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Bone marrow angiogenesis is increased in myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML), but has not been studied in inherited or acquired marrow failure syndromes. Shwachman-Diamond syndrome (SDS) carries a high risk of MDS/AML and is characterised by marrow stromal dysfunction. Compared with controls, SDS patients without MDS/AML had higher marrow microvessel density. Stromal VEGF gene expression, stromal vascular endothelial growth factor (VEGF) secretion and VEGF levels in serum and marrow mononuclear cells were normal. Future studies should investigate the mechanism for increased angiogenesis in SDS, and whether SDS marrow, with its increased angiogenesis, promotes progression of malignant clones.

The most common myeloid malignancy seen in children with neurofibromatosis type 1 (NF-1) is juvenile myelomonocytic leukemia (JMML), a myeloproliferative disease. The vast majority of these children have inherited the neurocutaneous disease from an affected mother; boys are more often affected than girls. We present the rare finding of a 7-year-old girl with NF-1 who developed JMML. She inherited her NF-1 from the father. At the time of her initial presentation, clonogenic assays of bone marrow mononuclear cells did not show the spontaneous growth of granulocyte-macrophage colony-forming units or hypersensitivity to granulocyte-macrophage colony-stimulating factor that is characteristic of this disorder. After 1 month, repeat evaluations of the patient's clinical and laboratory test results became fully consistent with those for a diagnosis of JMML. This illustrates the stepwise evolution of this myeloproliferative disorder in NF-1 and the importance of close follow-up and reassessment of these patients. Our case is only the second report of JMML in a girl who inherited NF-1 from her father.

Shwachman-Diamond syndrome (SDS) is an inherited multisystem disorder characterized by exocrine pancreatic dysfunction and varying degrees of cytopenia. In addition, various immunological abnormalities have been noted. To clarify the issue of immunological competence or incompetence in SDS, we prospectively studied immune function in 11 patients with SDS. Seven suffered from recurrent bacterial infections and six from recurrent viral infections. Varying degrees of impairment were readily identified. All patients had neutropenia; total lymphocyte counts, however, were normal in all except one patient. Nine patients had B-cell defects comprising one or more of the following abnormalities: low IgG or IgG subclasses, low percentage of circulating B lymphocytes, decreased in vitro B-lymphocyte proliferation and a lack of specific antibody production. Seven out of nine patients studied had at least one T-cell abnormality comprising a low percentage of total circulating T lymphocytes or CD3+/CD4+ cell subpopulations or decreased in vitro T-lymphocyte proliferation. Five out of six patients studied had decreased percentages of circulating natural killer cells. Moreover, neutrophil chemotaxis was significantly low in all the patients studied. These data point to a major immunodeficiency component in SDS that places patients at heightened risk of infections, even if neutrophil numbers are protective. This finding broadens the definition of the syndrome substantially: it suggests that the SDS marrow defect occurs at the level of an early haematological-lymphocytic stem cell or that a combined marrow and thymic stromal defect accounts for the aberrant function of haematopoietic and lymphopoietic lineages.

Children with neurofibromatosis type 1 (NF1) are at increased risk of developing malignant myeloid disorders, particularly juvenile chronic myelogenous leukemia/juvenile myelomonocytic leukemia (JCML/JMML). We investigated bone marrows from 11 such patients (8 boys and 3 girls) and detected allelic losses at the NF1 locus in 4 of them and probable losses in 2 others. To determine which hematopoietic cell lineages were derived from the abnormal clones, Epstein-Barr virus (EBV)-transformed cell lines and CD34+ cells were analyzed from 3 children with JCML with allelic losses in unfractionated marrow. CD34 cells from these 3 patients lacked the normal NF1 allele, whereas EBV cell lines retained it. Erythroblasts plucked from the burst-forming unit-erythroid colonies of one of these children lacked the normal NF1 allele. We also studied a 10-month-old boy with NF1 who developed an unusual myeloproliferative syndrome. His bone marrow and EBV cell line both showed loss of the normal NF1 allele. In our series and in the literature, male sex and maternal transmission of NF1 were associated with the highest risk of myeloid leukemia. These data (1) provide strong genetic evidence that NF1 functions as a tumor-suppressor in early myelopoiesis, (2) confirm the clonal nature of JCML/JMML, (3) suggest that the elevation in fetal hemoglobin seen in JCML/JMML is a result of primary involvement of erythroid progenitors in the malignant clone, (4) show consistent loss of NF1 in the CD34 cells of affected children and show that the malignant clone may also give rise to pre-B cells in some cases, and (5) implicate epigenetic factors in the development of leukemia in children with NF1.

Bone marrow samples from patients with pre-B acute lymphoblastic leukemia (pre-B ALL), either at diagnosis or at relapse, were transplanted into scid mice to determine whether these freshly obtained leukemic cells could proliferate in vivo and whether there were any differences in their in vivo growth characteristics. Cells from three patients who relapsed within 13 months of diagnosis proliferated rapidly in the murine bone marrow, spleen, and thymus, invaded peripheral organs, and resulted in morbidity and mortality of the animals within 4 to 16 weeks. Cells from two patients who relapsed 3.5 years after diagnosis grew much slower than the early relapse samples, taking up to 30 weeks to infiltrate the bone marrow of recipient mice. In contrast, leukemic cells were absent or were detected at low numbers in scid mice transplanted with cells obtained at diagnosis from three patients who have not yet relapsed. These results show an increased ability of leukemic cells from patients with aggressive lymphoblastic leukemia of poor prognosis to proliferate in scid mice.

In newly diagnosed patients with acute lymphoblastic leukemia (ALL), bone marrow (BM) morphology always shows "replacement" by blasts with decreased or absent normal hematopoietic elements. To answer the question of whether ALL blasts inhibit replication and maturation of normal marrow progenitors, we studied the interaction of normal marrow with BM specimens from 16 new cases of ALL. Irradiated ALL blasts, supernatant derived from ALL blasts in suspension cultures, and conditioned medium prepared from ALL blasts augmented the colony-forming ability of normal marrow erythroid burst-forming unit (BFU-E), granulocyte-macrophage colony-forming unit (CFU-GM), megakaryocyte colony-forming unit (CFU-MK), and multilineage colony-forming unit (CFU-GEMM) progenitors. In sharp contrast to published data on the suppressive effects of acute myeloblastic leukemia cells on normal hematopoiesis in vitro, our results indicate that the growth advantage of ALL cells over normal marrow elements is not mediated through an inhibitory mechanism derived from leukemia cells.

Serial studies of bone marrow (BM) hematopoiesis using clonogenic assays were performed in an infant with congenital amegakaryocytic thrombocytopenia. Initially, when the only hematological abnormality was isolated thrombocytopenia, the number of clonogenic BM hematopoietic progenitors was comparable to controls, including the number of megakaryocyte precursors. As the disease evolved into aplastic anemia over an 11-month period, the peripheral blood counts declined, and colony numbers from four classes of BM progenitors--termed BFU-E, CFU-GM, CFU-Mix, and CFU-Meg--also declined in parallel. When added to the marrow cultures, patient's plasma was not inhibitory to either control or to patient's BM colony growth. Similarly, no cellular inhibition of hematopoiesis was observed when patient's BM was cultured after depleting the sample of T lymphocytes and after adding the T lymphocytes back. Furthermore, stromal cells established from short-term and long-term cultures of patient's BM showed normal proliferative activity and yielded a "fertile" marrow microenvironment for patient's and control BM colony growth. Our data suggest that the central problem in congenital amegakaryocytic thrombocytopenia is an intrinsic hematopoietic stem cell defect, rather than an abnormality of the marrow milieu. The findings are consistent with either a progressive, quantitative attrition of progenitors or their inability to proliferate into colonies in vitro and into differentiated, functional cells in vivo.

We used a semisolid culture assay to quantitate leukemia cells in the bone marrow of patients with childhood acute lymphoblastic leukemia (ALL). In bone marrow cultures from 40 patients with newly diagnosed disease, the colonies that developed in vitro consisted of lymphoblasts with the same surface markers and abnormal karyotype as the original diagnostic marrow specimens. We also studied marrow cultures from 13 patients in chemotherapy-induced remission; 6 of these, including 1 obtained from a patient during successful engraftment after marrow transplantation, also yielded lymphoblast colonies in culture, with the same immunologic phenotype or abnormal karyotype as the original leukemic marrow. Four of these patients, including the one who underwent marrow transplantation, relapsed within 2 to 30 months of the abnormal cultures; the other two are still in remission, one of them 30 months after diagnosis. Bone marrow cultures from eight normal controls and from the other seven patients in remission did not yield lymphoblast colonies; all seven of the latter are still in remission. This assay appears to allow detection of small numbers of residual leukemic cells. We conclude that the technique will be valuable in monitoring the efficacy of chemotherapy and allogeneic bone marrow transplantation in acute lymphoblastic leukemia, as well as in evaluating the quality of purged marrow for autologous marrow transplantation.

To clarify the defective erythropoiesis in eight patients with Diamond-Blackfan anemia, we studied their bone marrow response in vitro to recombinant human interleukin-3 (IL-3) and recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF). In an erythropoietin-containing assay system, specimens from six of the eight patients yielded low numbers of erythroid colonies compared to control values, and in five of these no erythropoietin dose-response could be elicited. Addition of IL-3, GM-CSF or both to cultures from the six patients had no effect on CFU-E-derived colonies. In contrast, IL-3 but not GM-CSF induced a marked increase in the number (183%) and size of the BFU-E-derived colonies in five of the six cases and partially corrected the impaired dose-response to erythropoietin in four. Bone marrow from the other two patients yielded numbers of CFU-E and BFU-E colonies comparable to controls and manifested similar increments in colonies with increasing concentrations of erythropoietin. When IL-3 was added to these cultures, further increments were observed in the number and size of BFU-E colonies. We conclude that IL-3 enhanced the marrow erythropoiesis in most of the patients and exerted a corrective effect on the aberrant colony formation in the presence of erythropoietin. The data raise the possibility of IL-3 as a therapeutic agent in Diamond-Blackfan anemia.

To determine the clinical value of tissue culture techniques in the study of acute leukemia, marrows from 50 children (40 acute lymphoblastic [ALL], 10 acute myeloblastic [AML]) were cultured by the use of an AML blast colony assay and the CFU-GEMM assay. In the AML assay, AML marrow gave rise to high numbers of blast colonies within 24 to 48 hr; in sharp contrast, 37 of 40 ALL marrows did not yield colonies in this assay. In the CFU-GEMM assay, AML marrow produced excessive numbers of monocyte-macrophage CFU-C colonies, an obvious background of individual macrophages and clusters, and occasional blast colonies. ALL marrow yielded very low numbers of granulocytic CFU-C colonies, no background of macrophage cells, and no blast colonies. These clear-cut differences in cellular growth kinetics in vitro between ALL and AML marrows should allow confirmation of the type of acute leukemia within 24 to 48 hr. The colony assays may also be valuable in differentiating ALL from AML in difficult diagnoses when conventional approaches are nondiagnostic.

Human marrow grown in a plasma clot gives rise to discrete colonies of nucleated red cells in response to erythropoietin (EPO). In 10 studies of human marrow with normal erythropoiesis, human EPO in doses up to 1 unit/ml produced a significant increase in colonies when compared to sheep EPO. To achieve 50% of maximum colony growth, only 0.1 units/ml of human EPO was needed in contrast to 0.5 units/ml of sheep EPO. In seven other experiments, nandrolone decanoate, 10(-7) to 10(-9) M, yielded a mean increase in colonies of 38% when compared to cultures without added androgen. This effect was entirely dependent on the presence of EPO. We conclude that the method is useful for the invitro study of factors affecting early events in erythropoiesis.