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Polymerase chain reaction-based screening of childhood acute lymphoblastic leukemia (ALL) samples showed that a TEL/AML1 fusion transcript was detected in 27% of all cases, representing the most common known gene rearrangement in childhood cancer. The TEL/AML1 fusion results from a t(12;21)(p13;q22) chromosomal translocation, but was undetectable at the routine cytogenetic level. TEL/AML1-positive patients had exclusively B-lineage ALL, and most patients were between the ages of 2 and 9 years at diagnosis. Only 3/89 (3.4%) adult ALL patients were TEL/AML1-positive. Most importantly, TEL/AML1-positive children had a significantly lower rate of relapse compared with TEL/AML1-negative patients (0/22 v 16/54, P = .004). Co- immunoprecipitation experiments demonstrated that TEL/AML-1 formed homodimers in vitro, and heterodimerized with the normal TEL protein when the two proteins were expressed together. The elucidation of the precise mechanism of transformation by TEL/AML1 and the role of TEL/AML1 testing in the treatment of childhood ALL will require additional studies.

A highly malignant human T-cell leukemia was identified by cell surface analysis as a member of the T-cell receptor (TCR) gamma delta lineage. Cytogenetic and molecular analysis showed a novel t(8;14)(q24;q11) rearrangement involving the J delta 1 gene segment on chromosome 14 and the distal end of chromosome 8 near the c-myc proto-oncogene locus. The gamma delta TCR of the leukemia blasts was functionally intact and could be activated to generate intracellular calcium flux and to target Fc receptor-mediated redirected tumor cell lysis. In addition, non- major histocompatibility complex restricted lysis of a limited target cell panel was shown by fresh leukemic blasts and by the in vitro- maintained leukemia cells that was comparable to known T-cell lines with natural killer-like activity. These data suggest that the T-cell leukemia potentially had in vivo functional cytolytic activity. However, whether this activity did contribute to the patient's clinical condition could not be determined.

Mixed hematopoietic chimerism (MC) is a common finding after allogeneic bone marrow transplantation (BMT), but the natural history of this phenomenon remains unclear. To understand the evolution and the implications of this finding, we performed a prospective analysis of the development of mixed chimerism in 43 patients with hematologic malignancies who received bone marrow (BM) from human leukocyte antigen (HLA)-identical sibling donors. T-cell depletion in vitro with anti-T12 (CD6) monoclonal antibody and rabbit complement was used as the only method of graft-versus-host disease (GVHD) prophylaxis. Overall, MC was identified in peripheral blood (PB) and BM in 22 of 43 (51%) patients evaluated. MC was found by restriction fragment length polymorphism (RFLP) analysis in 21 of 40 (53%) patients, by cytogenetic analysis in 6 of 29 (21%) patients, and by red blood cell phenotyping in 4 of 9 (44%) patients. RFLP studies were performed at 0.5, 1, 3, 6, 9, and 12 months post-BMT and then every 6 months, and showed a high probability of developing MC in the first 6 months after BMT followed by stabilization after 12 months. Cytogenetic analysis was less sensitive in detecting MC. Once MC was detected after BMT, the percentage of recipient cells increased very slowly over more than 3 years of follow- up, and no patient reverted to complete donor hematopoiesis (CDH). Thus, recipient and donor cells remained in a relative state of equilibrium for prolonged periods that seemed to favor recipient cells over donor cells. Patient's disease, remission status, or intensity of the transplant preparative regimen did not influence the subsequent development of mixed chimerism. Early immunologic reconstitution was the only factor that correlated with the subsequent chimeric status of the patients. The percentage and absolute number of T3 (CD3) and T4 (CD4) positive cells at day 14 after BMT were significantly higher in the patients who maintained CDH but NK cell reconstitution was similar in both groups, suggesting that early reconstitution with T cells may play a role in preventing recovery of recipient cells after BMT. GVHD was also associated with maintenance of CDH, but the probability of relapse, survival, and disease-free survival was identical in patients with MC and CDH.

The Cancer and Leukemia Group B (CALGB) has been conducting a prospective cytogenetic companion study (CALGB 8461) to all CALGB treatment protocols for newly diagnosed adults with acute lymphoblastic leukemia (ALL). These protocols underwent a significant change in 1988 when a new intensive chemotherapy program was introduced (CALGB 8811). We asked whether karyotype continued to represent a significant prognostic factor in adult ALL patients after the change. A total of 256 patients had adequate pretreatment cytogenetic analyses: 67 before 1988 and 189 subsequently. The complete remission (CR) rate for the whole group was 80%. Patients with t(9;22), t(4;11), -7, or +8 had significantly lower probabilities of continuous CR and survival at 5 years (.11 and.12) than patients with a normal karyotype (.38 and.37) and patients with miscellaneous cytogenetic abnormalities (.52 and.49; P.001 for each comparison). When analyzed by treatment period, the CR rate before CALGB 8811 was 63%; subsequently, it was 86% (P.001). Patients with cytogenetic abnormalities other than t(9;22), t(4;11), -7, or +8 had better CR rates, disease-free survival (DFS), and survivals (P =.001, P =.04, and P =.004, respectively) after the change to the more intensive chemotherapy regimens. Patients with normal cytogenetics had improved CR rate but no improved DFS or survival, whereas no significant benefit for patients with t(9;22), t(4;11), -7, or +8 was seen. In a multivariate analysis, karyotype retained its prognostic significance for DFS but not for survival; it remained the most important factor for DFS. We conclude that cytogenetic analysis at diagnosis should be used to guide treatment decisions in adults with ALL.

Advances in the treatment of acute myeloid leukemia (AML) have occurred with the introduction of new therapies including high-dose cytarabine and the identification of powerful prognostic factors such as cytogenetics that predict for long-term outcome. To date, the prognostic impact of cytarabine dose escalation within various cytogenetic groups of AML has not been assessed. We describe 285 newly diagnosed patients with primary AML who had adequate karyotypes and were enrolled on a prospective Cancer and Leukemia Group B cytogenetic study. All patients were randomly assigned to postremission treatment with standard-, intermediate-, or high-dose cytarabine intensification. Patients were categorized to one of three cytogenetic groups: (a) core binding factor type [(CBF); ie., t(8;21) inv(16), t(16;16), and del(16)]; (b) normal; and (c) other abnormality karyotype. An evaluation of these patients after a median follow-up time of over 7 years was performed to determine the relationship of intensification to outcome by cytogenetic group. Patients included 57 patients with CBF AML, 140 patients with normal karyotype AML, and 88 patients with other cytogenetic abnormalities. The treatment outcome of CBF AML patients was superior, with an estimated 50% still in complete remission (CR) after 5 years as compared with 32 and 15% for patients with normal karyotype AML and other abnormality AML, respectively (P0.001). Univariate analysis showed the following nonkaryotype factors to predict a prolonged CR duration: (a) younger age (P0.008); (b) lower leukocyte count (P=0.01); (c) the presence of Auer rods (P=0.004); (d) a lower percentage of bone marrow blasts (P=0.001) at the time of diagnosis, (e) and a higher postremission cytarabine dose (P0.001). The impact of cytarabine dose on long-term remission was most marked (P0.001) in the CBF AML group (after 5 years, 78% of those with a dose of 3 g/m2 were still in CR, 57% of those with a dose of 400 mg/m2 were still in CR, and 16% of those with a dose of 100 mg/m2 were still in CR) followed by normal karyotype AML (P=0.01; after 5 years, 40% of those with a dose of 3 g/m2 were still in CR, 37% of those with a dose of 400 mg/m2 were still in CR, and 20% of those with a dose of 100 mg/m2 were still in CR). In contrast, cytarabine at all doses produced only a 21% or less chance of long-term continuous CR for patients with other cytogenetic abnormalities. A multivariate analysis of CR duration assessed the independent impact of each of these variables on cure. Significant factors entering this model in descending order of importance were cytogenetic group (CBFnormalother abnormality; P=0.00001), cytarabine dose (3 g/m2400 mg/m2100 mg/m2; P=0.00001), logarithm of leukocyte count at the time of diagnosis (P=0.0005), and histological subtype of AML (P=0.005). This study demonstrates that the curative impact of cytarabine intensification varies significantly among cytogenetic groups and results in a substantial prolongation of CR among patients with CBF and normal karyotypes, but not in those with other karyotypic abnormalities. These findings support the use of pretreatment cytogenetics in risk stratification of postremission AML therapy.

Recent studies have documented an increased risk of therapy-related myelodysplastic syndrome or acute myelogenous leukemia (t-MDS/AML) after autologous bone marrow transplant (ABMT) for non-Hodgkin's lymphoma (NHL). To develop methods to identify patients at risk for this complication, we have investigated the predictive value of clonal bone marrow (BM) hematopoiesis for the development of t-MDS/AML, as defined by an X-inactivation based clonality assay at the human androgen receptor locus (HUMARA), in a group of patients undergoing ABMT for NHL from a single institution (Dana-Farber Cancer Institute, Boston, MA). One hundred four female patients were analyzed. At the time of ABMT, the prevalence of polyclonal hematopoiesis was 77% (80/104), of skewed X-inactivation pattern (XIP) was 20% (21/104), and of clonal hematopoiesis was 3% (3/104). To determine the predictive value of clonality for the development of t-MDS/AML, a subgroup of 78 patients with at least 18 months follow-up was analyzed. As defined by the HUMARA assay, 53 of 78 patients had persistent polyclonal hematopoiesis, 15 of 78 had skewed XIP, and 10 of 78 (13.5%) either had clonal hematopoiesis at the time of ABMT or developed clonal hematopoiesis after ABMT. t-MDS/AML developed in 2 of 53 patients with polyclonal hematopoiesis and in 4 of 10 with clonal hematopoiesis. We conclude that a significant proportion of patients have clonal hematopoiesis at the time of ABMT and that clonal hematopoiesis, as detected by the HUMARA assay, is predictive of the development of t-MDS/AML (P = .004).

Therapy-related acute myelogenous leukemia and myelodysplastic syndrome (t-AML/MDS) are being reported with increasing frequency as a complication of ABMT for Hodgkin's disease and non-Hodgkin's lymphoma. At present there is no method available to predict who is at risk or is destined to develop this nearly universally fatal disorder. We therefore investigated whether clonal growth of cells is predictive of the development of t-AML/MDS. In a patient who developed secondary AML/MDS 18 months after ABMT, X-linked clonality analysis at the human androgen receptor locus was performed on serial banked samples, and documented transition from polyclonal to clonal hematopoiesis. Clonal cells could be identified 6 months after transplant (1 year prior to the diagnosis of t-AML/MDS), at a time when there was no morphologic or clinical evidence of disease. Clonality analysis can be predictive of the development of t-AML/MDS after ABMT and may offer important insights into associated risk factors and strategies to minimize the risk of t-AML/MDS.

PURPOSE To examine, in newly diagnosed patients with acute promyelocytic leukemia (APL), the prognostic significance of secondary cytogenetic changes and the relationship between such changes and the two major promyelocytic leukemia-retinoic acid receptor alpha (PML-RAR alpha) mRNA types. PATIENTS AND METHODS One hundred sixty-one patients with t(15;17)(q22;q11-12) enrolled onto Cancer and Leukemia Group B (CALGB) protocol 8461, a prospective study of cytogenetics in acute myeloid leukemia (AML), were studied. Eighty of these 161 patients were treated solely with chemotherapy and evaluated for response to treatment and survival. PML-RAR alpha mRNA type was determined using reverse transcriptase polymerase chain reaction (RT-PCR) in 56 patients. RESULTS The incidence of secondary cytogenetic abnormalities was 32%. Among 80 patients treated with chemotherapy, the presence of a secondary chromosome abnormality was associated with longer complete remission (CR) duration (median, 29.9 v 15.7 months; P = .03) and longer event-free survival (EFS) duration (median, 17.0 v 12.2 months; P = .03). There was no difference in overall survival (P = .28). In a separate group of 56 patients with both cytogenetic and molecular data, 32 had the type L PML-RAR alpha transcript (intron 6 PML breakpoint). Of these 32 patients, four (12.5%) had chromosome changes in addition to t(15;17), whereas 12 of 20 patients (60%) with the type 5 PML-RAR alpha transcript (intron 3 PML breakpoint) had secondary cytogenetic changes (P < .001). CONCLUSION (1) Secondary cytogenetic changes do not confer a poor prognosis in APL patients treated with anthracycline/cytarabine (Ara-C)-based chemotherapy; and (2) A highly significant relationship exists between the PML-RAR alpha 5 isoform (intron 3 PML genomic breakpoint) and secondary cytogenetic changes in APL.

Polymerase chain reaction-based screening of childhood acute lymphoblastic leukemia (ALL) samples showed that a TEL/AML1 fusion transcript was detected in 27% of all cases, representing the most common known gene rearrangement in childhood cancer. The TEL/AML1 fusion results from a t(12;21)(p13;q22) chromosomal translocation, but was undetectable at the routine cytogenetic level. TEL/AML1-positive patients had exclusively B-lineage ALL, and most patients were between the ages of 2 and 9 years at diagnosis. Only 3/89 (3.4%) adult ALL patients were TEL/AML1-positive. Most importantly, TEL/AML1-positive children had a significantly lower rate of relapse compared with TEL/AML1-negative patients (0/22 v 16/54, P = .004). Co-immunoprecipitation experiments demonstrated that TEL/AML-1 formed homodimers in vitro, and heterodimerized with the normal TEL protein when the two proteins were expressed together. The elucidation of the precise mechanism of transformation by TEL/AML1 and the role of TEL/AML1 testing in the treatment of childhood ALL will require additional studies.

The ABPL tumor cell lines represent a group of myeloid cell lines which contain an altered myb locus due to viral insertional mutagenesis within the third exon of c-myb. Immunoprecipitation analysis of the proteins produced in three ABPL lines revealed an interesting anomaly. Despite the invariant position of the virus integration event, the three ABPL tumor cell lines we examined (ABPL-1, ABPL-2 and ABPL-4) produced three different sized proteins. In this report, we examined the molecular basis for this protein size heterogeneity. Molecular cloning and sequence analysis of the cDNAs derived from the myb transcripts show that ABPL-1 tumor produces a tripartate mRNA containing sequences derived from the viral gag and env genes fused to the myb coding region. This results in the synthesis of a 74 kd protein. In the ABPL-2 tumor line, a gag-myb fusion protein is produced which is of 68 kd. In ABPL-4 cell line a gag-myb fusion protein is produced which contains an internal deletion of coding sequences derived from exons 13 and 14. This deletion results in the synthesis of a 59 kd protein in ABPL-4 tumor cell line. These observations were further confirmed by RNase protection assays which demonstrate the presence of aberrantly spliced mRNAs in ABPL-1 and ABPL-4 tumor cells but not in cells containing an undisrupted c-myb locus. In vitro translation and immuno-precipitation analysis of the cRNAs derived from the ABPL-1, ABPL-2 and ABPL-4 cDNAs show the synthesis of protein products that were identical to Myb proteins produced by these tumors in vivo. These results suggest that integration of Mo-MuLV within the c-myb locus not only results in deletions of the 5' end of the transcript but splicing aberrations within the encoded mRNA, which results in the synthesis of a heterogeneous array of proteins, not seen in normal hematopoietic cells.

The myb gene has been shown to be an important regulator of hematopoietic cell proliferation, differentiation and apoptosis. Activation of the myb gene into an oncogenic form has involved structural alterations to the coding sequences. Thus, the v-myb gene encoded by the Avian Myeloblastosis Virus, is truncated at both the 5' and 3' ends. Additionally, tumor cells containing rearrangements in the myb locus, such as the ABPL tumors or NFS60 tumor cell line have recently been shown to display a heterogeneity of structure. In this study, we examined the growth and differentiation properties of clonal cell lines derived from 32Dcl3 which harbor myb transgenes; derived from v-myb, and the ABPL-1, ABPL-2, ABPL-4 and NFS-60 cell lines. Retroviral vectors containing the appropriate myb cDNAs were produced, transfected into packaging cell lines, and the viruses were used to generate the 32D derivative cell clones. Abrogation of IL-3 dependence was never observed in any cell line. Expression of c-myb, ABPL-1-myb and ABPL-2-myb isoforms in 32D cells resulted in a block to their ability to terminally differentiate into granulocytes at the pro-myelocytic stage. However, expression of ABPL-4-myb or NFS60-myb in these cells failed to result in a similar effect. These cells differentiated into granulocytes in the presence of G-CSF, albeit more slowly than control 32Dcl3 cells. We also examined the ability of various Myb-isoforms to transactivate transcription of reporter genes containing Myb-binding elements in their promoter/enhancer sequences, to determine whether the phenotypic effects produced by these various isoforms correlate with their ability to transactivate transcription. Our results show that while v-myb and c-myb transactivated transcription equally well, the NFS60-myb exhibited the highest levels of transcriptional transactivation. The ABPL-1, ABPL-2 and ABPL-4-myb isoforms showed very low levels of transcriptional transactivation potential with the same reporter genes. These results suggest that the ability of various Myb-isoforms to transactivate transcription does not by itself correlate with their ability to induce a block to G-CSF-induced terminal differentiation of myeloid precursor cells.

Cell line NKL was established from the the peripheral blood of a patient with CD3-CD16+CD56+ large granular lymphocyte (LGL) leukemia. The neoplastic LGL of this patient mediated natural killing and antibody-dependent cellular cytotoxicity (ADCC) and exhibited proliferative responses similar to normal CD16+CD56dim natural killer (NK) cells. The Morphology of NKL cells resembles that of normal activated NK cells. The karyotype of NKL is 47, XY, add (1) (q42), +6 del (6) (q15 q23), del (17) (p11). NKL cells express CD2, CD6, CD11a, CD26, CD27, CD29, CD38, CD43, CD58, CD81, CD94, CD95, class II MHC, and the C1.7.1 antigen, but do not express detectable levels of CD3, CD4, CD5, CD8, CD14, CD19, CD20, CD28, alpha/beta or gamma/delta T cell receptors on the cell surface. The density of the CD16, CD56, and CD57 antigens declined markedly on NKL cells during prolonged im vitro culture. Nevertheless, NKL cells can mediate ADCC as well as natural killing. NKL cells are strictly dependent on interleukin-2 (IL-2) for sustained growth and die if deprived of IL-2 for more than 7 days. NKL cells proliferate in response to concentrations of IL-2 as low as 1 pM, but an optimal proliferative response requires approximately 100 pM IL-2. NKL cells growing in the presence of IL-2 express abundant IL-2R alpha with little or no detectable IL-2 beta or gamma chain on the cell surface; NKL cells deprived of IL-2 express high levels of both IL-2R alpha and beta. IL-4, IL-7, and IL-12, unlike IL-2, do not maintain the viability of NKL cells. Furthermore, IL-1, IL-4, IL-6, IL-7, IL-12, tumor necrosis factor-alpha (TNF-alpha), interferon-alpha (IFN-alpha) and IFN-gamma do not support the growth of NKL cells. The NKL cell line may prove useful for studies of human NK cell biology.

We report two patients with a distinctive biphenotypic hematologic disorder characterized by lymphoblastic lymphoma (LBL), eosinophilia, and myeloid malignancy and/or hyperplasia associated with a t(8;13)(p11;q11) chromosomal translocation in both bone marrow and lymph node specimens. Both patients presented with lymphadenopathy pathologically classified as LBL with a T-cell immunophenotype, myeloid hyperplasia of the bone marrow, and peripheral blood eosinophilia. The first patient achieved clinical complete remission after receiving several regimens of chemotherapy and remains disease-free 16 months after undergoing allogeneic bone marrow transplantation. The second patient developed progressive lymphadenopathy despite several courses of chemotherapy directed against non-Hodgkin's lymphoma. Eight months after his initial presentation, he developed acute myelogenous leukemia that was refractory to therapy. Comparison of these patients with four similar cases recently reported in the literature suggests that this constellation of findings constitutes a distinctive clinicopathologic syndrome. Molecular analysis of the t(8;13) translocation breakpoint may identify genes located in this region and provide insight into the pathogenesis of this interesting biphenotypic hematologic malignancy.

An unbalanced translocation between chromosomes 1 and 16, der(16)t(1;16), resulting in trisomy 1q and loss of genetic material from 16q, has been thus far suggested to constitute a nonrandom secondary abnormality in two types of closely related solid tumors - Ewing sarcoma and peripheral primitive neuroepithelial tumor (PNET). We report on three cases of soft tissue tumors, a myxoid liposarcoma, a PNET and a rhabdomyosarcoma, and four cases of hematologic disorders, two acute lymphoblastic leukemias (ALL), an acute mixed leukemia and a refractory anemia, that in addition to primary chromosome abnormalities displayed the presence of the der(16)t(1;16). All three cases of acute leukemia were Philadelphia (Ph) chromosome-positive and all displayed both lymphoid and myeloid antigens. Our results and review of the literature indicate that the occurrence of der(16)t(1;16) is not limited to Ewing sarcoma and PNET, but that acquisition of this abnormality may represent a more general pathway of clonal evolution in several different tumor types including Ph chromosome-positive ALL, myxoid liposarcoma, rhabdomyosarcoma, breast cancer, endometrial adenocarcinoma, myelodysplastic syndromes, acute myeloid leukemia, retinoblastoma, and Wilms' tumor.

We investigated whether recombinant alpha 2b interferon (r alpha 2bIFN) would reduce the proportion of bone marrow Philadelphia chromosome (Ph) cells in chronic-phase chronic myelogenous leukemia (CML) by treating 107 previously untreated patients daily with r alpha 2bIFN at 5 x 10(6)IU/m2 subcutaneously. Patients with complete remission, partial remission, or partial hematologic remission received treatment until progression; those with progressive disease were taken off study and observed for survival. Sixty-three (59%) of the patients achieved at least a partial hematologic remission (24 complete remissions and 39 partial remissions). The median time to response for the 63 responders was 3.4 months, with a median duration of remission of 52 months and with 81% of responders continuing in remission beyond 12 months. The median survival for the 107 patients was 66 months. Of 78 patients with cytogenetic follow-up data, 31 (40%) achieved a partial cytogenetic response (n = 17) or a complete cytogenetic response (n = 14). The percentage of cytogenetic responders among all patients was 29% (31 of 107 patients). The median time to first cytogenetic response was 9 months. A major dose reduction of r alpha 2bIFN (or = 50%) was required at some time during treatment in 38% of patients, 26% required 10% to 49% dose reductions, and 36% had minor dose reductions ofor = 10%. No association was observed between dose received and the attainment of a cytogenetic response. None of the usual prognostic factors (sex, race, performance status, weight loss, time from diagnosis to treatment, hepatosplenomegaly, age, symptoms, hemoglobin, or platelet, blast, basophil, or white blood cell count) were significantly related to survival. These data provide confirmation that major cytogenetic responses to prolonged administration of subcutaneous r alpha 2bIFN occur in 20% to 38% (95% confidence interval) of chronic-phase Ph-positive patients. Although it is hypothesized that patients achieving major cytogenetic responses to r alpha 2bIFN should have prolonged remission duration and survival compared with nonresponders, analyses of the effect of cytogenetic responders by both "landmark" and time-dependent covariate techniques fail to provide statistically significant evidence for an effect of cytogenetic response on remission duration or survival. This may be due in part to an effect size insufficiently large to be detected with the number of patients treated in this study. Thus, confirmation of remission duration or survival benefit, if any, of r alpha 2bIFN therapy in Ph-positive chronic-phase CML must await the outcome of randomized trials comparing IFN with conventional agents.

The prognostic implications of t(9;22)(q34;q11) were assessed at a median follow-up of 3.5 years in 434 children receiving intensive treatment for acute lymphoblastic leukemia (ALL). Four-year event-free and overall survivals were 81% and 88%, respectively, in 419 children lacking t(9;22), but were 0% and 20%, respectively, in 15 children with t(9;22) (P less than .001). Poor outcome for children with t(9;22)- positive ALL was particularly notable because we have reported improved survival in other historically poor prognosis ALL cytogenetic categories when treated with similarly intensive therapy. We recommend that very intensive treatment approaches, including bone marrow transplantation in first remission, be considered for all children with t(9;22)-positive ALL.

Mixed hematopoietic chimerism (MC) is a common finding after allogeneic bone marrow transplantation (BMT), but the natural history of this phenomenon remains unclear. To understand the evolution and the implications of this finding, we performed a prospective analysis of the development of mixed chimerism in 43 patients with hematologic malignancies who received bone marrow (BM) from human leukocyte antigen (HLA)-identical sibling donors. T-cell depletion in vitro with anti-T12 (CD6) monoclonal antibody and rabbit complement was used as the only method of graft-versus-host disease (GVHD) prophylaxis. Overall, MC was identified in peripheral blood (PB) and BM in 22 of 43 (51%) patients evaluated. MC was found by restriction fragment length polymorphism (RFLP) analysis in 21 of 40 (53%) patients, by cytogenetic analysis in 6 of 29 (21%) patients, and by red blood cell phenotyping in 4 of 9 (44%) patients. RFLP studies were performed at 0.5, 1, 3, 6, 9, and 12 months post-BMT and then every 6 months, and showed a high probability of developing MC in the first 6 months after BMT followed by stabilization after 12 months. Cytogenetic analysis was less sensitive in detecting MC. Once MC was detected after BMT, the percentage of recipient cells increased very slowly over more than 3 years of follow-up, and no patient reverted to complete donor hematopoiesis (CDH). Thus, recipient and donor cells remained in a relative state of equilibrium for prolonged periods that seemed to favor recipient cells over donor cells. Patient's disease, remission status, or intensity of the transplant preparative regimen did not influence the subsequent development of mixed chimerism. Early immunologic reconstitution was the only factor that correlated with the subsequent chimeric status of the patients. The percentage and absolute number of T3 (CD3) and T4 (CD4) positive cells at day 14 after BMT were significantly higher in the patients who maintained CDH but NK cell reconstitution was similar in both groups, suggesting that early reconstitution with T cells may play a role in preventing recovery of recipient cells after BMT. GVHD was also associated with maintenance of CDH, but the probability of relapse, survival, and disease-free survival was identical in patients with MC and CDH.

The chromosome complements of human/mouse hybrid cell lines of mouse 3T3-4E and RAG parentage have been analyzed using chromosome banding methods. Three lines that were susceptible to lytic infection with poliovirus contained eleven to seventeen human chromosomes, including chromosome 19. Polio-resistant sublines of these contained no chromosome 19 and showed no other consistent change in the complement of human chromosomes. Human chromosome 19 therefore is essential for polio-sensitivity. Since polio sensitivity was correlated with receptor activity in these lines, we conclude that chromosome 19 carries the structural gene for the poliovirus receptor. Sensitivity to echo-7 and Rhino-1A viruses could not be related to the presence of a specific human chromosome.

Metaphase chromosome preparations of three male and one female Gorilla gorilla were stained to demonstrate quinacrine, Giemsa, centromeric heterochromatin, and, in one case, reverse-Giemsa bands. A standard karyotype is proposed based on chromosome banding pattern, centromeric index, and length. Three types of variation between homologous chromosomes are described: presence or absence of very bright fluorescence of the short arm or satellite region of acrocentric chromosomes, presence or absence of bright quinacrine bands at the distal ends of chromosome arms, and large differences in the size of the heterochromatic region on each of two biarmed chromosomes. At least half the chromosome pairs show polymorphisms of these types. Satellite associations were scored for each animal. In one case the two smallest pairs of chromosomes were preferentially involved in associations.

We assessed the prognostic significance of leukemia cell cytogenetics by analyzing bone marrow aspirates obtained at time of diagnosis in 165 children on a single protocol for acute lymphoblastic leukemia (ALL). These children were assigned to six mutually exclusive cytogenetic categories as follows: (1) hyperdiploid, with 50 or more chromosomes (n = 35); (2) hyperdiploid, with 47 to 49 chromosomes (n = 11); (3) diploid (n = 42); (4) pseudodiploid (n = 34); (5) hypodiploid (n = 9); and (6) insufficient data (n = 34). At a median follow-up of 5 years, there were no statistically significant differences between any of these cytogenetic categories in either event-free or overall survival. Those children with chromosomal translocations (n = 26) appeared to fare the same as those lacking translocations (n = 105). The absence of karyotypic prognostic significance was observed not only within the overall group, but also when the results were stratified by standard- risk and high-risk status. Of the specific structural chromosome changes that we studied, only the Philadelphia chromosome (Ph) appeared to confer a poor prognosis, although there were too few such cases to achieve statistical significance. Although we did not detect the event- free survival differences that have been described previously in hyperdiploid, hypodiploid, and pseudodiploid childhood ALL, our findings must be viewed as preliminary given the small number of children in some of the cytogenetic categories. We think that the prognostic implications of these cytogenetic features might have been nullified by improvements in therapy.

Banded karyotypes were prepared for three independent sublines of clone 745A, a Friend virus-induced erythroleukemia cell line originally produced by Dr. C. Friend. Each subline had the same chromosome complement, with a near-diploid number of chromosomes, two-thirds of which appeared normal. The remaining one-third were structurally rearranged marker chromosomes, including eight whose origins could be determined from their banding patterns. A fourth subclone of line 745A, under different selection pressure, showed changes in five marker chromosomes but no changes in the normal chromosomes, suggesting that the markers contained unstable sites, perhaps viral integration sites. Another Friend virus-induced erythroleukemia cell line, FSD-1/F4, developed independently by Dr. W. Ostertag, had a near-diploid number of chromosomes, about one-fourth of which were abnormal chromosomes. The only similarity between these markers and those in subclones of 745A, other than participation of some of the same chromosomes in centric fusion, was the inclusion of the proximal two-thirds of chromosome 15 in one of the markers of each line. This adds to the number of mouse tumor cells or cell lines in which No. 15 is altered or duplicated. In FSD-1/F4 cells there was a striking increase in the size of the secondary constriction of one of the two chromosomes 19, suggesting that the rRNA genes on this chromosome had been amplified.

Differences in the number of chromosomes with secondary constrictions and in the size of the C-band region on certain chromosomes have been observed among the following inbred strains of Mus musculus: C57BL/10J, C57BR/cdJ, DBA/1J, CBA/J, BALB/cJ, and AKR. These differences are useful as indicators of the location of rRNA genes and as normal chromosome markers. The size of each C-band region appears to remain constant over many generations. Only one probable change in the size of a C-band region was found.

Chromosomes of the owl monkey, Aotus trivirgatus, with 2n = 54, 53, or 52, have been stained to show quinacrine (Q-) and Giemsa (G-) bands, and a karyotypic arrangement has been proposed based on lengths, centromeric index, and banding pattern. C-bands were present at the centromeric region of every chromosome and over the entire short arm of certain acrocentric chromosomes; 5-methylcytosine was concentrated in the same regions. Bright Q-bands at the telomeric ends of the short arms of some chromosomes probably represent a second type of repetitive DNA. Ag-staining showed that only the chromosomes bearing a secondary constriction are nucleolus organizer chromosomes.

Metaphase chromosome preparations were made from leukocyte cultures of normal individuals. The cells were fixed in methanol:acetic acid (3:1 v/v), then dropped on cold, wet slides which were air-dried before storage at 4 degrees C. The slides were stained to identify the chromosomes by one of the following procedures: (1) Quinacrine. Slides were stained for 10 min in quinacrine mustard solution, rinsed in running tap water for 2 min, and mounted in Tris-maleat buffer, pH 5.6.

Quinacrine (Q-band) and centromeric heterochromatin (C-band) patterns of metaphase chromosomes of two subspecies of Mus musculus were compared. M. m. musculus (the laboratory mouse) and M. m. molossinus (a subspecies from Southeast Asia) had similar Q-band patterns along the length of the chromosomes, but differences were observed in the centromeric region of some chromosomes. The two subspecies had very different distributions of C-band material. Antibodies to 5-methylcytosine were bound to regions of the chromosome corresponding to the C-bands in each animal. These findings support the idea that satellite DNA, which is concentrated in the C-band region, changes more quickly than bulk DNA. The interfertility of these two subspecies permits the development of a musculus strain carrying normal marker chromosomes for genetic studies.

Silver staining has been used to detect active nucleolus organizer regions (NOR's). By this criterion six mouse chromosomes, numbers 12, 15, 16, 17, 18 and 19, can have an NOR. The number and distribution of chromosomes with NOR's vary among inbred strains of Mus musculus musculus (C57BL/6J, BALB/cJ, C3H/HeJ and C3H/StCr1BR) and in M. musculus molossinus. In a musculus x molossinus F1 hybrid, nucleolus organizers from each parent are silver stained.—Chromosomes which have NOR's in diploid cells also show them in tetraploid cells and in established cell lines. The BALB/cJ strain shows Ag-staining of NOR's on chromosomes 12, 15, 18 and occasionally 16. In the RAG cell line, which was derived from BALB/c, active NOR's are seen on 12, 15 and 18, even after these chromosomes have undergone structural rearrangements in the cell line. Some correlation exists between the amount of Ag-stain and the size of a secondary construction region, with a large amount of Ag-stain present on a chromosome which has a prominent secondary constriction. There is no correlation between the amount of Ag-stain and the presence or absence of C-band material.

Nucleolus organizer regions (NORs) of rat chromosomes were stained by the Ag-AS method. The Ag-NORs were found on chromosomes 3, 11 and 12 in the ACI, Wistar Brown and Wistar Lewis inbred strains of rat. The size of the Ag-NOR on each pair of chromosomes varied from strain to strain. Rat-human somatic hybrid cells that retained human and lost some of the rat chromosomes had no Ag-NOR on rat chromosomes 3, 11 or 12. Since NORs can be Ag-stained only if their 18 + 28S rRNA genes are active, the activity of the rat rRNA genes must have been suppressed in the hybrid cells.

There is little evidence to suggest that T lymphocytes are involved in the leukemic process in chronic myeloid leukemia (CML). A case of CML in blast phase is described in which T-cell surface antigens were detected by immunofluorescence on the patient's blasts using monoclonal antibodies. In order to determine that the T-cell blasts were derived from the original CML clone, cells bearing the T3 antigen were isolated by fluorescence-activated cell sorting and chromosome analysis was performed. All metaphases examined had the Philadelphia chromosome, confirming their origin from CML.

Cytogenetic studies were performed in 18 consecutive children with acute nonlymphocytic leukemia (ANLL) between 1981 and 1983. Three children with acute myelomonocytic leukemia (AMMoL; M4, FAB classification) had the following unique bone marrow morphology and cytogenetic abnormality: eosinophilic precursors with dysplastic violaceous granules and a pericentric inversion of chromosome 16. Surface marker analysis of leukemic cells from these patients, using a panel of monoclonal antibodies, revealed the expression of a series of monocyte markers. The association of an inversion of chromosome 16 with abnormal eosinophil morphology in the M4 subtype of ANLL appears to represent a unique subgroup of patients.

The H-Y locus is on the short arm of the human Y chromosome in most individuals but on the long arm in at least one of 17 individuals with structural abnormalities of the Y.

A new human megakaryocytic cell line (Dami) has been established from the blood of a patient with megakaryoblastic leukemia. The Dami cells grow primarily in suspension with a doubling time of 24 to 30 hours. By light and electron microscopy, the Dami cells range in size from 12 to 120 micron in diameter and have lobulated nuclei characteristic of megakaryocytes. At least 89% of the cells react with monoclonal antibodies against platelet glycoproteins (GP) Ib and IIB/IIIa, and glycophorin. The cells do not react with antibodies against lymphoid, monocyte, granulocyte, or macrophage antigens. Thirteen percent of the cells become polyploid, spontaneously achieving greater than 4N DNA ploidy levels. In response to phorbol myristate acetate (PMA), the proportion of cells with ploidy levels greater than 4N increased threefold and could be separated into discrete ploidy groups. PMA also increased the expression of GPIb, the GPIIb/GPIIIa complex,l and von Willebrand factor. Cytogenetic analysis revealed a human male hyperdiploid karyotype with a modal chromosome number of 54 to 64 and several consistent clonal chromosomal abnormalities. These included a partial deletion of chromosome 5 and a translocation involving chromosome 3. In contrast to other megakaryocytic cell lines in which only a small portion of the cells express the megakaryocytic phenotype, nearly all of the Dami cells express platelet glycoproteins. Thus, the Dami cells provide a superior model in which to study human megakaryocyte biochemistry and differentiation.

Fixed metaphase chromosomes of gorilla and chimpanzee were UV-irradiated to produce regions of single-stranded DNA and then treated with antibodies specific for the minor DNA base 5-methylcytosine (5 MeC). An indirect immunofluorescence technique was used to visualize sites of antibody binding. In the gorilla six pairs of autosomes contained major fluorescent regions, indicating localized regions of highly methylated DNA. These corresponded, with the exception of chromosome 19, to the major regions of constitutive heterochromatin as seen by C-banding. The Y chromosome also contained a highly fluorescent region which was located just proximal to the intense Q-band region. In the chimpanzee no comparable concentrations of highly methylated DNA were seen. Smaller regions of intense 5 MeC binding were present on perhaps six chimpanzee chromosomes, including the Y. Five of these corresponded to chromosomes which were highly methylated in the gorilla.--There is diversity among the human, gorilla and chimpanzee in both the size and location of concentrations of 5 MeC, supporting the idea that satellite DNA evolves more rapidly than DNA in the remainder of the chromosome.

A translocation involving the short arm of chromosome #1 and the short arm of chromosome #7, [t(1;7)(p11;p11)] was present in four patients with myelodysplastic syndrome (MDS). Two of these patients had prior lymphoproliferative disorders and developed MDS following prolonged therapy with alkylating agents. One of the patients with prior therapy history has two additional independent abnormal clones: one with a partial deletion of the long arm of #7 and the other with t(1;7)(q21;q11). A third patient had a family history of leukemia in both the father and a brother, both of whom developed acute nonlymphocytic leukemia following an MDS phase. The last patient was an elderly woman with no predisposing features.

Cells from four different mouse-human somatic cell hybrids were stained with quinacrine to identify each metaphase chromosome and with ammoniacal silver by the Ag-AS method to locate nucleolus organizer regions. Each of the hybrids contained human acrocentric chromosomes. None of these human acrocentric chromosomes was stained with silver in any hybrid cell. Diploid cells were available from the human parent of one of the hybrids. In these cells both copies of nos. 13 and 15 stained with silver; the same chromosomes in the hybrid cell were not stained. These results support earlier reports that the expression of human ribosomal RNA (rRNA) genes is suppressed in mouse-human hybrid cells. Further, they suggest that silver staining by the Ag-AS method reflects activity of rRNA genes rather than just the presence of these genes.

Methaphase chromosomes from karyotypically normal adult humans (three males, six females) and one male with a 13p - chromosome were stained by quinacrine and then by the Ag-AS silver staining method to reveal nucleolus organizer regions (NORs). Each person had a characteristic number of Ag-stained chromosomes per cell, always fewer than 10. Determination of the mean Ag-size of each chromosome showed that each of the 10 individuals had a unique distribution of Ag-stain. Within each individual, there was some variation from cell to cell in the number of acrocentric chromosomes that were Ag-stained; this was not random, and the same chromosomes (those that had at most a small amount of Ag-stain) tended to be unstained in every cell. Satellite associations were scored on the same cells. Chromosomes that had no Ag-stain were involved in satellite association less than 20% as often as those that had some Ag-stain. Chromosomes that had a small amount of Ag-stain were involved in association about 50% as often as those that had a large amount of stain. Regression analysis of the 50 (of a total of 100) acrocentric chromosomes which could be individually identified by quinacrine markers showed that the frequency with which a chromosome was involved in satellite association was strongly correlated with the amount of Ag-stained material in the NOR.

Low-level methotrexate (MTX) resistance (less than 20-fold) was induced by gradual selection pressure in four human head and neck squamous cell carcinoma lines established in culture from biopsies of patients not previously treated with MTX. Each parental and resistant line was characterized with respect to MTX uptake and polyglutamylation, dihydrofolate reductase (DHFR) content, and growth rate. Relative DHFR gene copy numbers and amounts of DHFR-related cytoplasmic messenger RNA were analyzed by plasmid complementary DNA hybridization in a dot blot assay and were correlated with the amount of gene product. The resistant lines were not cloned in order to simulate in vitro the conditions which might exist in an in vivo setting, where multiple resistant subpopulations of cells may be present in a tumor. The study was restricted to cells with low-level resistance since these are likely to be the clinically most relevant type. Of the four resistant lines characterized, one showed a severe defect in MTX uptake and polyglutamylation, another was a DHFR overproducer with only small changes in uptake and polyglutamylation, a third was likewise a DHFR overproducer but also showed lower MTX uptake, and the fourth was minimally altered except for growth rate. The diversity in resistance phenotype among these cells in vitro suggests that in vivo resistance in patients with head and neck carcinoma who are treated with MTX may similarly involve multiple mechanisms and that further therapeutic intervention using MTX or other antifolates should take this into account.

A human fibrosarcoma line, HT1080–6TG, with a near diploid number of chromosomes, has an average of 7.3 chromosomes with an Ag-stained nucleolus organizer region (NOR). Cells of this line with an increased number of chromosomes have an increased number of Ag-stained NORs. This cell line has been used as the human parent in constructing mouse-human and rat-human hybrids that segregate rodent chromosomes. The hybrid cell lines, which have 100 or more chromosomes per cell, show a proportionate increase in the number of Ag-stained NORs (means, 11.4–16.8). The frequency of association of acrocentric chromosomes increases in a similar fashion. There is no evidence of inactivation of human NORs in these cells.

Chromosomes of the owl monkey, Aotus trivirgatus, with 2n=54, 53, or 52, have been stained to show quinacrine (Q-) and Giemsa (G-) bands, and a karyotypic arrangement has been proposed based on lengths, centrometric index, and banding pattern. C-bands were present at the centromeric region of every chromosome and over the entire short arm of certain acrocentric chromosomes; 5-methylcytosine was concentrated in the same regions. Bright Q-bands at the telomeric ends of the short arms of some chromosomes probably represent a second type of repetitive DNA. Ag-staining showed that only the chromosomes bearing a secondary constriction are nucleolus organizer chromosomes.

We assessed the prognostic significance of leukemia cell cytogenetics by analyzing bone marrow aspirates obtained at time of diagnosis in 165 children on a single protocol for acute lymphoblastic leukemia (ALL). These children were assigned to six mutually exclusive cytogenetic categories as follows: (1) hyperdiploid, with 50 or more chromosomes (n = 35); (2) hyperdiploid, with 47 to 49 chromosomes (n = 11); (3) diploid (n = 42); (4) pseudodiploid (n = 34); (5) hypodiploid (n = 9); and (6) insufficient data (n = 34). At a median follow-up of 5 years, there were no statistically significant differences between any of these cytogenetic categories in either event-free or overall survival. Those children with chromosomal translocations (n = 26) appeared to fare the same as those lacking translocations (n = 105). The absence of karyotypic prognostic significance was observed not only within the overall group, but also when the results were stratified by standard-risk and high-risk status. Of the specific structural chromosome changes that we studied, only the Philadelphia chromosome (Ph) appeared to confer a poor prognosis, although there were too few such cases to achieve statistical significance. Although we did not detect the event-free survival differences that have been described previously in hyperdiploid, hypodiploid, and pseudodiploid childhood ALL, our findings must be viewed as preliminary given the small number of children in some of the cytogenetic categories. We think that the prognostic implications of these cytogenetic features might have been nullified by improvements in therapy.

Therapeutic options for children with de novo or secondary myelodysplastic syndromes (MDSs) are limited. We report the outcome of eight pediatric patients (median age 12 years, range 3 to 19 years) with myelodysplasia who underwent allogeneic bone marrow transplantation between 1984 and 1987. Two of the eight children had developed secondary myelodysplasia after alkylating agent-based combination chemotherapy. Five patients had clonal chromosomal abnormalities, including four patients with monosomy 7. Seven of eight patients engrafted. Two of these seven subsequently died of complications of acute or chronic graft-v-host disease (GVHD), and a third patient died at 21 months of pulmonary fibrosis. None of the patients have had recurrence of disease. The four surviving patients remain in complete remission at a median follow-up of 19 months (range 10 to 44 months).

THE wood lemming, Myopus schisticolor Liljeborg, is distinguished by an aberrant sex ratio, with a considerable excess of females, and by the fact that some females produce only daughters1,2. Fredga and his associates3 have provided a basis for understanding both these characteristics. They observed that 82 out of 181 female wood lemmings studied (45%) had an XY sex chromosome constitution, with chromosomal G-banding and C-banding patterns indistinguishable from those of XY males. On the other hand, the XY females were anatomically normal and indistinguishable from XX females. Furthermore, meiotic studies3 showed that the germ line in the somatically XY females was XX. The second X chromosome in the germ cells must have arisen by non-disjunction from the single X present in the XY cells. Thus all progeny from such females must have received copies of the same X chromosome. How does one reconcile these observations with the apparent function of the Y chromosome in mammalian sex determination4, or with more recent evidence that a particular Y-linked gene which controls presence of H–Y antigen is critical for differentiation of the male gonad? We have approached these questions serologically by typing male and female wood lemmings for expression of H–Y antigen, and we have found that all female wood lemmings are H–Y−.

HUMAN–mouse cell hybrids usually exhibit preferential loss of human chromosomes1,2. After a time interval, which depends in part on the cell types used, most or sometimes all the human chromosomes segregate out from the hybrid cells3. In the course of investigation of the phenomenon of preferential loss of human chromosomes from hybrids between the mouse cell line RAG and human leukocytes, we isolated and analysed sixteen human–mouse (RH) hybrids. Seven of these hybrids had retained the human Y chromosome. Five of these had only one copy per cell of Y, one had two copies per cell and one, RH-28, had four copies of the Y in many cells. We decided to study more extensively this hybrid which seemed to have lost all the human chromosomes except number 17 and the Y.

Silver staining has been used to detect active nucleolus organizer regions (NOR's). By this criterion six mouse chromosomes, numbers 12, 15, 16, 17, 18 and 19, can have an NOR. The number and distribution of chromosomes with NOR's vary among inbred strains of Mus musculus musculus (C57BL/6J, BALB/cJ, C3H/HeJ and C3H/StCr1BR) and in M. musculus molossinus. In a musculus x molossinus F1 hybrid, nucleolus organizers from each parent are silver stained.—Chromosomes which have NOR's in diploid cells also show them in tetraploid cells and in established cell lines. The BALB/cJ strain shows Ag-staining of NOR's on chromosomes 12, 15, 18 and occasionally 16. In the RAG cell line, which was derived from BALB/c, active NOR's are seen on 12, 15 and 18, even after these chromosomes have undergone structural rearrangements in the cell line. Some correlation exists between the amount of Ag-stain and the size of a secondary construction region, with a large amount of Ag-stain present on a chromosome which has a prominent secondary constriction. There is no correlation between the amount of Ag-stain and the presence or absence of C-band material.

A deletion of the albsino (c) locus on mouse chromosome 7 has been demonstrated using Q- and G-banding methods in a mouse heterozygous for the radiation-induced lethal albino allele, c 25H . The deletion, which is thought to be 1-6 cM long, represents about 7.6% of the length of the metaphase chromosome.