT-PCR is specific for the t(9;11) translocation. PCR negativity can be achieved in responding patients already 1 month after induction chemotherapy. The fast reduction of MLL-AF9 positive blast cells below the detection limit of RT-PCR seems to be a prerequisite for long-term CR. The results of RT-PCR may be useful for treatment decisions (eg BMT).

Acute Disease↗

PubMed1999

Quantification of minimal residual disease in patients with BCR-ABL-positive acute lymphoblastic leukaemia using quantitative competitive polymerase chain reaction.

We analysed 20 patients with BCR-ABL-positive acute lymphoblastic leukaemia (ALL) by quantitative competitive polymerase chain reaction (QC-PCR) to study the kinetics of the leukaemic clone. Consecutive samples of 16 patients (minor-bcr, n = 10; major-bcr, n = 6) were analysed after conventional chemotherapy and/or bone marrow transplantation (BMT). DNA competitor templates co-amplifying with either p210 or p190 BCR-ABL cDNA were used for quantification of leukaemia-specific BCR-ABL mRNA. In all samples, total ABL transcripts were measured as internal control, and the percentage of BCR-ABL/ABL molecules was calculated. Following induction chemotherapy the number of BCR-ABL transcripts was reduced by a maximum of 2-3 logs. In most patients, additional chemotherapy did not lead to further reduction of BCR-ABL mRNA. In two patients, conventional chemotherapy plus autologous BMT in complete haematological remission resulted in a total reduction of the transcript level of more than 3 logs. In two other patients, allogeneic BMT caused a transient reduction of the BCR-ABL transcripts below the detection level of our method (<1 blast cell in 105 normal cells) for a period of 7 and 11 months, respectively. The achievement of PCR negativity did not guarantee sustained remission. Both patients relapsed and BCR-ABL transcript levels rose by more than 1 log prior to frank relapse. Our data demonstrate that quantification of BCR-ABL mRNA allows the evaluation of the dynamics of the leukaemic clone and thus is valuable for the evaluation of minimal residual leukaemia following various therapies and the early detection of increasing BCR-ABL transcripts prior to relapse.

Adult↗