Immunologic abnormalities in an animal model of chronic hypoplastic marrow failure induced by busulfan.

The immunology of chronic hypoplastic marrow failure (CHMF, aplastic anemia) was studied in an experimental murine model of the disease induced by busulfan. B lymphocytes of peripheral blood, spleen, and bone marrow were reduced to 30%-40% and T lymphocytes of thymus, spleen, marrow, and blood were decreased to 20%-70% of control values. IgG and IgM antibody titer to sheep red blood cells were reduced to one-third of control levels, and splenic IgG, but not IgM, plaque-forming cells were fewer on day 7 after antigen stimulation. The proliferative responses to phytohemagglutinin or concanavalin A were reduced in cultures of peripheral blood lymphocytes, splenic lymphocytes, and thymocytes, and cutaneous delayed-type hypersensitivity induced by dinitrofluorobenze was not detected in mice with CHMF. The results demonstrate disturbance of a variety of cellular and humoral functions and suggest that the disturbance was due to quantitative and possibly qualitative abnormalities of the cell types subserving these functions. The results suggest that residual cell injury, the lesion underlying experimental CHMF, is not confined to the myeloid stem cell but also involved cells of the lymphoid series.     

A proliferative defect of marrow cells in experimental chronic hypoplastic marrow failure (aplastic anaemia)

Marrow cells from control mice and mice with chronic hypoplastic marrow failure (CHMF, aplastic anaemia) were grown in tissue culture and growth was assessed by measuring the number of cells/colony and uptake of 3H-thymidine/colony. Cells from mice with CHMF showed impaired proliferation in response to colony stimulating factor. Mixing experiments suggested that the impairment of proliferation was not dut to alteration in suppressor or helper cells but to an intrinsic lesion of the marrow cells themselves.     

Biology and clinical management of hypoplastic MDS: MDS as a bone marrow failure syndrome

Hypoplastic MDS is a subset of MDS characterized by marrow hypocellularity diagnosed in 10–15% of MDS patients. The pathogenesis of this disease shares features of aplastic anemia with activation of the effector T cells against hematopoietic stem and progenitor cells and high-risk MDS with acquisition of somatic mutations that provide survival and growth advantage of these cells in the inflammatory bone marrow microenvironment. Clonal evolution in hypoplastic MDS may be associated with accumulation of DNA damage and progression to AML while clonal hematopoiesis in aplastic anemia is strongly related to immune escape of the hematopoietic cells. Distinction of hypoplastic MDS from other acquired and inherited bone marrow failure syndromes is frequently challenging but it is critical for the appropriate clinical management of the patients. Treatment with immunosuppression is an important component of the clinical approach to patients with hypoplastic MDS while hypomethylating agents and early allogeneic bone marrow transplantation are also considerations in some patients. In this review, we summarize the current literature on the biology of hypoplastic MDS, the differences between this disease and other bone marrow failure syndromes, and the treatment algorithm for patients with this subtype of MDS.     

A mouse model of lymphocyte infusion-induced bone marrow failure

OBJECTIVE: To develop a mouse model for the study of the pathophysiologic mechanism and treatment of human bone marrow (BM) failure. MATERIALS AND METHODS: Unmanipulated B6D2F1 or CByB6F1 hybrid mice were infused with 10-40 x 10(6) lymph node (LN) cells from their C57BL/6 (B6) parent. Pancytopenia was monitored by cell counting, while marrow damage was assessed by histological staining. Destruction of BM hematopoietic progenitor/stem cells was measured by colony formation in vitro and irradiation protection in vivo. Serum interferon-gamma (IFN-gamma) concentration was measured by enzyme-linked immunosorbent assay. BM T cell Vbeta and Fas expressions were analyzed by flow cytometry. Treatment effects of immunosupressive agents cyclosporine, antithymocyte globulin (ATG), anti-IFN-gamma, and anti-tumor necrosis factor-alpha (anti-TNF-alpha) were tested. RESULTS: Infusion of 30-40 x 10(6)B6 LN cells led to rapid development of severe pancytopenia, BM hypoplasia, and death. Affected mice had drastically reduced hematopoietic progenitor and stem cells. BM of affected mice showed lymphocyte infiltration, oligoclonal T cell expansion, and upregulated Fas expression. Serum IFN-gamma concentration increased two- to three-fold. Timed administration of cyclosporine or ATG abrogated pancytopenia. Treatment with anti-IFN-gamma antibody reliably rescued mice, and treatment with anti-TNF-alpha antibody extended animal survival significantly. CONCLUSION: This mouse model indicates that activated lymphocytes and type I cytokines play important roles in marrow destruction in lymphocyte infusion-induced BM failure.     

Primary splenic lymphoma with hypoplastic bone marrow

A 44-year-old man was admitted because of persistent fever and pancytopenia. Because his bone marrow was hypoplastic and the karyotype of his marrow cells was normal, he was given a diagnosis of aplastic anemia, and treated with glucocorticoids and granulocyte colony-stimulating factor. Splenomegaly was later found and a splenectomy performed: pathological findings on resected tissue specimens disclosed non-Hodgkin's lymphoma, B-cell diffuse large. The patient was transferred to our hospital, where a bone marrow biopsy revealed lymphoma cells infiltrating his hypoplastic marrow. Complex chromosomal abnormalities were detected in marrow cells, but no lymphadenopathy was observed. A diagnosis of primary splenic lymphoma with infiltration of lymphoma cells into bone marrow was made, and chemotherapy was accordingly started. After multiple cycles of chemotherapy, the patient's marrow recovered to a normal state and his karyotype abnormalities disappeared. Six months later, pancytopenia reappeared and lymphoma cells were again detected in the patient's bone marrow. We reasoned that the hypoplastic state of his bone marrow was associated with the lymphoma, and that cytokines, including interferon-gamma, may have been responsible for this association.     

Cyclosporin A therapy in hypoplastic MDS patients and certain refractory anaemias without hypoplastic bone marrow

We report 17 cytopenic patients with myelodysplastic syndrome (MDS) of refractory anaemia (RA) subtype with hyper-, normo- or hypo-cellular bone marrow (BM), who were treated with cyclosporin A (CyA). Substantial haematological response was observed in 14 patients (82%): their anaemia improved and all transfusion-dependent patients achieved transfusion independence. Complete trilineage recovery was observed in four patients (23%). The CyA therapy has not yet failed in any of the 14 successfully treated patients during follow-up times ranging from 5 to 30 months. CyA was well tolerated in 14 patients; serious side-effects required termination of the therapy in three patients in whom the blood count rapidly deteriorated to former levels upon cessation of therapy. Two patients benefited from a combination therapy of CyA and erythropoietin. Six patients experienced various autoimmune phenomena. CyA could thus offer an alternative treatment for certain MDS patients with RA regardless of hyper-, normo- or hypo-cellularity of bone marrow (BM). The mechanism of the beneficial effect of CyA is discussed and remains the subject of an ongoing study.     

低增生型骨髓增生异常综合征的骨髓病理观察

目的：评估骨髓活检在骨髓增生异常综合征尤其是低增生型病例时的诊断价值。方法：对比分析５３例骨髓增生异常综合征的患者的骨髓涂片与切片的诊断结果。结果：骨髓活检病理检查对于诊断骨髓增生异常综合征,尤其在低增生型骨髓增生异常综合征患者有很大帮助。结论：骨髓活检是确诊低增生型骨髓增生异常综合征的必要手段。     

Viruses and bone marrow failure.

Many agents are associated with bone marrow failure, including toxins, inherited metabolic defects, ionizing radiation, and viral infection. In most cases, the etiologic agent is unknown. Many of these unclassified cases have symptomatic, immunologic, or epidemiologic similarities to viral infections. Viruses from different taxonomic families have been implicated in bone marrow failure syndromes, and they appear to cause hematosuppression by a variety of mechanisms. Some of the viruses involved in relatively well characterized suppressive interactions will be reviewed, including parovovirus B19, dengue, hepatitis viruses, Epstein-Barr virus, cytomegalovirus and the human immunodeficiency virus.     

Ectopic bone marrow development in experimental busulfan-induced hypoplastic anemia in mice

Summary The intramuscular implantation of devitalized bone matrix in 42 mice with busulfan-induced bone marrow failure and in 42 control mice led to the sequential formation of ectopic cartilage, bone and bone marrow. The morphological volumetric estimation of these components in the hypoplastic mice showed a significant increase in cartilage and a decrease in hematopoietic bone marrow as compared with control mice. The cellularity in the ectopic hematopoietic bone marrow was similar to that of sternal bone marrow. The possible significance of these findings is discussed.Supported by grants from FAPESP and CNPqFellow from CAPES. Present address: State University of Londrina, Department of Morphology, Londrina, Brazil     

Defective stromal cell function in a mouse model of infusion-induced bone marrow failure

OBJECTIVE: To study bone marrow (BM) stromal damage in a mouse model of infusion-induced BM failure. MATERIALS AND METHODS: Sublethally irradiated CByB6F1 mice were infused with 5 x 10(6) C57BL/6 (B6) lymph node (LN) cells. Recipient BM cells were taken at 3, 7, 10, and 14 days following LN infusion and were cultured in vitro in alpha-modified Eagle media for 2-3 weeks. Peripheral blood and was analyzed by complete blood counts while BM lymphocyte infiltration/expansion was analyzed by flow cytometry. Marrow cells from affected and control mice were mixed and cultured in vitro to test nonspecific stromal damage. RESULTS: Donor lymphocytes infiltrated host BM within 3-7 days and expanded significantly between 7 and 10 days, concurrent with the development of leukopenia, thrombocytopenia, and marrow hypoplasia. BM cells from mice at 7, 10, and 14 days after B6-LN cell infusion were progressively defective in forming stromal feeder layers. A 1:1 mixture of BM cells from affected CByB6F1 mice and normal B6 mice failed to form an effective stromal feeder layer that could support cobblestone colony formation, indicating that lymphocytes in the BM of affected CByB6F1 mice were able to damage stromal cells in the normal B6 BM. CONCLUSION: Activated lymphocytes destroy both hematopoietic and stromal cells as innocent bystanders in the infusion-induced BM failure model.     

Irreversible bone marrow failure with chlorambucil.

Two cases of irreversible bone marrow failure are described, one with rheumatoid disease and one with systemic lupus erythematosus. Each case was associated with prior chlorambucil administration, effective in controlling the clinical manifestations (total dosage 398 and 1,764 mg respectively). The irreversibility of the bone marrow depression in the two cases presented stands in contrast to published assurances that chlorambucil-associated leukopenia is dose-related and readily reversible. The cases illustrate that chlorambucil therapy should not be continued after initial leukopenia, until peripheral counts or marrow cellularity has returned to normal. Titration of drug dosage and leukocyte count, as frequently employed with cyclophosphamide and other alkylating agents, must be presumed hazardous. Additional studies are needed to determine if irreversible bone marrow depression is dose-related or idiosyncratic.     

Experimental production of hypoplastic left heart syndrome in the chick embryo

The hypothesis is examined that hemodynamic alterations at the site of the primordial mitral valve may induce malformations that simulate the clinical findings of hypoplastic left heart syndrome. Surgical placement of a nylon device, approximately 90 μ in diameter, into the region of the left atrioventricular (A-V) canal was accomplished in 192 embryos (Hamburger-Hamilton stages 23 to 25). Thirty-nine pairs of experimental and control embryos survived more than 12 days. Twenty-six experimental embryos exhibited various malformations: hypoplastic left atrium and ventricle, mitral valvular atresia, aortic valvular stenosis and tubular hypoplasia of the aorta and brachlocephalic vessels. These findings reemphasize the probable morphogenetic role of blood flow pathways. The findings further implicate involvement of the left A-V canal as well as premature closing of foramen ovale and aortic valvular abnormalities in the hypoplastic left heart syndrome.     

Bone marrow necrosis. acute microcirculation failure in myelomonocytic leukemia.

We saw bone marrow necrosis in a case of acute myelomonocytic leukemia. The diagnosis was made during the patinet's life, and the bone marrow microcirculation was studied immediately postmortem. Histology and injection of the bone marrow arteries showed an acute microcirculation failure. The pathogenesis and possible relationship with soluble immune complexes was studied.     

Management of infection in children with bone marrow failure.

The development of new and often more successful regimens of treatment for childhood blood and malignant diseases has usually been associated with a parallel increase in infectious problems. This is because these successes have often, in the absence of new effective drugs, been achieved by increasing drug dose intensity to new limits. This chapter is not intended to deal with every possible infection, but rather to be a practical guide to the current management of infection. The last few years have seen major improvements in the development of haematopoietic growth factors, new antifungal agents, new antibiotics and new ways to use aminoglycosides. Attempts are being made to identify good and poor risk factors for the outcome of infection in order to facilitate shorter courses and possibly home or day care use of antimicrobial agents. In addition the different needs of children are being recognized in view of the restricted use of quinolones in this group and the different organisms and types of infection that they experience.