Idiopathic myelofibrosis in a cat and in three dogs

Idiopathic myelofibrosis (IMF) in an 8-year-old cat and in three dogs, aged 4, 8 and 3 years, respectively, is discussed. Haematologically, the prefibrotic IMF of the FeLV (feline leukaemia virus)-positive cat exhibited an aleukaemic pattern of development with thrombocytosis; gross-pathologically, it exhibited a splenomegaly, and histologically, abnormal (polymorphic) medullary megakaryocytopoiesis and increased neutrophilic granulocytopoiesis with neoplastic bilinear extramedullary haematopoiesis (myeloid metaplasia, MM) in the spleen and liver. Haematologically, the canine IMFs exhibited anaemia, with white blood cell values ranging between leucocytosis and leucopenia, and thrombocyte values from the normal range to thrombocytopenia. Gross-pathologically, they exhibited hepatosplenomegaly, and histologically, a medullary proliferation of abnormal (polymorphic) megakaryocytes with conspicuous concentration in clusters, reticulin fibrosis and, in two cases, the occurrence of distended sinusoids with intravascular haematopoiesis. Extramedullary neoplastic haematopoiesis (MM) was found in the spleen and liver in particular. From the differential diagnostic perspective, the following morphological criteria are particularly relevant: largely mature, polymorphic megakaryocytes, distended bone marrow sinusoids, only a small number of blast cells in the bone marrow, MM of the spleen and liver.     

Bone marrow histopathology following cytoreductive therapy in chronic idiopathic myelofibrosis

AIMS: To analyse systematically therapy-induced lesions of haematopoiesis in chronic idiopathic myelofibrosis (IMF). METHODS AND RESULTS: A total of 759 sequential bone marrow (BM) biopsies (median interval 32 months) were performed in 261 patients with IMF. Besides a control group (symptomatic treatment), monotherapies included busulfan, hydroxyurea and interferon. In all therapy groups hypoplasia of varying degree was a frequent finding and often accompanied by a patchy distribution of haematopoiesis. Most conspicuous was gelatinous oedema showing a tendency to develop discrete reticulin fibrosis (scleroedema). Minimal to moderate maturation defects of megakaryopoiesis and erythroid precursors occurred, but overt myelodysplastic features were most prominent following hydroxyurea and busulfan therapy. Acceleration and blastic crisis were characterized by the appearance of immature and CD34+ progenitor cells. Concerning the dynamics of fibrosis, no differences were observed between controls and the various therapy groups. In 143 patients (55%) without or with little reticulin at onset, an increase in myelofibrosis was detectable that progressed to overt collagen fibrosis. CONCLUSIONS: Therapy-related bone marrow lesions in IMF comprise a strikingly variable spectrum that may include aplasia with scleroedema and a patchy distribution of myelodysplastic haematopoiesis associated with progressive myelofibrosis.     

Morphology of the bone marrow after stem cell transplantation

In many haematological conditions the only curative option is stem cell (SCT) or bone marrow (BM) transplantation. Little information exists about BM morphology following non-ablative engraftment. During the pretransplantation period and depending on the kind of pretreatment, there may be hypoplasia, residual disease and varying degrees of fibrosis. In the post-transplantation period, after 1-3 weeks of transfusion-dependent pancytopenia, the first signs of successful engraftment are indicated by the recurrence of neutrophils, monocytes and erythrocytes in the peripheral blood. In the BM there is slow regeneration of erythropoiesis, followed by the other lineages of haematopoiesis and increase in reticulin fibres or even a resolution of fibrosis. Diagnostic problems arise when neoplastic lympho- or haematopoiesis are maintained following transplantation. Moreover, there may be a significant graft versus tumour response reaction or an already relapsing disease needing aggressive treatment. On the other hand, a conspicuous dyshaematopoiesis should not be mistaken as representing a myelodysplastic syndrome. The presence of granulomas being treatment-related or a manifestation of intercurrent granulomatous disease has to be considered. More advanced knowledge of the histological features of regenerating BM will certainly aid the recognition of relapsing disease and is needed for the adequate reporting of post-transplant alterations associated with a successful or failing engraftment.     

Focal lymphoid aggregates (nodules) in bone marrow biopsies: differentiation between benign hyperplasia and malignant lymphoma--a practical guideline.

AIMS: To provide practical guidelines for the differentiation between benign and malignant focal lymphoid aggregates (lymphoid nodules) in routinely referred bone marrow trephine biopsies, using a synoptic approach including clinical data and histological workup. METHODS: For easy identification of very small lymphoid infiltrates the chloroacetate esterase stain was applied as a screening procedure. This allowed the identification of 491 formalin fixed, paraffin wax embedded specimens with one or more lymphoid nodules. Examination of lymphoid infiltrates included such variables as histotopography, demarcation, cytology, reticulin fibres, and immunohistochemistry with a set of monoclonal antibodies (CD20, CD45R, CD45R0, CD3, CD43). Evaluation of clinical and morphological data was carried out independently. In case of malignant lymphomas, a correlation with corresponding lymph node findings was made. RESULTS: 352 patients had benign focal lymphoid aggregates usually associated with systemic autoimmune diseases, chronic myeloproliferative disorders, toxic myelopathy, and viral infections. Discrete nodular infiltrates of (small cell) malignant lymphomas (n = 93) simulating benign hyperplasia were found in chronic lymphocytic leukaemia, germinal centre cell lymphomas (CB-CC), and lymphoplasmacytic/cytoid lymphomas (LPI). In addition to immunoreactivity, certain histological variables proved distinctive. These were: (1) histotopography, that is, localisation of the lymphoid aggregates within the bone marrow space; (2) relation to the surrounding tissue: margination or interstitial spillage of lymphoid cells; and (3) increase in reticulin fibres. CONCLUSIONS: A combined diagnostic procedure identifying several distinctive features, in particular histotopography and immunohistochemistry, provides a most promising way of discriminating reactive from neoplastic lymphoid nodules in the bone marrow.     

Lymphoid antigenic determinants of the chicken: ontogeny of bursa-dependent lymphoid tissue

The ontogenic development of the bursa-dependent lymphoid tissue in the chicken has been studied using rabbit antisera specific for B lymphocyte sub-populations and two elements of the bursal microenvironment. The antigens investigated were: the chicken B lymphocyte antigen ( CBLA ); mature B lymphocyte antigen ( CMBLA ); a foetal-associated antigen ( CFAA ) present on embryonic haemopoietic cells and adult bone marrow and bursa cells; immunoglobulin (Ig) and IgG; a bursa-specific cortical reticulin fibre antigen ( CBRFA ); a gut-associated mucin antigen ( CGAMA ) present on bursal medullary reticular epithelial (REp) cells. The development of suspected precursor cells was examined using a rabbit antiserum specific for foetal spleen cells. The major finding was the interrelationship between developing B cells and the bursal microenvironment. The first CBLA - and CFAA -positive cells were detected in the bursa at day 8 of incubation but their precise localization was difficult to assess. In 12-15 day embryos, both these cells were found predominantly in the tunica-propria in close proximity to cells bearing the reticulin fibre antigen CBRFA . This close association between CBLA -, CFAA - and CBRFA determinants represents the earliest stages of B cell differentiation and mimics that found in the adult bursa cortex. By day 18, the majority of bursa cells expressed CBLA and Ig and were localized in the developing medullary follicles, the REp cells of which were CGAMA -positive, demonstrating a very early interaction between intestinal tract contents, bursal REp cells and B cell maturation. Around hatching some bursa cells showed a marked increase in the membrane expression of CBLA and Ig, and the simultaneous expression of CMBLA and IgG. These cells were present in medullary follicles; CBRFA was present on cortical reticulin fibres which provided a supporting framework for the more immature CFAA -positive cells.     

Gelatinous bone marrow transformation in a case of idiopathic myelofibrosis: a morphological paradox

A 74-year-old woman with severe, but asymptomatic weight loss was found to have splenomegaly, thrombocytosis, and neutrocytosis. A trephine biopsy showed a hypercellular bone marrow with a proliferation of abnormal megakaryocytes, mild reticulin fibrosis, and osteosclerosis, i.e., features of an early stage of idiopathic myelofibrosis. In contrast to this predominant pattern, the marrow also contained a distinct hypocellular focus of gelatinous transformation (GMT) in which hematopoietic and fat cells were replaced by gelatinous substances that were characterized as hyaluronic acid mucopolysaccharides histochemically. GMT is a rare disorder of unknown pathogenesis, and is an unspecific indicator of severe illness which most often occurs in patients with a background of weight loss. This is the first reported case of gelatinous changes in an otherwise fibrotic bone marrow, a constellation which a priori seemed to be incompatible.     

Strategies of hemopoietic stress adaptation within the medullary cavity

Gravimetric determination of total bone water space was used as an index of available bone marrow space in mice following various specific stressors, i.e., splenectomy, hypoxia, bone fracture, and estrone-induced osteosclerosis. Data was corrected for bone weight and was reported as specific bone marrow volume (total bone water space/mg dry bone X 100). A direct relationship was observed between specific bone marrow volume and medullary hemopoietic activity induced by stress. Absolute and/or relative marrow space increased following splenectomy, hypoxia, and fracture. Osteosclerotic animals shift most hemopoietic activity from marrow to spleen, and splenectomized osteosclerotic animals become anemic. Both intact and splenectomized hypoxic animals develop increased specific bone marrow volume and successfully compensate for hypoxia with enhanced erythropoiesis. Animals sustaining a fracture callus increase both specific bone marrow volume and hemopoietic activity at the callus without an increase in hemopoietic demand. Increased specific bone marrow volume extends the marrow bone interface, where primitive stem cells accumulate, while expanding marrow stromal space, where stem cells lodge, proliferate and differentiate. Therefore, it would appear that availability of competent marrow space may play an integral part in passively permitting hematopoiesis and in determining hemopoietic reserve capacity. Stem cell migration increases during intensified hemopoietic demand, which also may be related to available marrow space. Mice have a low medullary hemopoietic reserve capacity; subsequently, when available medullary hematopoietic stroma becomes occupied, stem cells are more likely to migrate from the marrow to extra-medullary sites where they mature before entering the circulating pool.     

Pathology of autoimmune myelofibrosis. A report of three cases and a review of the literature

We identified 3 patients with autoimmune myelofibrosis (AM) lacking American Rheumatism Association criteria for systemic lupus erythematosus (SLE). They had 1 or 2 cytopenias and lacked serologic evidence for SLE. Autoimmune features included psoriatic arthritis and positive direct Coombs test (DCT) result, DCT-positive autoimmune hemolytic anemia, and synovitis with polyclonal hypergammaglobulinemia. Bone marrow biopsy specimens from each patient were evaluated by routine morphologic and immunohistochemical examination. They demonstrated marked hypercellularity (2 cases) or hypocellularity (1 case), moderate erythroid hyperplasia (all cases) with left-shifted maturation (2 cases), intrasinusoidal hematopoiesis (all cases), slightly to moderately increased megakaryocytes (2 cases), and grade 3 to 4 reticulin fibrosis (all cases). All lacked basophilia, eosinophilia, bizarre megakaryocytes, clusters of megakaryocytes, and osteosclerosis. Mild to moderate bone marrow lymphocytosis was noted in all cases. In 2 cases, increased small T cells and B cells formed nonparatrabecular, loose aggregates. AM is a clinicopathologic entity that may lack features of SLE. Loose aggregates of bone marrow T and B lymphocytes and the absence of morphologic and clinical features of myeloproliferative disease or low-grade lymphoproliferative disease are clues that distinguish AM from better known causes of bone marrow fibrosis.     

A developmental investigation of the liver, bone marrow and spleen of the stripe-faced dunnart (Sminthopsis macroura)

The development of the liver, bone marrow and spleen have been investigated in the stripe-faced dunnart. At birth, the liver was undergoing haematopoiesis but the level declined rapidly and by day 50 after birth the liver was histologically mature. Both the bone marrow and spleen were non-haematopoietic at birth but initiated haematopoiesis shortly thereafter. Bone marrow was initially detected at day 11 postpartum. By 57 days after birth, adipocytes had infiltrated the marrow and were abundant by day 60 after birth. Mitotic cells were observed in remaining areas of marrow until at least 170 days postpartum. The spleen at birth was undifferentiated, with trabeculae appearing by day 42. Red and white pulp areas became apparent by day 43 and were well defined by day 57 after birth. In summary, the pattern of the development of the liver, bone marrow and spleen in the stripe-faced dunnart were similar to that observed in eutherians and other metatherians studied to date.     

Grading of marrow fibrosis in chronic myeloid leukemia--a comprehensive approach

In the course of Chronic myeloid leukemia (CML), appearance of increased number of blasts may herald evolution of accelerated phase as well as onset of marrow fibrosis (MF) thereby necessitating the need to perform trephine biopsy for correct diagnosis and appropriate treatment. In the existing grading systems of MF, a comprehensive view has not been taken of the variability of density and area occupied by reticulin and collagen fibres. To overcome this shortcoming, we quantitated the reticulin and collagen content of marrow, its pattern of distribution and percentage area occupied by each type of fibres in every individual case. We performed 50 bone marrow (BM) trephine biopsies in patients of CML in order to assess the incidence and degree of MF. Various grades of MF were correlated with peripheral smear including blast count, bone marrow aspirate and LAP score of the case. A positive correlation was found between increasing grades of MF and number of megakaryocytes in the BM.     

Bone changes in polycythaemia vera and myelosclerosis

To study the problem of new bone formation in myelosclerosis bone biopsies have been performed in cases of polycythaemia vera, which may be regarded as a pre-myelosclerotic condition, and in primary myelosclerosis; morphological studies of bone and reticulin were made and osteoid and bone matrix was quantitatively assessed. Relevant metabolic studies were also carried out, but were predominantly normal. No new bone formation was detected in polycythaemia vera and some bone was osteoporotic; no significant increase in osteoid was found. With the use of polarized light it was found that new bone formation in myelosclerosis resulted from the ossification of wavy argyrophilic fibres in marrow: the presence of a dense network of these wavy fibres was a pre-requisite of new bone formation and ossification of the non-refractile branched reticulin fibres was not observed.     

Silicotic lesions of the bone marrow: histopathology and microanalysis

Silica deposition and characteristic nodular silicotic lesions of the bone marrow, virtually unknown features of silicosis, are described in a case of severe lung silicosis with silicotic granulomas of the liver and spleen. Scanning electron microscopy and X-ray microanalysis confirmed the presence of quartz and feldspars. The bone marrow lesions included inconspicuous accumulations of silica-containing macrophages, free silica, slight lymphocyte and plasma cell infiltration, and reticulin fibre formation; and development of slightly larger partly fibrous silicotic nodules, comparable to those of the lung, liver, and spleen. Silicosis must therefore be considered in the differential diagnosis of bone marrow granulomas.     

Normal reticulin level in iliac bone marrow

While the level of marrow reticulin may be a factor that is used when the presence of a hematologic disorder is being considered, to our knowledge no study has graded the amount of reticulin present in normal iliac bone marrow. Grading reticulin stains of bone biopsy specimens from 100 hematologically normal patients documented that the normal amount of reticulin in the marrow is low. Twenty-seven percent of the patients had marrow reticulin grade 0 using the Bauermeister scale, 42% had grade N, 27% had grade 1, and 4% had grade 2; no patient had a Bauermeister grade 3 or 4 reticulin level. Knowledge of the normal range of reticulin is essential when the reticulin level is used as a factor in evaluating the possibility of a hematologic disorder.     

Pro-megakaryoblasts in bone marrow tissue from patients with primary (idiopathic) osteo-myelofibrosis (agnogenic myeloid metaplasia). An immunomorphometric study on trephine biopsies

An immunomorphometric study was performed on bone marrow biopsies from 40 patients with primary osteomyelofibrosis--OMF, (agnogenic myeloid metaplasia) by employment of a monoclonal antibody against glycoprotein IIIa (Y2/51) to determine the number of pro-megakaryoblasts. Specimens from 15 individuals without any hematological disorder served as controls. With reference to the pertinent literature on megakaryocyte precursors and following a pilot study on corresponding smears, in tissue sections pro-megakaryoblasts were characterized by a size of 42.1 +/- 2.6 microns 2 (diameter 7.5 +/- 0.3 microns). In comparison with controls, in OMF no relevant increase in the number of pro-megakaryoblasts per square and cubic millimeter bone marrow was evaluable. The relative frequency of these precursors was significantly reduced due to an increase in the total amount of conspicuously large and abnormal megakaryocytes. Statistical analysis failed to reveal any correlations between counts for pro-megakaryoblasts or the total number of Y2/51--positive megakaryocytic elements with the density of argyrophilic fibers (determined by morphometry) or the platelet values. Our findings imply that in OMF the marked increase in circulating progenitor cells of the megakaryocyte lineage may be generated by extramedullary, probably splenic hematopoiesis. Moreover, the evolution of medullary fibrosis is thought to be associated with the striking predominance of large atypical, possibly overaged and hyperpolyploid megakaryocytes and not with an increase in precursor cells.     

Long-term survival in infantile malignant autosomal recessive osteopetrosis secondary to homozygous p.Arg526Gln mutation in CLCN7

Infantile malignant autosomal recessive osteopetrosis (ARO; OMIM 259700) has been reported to be associated with mutations in TCIRG1, CLCN7, or OSTM1. ARO caused by homozygous (or compound heterozygous) mutations in CLCN7, as described here, is usually diagnosed at birth or early in infancy due to generalized osteosclerosis and severe hematologic deficits. The maximal life expectancy of patients with ARO in the absence of bone marrow transplantation is thought to be 10 years. We report on a 25-year-old Thai man who is affected with ARO. Clinical features include proportionate short stature, vision impairment, esotropia, exophthalmos, mild hearing loss, and hepatosplenomegaly. Pancytopenia was present and the patient had frequent illnesses. Radiographs showed generalized osteosclerosis with almost no visible of bone marrow spaces. Dense maxilla and mandible with impacted and malformed teeth were observed. Multiple fractures were reported. He developed osteomyelitis of the mandible on four separate occasions, and partial mandibulectomy was performed. Molecular studies showed that there were no pathogenic mutations in TCIRG1. However, mutation analysis of CLCN7 revealed a homozygous missense mutation (p.Arg526Gln). This patient is, it appears, the longest lived individual with ARO ever reported. Evaluation of osteoclastogenesis in our patient demonstrated very large immature osteoclasts with a high number of nuclei.     

Ovariectomy-associated changes in bone mineral density and bone marrow haematopoiesis in rats

The relationship between the bone mass loss and bone marrow haematopoiesis in osteoporosis remains obscure. We selected 3-month-old female Sprague–Dawley rats and randomly divided them into six groups. Three groups were ovariectomized (OVX), while the other three groups were sham operated (Sham). Four, 8 and 12 weeks after the surgical procedure, the rats were euthanized and sampled. The left femur was used for measurement of bone mineral density (BMD). The right femur distal metaphysic cancellous bone was processed for morphological evaluation. Our results showed that the femur BMD in the 4-week OVX group was not significantly decreased compared with that of the 4-week Sham group, but that the volume of adipose tissue in the bone marrow was markedly increased. The femur BMD in the 8-week OVX group was decreased significantly compared with that of the 8-week Sham group ( P   <   0.05). Meanwhile, the volume of haematopoietic tissue decreased and the volume of adipose tissue increased. The number of megakaryocytes was decreased ( P   <   0.05). Interestingly, the osteoclasts and mast cells were increased in number in the 8-week OVX group ( P   <   0.05). These changes became obvious in the 12-week OVX rats, in contrast to the Sham groups. The volume of trabecular bone and the number of osteoblasts in the 12-week OVX group decreased significantly. Increased reticulin fibres were observed only in the 12-week OVX group. Our studies demonstrated a reciprocal correlation between bone-forming osteoblasts and marrow adipose tissue and suggest that OVX rats may be valuable as an animal model to study hypohaemopoiesis.     

Oestrogen-deficiency inducing haematopoiesis dysfunction via reduction in haematopoietic stem cells and haematopoietic growth factors in rats

Haematopoiesis is a self-renewing and multi-directional differentiation process of haematopoietic stem cells (HSCs), which is modulated very precisely by the haematopoietic microenvironment in bone marrow. Our previous study has demonstrated that oestrogen-deficiency leads to haematopoiesis dysfunction which manifests as a decrease in haematopoietic tissues and an increase in adipose tissues in bone marrow. However, the mechanism involved in the oestrogen-deficiency effects on haematopoiesis dysfunction is not completely understood. In this study, we established an oestrogen-deficiency rat model by ovariectomy (OVX group). Haematopoiesis was evaluated at the 12th, 16th, 20th, 24th and 28th weeks after operation in the OVX group and its control (Sham group) by pathological examination; the number and function of HSCs were evaluated by flow cytometry analysis and colony-forming assay respectively. Haematopoietic growth factors levels including granulocyte/macrophage-colony-stimulating factor (GM-CSF), stem cell factor (SCF) and interleukin-3 (IL-3) were examined by ELISA kits at different time points. We found that in the OVX group, haematopoiesis dysfunction in bone marrow was observed (P < 0.05) from the 12th week when compared with the Sham group, and extramedullary haematopoiesis began to appear in the liver and spleen from the 16th week. The number of HSCs and colony-forming units-granulocyte/macrophage (CFUs-GM) in bone marrow was reduced significantly (P < 0.05) from the 20th and 16th week respectively. Furthermore, GM-CSF, SCF and IL-3 in the OVX group decreased significantly (P < 0.05) since the 12th, 16th and 24th week respectively. Taken together, these results suggested that oestrogen is required for normal haematopoiesis. Oestrogen-deficiency inducing haematopoiesis dysfunction may be via reduction in HSCs and haematopoietic growth factors at a late stage.     

Reticulin fibre content of bone marrow infiltrates of malignant non-Hodgkin's lymphomas (B-cell type,low malignancy) — a morphometric evaluation before and after therapy

Summary A morphometric study was performed on bone marrow infiltrates of non-Hodgkin's lymphomas (B-cell type, low malignancy) to evaluate the content of argyrophilic (reticulin) fibres in the various subtypes before and after therapy. In congruence with the corresponding lymph node lesions, subtypes consisted of lymphocytic lymphoma — chronic lymphocytic leukaemia (CLL,n = 39), centroblastic-centrocytic lymphoma (CB-CC,n = 35), lymphoplasmacytoid immunocytoma (LPI,n = 22) and finally hairy cell leukaemia (HCL,n = 21). In comparison with control specimens, morphometric measurements on trephine biopsies (initial staging procedure) disclosed a borderline or minimal increase in reticulin in CLL and moderate fibrosis in CB-CC and LPI, whereas HCL had the greatest increase in fibres. The marrow surrounding focal or patchy lymphoma infiltrates of CLL and CB-CC displayed no relevant changes in fibre density with respect to the control samples. Following chemotherapy, repeated trephine biopsies (restaging procedure) were obtainable from 38 patients. There was no significant decrease in the fibre content of CLL, CB-CC and LPI infiltrates. In HCL an incomplete reduction was recorded after interferon treatment. So-called benign lymphoid lesions may be distinguished from focal-patchy infiltrates of CB-CC and LPI not only by showing a central localization, but also by the absence of significant amounts of reticulin. However, considering the density of the reticulin fibres, a clear-cut discrimination of these lymphoid aggregates from an early nodal-central growth pattern of CLL is not feasible in many cases.     

Combined effect of IL-17 and blockade of nitric oxide biosynthesis on haematopoiesis in mice

Aim: The study was undertaken to extend our investigation concerning both the in vivo activity of interleukin (IL)-17 and the specific role of nitric oxide (NO) in IL-17-induced effects in the process of haematopoiesis. Methods: CBA mice were simultaneously treated with IL-17 and/or nitric oxide synthase (NOS) inhibitor, l -NAME, for 5 days and changes within various haematopoietic cell lineages in bone marrow, spleen and peripheral blood were analysed. Results: Findings showed that administration of both IL-17 and l -NAME stimulated increase in net haematopoiesis in normal mice. IL-17-enhanced myelopoiesis was characterized by stimulation of both femoral and splenic haematopoietic progenitor cells and morphologically recognizable granulocytes. Additionally, IL-17 induced alterations in the frequency of erythroid progenitor cells in both bone marrow and spleen, accompanied with their mobilization to the peripheral blood. As a consequence of these changes in the erythroid cell compartments, significant reticulocytosis was observed, which evidenced that in IL-17-treated mice effective erythropoiesis occurred. Exposure of mice to NOS inhibitor also increased the number of both granulocyte-macrophage and erythroid progenitors in bone marrow and spleens, and these alterations were followed by the mobilization of erythroid progenitors and elevated content of reticulocytes in peripheral blood. The specific role of NO in IL-17-induced haematopoiesis was demonstrated only in the IL-17-reducing effect on bone marrow late stage erythroid progenitors, CFU-E. Conclusion: The results demonstrated the involvement of both IL-17 and NO in the regulation of haematopoietic cell activity in various haematopoietic compartments. They further suggest that IL-17 effects are differentially mediated depending on the haematopoietic microenvironments.     

Histologische und hämatologische Befunde bei der CML

An immunohistochemical and morphometric study was performed on bone marrow biopsies in 604 patients with chronic myelogenous leukemia (CML) to compare morphological and clinical features and to evaluate effects of interferon (IFN) and chemotherapy. Following morphometry significant correlations were calculated between number of CD61(+) megakaryocytes, including their precursors with fiber density. This finding is in line with the close functional relationship between megakaryopoiesis and fibroblasts regarding the complex pathomechanism of myelofibrosis. The latter was observed in about 28% of patients already at diagnosis. In a similar way, the frequency of CD68(+) macrophages was correlated with the amount of Ret40f(+) nucleated erythroid precursors, implicating an involvement of this cell lineage in iron turnover, hemoglobin synthesis, and degradation of the expelled nuclei from normoblasts. The (alpha-D-galactosyl residue-expressing) Pseudo-Gaucher cells were detectable in 30% of pretreatment specimens. Moreover, significant associations were calculable between reduction in erythropoiesis or increase in fibers with clinical features such as hemoglobin level, percentages of myelo- and erythroblasts in the peripheral blood, and spleen size. These variables are in keeping with more advanced stages of CML. Based on our morphometric evaluations, a classification into three different histological subgroups: granulocytic, megakaryocytic, and myelofibrotic was carried out. This simplified staging system was correlated with corresponding sets of hematological data. Sequential biopsies in 173 patients with monotherapy by IFN, hydroxyurea (HU), or busulfan (BU) revealed a fibrogenic effect of IFN in contrast to a fiber-reducing property of HU. The dynamics of myelofibrosis and changes of major cell lineages during treatment were readily demonstrable by calculating corresponding indices. These included the ratios between quantitative differences of corresponding variables at repeated examinations and time. Thus, in patients with complete hematological remission following IFN administration, regeneration of erythropoiesis was found to be accompanied by an increase in the total number of CD68(+) macrophages, including activated subpopulations. Histological subgroups showed a transition from a (nonfibrotic) granulocytic and megakaryocyte pattern to the myelofibrotic subtype in about 40% of patients. This change was opposed to a numerical reduction in the myelofibrotic subtype which occurred in 17 patients (36%), but predominantly in those under HU therapy. In conclusion, the striking heterogeneity of bone marrow features in CML warrants a careful morphological evaluation of trephine biopsies and appropriate means of processing to achieve relevant correlations with clinical data and, thus, allows a more elaborate insight into the dynamics of the disease process.