[Molecular implication of Ph positive leukemias: treatment with alpha-interferon in Ph positive acute leukemia]

Patients with Philadelphia chromosome-positive acute leukemia (Ph + AL) were treated with natural interferon-alpha (IFN-alpha) after entering complete remission. In this study, subsequent cytogenetic analysis during complete remission in Ph + AL patients with major-BCR rearrangement revealed that the percentage of bone marrow cells with the Ph chromosome increased, while the bone marrow maintained a remission status. This cytogenetic-hematologic discrepancy led us to consider that the Ph + metaphases might be derived from cells with a non-lymphoid lineage rather than residual leukemic lymphoblasts. After administration of IFN-alpha, the percentage of bone marrow cells with a Ph chromosome decreased. Although this study is on going and we do not yet have the final results, treatment of IFN-alpha should be attempted on more patients with such a genetic abnormality.

Comparison between immunogenotypic findings in de novo AML and AML post MDS

We compared immunogenotypic findings in 73 patients with de novo acute myeloid leukemia (AML) and 30 patients with AML developed in myelodysplastic syndrome (AML post MDS) to determine the biological difference between these hematopoietic neoplasias. Lymphoid-associated antigens were detected in 13 patients with de novo AML, four of whom exhibited rearrangement of the immunoglobulin heavy-chain (IgH) gene. T-cell receptor (TCR) gene rearrangements were detected in 10 patients with de novo AML who did not have lymphoid-associated antigens, none of whom carried rearranged IgH. This group included two AML patients with trilineage dysplasia. Neither lymphoid markers nor IgH rearrangement was detected in any of the 30 patients with AML post-MDS; TCR rearrangements were detected in eight out of 30 patients, TCR-beta rearrangements in six out of 30, and TCR-delta rearrangements in five out of 30. The TCR rearrangement without rearranged IgH in some AML post MDS patients might not be due to a common recombinase activity, and this alteration may link to genomic instability. Some patients with de novo AML also showed this pattern, suggesting a close biologic association between AML post MDS and some patients with de novo AML.

Two additional cases of acute myeloid leukemia with t(7;11)(p15;p15) having low neutrophil alkaline phosphatase scores

We report two additional patients with acute myeloid leukemia (AML) and a translocation between chromosomes 7 and 11: t(7;11)(p15;p15). One patient was diagnosed as having AML-M2 and the other as AML with myelofibrosis. Both patients had low-level neutrophil alkaline phosphatase (NAP) scores. In the literature, only 15 AML patients with t(7;11)(p15;p15) have been reported; nine of them had an AML-M2 morphology, and all had a decreased NAP score. Moreover, mean survival of the reported AML patients with t(7;11)(p15;p15) was 15 months, although 85% of them obtained complete remission, indicating that this type of leukemia frequently tends to relapse. These findings indicate a strong association between the chromosome abnormality and hematologic manifestations of this disease.

Interleukin-7 enhances colony growth and induces CD20 antigen of a Ph+ acute lymphoblastic leukemia cell line, OM9;22

A newly established human leukemia cell line, OM9;22, is reported, with B-precursor immunophenotype (CD10+ CD19+ CD22+ HLA- DR+ C mu-) and CD13 antigen, originated from a 19-year-old female patient with Philadelphia (Ph) chromosome-positive acute lymphoblastic leukemia (ALL). The OM9;22 cells carry a Philadelphia (Ph) translocation and hybrid message detected by a minor-breakpoint cluster region (BCR) exon 1/ABL exon 2 junctional probe using reverse transcriptase polymerase chain reaction. The genetic alterations are consistent with those observed in the donor's leukemia cells, allowing us to conclude that this cell line is a minor-BCR rearranged Ph-positive ALL (Ph+ ALL). Colony formation of the OM9;22 cells in methylcellulose culture is enhanced by the addition of human interleukin 7 (IL-7). In liquid culture, more than 80% of IL-7-treated OM9;22 cells express CD20 antigen but fail to express surface immunoglobulins or cytoplasmic mu-chain, indicating that the cells have a potential of limited maturation by IL-7. By contrast, IL-4 suppresses the colony formation of the OM9;22 cells. These findings suggest that this cell line might be a model of B-precursor human leukemia with proliferative capability by IL-7.

Acute myeloid leukemia with concomitant expression of T-/B-lymphoid antigens and immunogenotypic alterations exhibiting t(7;12)(q32;q24)

We report here a patient with acute myeloid leukemia (AML) expressing both T- and B-lymphoid-associated antigens. The leukemia cells in this case had rearrangements of not only immunoglobulin heavy-chain but also T-cell-receptor beta- and delta-chain genes. Although a relatively large number of AML patients with lymphoid markers have been reported, only about a dozen AML patients expressing both T- and B-lymphoid markers have been reported so far.

The methylation status of the major breakpoint cluster region in human leukemia cells, including Philadelphia chromosome-positive cells, is linked to the lineage of hematopoietic cells

The Philadelphia (Ph) translocation [t(9;22)(q34;q11)] is the most common genetic abnormality in human leukemia; a transposition of the ABL gene to the major-breakpoint cluster region (M-BCR) is associated with the pathogenesis in Ph+ chronic myelogenous leukemia (Ph+ CML) and in some cases of Ph+ acute leukemia (Ph+ AL). Our current understanding of the methylation of human genomes allows us to consider the association between the epigenetic phenomenon and the control of differentiation and proliferation in mammalian cells. In order to determine whether the methylation status of the M-BCR is associated with breakpoint-localization in this region and with the lineage of hematopoietic cells, we have examined 28 patients with Ph+ leukemias, including nine with Ph+ AL, six patients with acute myeloblastic leukemia without Ph (Ph- AML), and five patients with Ph- acute lymphoblastic leukemia (Ph- ALL); using the restriction endonuclease isochizomers, MspI and HpaII. In CML patients in the chronic phase, the hypomethylated status within the normal M-BCR allele is heterogeneous. In contrast, patients with Ph+ CML in the lymphoid blast crisis phase exhibited a 2.5/2.7 kb band with a complete disappearance of the germline M-BCR fragment (type L). This pattern is consistently noted in Ph- ALL cells, and the pattern is quite different from that found in myeloid blast crisis or Ph- AML (type M). In patients with M-BCR-nonrearranged Ph+ ALL, it is suggested that the M-BCR methylation patterns are cell-lineage specific but some Ph+ ALL cells had a hypomethylation pattern that was identical to that observed in Ph- AML, suggesting a distinction of genetic diversity of leukemia cells with the Ph chromosome, especially Ph+ AL.

Clinical and cytogenetic significance of myelodysplastic syndromes with disease evolution

We performed a retrospective study of 83 patients with myelodysplastic syndrome (MDS) to clarify the clinical and cytogenetic implications of disease evolution. Twenty-three patients showed disease progression; six of the 11 patients whose disease evolved within 100 days showed complex cytogenetic aberrations and most of them died within 300 days. Of the patients who survived more than 300 days, those with high bone marrow (BM) blast percentages experienced significant disease progression, but we noted no cytogenetic indicators for disease evolution at the later phase. Sixty percent of patients showing karyotypic evolution without disease evolution had deletion-type chromosome changes. The most frequent anomaly in patients with disease evolution who survived more than 300 days was an additional numerical change, whereas patients with disease evolution who survived less than 300 days showed karyotypic instability. It was difficult to predict disease progression for patients whose disease evolved more than 300 days after diagnosis, but in some patients the presence of additional numerical changes was related to disease progression. The cutoff level of early disease evolution was 100 days after diagnosis, and most patients with complex abnormalities survived less than 300 days with or without disease evolution.

Myelodysplastic syndrome evolving into a myeloproliferative disorder: one disease or two?

We report two patients who had been initially diagnosed as having a myelodysplastic syndrome but subsequently progressed into a leukothrombocytosis state which mimicked a chronic myeloproliferative disorder. Both patients had anemia and mild neutropenia without thrombocytopenia at the time of their diagnosis of myelodysplastic syndrome, and dyshematopoietic features were present in the bone marrow. After treatment with vitamin D3 for 7 and 18 months, respectively, they developed leukothrombocytosis which responded to hydroxyurea. We speculate that these and other similar patients with this unusual course might constitute an entity distinct from the typical myelodysplastic syndromes or chronic myeloproliferative disorders.

Therapy for Philadelphia chromosome-positive acute lymphoblastic leukemia: possible use of interferon on the basis of some novel concepts

Current understanding of molecular genetics enables the establishment of new categories based on pathogenesis. Philadelphia (Ph) chromosome-positive leukemia has been reclassified into two molecularly distinct subsets, and the leukemogenesis at the cell level might be linked to the molecular changes. Therefore, treatment for leukemia patients with Ph chromosome could be based on the molecular characteristics. In this review, we discuss the strategy of treating patients with Ph-positive acute lymphoblastic leukemia and the benefit of the combined modality of interferon and chemotherapy.

T-cell receptor beta chain gene rearrangement in acute myeloid leukemia always occurs at the allele that contains the undermethylated J beta 1 region

The epigenetic phenomenon could play a role in the interaction between chromatin and DNA-binding enzymes, allowing us to consider an association between the phenomenon and gene rearrangement. The correlation between methylation status and rearrangement of the T-cell receptor (TCR) beta chain gene in leukemia cells obtained from patients with acute myeloid leukemia (AML) was examined. All of the AML patients with a TCR-beta rearrangement had hypomethylated CCGG sequences within the J beta 1 region on the rearranged allele, while the germline allele had completely methylated CCmeGG sequence in this region, indicating a strong association between hypomethylation status and rearrangement of the TCR beta chain gene. In the DNA from AML patients with or without a TCR-beta rearrangement, the C beta 2 region contained completely methylated CCmeGG sequences, even though they express T-cell-associated antigens, including CD7; this pattern is quite different from that observed in T-cell neoplasias. Moreover, some AML patients showed a TCR-beta rearrangement without the presence of immunoglobulin heavy-chain gene rearrangement, suggesting that TCR beta chain gene involvement in AML is required for unknown factors other than common recombinase activity.

Trisomy of chromosome 8 in myelodysplastic syndrome. Significance of the fluctuating trisomy 8 population

Chromosome analyses were performed in five patients with myelodysplastic syndrome (MDS) who showed trisomy of chromosome 8 during the course of their disease. Four of these patients showed trisomy 8 at the diagnosis of MDS, and the remaining one had trisomy 8 when the leukemia phase developed. The proportion of bone marrow (BM) cells with trisomy 8 in the four patients who showed trisomy 8 at MDS diagnosis fluctuated, and this fluctuation was not related to the percentage of blasts in the BM or to progression of the disease. However, in two patients, metaphase cells with trisomy 8 disappeared when their anemic state improved, although leuko-thrombocytopenia was still present, suggesting that the decrease in the number of BM cells with trisomy 8 reflects hematologic features in some MDS patients. These findings indicate that trisomy 8 in our MDS patients was possibly not the primary event in the genesis of the disease, and that there may have been competition between a normal karyotype clone and a trisomy-8-positive clone. Our results further suggest that the presence of a clone with trisomy 8 is not always a sign of disease progression or of poor prognosis in MDS patients.

Cytogenetic and clinical findings of myelodysplastic syndromes with a poor prognosis. An experience with 97 cases

BACKGROUND

Clinical and cytogenetic analyses were performed in 97 patients with myelodysplastic syndromes (MDS) to evaluate risk factors for poor prognosis.

METHODS/RESULTS

Among them, 22 patients survived for less than 1 year: 10 of these had complex chromosomal abnormalities (complex aberrations), but only 5 of the remaining 75 patients who survived longer than 12 months did. Leukemia did not develop in approximately half of the patients who died within 1 year. The occurrence rate of leukemic transformation appears to depend on MDS subtypes rather than cytogenetic changes. In contrast, the percentage of patients who survived for less than 1 year is related to chromosomal changes, especially to complex aberrations. Of particular interest in this study is that 7 of 11 patients with MDS who had myelofibrosis survived for less than 1 year, and 5 of 7 patients with secondary MDS were included in this group showing a poor prognosis. By hematologic analysis, significant differences were found in the hemoglobin values and platelet counts of patients who survived for less than 1 year.

CONCLUSIONS

From this analysis, three major risk factors for a poor prognosis were identified: complex aberrations, a history of chemotherapy or radiation therapy (secondary MDS), and development of myelofibrosis. The survival probability in the patients with MDS having at least one of these three factors was significantly low when compared with that in patients without these factors, indicating that cytogenetic analysis in combination with observance of certain clinical manifestations is important in therapeutic management of patients with MDS.

[Immunogenotypes and surface marker analysis in Ph1 positive chronic myelogenous leukemia in the blastic crisis]

Immunophenotypic and immunogenotypic changes in 23 patients with Ph positive chronic myelogenous leukemia in blast crisis were determined using a panel of monoclonal antibodies and gene probes. According to the immunophenotypes, 9 patients were considered to be in lymphoid blast crisis, including 7 patients with lymphoblastic crisis and 2 patients with lymphoid/myeloid mixed blast crisis. Leukemia cells from the remaining 14 patients showed myeloid phenotypes and 10 of these had platelet-associated antigens. Rearrangement of the immunoglobulin (Ig) gene was observed in all the 9 patients with lymphoid blast crisis, and Ig gene rearrangement was associated with the expression of CD19 antigen. Two patients with myeloid blast crisis showed rearrangements of T-cell-receptor gene, but, dissociation between phenotypes and genotypes was not frequently observed in patients with blast crisis.

Leukemic phase of intermediate non-Hodgkin's lymphoma with cells showing different matured stages in invaded various organs

A 56-year-old male was admitted to our hospital with lymphocytosis (16.4 x 10(9)/l; 79% lymphocytes including 50% small lymphocytes), generalized lymphadenopathy, massive splenomegaly, and heavily infiltrated bone marrow. Immunophenotype analysis of the neoplastic cells in the bone marrow revealed that they were B cells (CD20 + CD19 + Ia1 + sIgM+) positive for CD10. By contrast, the cells in the lymph node were CD20 + CD19 + Ia1 + sIgM+ but negative for CD10. The patient was tentatively diagnosed as having lymphosarcoma cell lymphoma, however, the final diagnosis was leukemic phase of intermediate lymphocytic lymphoma. We concluded that CD10+ neoplastic cells in the bone marrow and peripheral blood had differentiated to CD10- cells.

Immunogenotypes and clonal culture analysis in B-precursor acute lymphoblastic leukemia

Immunogenotypic changes in 32 patients with B-precursor acute lymphoblastic leukemia (ALL), including three patients with t(4;11) and 13 with t(9;22), were determined using immunoglobulin heavy (IgH) chain gene probe and T-cell receptor beta, gamma and delta chain gene probes. Clonogenic assay was performed in 12 of the 32 patients. In this study, four patients had a germline configuration of the IgH chain gene, showing a dissociation between phenotypic and genotypic expression; three patients had Philadelphia-positive (Ph+) ALL. The immunogenotypic manifestation in Ph+ ALL does not depend on whether the leukemia cells had rearrangement within the major breakpoint cluster region (major-BCR) DNA sequence or the leukemia cells had myeloid-associated antigens. Colony assay using various recombinant cytokines demonstrated that the leukemia cells from four of 12 patients formed colonies in response to myelopoietic stimulants; three of the four patients were major-BCR-rearranged Ph+ ALL. Notably, cells from one patient with Ph+ ALL formed colonies on the addition of granulocytic colony-stimulating factor. This indicates not only the biological heterogeneity of ALL cells but also that some of the characteristics of the cells are related to specific chromosome changes.

Establishment of a new Hodgkin's cell line (HD-70) of B-cell origin

A new Hodgkin's cell line, designated HD-70, was established from the peripheral blood of a 69-year-old man with Hodgkin's disease of nodular sclerosing type. The cell line grows in a single cell suspension and has a doubling time of 28 hours. The cells have a round or irregular nucleus or multiple nuclei in relatively abundant cytoplasm that is positive for acid phosphatase, alpha-naphthyl butyrate esterase, and periodic acid-Schiff stains. HD-70 cells are positive for CD30 (Ki-1/Ber-H2), CD15 (Leu-M1), and CD71 (OKT9) antigens and contain cytoplasmic immunoglobulin (Ig) (A, kappa). Southern blot analysis showed that the cells have Ig heavy and kappa light chain gene rearrangement and lack T-cell receptor gene rearrangement. Chromosome analysis disclosed that the cells have a human karyotype with complicated abnormalities, including a 14q+. Heterotransplantation of the HD-70 cell line into newborn hamsters treated with antilymphocyte serum produced massive tumors with remarkable fibrosis and collagen band formation. These tumors displayed histologic features similar to those of the nodular sclerosing type tumor of the patient. Such fibrosis production and collagen band formation in heterotransplanted tumors suggest that a certain cytokine that induces fibrosis might be produced by HD-70 cells. This cell line may be useful for understanding the biology and pathogenesis of Hodgkin's disease.

Double 20q- anomaly in myelodysplastic syndrome

Two patients with myelodysplastic syndrome (MDS) whose bone marrow (BM) cells contained duplicate 20q- chromosomes are reported. No particular differences between the hematologic findings of four patients with single 20q- and the two patients with double 20q- chromosomes were noted. No differences in breakpoints on the 20q- chromosome were noted in these six patients, and the breakpoint was identified as 20q11. The presence of double 20q- chromosomes in MDS patients suggests, however, that the deleted chromosome has oncogenic activity.

Restoration of cytogenetically normal marrow cells after remission of lymphoblastic crisis in a case of Ph positive CML treated with alpha-interferon

A patient with Philadelphia (Ph) chromosome-positive chronic myelogenous leukemia (CML) who was treated with alpha-interferon (alpha-IFN) is reported. After the treatment, the number of Ph+ bone marrow (BM) cells decreased gradually and the intensity of the rearranged major breakpoint cluster region (M-BCR) gene became faint; however, a lymphoblastic crisis developed about 1 year later. At the time of the blast crisis, the rearranged M-BCR band was detected, indicating that the blast crisis clone was derived from CML cells. The patient was treated with a combination of vincristine, prednisolone, daunorubicin, and L-asparaginase, and a hematologic remission was obtained. During the remission status, no rearranged M-BCR fragment was detected by conventional Southern analysis. Thus, the hematologic and genetic alteration in this case appeared to be identical to Ph+ acute leukemia with M-BCR rearrangement. The current case therefore indicates that alpha-IFN can reduce the proportion of Ph+ cells, but is unable to prevent blast crisis. Furthermore, the quantitative reduction of the cell population with a Ph chromosome may have some effects in modifying the genetic manifestations and clinical features of Ph+ CML, e.g., the delay in the appearance of the blast crisis.

Treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia: a pilot study which raises important questions

Acute lymphoblastic leukemia (ALL) patients with a Philadelphia chromosome (Ph+ ALL) were treated with a combination of antineoplastic drugs recommended for both myeloid and lymphoid leukemia (BHAC-DMPV: behenoylcytosine arabinoside, daunorubicin, 6-mercaptopurine, prednisolone, and vincristine). Ph+ ALL patients with chromosome breaks which occur within the major breakpoint cluster region (M-BCR rearranged Ph+ ALL) were treated with natural interferon-alpha (IFN-alpha) after entering complete remission. In this study, four of seven patients with Ph+ ALL had M-BCR rearrangement, and all achieved complete remission with karyotypic normalization. Subsequent cytogenetic analysis during complete remission in two ALL patients with M-BCR rearrangement revealed that the percentage of bone marrow cells with the Ph chromosome increased, while the bone marrow maintained remission status. This cytogenetic-hematological discrepancy led us to consider that M-BCR rearranged Ph+ ALL might be a variant of chronic myelogenous leukemia, therefore, three Ph+ ALL patients with M-BCR rearrangement were treated with IFN-alpha after achieving complete remission. In contrast, only one of three patients with M-BCR non-rearranged Ph+ ALL obtained complete remission.

Clinical and cytogenetic characteristics of myelodysplastic syndromes developing myelofibrosis

Myelofibrosis occurs in various hematologic neoplasias, including myelodysplastic syndrome (MDS), with a relatively low incidence. To gain insight into the clinical and cytogenetic implications of MDS patients in whom myelofibrosis develops, statistical analysis was done on 82 primary MDS patients with successful cytogenetic results. Seven patients had myelofibrosis during the course of the disease (8.5%, Group I), 34 had abnormal karyotypes without myelofibrosis (41.5%, Group II), and the other 41 had abnormal karyotypes without myelofibrosis (50%, Group III). All of the MDS patients except one with myelofibrosis had cytogenetic abnormalities, and four of them had multiple chromosome abnormalities. In univariant analysis, MDS patients with myelofibrosis showed no significant differences in age, sex, or peripheral blood data. In contrast, patients with chromosome abnormalities evolved into myelofibrosis with a high incidence compared with those with normal karyotypes (14.6% versus 2.4%, P = 0.054). The occurrence of myelofibrosis was higher during the first 6 months after the diagnosis of MDS than in the next 6 months (6.1% versus 0%, P = 0.045). Most of the MDS patients survived for less than 10 months after myelofibrosis was evident. Furthermore, survival was significantly shorter in Group I compared with Groups II (P less than 0.05) and III (P less than 0.01). Among the MDS patients in whom myelofibrosis developed, some were associated with acute megakaryoblastic leukemia, indicating a heterogeneity of clinical features in MDS with myelofibrosis.

Establishment of a new Epstein-Barr virus nuclear antigen-positive B-cell line, BALL-2, with t(8;14) (q24;q32) chromosome abnormality from B-cell acute lymphoblastic leukemia, L2

A new Epstein-Barr virus nuclear antigen (EBNA)-positive B-cell line, designated BALL-2, was spontaneously established from the peripheral blood of a 14-year-old boy with an EBNA-negative B-cell acute lymphoblastic leukemia (B-ALL), L2 in the French-American-British classification. The BALL-2 cell line grew in suspension with or without forming clumps of cells. The cultured cells exhibited lymphoid morphology with indented or lobulated nuclei, prominent nucleoli, and relatively abundant cytoplasm. Immunologic and cytogenetic studies showed that the BALL-2 cell line expressed the B-cell phenotype, CpIg+, SmIg+, CD19+, CD20+, CD38-, Ia+, and had chromosome translocation, t(8;14) (q24;q32). The same phenotypic and chromosome markers were present in original leukemia cells. These results indicated that the cell line was derived from the patient's leukemia cells. Unexpectedly, however, BALL-2 cells were positive for EBNA and EB virus DNA. Gene analysis of the BALL-2 cell line showed biallelic rearrangements in the JH locus. One of the JH rearrangement comigrated with a rearranged c-myc gene, indicating the translocation had occurred between JH and c-myc loci. The t(8;14) abnormality is a known chromosome marker of Burkitt lymphoma and L3 type ALL. Our studies revealed that this translocation and myc gene rearrangement can also be found in L2 type B-ALL.

Methylation status of T-cell receptor beta-chain gene in B precursor acute lymphoblastic leukemia: correlation with hypomethylation and gene rearrangement

Epigenetic changes may play a role in genetic alterations in cancer cells, but little is known about this phenomenon. In this study we examined the correlation between rearrangement and methylation status of the T-cell receptor (TCR) beta-chain gene in 23 patients with B precursor acute lymphoblastic leukemia (ALL). In B precursor ALL, all patients had a CCmeGG sequence in the C beta 2 region, a pattern similar to that observed in normal mature B-cells. Approximately 55% of patients with B precursor ALL exhibiting a hypomethylated CCGG sequence at the J beta 1 region showed rearrangement of this region. Furthermore, the same allele of rearranged J beta 1 always contained an unmethylated sequence in the region, although another allele without rearrangement contained methylated J beta 1. By contrast, none of the patients had a rearrangement in the J beta 1 region without hypomethylation. Therefore, rearrangement of the J beta 1 region may link to the hypomethylation status of this region. A close association between hypomethylation of the J beta 1 region may promote accessibility to a putative common recombinase to produce TCR J beta 1 rearrangement. In contrast, about 45% of patients with a hypomethylated J beta 1 did not show rearrangement in this region, thus allowing categorization of B precursor ALL patients into subtypes, according to the combination of TCR beta-chain gene rearrangement and hypomethylation status, especially in the J beta 1 region.

Establishment of a novel heterotransplantable acute lymphoblastic leukemia cell line with a t(17;19) chromosomal translocation the growth of which is inhibited by interleukin-3

A cell line, designated HAL-01, was established from the blood cells of a patient with acute lymphoblastic leukemia (ALL) with a myeloid-associated marker. Both the cell line and the patient's fresh leukemia cells had the chromosomal translocation t(17;19)(q21;p13). Morphologically and cytochemically, the cells were lymphoid in appearance. Immunophenotyping of the donor's leukemia cells revealed that they express B lineage antigens (CD10+, CD19+, CD20+, CD22+); the myeloid-associated antigen (CD13) detected in the donor's leukemia cells was not expressed by the established cell line. The HAL-01 cells have a rearrangement of the immunoglobulin heavy chain gene, while the T-cell receptor beta-chain genes remain in the germline configuration. The gene encoding the binding proteins for the kappa-light chain enhancer (kappa E2), which is involved in pre-B-ALL cells with the t(1;19) (q23;p13) translocation, is not rearranged in the cell line. The HAL-01 cells were transplantable into the peritoneum of untreated nude mice where they grew as an ascites tumor. The growing tumor cells also infiltrated lymph nodes, liver, spleen, kidney, and bone marrow without exhibiting a particular change in the morphology of the neoplastic cells. Clonogenic assay in methylcellulose culture demonstrated that the proliferation of the HAL-01 cells was suppressed by interleukin-3 (IL-3) in a dose-dependent fashion, with maximum inhibition occurring at concentrations greater than 100 U/ml. Treatment with IL-3 reduced the number of viable cells as well as induced morphological changes without concomitant changes in cytochemical reactions or immunophenotypic expression. Reduction of 3H-thymidine incorporation by exposure of IL-3 was blocked by the pretreatment of neutralizing anti-IL-3 antibody, but not by neutralizing anti-TGF-beta antibody. Thus, HAL-01 is a unique ALL cell line exhibiting proliferative suppression by IL-3 that may prove useful in studying the interactions of cytokines in ALL.