Telomere dynamics and cytogenetic changes in human hematologic neoplasias: a working hypothesis

Chromosome termini, termed telomeres, provide important protection to avoid loss of master gene(s) that may exist at subtelomeric regions. Moreover, erosion of telomeres by cell division through end-replication problems resulted in telomeric-associated cytogenetic aberrations. To maintain a telomere length related to cell immortality, telomerase activity is upregulated in cancer cells, therefore, telomerase is considered to be a new marker of neoplasias. In this paper, we review and make suggestions regarding key aspects of telomere dynamics in both normal hematopoiesis and in malignant hematologic diseases.

Telomerase activity and cytogenetic changes in chronic myeloid leukemia with disease progression

Progressive telomere shortening is thought to be important in the regulation of cellular senescence and that the upregulation or reactivation of telomerase activity may be a critical if not rate limiting step in the development of neoplastic cells. To obtain information about telomeres and telomerase activity in hematopoietic neoplasia at various disease stages, we evaluated 54 samples obtained from 41 patients with chronic myeloid leukemia (CML) using a combination of fluorescent-telomeric repeat amplification protocol and an internal telomerase assay standard. The terminal restriction fragment (TRF) lengths in the blast phase was reduced compared to that in the chronic phase (4.53 +/- 0.72 kb vs 6.13 +/- 1.68 kb; P = 0.0005). All samples obtained from CML in the chronic phase (n = 33) had detectable telomerase activity above background, regardless of age. In the blast phase (n = 21), a significant increase of telomerase activity was detected compared to that in the chronic phase (33.84 +/- 37.86% vs 6.08 +/- 3.21; P = 0.016). Among patients in the blastic phase, 50% of patients had moderate to high telomerase activity (>10 relative value), and the remaining patients had telomerase activity higher than that in the normal peripheral blood cells. No significant differences in hematologic findings, duration of chronic phase or blast phase, and telomere length in the blastic phase were noted between these two groups separated by telomerase activity. CML patients with moderate to high telomerase activity had a high frequency of additional cytogenetic changes (P = 0.01).

Technical improvement in determining telomerase activity in hematologic neoplasias: a possibility of single cell determination of telomerase activity

Chromosome termini, telomeres, provide important protective structure to avoid loss of master gene(s) that may present at subtelomeric regions. Since the telomere length might reflect the cell division, some biological aspects, including cellular senescence and cancer biology, of telomere length have been reported. To maintain a telomere length related to cell immortality, reactivation of telomerase in cancer cells is observed in approximately 85% of more than 1500 samples obtained from primary cancer tissues. Thus, telomerase is considered to be a new marker of neoplasias. In this paper, we present new techniques, including fluorescent TRAP that makes it possible to detect telomerase activity semi-quantitatively and in situ TRAP assay that allows us to determine the exact telomerase-positive cells.

Clinical aspects, cytogenetics and disease evolution in myelodysplastic syndromes

Myelodysplastic syndrome (MDS) is a morphologically characterized hematologic entity that is one of the clonal myeloproliferative disorders. Approximately 50 approximately 70% of MDS patients have cytogenetic abnormalities; these are usually chromosomal deletions, but some involve translocations such as t(1;7) (q10;p10). Translocations involving chromosomal regions 3q26 or 22q11 are often therapy-related. Recent studies have demonstrated that cytogenetic changes in MDS patients have clinical relevance. Accordingly, there are now scoring systems for predicting the prognoses of MDS patients. In this review, we describe the clinical significance of cytogenetic changes in MDS. We include MDS with some atypical forms, such as MDS with hypocellular bone marrow, MDS with minimal dysplasia, and MDS with myelofibrosis.

Pattern of expression and their clinical implications of the GATA family, stem cell leukemia gene, and EVI1 in leukemia and myelodysplastic syndromes

Transcription factors play a key role in controlling the cellular differentiation of hematopoietic cells. Among the known transcription factors, both GATA-1 and SCL play roles in the cellular differentiation of erythrocytic and megakaryocytic lineages, while GATA-2 is thought to maintain and promote the proliferation of early hematopoietic progenitors. In this review, the clinical implications of expression of the GATA family, SCL, and EVI1 gene in various types of human leukemia are discussed. De novo acute myeloid leukemia (AML) patients may be subdivided into three categories depending on the expression pattern of transcription factors, i.e., GATA-1(+)SCL(+), GATA-1(+)SCL(-), and GATA-1(-)SCL(-). AML patients with both GATA-1 and SCL expression have a poor prognosis and have some characteristic clinical and hematologic features. The EVI1 gene may be expressed through at least two pathways in hematologic malignancies; one is related to chromosomal changes at 3q26, while the other is related to myelodysplasia regardless of chromosomal changes at 3q26 region. These findings suggest that the pattern of expression in transcription factors in abnormal hematopoietic cells is reflected in the malignant phenotype and play a role in the pathogenesis of the disease.

Replication errors in hematological neoplasias: genomic instability in progression of disease is different among different types of leukemia

Genetic alteration, including genomic instability, is an ultimate step toward the malignant process. One approach to delineating replication errors in cancer cells is to determine the alterations of microsatellites, which are short, repeated nucleotide sequences existing throughout the genomes. We used a fluorescent system to assess microsatellite changes in seven loci (D2S123, D3S643, D5S107, LPL, D17S261, TP53, and D18S34) of 73 consecutive patients with various hematological neoplasias. De novo acute leukemia patients had a low frequency (<1%) of microsatellite alterations at each locus, and none of them demonstrated multiple microsatellite changes. In chronic myeloid leukemia patients, no microsatellite instability was detected in the chronic phase, whereas a relatively high frequency (25%) of multiple microsatellite changes was evident in the blastic phase, and half of these patients had multiple microsatellite changes. About 50% of the patients with myelodysplastic syndrome (MDS) and post-MDS acute myeloid leukemia (post-MDS AML) had microsatellite alterations. We next compared microsatellite alterations in two different hematological phases (MDS and post-MDS AML phases); 5 of 11 patients with post-MDS AML had de novo appearance of microsatellite instability during disease progression. This indicates that genomic instability at multiple microsatellite loci could occur either before or after leukemic transformation in MDS patients. We concluded that genomic instability in chronic myeloid leukemia might be linked to blastic transformation in combination with cytogenetic changes. In contrast, MDS patients had replication errors as a relatively early genetic event as well as a late genetic event. These results suggest that the involvement of genomic instability in the progression of disease is different among various types of leukemia.

High prevalence of T cell receptor D delta 2(D delta)J delta rearrangement in CD7-positive early T cell acute lymphoblastic leukemia

We have studied the molecular characteristics of the T cell receptor (TcR) genes in 16 patients with CD7+ early T cell acute lymphoblastic leukemia (T-ALL), defined as being positive for CD7 but negative for CD3/4/8, myeloperoxidase (MPO), and CD19/20. Using gene analysis, rearrangement was demonstrated in one patient for immunoglobulin heavy chain (IgH) gene, five for TcR-beta gene, and four for TcR-gamma gene. Fifteen patients (94%) had rearranged band(s) involving the joining region of the TcR-delta chain gene. In nine cases these were the only rearrangements, whereas in six cases TcR-beta and/or TcR-gamma gene rearrangements were found as well. The D delta 2(D delta)J delta 1 rearrangement was demonstrated in 87.5% (14/16) of cases. D delta 2(D delta)J delta 3 was recognized in one patient, D delta 2D delta 3 was found in three, and V(D)DJ using only V delta 2 and V delta 3 was recognized in two patients. We found no V2D delta 3, V3D delta 3, or V1(D)DJ delta rearrangement patterns. Five of nine cases with DDJ delta were positive for cytoplasmic CD3 epsilon(CyCD3 epsilon). Our data suggest that DDJ delta joining occurs at an early stage during T cell differentiation, followed by rearrangements of V delta to the DDJ delta complex. Furthermore, our findings suggest that DDJ delta recombination occurs earlier than expression of CyCD3 epsilon protein products. DDJ delta rearrangements have never been observed in non-T cell malignancies, such as precursor-B-ALL or acute myeloid leukemia. Therefore, detection of DDJ delta rearrangement in the TcR-delta locus is a useful tool to establish lineage and clonality of leukemic cells in the most immature stages of T cell development.

A possible correlation between interferon-stimulated gene expression and cytogenetic responses in chronic myelogenous leukemia patients treated with alpha-interferon

We studied the expression of the interferon-stimulated genes (ISGs), ISG-54 and 2',5'-oligoadenylate synthetase (2'-5' OAS), using the reverse transcription-polymerase chain reaction in 22 patients with chronic myelogenous leukemia (CML), who were treated with alpha-interferon (alpha-IFN). At the time of diagnosis, 7 patients (31.8%) showed no detectable expression of either gene, whereas 8 expressed both. The remaining 7 expressed neither ISG-54 nor 2'-5' OAS. After alpha-IFN treatment, 5 of the 7 CML patients who had not previously express ISGs expressed either ISG-54 or 2'5' OAS or both and 6 of the 7 who had previously expressed either ISG-54 or 2'-5' OAS expressed both. Three of the 7 (42.9%) CML patients who expressed both genes before and after alpha-IFN administration showed cytogenetic responses, as did 6 of the 11 (54.5%) in whom ISG expression was induced. In contrast, cytogenetic responses occurred in none of the patients in whom ISG expression was not induced. These results suggest that induction of ISG-54 and 2'-5' OAS expression by alpha-IFN may be an indicator of cytogenetic responses and, therefore, of value for monitoring CML patients.

Non-radioisotopic and semi-quantitative procedure for terminal repeat amplification protocol

We have used fluorescence-labeled primers and an auto-sequencer to detect telomerase activity quickly and easily. The current procedure is superior to the original telomeric repeat amplification protocol in several respects: 1) the result is obtained in real time during electrophoresis, 2) semi-quantitative results are possible without using a photo-capture system, and 3) no radioisotope is needed.

Near-hexaploid Ph-positive acute myeloid leukemia with major-BCR/ABL transcript

We describe the first case of acute myeloid leukemia (AML) with a Philadelphia (Ph) translocation and a near-hexaploid range chromosome number, whose leukemic cells had the major-BCR/ABL transcript. The genesis of near-hexaploid leukemic cells might be due to endoreduplication of triploid leukemic cells with the Ph, since the relapsed leukemic cells had triploid range chromosomes with double Ph chromosomes.

The expression pattern of erythrocyte/megakaryocyte-related transcription factors GATA-1 and the stem cell leukemia gene correlates with hematopoietic differentiation and is associated with outcome of acute myeloid leukemia

To understand the clinical implications of transcription factors and their biologic roles during cellular differentiation in the hematopoietic system, we examined the expression of GATA-1, GATA-2, and stem cell leukemia (SCL) gene in human leukemia cell lines and various leukemia patients using the reverse transcriptase-polymerase chain reaction. Cell lines exhibiting megakaryocytic or erythrocytic phenotypes had GATA-1, GATA-2, and SCL gene transcripts, while monocytic cell lines had no detectable GATA-1, GATA-2, or SCL gene mRNA. In some myeloid cell lines, GATA-1 expression, but not SCL gene expression, was detected; GATA-1 expression in HL-60 cells was downregulated during the process of monocytic differentiation. We next examined GATA-1, GATA-2, and SCL gene expression in 110 leukemia samples obtained from 76 patients with acute myeloid leukemia (AML), 19 with acute lymphoblastic leukemia (ALL), and 15 with chronic myeloid leukemia in blast crisis (CML-BC). SCL gene expression was usually accompanied by GATA-1 expression and was preferentially detected in patients with leukemia exhibiting megakaryocytic or erythrocytic phenotypes, while patients with monocytic leukemia were clustered in the group with no detectable GATA-1 expression. None of the patients with ALL or CML-lymphoid-BC expressed SCL. De novo AML patients with SCL gene expression had a lower complete remission (CR) rate and had a significantly poorer prognosis. Among the patients with AML not expressing SCL, a high percentage of patients with CD7+ AML and CD19+ AML had detectable GATA-1, while patients with GATA-1-negative AML had the best CR rate (87.5%). Our results suggest that the expression pattern of transcription factors reflects the lineage potential of leukemia cells, and GATA-1 and SCL gene expression may have prognostic value for the outcome of patients with AML.

Ecotropic virus integration site-1 gene preferentially expressed in post-myelodysplasia acute myeloid leukemia: possible association with GATA-1, GATA-2, and stem cell leukemia gene expression

We investigated expression of the human ecotropic virus integration site-1 (EVI1) gene in patients with leukemia and myelodysplastic syndrome (MDS) using the reverse transcriptase-polymerase chain reaction (RT-PCR) method. The EVI1 transcripts were detected in 5 (10.0%) of 50 patients with de novo acute myeloid leukemia (AML), including two AML patients with trilineage myelodysplasia, and in 8 (34.8%) of 23 patients with post-myelodysplastic syndrome AML (post-MDS AML). EVI1 expression was also detected in 6 (35.3%) of 17 MDS patients and three of six patients with chronic myeloid leukemia (CML) in myelomegakaryoblast crisis. No EVI1 transcripts were detected in patients with acute lymphoid leukemia (n = 15) or CML in lymphoid blast crisis (n = 4). Chromosomal abnormalities at the 3q26 region, where the EVI1 gene is located, were found in one patient with MDS and two patients with CML myelomegakaryoblast crisis who had EVI1 expression. Our results showed that EVI1 expression was frequent in patients with post-MDS AML and AML with trilineage myelodysplasia, regardless of the presence or absence of 3q26 abnormalities. EVI1 expression was accompanied by expression of GATA-1 and GATA-2, and often by stem cell leukemia (SCL) gene expression. In patients with post-MDS AML, EVI1 expression was not always associated with a 3q26 abnormality, whereas EVI1 expression in CML myelomegakaryoblast crisis was often linked to a 3q26 abnormality. Our results suggest that the leukemogenic role of EVI1 expression may differ between post-MDS AML and leukemia, with EVI1 expression associated with a 3q26 abnormality.

[The expression pattern of transcription factors (GATA, SCL) and biological characteristics in various leukemia cells]

We have studied gene expression of GATA-1, GATA-2, and SCL, which are known as cell-specific transcription factors, in 110 various leukemias consisted of 76 patients with acute myeloid leukemia (AML), 19 with acute lymphoblastic leukemia (ALL), and 15 with chronic myeloid leukemia (CML) in blast crisis by the revearse transcription-polymerase chain reaction assay. Accordingly, we divided into three groups. Group I (GATA-1+SCL+): patients with AML exhibiting phenotypic characteristics of erythroid or megakaryocytic lineage and most of CML myeloid blast crisis were included. Group II (GATA-1+, SCL-): Not only CD7-positive and CD19-positive AML, but also a part of Ph+ALL demonstrated this pattern. Leukemia in this group is considered to have a capability to differentiate into myeloid and lymphoid lineages. Group III (GATA-1-, SCL-): patients in this group consisted of leukemias which are differentiated into specific cell-lineages, either myeloid or lymphoid, when compared to groups I or II. Our data suggest that the expression pattern of transcription factors reflects lineage potential in leukemia cells, leading to classification of leukemias.

Late appearance of a Philadelphia translocation with minor-BCR/ABL transcript in a t(7;11)(p15;p15) acute myeloid leukemia

We describe a patient with a t(7;11)(p15;p15) acute myeloid leukemia who was subsequently found to harbor the Philadelphia (Ph) translocation, in addition to the t(7;11), at the second relapse. A BCR/ABL transcript was detected at the second relapse by reverse transcription-polymerase chain reaction assay; the leukemic cells had a BCR/ABL fusion gene involving the minor breakpoint cluster region (minor-BCR; situated in intron 1 of the BCR gene). Although the Ph translocation is commonly detected in de novo acute leukemia and chronic myeloid leukemia as the primary leukemia-specific chromosomal translocation, our case suggests that this cytogenetic change might occur as an additional chromosomal change in neoplastic cells. Moreover, minor-BCR/ABL rearrangements may also occur as a late appearance of Ph translocation.

Double-minute chromosomes appearing in a patient with myelodysplastic syndrome with disease evolution

We present the first case of a myelodysplastic syndrome (MDS) demonstrating an association between the appearance of double-minute chromosomes (dmin) and disease progression. This 59-year-old Japanese woman showed a deletion of the long arm of chromosome 5 [del(5)(q21q34)] and monosomy 9, when she was diagnosed as having refractory anemia with an excess of blasts (RAEB). Subsequential cytogenetic analyses demonstrated that the neoplastic cells in the peripheral blood had six copies of dmin, when the disease progressed into RAEB in transformation (RAEBt). This cytogenetic change was consistently observed when the patient developed the leukemia phase. The findings in this case suggest that the appearance of dmin may be linked to progression of the disease.

EVI1 expression associated with a 3q26 anomaly in a leukemia cell line derived from the blast crisis of chronic myeloid leukemia

Two leukemia cell lines, TS9;22 and YS9;22, were established from different individuals with Philadelphia chromosome (Ph)-positive chronic myeloid leukemia in blast crisis. The reverse transcript-polymerase chain reaction (RT-PCR) technique revealed that both cell lines expressed GATA-1, GATA-2, and the stem cell leukemia (SCL) gene, consistent with a megakaryocyte lineage. Chromosome analysis revealed that TS9;22 cells show the Ph translocation without abnormality of chromosome 3. In contrast, YS9;22 cells show the Ph translocation and dic(3)(q26;p12). Northern analysis revealed that YS9;22 cells express the EVI1 (ecotropic virus integration-1) gene, possibly because of the chromosomal translocation in the 3q26 region; TS9;22 cells do not express EVI1. However, no rearrangements were detected over 600 kb upstream or over 900 kb downstream of EVI1 in the YS9;22 cell line, suggesting a different mechanism of EVI1 activation from that in leukemia cells with either a t(3;3)(q21;q26) or inv(3)(q21q26). These results indicate that EVI1 expression in YS9;22 cells is linked to the 3q26 abnormality and that EVI1 activation plays an oncogenic role in the blastic transformation of chronic myeloid leukemia.

Telomere shortening in leukemic cells is related to their genetic alterations but not replicative capability

We compared telomere length in donor leukemic cells and corresponding established cell lines from three patients with chronic myeloid leukemia (CML) and three with acute lymphoblastic leukemia (ALL) to study the relation between the immortalization capacity of hematologic neoplasms and telomere length. Six of the seven established leukemia cell lines (four CML and two ALL) carried additional chromosome changes and had shorter telomere repeats than those of the donor patients' leukemic cells; the remaining ALL line showed no significant difference in telomere length between fresh leukemic cells and the corresponding cell line. Thus, most established leukemic cells lose effective telomerase activity during the process of establishment, and reduction in telomere length of established leukemic cells appeared to be associated with the presence of additional chromosome changes.

Hypomethylated status, but not RAG-1, is required for T-cell receptor-beta-chain gene rearrangement in acute leukemia cells

We studied the relation between the level of recombinase activating gene (RAG-1) and the methylation status of T-cell receptor (TCR)-beta-chain gene in TCR-beta rearrangement in acute leukemias, including 21 patients with B-precursor acute lymphoblastic leukemia (ALL) and 23 with acute myeloid leukemia (AML). The rearrangement of the TCR beta-chain gene in acute leukemia always occurs at the allele that contains hypomethylated cytosine-cytosine- guanine-guanine (CCGG) sequences within either the TCR-J beta 1 or TCR-J beta 2 regions. Moreover, all B-precursor ALL patients with TCR-beta rearrangement had hypomethylated TCR-beta with or without the presence of RAG-1 activity detectable by reverse transcript-polymerase chain reaction, whereas none of the AML patients with TCR-beta rearrangement and hypomethylated TCR-beta had detectable RAG-1 activity. Some ALL patients had hypomethylated TCR-beta and RAG-1 activity without TCR-beta rearrangement, and most of them showed t(4;11)(q21;q23) or t(9;22)(q34;q11). These results indicate a correlation between the hypomethylation status of the TCR-beta and its rearrangements, but some unknown blockage factor for this association exists in B-precursor ALL patients with specific chromosomal translocations.

Percentages of bone marrow blasts and chromosomal changes in patients with refractory anemia help to determine prognoses

We statistically analyzed the hematologic findings of patients with refractory anemia (RA) to identify parameters associated with a poor prognosis. We first separated the RA patients into two groups: one group with disease progression and one without. The patients with disease progression were predominantly male and had a significantly higher percentage of bone marrow (BM) blasts at the time of diagnosis (3.06 +/- 1.29% vs. 1.44 +/- 1.38%, P < 0.005). This finding was confirmed when the patients were separated into the two groups; those who survived and those who expired (BM blasts: 2.68 +/- 1.59% vs. 1.37 +/- 1.27%, P < 0.005). The survival probabilities were calculated depending on whether or not the RA patients had > or = 3% BM blasts. The RA patients with > or = 3% BM blasts had a significantly worse prognosis (P < 0.01) than the patients with < 3% BM blasts. Notably, the RA patients with > or = 3% BM blasts did not show any significant differences in the incidence of disease progression, mortality rate, or survival probability, when compared with the patients with RA with an excess of blasts (RAEB). The present findings indicate that RA patients are heterogeneous with regard to prognosis, and the RA patients with > or = 3% BM blasts might have a poorer prognosis than those with fewer BM blasts. Thus we propose a general approach in predicting the prognosis of RA patients: those with complex chromosomal changes will expire shortly. Secondly, when the patients do not have any complex changes, the prognosis might be linked to the percentage of BM-blasts at the MDS diagnosis.

Telomere shortening associated with disease evolution patterns in myelodysplastic syndromes

We identified the telomere length at different hematological phases in 16 patients with myelodysplastic syndromes (MDS), showing disease evolution with a conventional Southern blot hybridization using the (TTAGGG)4 probe. The MDS patients studied were classified into three groups according to the pattern of telomere length reduction. The first group had telomere shortening at the time of disease diagnosis. In four of the six MDS patients in this group, the disease progressed within 6 months postdiagnosis and each of them survived for less than 1 year. Moreover, in this group four patients showed a 5q anomaly with or without additional changes, and 50% of patients in this group had complex chromosome abnormalities. The patients in the second group showed reductions in telomere length after disease progression; two of these three patients showed gradual disease progression and had one or two chromosome abnormalities. The third group comprised the remaining seven MDS patients; they showed no telomere reduction by disease evolution. Two patients in this group experienced rapid disease progression. These results may indicate that telomere reduction is linked to disease evolution in some MDS patients, perhaps as a result of genomic instability because patients with complex chromosome abnormalities were clustered in the first group. However, because some MDS patients show disease progression without telomere reduction, genetic changes, including point mutations of certain gene(s), may also contribute to disease progression. We further noted that telomere shortening at the time of MDS diagnosis might indicate a poor MDS prognosis.

GATA-1, GATA-2, and stem cell leukemia gene expression in acute myeloid leukemia

Transcription factors play an important role in the normal developmental process of hematopoietic cells. However, expression of transcription factors and its implication in various human leukemias is not well understood. We have studied GATA-1, GATA-2, and stem cell leukemia (SCL) gene expression in 30 patients with acute myeloid leukemia (AML) by the reverse transcription-polymerase chain reaction assay. In AML both GATA-1 and SCL genes were commonly expressed in M6 and M7 leukemias, and also in leukemias bearing the platelet-associated antigen. We found some AML patients with GATA-1, but not SCL expression. Most CD7+ AML and t(8;21)(q22;q22)-AML were included in this group, which often demonstrated immunoglobulin heavy chain and/or T-cell receptor gene rearrangements. Consequently, GATA-1+ SCL- AML may originate from early myeloid progenitors. Moreover, most AML patients of the M3, M4, or M5 groups were GATA-1- SCL-. Our data suggest that the expression pattern of transcription factors may help to define distinct phenotypes of AML cells.

Clinical and biologic characteristics of CD7+ acute myeloid leukemia. Our experience and literature review

Six patients with acute myeloid leukemia (AML) expressing CD7 antigen (CD7+ AML) were studied. They consisted of five patients with M1 and one with an M2 morphology. Two cases expressed other lymphoid-associated antigens, in addition to CD7. The complete remission rate was 50%. One patient had central nervous system recurrence. Cytogenetic analysis demonstrated normal karyotypes in all the cases. All but one had germline configurations of the T-cell receptor (TCR) genes and immunoglobulin heavy chain gene. However, all did not have detectable recombinase activating gene-1 activity by the RT-PCR technique. We performed colony formation assay in two patients, and no enhancement of colony formation by granulocyte colony-stimulating factor was noted. The results presented here, together with those reported previously, suggest that CD7+ AML may demonstrate lineage infidelity.

[Molecular diagnosis and therapeutic strategy for Philadelphia chromosome-positive acute leukemia]

We focused on biological characteristics of Philadelphia chromosome-positive acute leukemia (Ph+ AL) and treated those patients with BHAC-DMPV induction chemotherapy. After obtaining complete remission, we attempted to treat with allogeneic bone marrow transplantation, while those without suitability for marrow transplantation were treated with alpha-interferon (IFN-alpha), in order to obtain prolong remission status. Chromosomal and molecular analyses, including BCR rearrangement and BCR -ABL mRNA, before and after IFN-alpha treatment demonstrated a recovery of normal hematopoiesis by the treatment of INF-alpha, however, suppressive effect for the blast cells by IFN-alpha was insufficient. To clarify the mechanism of IFN-alpha on the Ph+ leukemia cells, we studied expression of interferon stimulated genes (ISGs). However, an association between expression of ISGs and therapeutic effectiveness was not evident. Although, the exact anti-neoplastic mechanism of IFN-alpha is not established yet, our study demonstrated the possibility for utilization of IFN-alpha in some Ph+ AL patients as a maintenance therapy to obtain long survivals. Therefore, studies using a large number of patients with Ph+ AL should be performed, in order to establish induction and maintenance therapies reflecting biological characteristics of Ph+ AL.

Molecular genetic, cytogenetic, and immunophenotypic analyses in Castleman's disease of the plasma cell type

Systemic Castleman's disease shows characteristic morphologic features in the lymph node and laboratory findings, but patients with this disease have variable clinical courses. The disease may constitute a spectrum of benign to malignant diseases. Thus, the clonal nature of the proliferating lymphoid cells was determined to obtain further insight into the malignant process of the disease. Two cases of systemic Castleman's disease were evaluated immunophenotypically, immunogenotypically, and cytogenetically. Both patients had a chronic relapsing clinical course. One patient had a clonal rearrangement of the immunoglobulin (Ig) lambda chain gene, but no restriction of the light chain expression was detected. This patient showed germ-line configurations of the Ig heavy-chain and T-cell receptor (TCR) beta chain genes; no detectable abnormal metaphases in the lymph node were noted. Another patient had predominance of lambda chain-positive plasma cells in the lymph node with a clonal chromosome change, but had germ-line Ig and TCR beta chain genes. The authors identified clonal changes in two cases of systemic Castleman's disease; one had a clonal immunogenotypic change and the other had a clonal cytogenetic change with an Ig light chain deviation. In both cases, however, a discordance of immunogenotypic and immunophenotypic changes was evident. Thus, the alteration may represent a type of lymphoproliferative disorder that lies between benign and malignant diseases.

Cytogenetic and immunogenotypic alterations of blast crisis cells in chronic myelogenous leukemia independently linked to immunophenotypic expression

Chronic myelogenous leukemia (CML) is a disease of the hematopoietic stem cells, which can differentiate into either B-lymphoid or myeloid cells, because most of them develop either lymphoid or myeloid blast crisis. Immunophenotypic, genotypic, and cytogenetic analyses of 22 patients (24 episodes) with Philadelphia (Ph) positive CML in blast crisis were performed to determine the genetic alterations of the blast crisis cells. In B-lymphoid blast crisis, all the five patients had immunoglobulin heavy-chain (IgH) rearrangements and most of them showed normal karyotypes. Among the five patients, T-cell receptor (TCR) genes were rearranged at the following occurrence rates: 20% in TCR-beta, 60% in TCR-gamma, and 40% in TCR-delta chain genes. A high incidence of additional chromosome changes was noted in patients with B-lymphoid/myeloid-mixed blast crisis, but about 80% of them had rearranged IgH and about 40% had TCR rearrangements. In contrast, most of the patients with non-lymphoid blast crisis showed further chromosomal abnormalities, including +8, +19, i(17q), and double Ph, and most of them had germline configurations of IgH and TCR-gamma chain genes. Notably, only one patient (dual lymphoid and myelomegakaryoblast crisis) in this group exhibited IgH rearrangement, and TCR-beta and TCR-delta rearrangements were also rarely noted. Rearrangement of the IgH gene in CML blast crisis might be linked to expression of lymphoid markers, especially CD19.