A human minor histocompatibility antigen specific for B cell acute lymphoblastic leukemia.

Human minor histocompatibility antigens (mHags) play an important role in the induction of cytotoxic T lymphocyte (CTL) reactivity against leukemia after human histocompatibility leukocyte antigen (HLA)-identical allogeneic bone marrow transplantation (BMT). As most mHags are not leukemia specific but are also expressed by normal tissues, antileukemia reactivity is often associated with life-threatening graft-versus-host disease (GVHD). Here, we describe a novel mHag, HB-1, that elicits donor-derived CTL reactivity in a B cell acute lymphoblastic leukemia (B-ALL) patient treated by HLA-matched BMT. We identified the gene encoding the antigenic peptide recognized by HB-1-specific CTLs. Interestingly, expression of the HB-1 gene was only observed in B-ALL cells and Epstein-Barr virus-transformed B cells. The HB-1 gene-encoded peptide EEKRGSLHVW is recognized by the CTL in association with HLA-B44. Further analysis reveals that a polymorphism in the HB-1 gene generates a single amino acid exchange from His to Tyr at position 8 within this peptide. This amino acid substitution is critical for recognition by HB-1-specific CTLs. The restricted expression of the polymorphic HB-1 Ag by B-ALL cells and the ability to generate HB-1-specific CTLs in vitro using peptide-loaded dendritic cells offer novel opportunities to specifically target the immune system against B-ALL without the risk of evoking GVHD.

Donor leukocyte infusions for chronic myeloid leukemia relapsed after allogeneic bone marrow transplantation.

PURPOSE: Treatment options for patients with chronic myeloid leukemia (CML) who relapse after allogeneic bone marrow transplantation (BMT) are limited. Treatment with lymphocytes from the original marrow donor and the influence on the malignant clone was studied in these patients. PATIENTS AND METHODS: Seven patients with CML that had relapsed after BMT with T-cell-depleted grafts were treated. Six patients received leukocyte infusions from the original marrow donor. One patient received a second BMT with unseparated marrow from the same sibling donor. Chimerism was studied using erythrocyte and cytogenetic markers. Residual leukemic cells were monitored by cytogenetic analysis of the Philadelphia (Ph) chromosome and by polymerase chain reaction (PCR) of the breakpoint cluster region/Abelson (BCR-ABL) fusion gene. RESULTS: In five patients with hematologic relapse, the Ph chromosome disappeared 1 to 3 months after the leukocyte infusions. Cytogenetic analysis and in situ hybridization (ISH) showed only donor cells during further follow-up. Four to five patients became negative for the BCR-ABL translocation by PCR. Graft-versus-host disease (GVHD) always preceded response and was severe in two patients. One patient with cytogenetic relapse showed no response after leukocyte infusions. GVHD after second BMT was of moderate severity. One year after second BMT, PCR for the BCR-ABL translocation was negative. CONCLUSION: Infusion of donor leukocytes is an effective treatment with a low mortality in patients with CML relapsed after BMT with a T-cell-depleted graft. Longer follow-up and more patients will be needed to know whether cure will be permanent.

Molecular diversity in AML1/ETO fusion transcripts in patients with t(8;21) positive acute myeloid leukaemia.

Patients with acute myeloid leukaemia with maturation (AML-M2) that carried the t(8;21) were tested for the presence of chimeric AML1/ETO mRNA. After RT-PCR, an expected band of 208 bp was observed on gel, as well as some slower migrating bands. The base composition of one of the additional products was determined and was found to contain a new 68-bp ETO sequence present at the fusion of AML1 and ETO genes. The derived protein sequence results in a truncated AML1 gene still containing the putative DNA binding domain. Molecular diversity in the AML1-ETO transcripts will have consequences for the detection of minimal residual disease and antisense studies.

Sporadic mutations of the p53 gene in multiple myeloma and no evidence for germline mutations in three familial multiple myeloma pedigrees.

The recent finding that eight out of 10 multiple myeloma cell lines have p53 gene mutations prompted us to examine the p53 tumour suppressor gene in 25 non-related multiple myeloma patients. None of 19 patient bone marrow samples available for Southern blot analysis showed rearrangements in the p53 gene and only one patient showed loss of the p53 locus. DNA encompassing exons 5, 7, and 8, where p53 mutations commonly cluster, was amplified by PCR. Single-strand conformation polymorphisms of the PCR-amplified exon 5 region were detected in two patients. Direct sequencing of the mutant band revealed that one patient had a C to T transition at codon 138 (Ala to Val) and one patient had a G to C transversion at codon 139 (Lys to Asn). p53 mutations in germline cells in hereditary cancer syndromes predispose the family members to the development of malignancies. We therefore searched for p53 germline mutations in exons 5, 7, and 8 in the affected individuals from three families each with two multiple myeloma patients (these patients include three individuals from the non-related group mentioned above). Using Southern blotting, polymerase chain reaction/single-strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing, no germline mutations were found. These results indicate that mutations in exons 5, 7, and 8 of the p53 gene are infrequent in multiple myeloma.

In AML t(8;21) colony growth of both leukemic and residual normal progenitors is restricted to the CD34+, lineage-negative fraction.

In an earlier study we observed residual normal colonies in the CD34+, lineage-negative fraction in AML with a differentiated phenotype. The phenotype of both normal and leukemic progenitors in AML M2, t(8;21) was the subject of this study. The specific translocation enabled discrimination of normal and leukemic cells. Bone marrow samples from eight patients were evaluated for CD34 and the differentiation markers CD33, CD19 and CD56. Growth in all phenotypic fractions was measured in a single cell assay, which enabled quantification of plating efficiency, colony size and determination of progenitor cell origin. No growth was observed in the CD34-negative fraction. In the CD34+, lineage-positive fraction only clusters up to 20 cells were found in 6/8 samples. In 7/8 samples highly proliferative myeloid, erythroid and mixed colonies were cloned from the CD34+/CD56-CD19-CD33- fraction with a frequency between 1 and 12%. Such large colonies grew at a lower frequency (1-6%) from the CD34+/CD56 fraction (4/8 samples), the CD34+/CD56-CD19- fraction (5/8 samples) and from the CD34+/CD19- fraction (1/8 samples), respectively. Among the colonies consisting of more than 150 cells, only 3/45 evaluated were positive for the AML1/ETO fusion transcript. On the other hand, 8/19 colonies with less than 150 cells were AML1/ETO positive. This study shows that like normal progenitors leukemic progenitors are also present exclusively in the lineage-negative fraction in AML M2 t(8;21). A similar hierarchy of proliferation and differentiation was found for these leukemic progenitors, the smaller colony size fitting with their limited proliferation capacity. The frequency of leukemic progenitors was in the same range as their normal counterparts and detectable only after enrichment for the CD34+, lineage-negative population.

Bax mutations in cell lines derived from hematological malignancies.

Many genes are involved in cell cycle control, DNA repair and induction of cell death. Alterations in these genes have been responsible for the development of cancer as well as for resistance to cancer therapy. Recently, an emerging family of bcl2-like genes has been identified that plays a role in the regulation of cell death. Its members are highly conserved in several domains which have been shown to be important for homodimerization or heterodimerization. The ratio between BAX/BCL2 heterodimers and BAX/BAX homodimers appears to be pivotal in deciding the life of death of a cell. We recently detected mutations in evolutionary highly conserved domains of the bax gene in cell lines derived from hematologic malignancies. Similar artificially generated mutations in other bcl2-like family members bcl2, bclxl, or ced9 have been shown to alter their function. This suggests a role for bax mutations in the multi-step pathogenesis of hematological malignancies.

Acquired skewing of Lyonization remains stable for a prolonged period in healthy blood donors.

The pattern of X-chromosome inactivation (XCIP), or Lyonization, can be used to distinguish monoclonal from polyclonal cell populations in females. However, a skewed XCIP exists in hematopoietic cells in approximately 40% of healthy elderly females, interfering with interpretation of clonality assays. In hematopoiesis, an active stem cell pool is assumed to be present within a larger population of inactive stem cells, with a continuous exchange of cells between the two compartments. The assumption that the active stem cell pool size decreases with age may explain the phenomenon of acquired skewing occurring by chance and predicts the XCIP of this population to fluctuate. This fluctuation should be reflected in the XCIP of peripheral granulocytes. We examined the XCIP for fluctuations in time in peripheral granulocytes, monocytes and T cells of young, middle-aged and elderly healthy females. We used an optimized HUMARA PCR assay that eliminates unbalanced DNA amplification. We found no fluctuations in XCIP in any age group in up to 18 months follow-up. We conclude that acquired skewing arises gradually in life without fluctuations in XCIP and that analysis at multiple time points cannot distinguish monoclonal hematopoiesis from normal, skewed hematopoiesis.

Phosphorothioate BCR-ABL antisense oligonucleotides induce cell death, but fail to reduce cellular bcr-abl protein levels.

The bcr-abl oncogene is a fusion gene resulting from a reciprocal translocation which forms the hallmark of chronic myeloid leukemia (CML). Antisense oligonucleotides complementary to the two possible mRNA breakpoints were found to inhibit cell growth of CML patient cells and cell lines, but doubt exists about their specificity. In order to test the specificity, phosphorothioate and 3' phosphorothioate capped antisense BCR-ABL oligonucleotides of different length were used. Stability, cellular uptake of oligonucleotides and effect on cell growth were studied in two CML cell lines, BV173 and LAMA-84. Phosphorothioate antisense BCR-ABL oligonucleotides were most stable, showed the highest uptake and induced cell death in BV173 but not in LAMA-84 cells. We selected the most effective antisense oligonucleotide for further analysis. The BV173 and LAMA-84 cell lines do not express the normal c-abl protein, we therefore used a c-abl specific monoclonal antibody for the detection of p210bcr-abl expression by flow cytometry. Dead cells found after treatment were gated out of analysis. Although BCR-ABL antisense oligonucleotides can induce apoptosis, no reduction of p210bcr-abl levels could be detected in living cells after treatment with antisense oligonucleotides. We conclude that antisense mediated inhibition of translation of mRNA into p210bcr-abl is not the mechanism responsible for the induction of apoptosis in cell line BV173.

Specific detection of myeloma plasma cells using anti-idiotypic single chain antibody fragments selected from a phage display library.

Bone marrow plasma cells constitute the bulk of malignant cells in multiple myeloma patients. B-lymphocytes having immunoglobulin heavy chain gene rearrangements identical to those of the malignant clone (clonally related B-lymphocytes) may function as malignant plasma cell precursors. We and others proposed the use of anti-idiotypic antibodies to isolate and study clonally related B-lymphocytes. This strategy failed until now because anti-idiotypic antibodies raised by conventional hybridoma techniques proved to react frequently with epitopes shared by different idiotypes. Recently, we succeeded in selecting specific single chain Fv antibodies from phage libraries. To select single chain Fv bearing phages specifically directed against the immunoglobulin idiotype expressed by myeloma tumor cells we panned a semisynthetic phage library against purified myeloma paraprotein Fab fragments. The selection was performed in the presence of soluble polyclonal immunoglobulin as a competitor. Three independent selections for three myeloma patients yielded 10-26 clones. Between two and seven of the selected clones were reactive with patient Fab and not with polyclonal immunoglobulin in enzyme-linked immunosorbent assays. Five out of six anti-idiotypic single chain Fvs were able to specifically stain fixed monoclonal plasma cells in myeloma bone marrow. Idiotype specificity of these single chain Fvs was confirmed by flow cytometry since they did not react with monoclonal plasma cells of other patients, a panel of nine myeloma cell lines, isolated polyclonal bone marrow plasma cells and cultured B-lymphocytes. Using these anti-idiotypic reagents we were able to detect 25 myeloma plasma cells in a background of 50000 immunoglobulin isotype-matched cells of the myeloma cell line UM-1 or 50000 donor bone marrow cells (sensitivity 0.05%). This paper shows that highly specific anti-idiotypic single chain Fv antibody fragments selected from a phage display library can be used to detect rare idiotypic cells in patient samples.

Long-term follow-up of persisting mixed chimerism after partially T cell-depleted allogeneic stem cell transplantation.

Using red cell phenotyping (RCP) and/or cytogenetics (CYT) we identified 19 patients with persisting mixed chimerism (MC) among 231 patients transplanted with partially T cell-depleted stem cell grafts from HLA-identical siblings. Persisting MC is defined as MC for more than 2 years in patients without any evidence of relapse. Median leukemia-free survival in these patients was 150 (range, 50-218) months. Diagnoses were ALL (n= 10); AML (n = 2); CML (n = 2); NHL (n = 2); MDS (n= 1); MM (n = 1) and SAA (n = 1). Purpose of this study was the long-term follow-up of MC and definition of patterns of chimerism in the various subsets of PBMCs and granulocytes. Using a PCR-STR technique CD3(+)/CD4(+) (T4 lymphocytes), CD3(+)/CD8(+) (T8 lymphocytes), CD45(+)/CD19(+) (B lymphocytes), CD45(+)/CD14(+) (monocytes), CD45(+)/CD15(+) (granulocytes) and CD3(-)/CD56(+) (NK-cells) were analyzed. The majority of patients with persisting MC were conditioned with a less intensive conditioning regimen and had little GVHD. Sequential monitoring of the chimerism resulted in a group of patients (n = 7) with very slow transient mixed chimerism that resulted in complete DC after median 7 years. Another nine patients had a relatively high percentage of persisting autologous cells for a median of 12 years and in three patients we observed a stable low percentage of autologous cells. Only two out of 19 patients (AML-CR1, CML-CP1) relapsed during follow-up. Both patients had a relatively high percentage of autologous cells. Chimerism in granulocytes and PBMC subsets was analyzed at a median of 8 years after SCT in nine patients. In five patients mixed chimerism simultaneously detected by RCP and CYT was associated with MC in all subsets. Within each individual patient the percentages of donor and recipient cells were very different between the different subsets. Two CML-CP1 patients were mixed chimera in only two subsets and in one patient these subsets represented pending relapse. In another two patients mixed chimerism with a very low number of autologous red cells was not found in the PBMCs because of the different sensitivity level of the RCP and the PCR-STR technique. We conclude that in patients with persisting mixed chimerism after partially T cell-depleted SCT a remarkable number of patients had lymphoid malignancies, the majority of the patients were conditioned with less intensive conditioning regimens and the mixed chimerism was not correlated with relapse. Chimerism in granulocytes and PBMC subsets did show great intra-individual differences in the subsets and these data correlated well with RCP and CYT data with the exception of the NK cells.

Antisense BCR-ABL oligonucleotides induce apoptosis in the Philadelphia chromosome-positive cell line BV173.

BCR-ABL antisense oligonucleotides can specifically reduce colony formation of early hematopoietic progenitor cells from chronic myeloid leukemia (CML) patients. Little is known about the mechanism of this inhibition. We studied the inhibition of the bcr-abl oncogene using fluorescein-labeled phosphorothioate oligonucleotides in the Philadelphia chromosome-positive cell line BV173. Oligonucleotide stability, uptake, bcr-abl mRNA degradation, inhibition of cell proliferation, and cell death were studied. The oligonucleotide uptake was directly dependent on the extracellular concentration and was constant over the first 18 h of incubation. After that the uptake rate decreased. We detected a decrease in bcr-abl mRNA after 3 days of treatment with antisense oligonucleotides, but much less in controls. The controls used in the experiments were the sense oligonucleotide, equimolar amounts of sense and antisense, and an untreated control. Antisense oligonucleotides completely inhibited cell growth of BV173 cells and did not inhibit growth of HL-60 cells, whereas control oligonucleotides had no such effect on either cell line. An oligonucleotide specific for the other CML breakpoint was also effective in reducing cell growth of BV173. By the use of a DNA double staining technique to discriminate between necrotic and apoptotic cells, we detected a large number of apoptotic cells in antisense treated BV173 cultures after 5 days of treatment as compared to controls. We conclude that antisense BCR-ABL oligonucleotides reduce bcr-abl mRNA expression in BV173 cells mainly in a sequence-specific manner and induce apoptosis.

Degradable dU-based DNA template as a standard in real-time PCR quantitation.

Development of real-time quantitative PCR assays requires suitable positive controls. For assays with clinical applications, these controls may be difficult to obtain because some molecular aberrations are rare and patient material may be available in limited amounts. Because of the risk of introducing contaminations in the laboratory, cloned DNA is not a desirable alternative. We describe the use of dU-containing DNA as a positive control template in real-time quantitative PCR. dU-DNA constructs can be decontaminated by adding uracil N-glycosylase (UNG) to the reaction mixture. In addition, dU-DNA can be used for accurate quantification, because it allows quantification to be expressed in numbers of molecules. Since synthetic dU-DNA constructs can easily be quantitated spectroscopically, they provide a more accurate control than arbitrary cell line units. We applied this method for the detection of the E2A-Pbx1 gene fusion and show that UNG-containing reactions can be employed for diagnostics without loss of sensitivity, and that for positive and quantitative controls UNG negative reactions can be used. The use of dU-DNA provides a novel type of control template that can easily be integrated into existing PCR protocols.

The type of factor VIII deficient plasma used influences the performance of the Nijmegen modification of the Bethesda assay for factor VIII inhibitors.

We have investigated the influence of the type of factor VIII deficient plasma used on the assay results of the Nijmegen modification of the Bethesda method for factor VIII inhibitors. Immuno depleted factor VIII deficient plasmas, lacking besides factor VIII also von Willebrand factor, gave decreased inhibitor titres compared to assay results with factor VIII deficient plasmas containing von Willebrand factor suggesting the need of the latter in the test system for the stability of factor VIII:C. Moreover the performance of the assay with immuno depleted plasma was contaminated in a certain type of this plasma by the presence of a factor VIII:C inhibitor. Chemically depleted factor VIII deficient plasma appeared to give falsely elevated titres when used in combination with other types of deficient plasmas as substrate plasma in the factor VIII:C assay due to the presence of activated factor Va in the preparation. Suggestions are described with respect to the observed limitations in order to obtain reliable results.

Semi-automated detection of the factor V mutation by allele specific amplification and capillary electrophoresis.

Recently a point mutation (G1691A) in the coagulation factor V gene was shown to cause resistance for cleavage by activated protein C. The mutation is associated with an increased thrombotic risk and thus-far the most common genetic cause of thrombophilia. Current techniques to investigate the single base pair mutation at the DNA level use an assay based upon the polymerase chain reaction followed by restriction enzyme digestion or Southern blotting and allele specific probing. The method we describe here consists of a single PCR in which two specially designed allele specific primers and two consensus primers were used in one reaction to distinguish between homozygous normal, heterozygous and homozygous mutant individuals. Amplification products were analysed using Capillary Electrophoresis and on line UV monitoring. The Allele Specific Amplification Protocol and subsequent CE analysis (ASAP-CE) is a convenient, fast, automated and highly reproducible method that can be used in a routine laboratory setting.

Analysis of expression of chorionic gonadotrophin transcripts in prostate cancer by quantitative Taqman and a modified molecular beacon RT-PCR.

Expression of human chorionic gonadotrophin (hCG) is associated with trophoblastic, testicular and other malignancies such as bladder, pancreatic, cervical, breast and prostate cancer. In the prostate, however, hCG expression, associated with neuroendocrine cells, is also found in normal tissue. Of the six highly homologous genes that all encode the beta-subunit of hCG, the beta 7 gene is reportedly the only gene expressed in several non-transformed tissues. The beta 3, 5 and 8 genes would be variably expressed in malignant tissue and placenta, but not in normal tissue. To assess to what extent this expression difference can also be found in the prostate, we compared the levels of the different hCG beta transcripts in concurrent normal and cancerous prostate tissues obtained from 17 patients. To this end, we developed a Taqman real-time fluorescent RT-PCR assay for hCG beta, and a quantitative assay specific for the beta 3, 5 and 8 genes, modified from the molecular beacon principle. This latter assay proved highly specific and capable of reliably distinguishing between these hCG beta transcripts that differ in only one nucleotide. Surprisingly, median expression levels of hCG beta were lower in prostate cancer when compared with normal tissue from the same patient. In contrast, hCG beta 3, 5 and 8 transcripts were found in normal tissue and did not differ in prostate cancer, arguing against a specific role of these transcripts in the development of prostate cancer.

Survival in first or second remission after lymphocyte-depleted transplantation for Philadelphia chromosome-positive CML in first chronic phase.

We studied the outcome of BMT in 38 consecutive CML patients in CP1 who received transplants depleted of lymphocytes using counterflow centrifugation. In all patients the conditioning regimen was intensified by the addition of anthracyclines. Donors were HLA, MLC-identical siblings. Six patients (16%) died within 6 months. All 37 patients with a follow-up of more than 0.5 months engrafted and only one (3%) suffered from acute GVHD > or = grade 3. Chronic GVHD was evaluable in 33 patients and was extensive in six (18%). The projected 5-year probabilities of hematologic, cytogenetic and molecular relapse were 30% (95% confidence interval (CI), 10-49%), 35% (95% CI, 14-56%), and 34% (95% CI, 13-55%), respectively. The projected 5-year probability of survival was 68% (95% CI, 50-86%). Projected at 5 years, probabilities of leukemia-free survival (LFS) in hematologic, cytogenetic and molecular remission were 55% (95% CI, 37-73%), 51% (95% CI, 32-69%), and 51% (95% CI, 32-70%), respectively. All patients with relapse but one who relapsed in blastic phase were treated with retransplantation (n = 1) or with the infusion of lymphocytes (n = 6). Six patients regained second hematologic remission and five entered second cytogenetic and molecular remission. Including these patients, the probability of survival in first or second hematologic remission at the end of follow-up was 68% (95% CI, 50-86%). The probabilities of survival in first or second cytogenetic and molecular remission at the end of follow-up were both 61% (95% CI, 42-80%). We advocate revaluation of T cell depletion of donor marrow for patients with CML-CP1, especially for those at high risk of developing GVHD.

Dynamics of circulating t(14;18)-positive cells during first-line and subsequent lines of treatment in follicular lymphoma.

In follicular lymphoma the t(14;18) might be useful as a tumor marker in predicting the quality of the response to treatment. We investigated whether analyzing numbers of t(14;18)-positive cells in peripheral blood correlated with remission status in individual patients receiving a variety of treatments. Numbers of circulating t(14;18)-positive cells were determined by real-time polymerase chain reaction (PCR) technique. Disease parameters and response to treatment were related to the pre- and post-treatment numbers of circulating t(14;18)-positive cells for 53 follicular lymphoma patients. In these 53 patients, 70 treatment episodes were investigated. A content of more than 328 t(14;18)-positive cells per 75,000 cells prior to therapy correlated with the more advanced stage IV disease ( P=0.01), bone marrow involvement ( P<0.01), and overt leukemic lymphoma ( P=0.04). Therapy episodes that cleared circulation from t(14;18)-positive cells with more than one log resulted in a significantly longer progression-free survival than treatment episodes with less than one log decline (26 versus 12 months, respectively) ( P<0.01). After first-line treatment episodes, numbers of circulating t(14;18)-positive cells declined in fairly all cases, irrespective of the clinical response. However, for second or later lines of treatment, declining numbers of lymphoma cells correlated with a clinical remission, whereas increasing numbers of lymphoma cells were associated with clinically stable or progressive disease. From this, we conclude that quantitation of circulating t(14;18)-positive cells in peripheral blood is of only limited clinical significance in predicting treatment efficacy for the individual follicular lymphoma patient.

Transcription of the MAGE-1 gene and the methylation status of its Ets binding promoter elements: a quantitative analysis in melanoma cell lines using a real-time polymerase chain reaction technique.

The human MAGE gene family comprises at least 12 highly homologous genes. This makes it very difficult to assess expression of a single member quantitatively by means of Northern blotting. In order to investigate expression of the MAGE-1 gene quantitatively we therefore used the recently developed real-time polymerase chain reaction (PCR), a novel fluorescence-based quantitative PCR technique. This powerful technique enables detection of expression levels which differ by as much as a factor of 10(5) in magnitude. MAGE-1 expression is known to correlate with demethylated status of the Ets binding sites of its promoter. In a panel of 19 melanoma and nine non-melanoma cell lines we were able to confirm the relationship between MAGE-1 expression and demethylation of the Ets binding promoter region. Five cell lines, however, showed only very slight expression, while the two essential Ets promoter elements were largely demethylated. Earlier studies have shown that treatment of MAGE-1-negative cell lines with the demethylating agent 5-aza-2'-deoxycytidine (DAC) is sufficient to induce MAGE-1 expression. We were able to induce clear MAGE-1 expression in two of the non-expressing cell lines by incubation with DAC, although this expression did not reach very high levels. Consistent with this low level of induction is the observation that the Ets binding sites of the MAGE-1 promoter were not completely demethylated in the DAC-treated cell populations. In conclusion, we show in this study that the real-time PCR technique is a very useful tool for the quantification of expression of highly homologous genes.

Contamination-free and automated composition of a reaction mixture for nucleic acid amplification using a capillary electrophoresis apparatus.

The acceptance of the polymerase chain reaction (PCR) as an amplification method in molecular diagnostics and the rapid development of capillary electrophoresis (CE) as an analysis method of those PCR products was a reason for us to investigate further integration of those two techniques. Using a fused-silica capillary as a pipette we were able to compose a PCR mixture in the CE apparatus. Because a capillary can be thoroughly rinsed and the CE apparatus is a closed system, the risk of contamination and therefore the occurrence of false positive results is minimized. The fact that a CE system can be fully automated contributes to a more reproducible and standardized PCR composition protocol.

Molecular Diagnosis of Acute Myeloid Leukemia with Maturation, FAB-Type M2.

Nonrandom chromosome abnormalities frequently are seen in particular subtypes of human leukemia and lymphoma. These abnormalities are considered to be involved in the neoplastic transformation and in tumor progression. The translocation (8;21) (q22;q22) is consistently associated with acute myeloid leukemia with maturation (French-American-British classification subtype M2; AML-M2). It accounts for 40% of pediatric type AML-M2 Molecular cloning of the chromosome 8-21 translocation breakpoint showed clustering on chromosome 21 within a limited region in the AML1 gene and on chromosome 8 within a limited region in the ETO gene (Eight Twenty One) also called MTG8 (Myeloid Translocation Gene on chromosome 8) (1-7). The t(8;21) results in a chimerical AML1/ETO gene on the der(8) chromosome. Rearrangement of AML1 was also detected in a patient with 8q- and only one chromosome 21, but without 21q+. This indicates that the molecular events on the der(8) chromosome leading to the chimerical AML1/ETO gene are more important than the events on the reciprocal 21q+ chromosome (8).