Macrophages in normal human bone marrow and in chronic myeloproliferative disorders: an immunohistochemical and morphometric study by a new monoclonal antibody (PG-M1) on trephine biopsies

Insufficiency of non-canonical PRC1 synergizes with JAK2V617F in the development of myelofibrosis

Insufficiency of polycomb repressive complex 2 (PRC2), which trimethylates histone H3 at lysine 27, is frequently found in primary myelofibrosis and promotes the development of JAK2V617F-induced myelofibrosis in mice by enhancing the production of dysplastic megakaryocytes. Polycomb group ring finger protein 1 (Pcgf1) is a component of PRC1.1, a non-canonical PRC1 that monoubiquitylates H2A at lysine 119 (H2AK119ub1). We herein investigated the impact of PRC1.1 insufficiency on myelofibrosis. The deletion of Pcgf1 in JAK2V617F mice strongly promoted the development of lethal myelofibrosis accompanied by a block in erythroid differentiation. Transcriptome and chromatin immunoprecipitation sequence analyses showed the de-repression of PRC1.1 target genes in Pcgf1-deficient JAK2V617F hematopoietic progenitors and revealed Hoxa cluster genes as direct targets. The deletion of Pcgf1 in JAK2V617F hematopoietic stem and progenitor cells (HSPCs), as well as the overexpression of Hoxa9, restored the attenuated proliferation of JAK2V617F progenitors. The overexpression of Hoxa9 also enhanced JAK2V617F-mediated myelofibrosis. The expression of PRC2 target genes identified in PRC2-insufficient JAK2V617F HSPCs was not largely altered in Pcgf1-deleted JAK2V617F HSPCs. The present results revealed a tumor suppressor function for PRC1.1 in myelofibrosis and suggest that PRC1.1 insufficiency has a different impact from that of PRC2 insufficiency on the pathogenesis of myelofibrosis.

Macrophage frequency in the bone marrow correlates with morphologic subtype of myeloproliferative neoplasm

Bone marrow (BM) fibrosis in myeloproliferative neoplasms (MPNs) is associated with a poor prognosis. The development of myelofibrosis and differentiation of mesenchymal stromal cells to profibrotic myofibroblasts depends on macrophages. Here, we compared macrophage frequencies in BM biopsies of MPN patients and controls (patients with non-neoplastic processes), including primary myelofibrosis (PMF, n = 18), essential thrombocythemia (ET, n = 14), polycythemia vera (PV, n = 12), and Philadelphia chromosome-positive chronic myeloid leukemia (CML, n = 9). In PMF, CD68-positive macrophages were greatly increased compared to CML (p = 0.017) and control BM (p < 0.001). Similar findings were observed by CD163 staining (PMF vs. CML: p = 0.017; PMF vs. control: p < 0.001). Moreover, CD68-positive macrophages were increased in PV compared with ET (p = 0.009) and reactive cases (p < 0.001). PMF had higher frequencies of macrophages than PV (CD68: p < 0.001; CD163: p < 0.001) and ET (CD68: p < 0.001; CD163: p < 0.001). CD163 and CD68 were often co-expressed in macrophages with stellate morphology in Philadelphia chromosome-negative MPN, resulting in a sponge-like reticular network that may be a key regulator of unbalanced hematopoiesis in the BM space and may explain differences in cellularity and clinical course.

Phenotypic characterization of macrophages in the BMB sample of human acute leukemia

Macrophages within tissues display a strong plastic ability in respond to environmental cues in both physiologic influences and disease. However, the macrophage phenotype and its distribution in the bone marrow biopsies (BMB) samples of human acute leukemia (AL) remain poorly understood. In this study, 97 BMB samples of patients with acute leukemia and 30 iron-deficiency anemias (IDA) as control group were evaluated with immunohistochemistry. In comparison with controls, the counts of CD68⁺, CD163⁺, and CD206⁺macrophages were remarkably increased in BMB samples of acute leukemia (P < 0.01), as well as their infiltration density was roaring up-regulation (P < 0.01). The expression levels of CD68⁺, CD163⁺, and CD206⁺macrophages were decreased in patients with complete remission, but there still existed statistically significant contrast to the control group (P < 0.01). The ratios of the CD163-positive cells or CD206-positive cells to CD68-positive cells were most prevalent in the BMB samples of human acute leukemia compared with the control group (P < 0.01), which support that macrophages were polarized to M2 macrophages.

Assessment of the Number and Phenotype of Macrophages in the Human BMB Samples of CML

Macrophages have emerged as a key player in tumor biology. However, their number and phenotype in human bone marrow of biopsy (BMB) samples of chronic myeloid leukemia (CML) and their association with disease progression from an initial chronic phase (CP) to accelerated phase (AP) to advanced blast phase (BP) are still unclear. BMB samples from 127 CML patients and 30 patients with iron-deficiency anemia (IDA) as control group were analyzed by immunohistochemistry. The expression levels of CD68, CD163, and CD206 in BMB samples of CML patients were significantly higher than those in the patients of control group (P < 0.01), and we observed that their positive expression was gradually elevated during the transformation of CML-CP to AP to BP (P < 0.01). However, the expressions of CD68, CD163, and CD206 in released group were downregulated and contrasted to these in control group; there exists statistical significance (P < 0.01). The percentage ratio of CD163 and CD206 to CD68 was pronounced to be increasing from CML-CP to AP to BP (P < 0.01). Hence, the higher proportion of CD68⁺, CD163⁺ and CD206⁺ macrophages in BMB samples can be considered a key factor for disease progression of CML patients. Targeting macrophages, especially the M2 phenotype may help in designing therapeutic strategies for CML.

Differential regulation of CXCL5 by FGF2 in osteoblastic and endothelial niche cells supports hematopoietic stem cell migration

Stem cell maintenance requires a specific microenvironment. Hematopoietic stem cells (HSCs) are mainly maintained by the endosteal osteoblast (OB) niche, which provides a quiescent HSC microenvironment, and the vascular niche, which regulates the proliferation, differentiation, and mobilization of HSCs. The systemic administration of FGF2 failed to induce normal hematopoiesis in bone marrow (BM) by reducing SDF-1, an important factor for hematopoiesis. Interestingly, SDF-1 levels were decreased in the OBs, but increased in vascular endothelial C166 cells when FGF2 was administered. We hypothesized that FGF2 induces changes in HSC migration from BM; therefore, we investigated FGF2-induced factors of HSC migration by a microarray chip. We searched the genes that were decreased in primary OBs, but increased in C166 cells upon FGF2 treatment. We confirmed selected genes that function in the extracellular region and identified the CXCR2-related chemokine candidate LIX/Cxcl5. A chemotaxis assay showed that CXCL5 induced the migration of HSCs (CD34(-/low)LSK). Our data suggest that the differential regulation of the chemokine CXCL5 between OBs and endothelial cells upon FGF2 treatment is involved in HSC mobilization from the OB niche or BM to peripheral blood.

89Zr-labeled dextran nanoparticles allow in vivo macrophage imaging

Tissue macrophages play a critical role both in normal physiology and in disease states. However, because of a lack of specific imaging agents, we continue to have a poor understanding of their absolute numbers, flux rates, and functional states in different tissues. Here, we describe a new macrophage specific positron emission tomography imaging agent, labeled with zirconium-89 ((89)Zr), that was based on a cross-linked, short chain dextran nanoparticle (13 nm). Following systemic administration, the particle demonstrated a vascular half-life of 3.9 h and was found to be located primarily in tissue resident macrophages rather than other white blood cells. Subsequent imaging of the probe using a xenograft mouse model of cancer allowed for quantitation of tumor-associated macrophage numbers, which are of major interest in emerging molecular targeting strategies. It is likely that the material described, which allows the visualization of macrophage biology in vivo, will likewise be useful for a multitude of human applications.

Detection of Aberrant Gene Expression in CD34+Hematopoietic Stem Cells from Patients with Agnogenic Myeloid Metaplasia Using Oligonucleotide Microarrays

Agnogenic myeloid metaplasia (AMM) is a clonal stem cell disorder that leads to ineffective hematopoiesis, bone marrow fibrosis, and extramedullary hematopoiesis. The molecular mechanisms underlying the development of this syndrome are currently unknown. Therefore, the aim of this study was to characterize aberrant gene expression in CD34+ hematopoietic stem cells from patients with AMM. We used oligonucleotide microarrays to analyze gene expression profiles in CD34+ hematopoietic stem cells from patients with AMM compared with expression in CD34+ cells from healthy individuals. We identified 95 highly differentially expressed genes (48 upregulated and 47 down-regulated) that are potentially involved in regulating abnormal hematopoietic proliferation and differentiation and confirmed many of them by quantitative polymerase chain reaction. Using class membership prediction analysis, we identified 75 genes whose expression profiles can accurately differentiate AMM samples from the controls. Using these 75 genes, we were able to discriminate patients with AMM from the controls by hierarchical clustering (Spearman's confidence correlation). The predictive power of these genes was verified by applying the algorithm to an unknown test set containing expression data from eight additional CD34+ samples (four AMM, four control). Our results indicate that a subset of genes may be used to differentiate patients with AMM from healthy individuals. Furthermore, we identify 95 genes whose aberrant expression may be involved in AMM.

Expression of the histiocytic marker PG-M1 in granuloma annulare and rheumatoid nodules of the skin

BACKGROUND

The expression of PG-M1, the most specific histiocytic marker, has not yet been studied in granuloma annulare (GA) and other palisaded granulomas of the skin. We evaluated the reactivity of PG-M1 with a series of GA and rheumatoid nodules (RN) to establish the sensitivity and potential usefulness of this marker in the diagnosis and characterization of these entities.

METHODS

Histological sections from 30 GA and 15 RN were immunostained with PG-M1. For comparison, additional sections were stained with KP-1 and lysozyme. The stains were recorded as negative, weakly positive (1+) and strongly positive (2+).

RESULTS

PG-M1 stained all cases of GA (100%). KP-1 and lysozyme stained 26 (86%) and 18 (60%) GA cases, respectively. PG-M1 exhibited a significantly stronger staining intensity (1.8 +/- 0.07) when compared with KP-1 (1.4 +/- 0.13) (p = 0.018) and with lysozyme (0.9 +/- 0.15) (p < 0.0001). All RN were stained by PG-M1 (100%). KP-1 and lysozyme stained 14 (93%) and six (40%) RN cases, respectively. PG-M1 staining intensity (1.6 +/- 0.13) was slightly higher than that of KP-1 (1.4 +/- 0.18) (p = 0.27) and significantly higher than that of lysozyme (0.4 +/- 0.13) (p < 0.0001).

CONCLUSIONS

PG-M1 is consistently and strongly expressed by the histiocytic population of GA and RN, being more sensitive and reliable than other histiocytic markers. We recommend its use in difficult cases in which the histiocytic nature of the lesion needs to be confirmed.

The histiocytic marker PG-M1 is helpful in differentiating histiocytes and histiocytic tumors from melanomas

Previous studies have shown that immunohistochemical stains for histiocytes are immunoreactive for melanomas. Accordingly, their value in differentiating histiocytes and histiocytic lesions from melanomas was questioned. PG-M1, the most specific histiocytic marker, was not evaluated in these studies. Our aims were to assess the reactivity of PG-M1 with a series of primary cutaneous and metastatic melanomas and to establish the potential usefulness of this antibody in the differentiation between histiocytes and histiocytic tumors and melanomas. PG-M1 staining was performed in 50 primary cutaneous and metastatic melanomas. For comparison, additional sections were stained with KP-1 and lysozyme (commonly used as histiocytic markers) and with S-100 and HMB-45 (commonly used as melanoma markers). The intensity (1+, 2+) and extent (1+ to 4+) were recorded semiquantitatively. PG-M1 stained weakly (1+) and focally (2+) only four cases of melanoma (8%). In contrast, histiocytes were strongly reactive for PG-M1 in all cases, being readily differentiated from melanoma cells including the positive cases. KP-1 stained melanoma cells in 44 cases (88%), lysozyme in 11 cases (22%), S-100 in 50 cases (100%), and HMB-45 in 48 cases (96%). No changes were found after restaining of selected KP-1 and lysozyme positive melanomas using an endogenous avidin/biotin blocking kit. PG-M1 is helpful in discriminating histiocytes and histiocytic lesions from melanoma cells. We recommend its inclusion in any antibody panel put together to distinguish between them.

Tumours of histiocytes and accessory dendritic cells: an immunohistochemical approach to classification from the International Lymphoma Study Group based on 61 cases

Neoplasms of histiocytes and dendritic cells are rare, and their phenotypic and biological definition is incomplete. Seeking to identify antigens detectable in paraffin-embedded sections that might allow a more complete, rational immunophenotypic classification of histiocytic/dendritic cell neoplasms, the International Lymphoma Study Group (ILSG) stained 61 tumours of suspected histiocytic/dendritic cell type with a panel of 15 antibodies including those reactive with histiocytes (CD68, lysozyme (LYS)), Langerhans cells (CD1a), follicular dendritic cells (FDC: CD21, CD35) and S100 protein. This analysis revealed that 57 cases (93%) fit into four major immunophenotypic groups (one histiocytic and three dendritic cell types) utilizing six markers: CD68, LYS, CD1a, S100, CD21, and CD35. The four (7%) unclassified cases were further classifiable into the above four groups using additional morphological and ultrastructural features. The four groups then included: (i) histiocytic sarcoma (n=18) with the following phenotype: CD68 (100%), LYS (94%), CD1a (0%), S100 (33%), CD21/35 (0%). The median age was 46 years. Presentation was predominantly extranodal (72%) with high mortality (58% dead of disease (DOD)). Three had systemic involvement consistent with 'malignant histiocytosis'; (ii) Langerhans cell tumour (LCT) (n=26) which expressed: CD68 (96%), LYS (42%), CD1a (100%), S100 (100%), CD21/35 (0%). There were two morphological variants: cytologically typical (n=17) designated LCT; and cytologically malignant (n=9) designated Langerhans cell sarcoma (LCS). The LCS were often not easily recognized morphologically as LC-derived, but were diagnosed based on CD1a staining. LCT and LCS differed in median age (33 versus 41 years), male:female ratio (3.7:1 versus 1:2), and death rate (31% versus 50% DOD). Four LCT patients had systemic involvement typical of Letterer-Siwe disease; (iii) follicular dendritic cell tumour/sarcoma (FDCT) (n=13) which expressed: CD68 (54%), LYS (8%), CD1a (0%), S100 (16%), FDC markers CD21/35 (100%), EMA (40%). These patients were adults (median age 65 years) with predominantly localized nodal disease (75%) and low mortality (9% DOD); (iv) interdigitating dendritic cell tumour/sarcoma (IDCT) (n=4) which expressed: CD68 (50%), LYS (25%), CD1a (0%), S100 (100%), CD21/35 (0%). The patients were adults (median 71 years) with localized nodal disease (75%) without mortality (0% DOD). In conclusion, definitive immunophenotypic classification of histiocytic and accessory cell neoplasms into four categories was possible in 93% of the cases using six antigens detected in paraffin-embedded sections. Exceptional cases (7%) were resolvable when added morphological and ultrastructural features were considered. We propose a classification combining immunophenotype and morphology with five categories, including Langerhans cell sarcoma. This simplified scheme is practical for everyday diagnostic use and should provide a framework for additional investigation of these unusual neoplasms.

Mimicry between neurokinin-1 and fibronectin may explain the transport and stability of increased substance P immunoreactivity in patients with bone marrow fibrosis

Bone marrow (BM) fibrosis may occur in myeloproliferative diseases, lymphoma, myelodysplastic syndrome, myeloma, and infectious diseases. In this study, the role of substance P (SP), a peptide with pleiotropic functions, was examined. Some of its functions-angiogenesis, fibroblast proliferation, and stimulation of BM progenitors-are amenable to inducing BM fibrosis. Indeed, a significant increase was found in SP-immunoreactivity (SP-IR) in the sera of patients with BM fibrosis (n = 44) compared with the sera of patients with hematologic disorders and no histologic evidence of fibrosis (n = 46) (140 +/-12 vs 18 +/-3; P <.01). Immunoprecipitation of sera SP indicated that this peptide exists in the form of a complex with other molecule(s). It was, therefore, hypothesized that SP might be complexed with NK-1, its natural receptor, or with a molecule homologous to NK-1. To address this, 3 cDNA libraries were screened that were constructed from pooled BM stroma or mononuclear cells with an NK-1 cDNA probe. A partial clone (clone 1) was retrieved that was 97% homologous to the ED-A region of fibronectin (FN). Furthermore, sequence analyses indicated that clone 1 shared significant homology with exon 5 of NK-1. Immunoprecipitation and Western blot analysis indicated co-migration of SP and FN in 27 of 31 patients with BM fibrosis. Computer-assisted molecular modeling suggested that similar secondary structural features between FN and NK-1 and the relative electrostatic charge might explain a complex formed between FN (negative) and SP (positive). This study suggests that SP may be implicated in the pathophysiology of myelofibrosis, though its role would have to be substantiated in future research. (Blood. 2001;97:3025-3031)

The Pathogenesis of Chronic Myeloproliferative Diseases

Chronic myeloproliferative disorders are operationally classified to include essential thrombocythemia, polycythemia vera, and agnogenic myeloid metaplasia. In most cases, clonal hematopoiesis, involving all 3 myeloid lineages, can be demonstrated. However, the underlying molecular lesions that are responsible for disease initiation and progression remain elusive. There are ongoing efforts to clarify the pathogenetic role of cytokines, bone marrow stromal cells and molecules, and intracellular aberrations in either signal transduction or apoptosis. This review discusses some of the current and past observations regarding the pathogenesis of chronic myeloproliferative disorders.

NF-kappa B as a central mediator in the induction of TGF-beta in monocytes from patients with idiopathic myelofibrosis: an inflammatory response beyond the realm of homeostasis

Immune-mediated mechanisms have been implicated in the etiology of idiopathic bone marrow fibrosis (IMF). However, the mechanism remains poorly defined. Compared with healthy controls, IMF monocytes are overactivated, with increased production of TGF-beta and IL-1. TGF-beta is central to the progression of fibrosis in different organs. In the lung, fibrosis is associated with up-regulation of TGF-beta-inducible genes. Because IL-1 and TGF-beta have pro- and antiinflammatory properties and neither appears to regulate the high levels of each other in IMF, we studied the mechanism of this paradigm. We focused on the role of RelA, a subunit of the transcription factor, NF-kappaB that is associated with inflammatory responses. We transiently knocked out RelA from IMF monocytes with antisense oligonucleotides and showed that RelA is central to IL-1 and TGF-beta production and to the adhesion of IMF monocytes. Because the NF-kappaB family comprises subunits other than RelA, we used aspirin and sodium salicylate to inhibit kinases that activate NF-kappaB and showed effects similar to those of the RelA knockout system. It is unlikely that RelA could be interacting directly with the TGF-beta gene. Therefore, we determined its role in TGF-beta production and showed that exogenous IL-1 could induce TGF-beta and adherence of IMF monocytes despite the depletion of NF-kappaB. The results indicate that IL-1 is necessary for TGF-beta production in IMF monocytes, but NF-kappaB activation is required for the production of endogenous IL-1. Initial adhesion activates NF-kappaB, which led to IL-1 production. Through autocrine means, IL-1 induces TGF-beta production. In total, these reactions maintain overactivation of IMF monocytes.

Erythropoietic reconstitution, macrophages and reticulin fibrosis in bone marrow specimens of CML patients following allogeneic transplantation

A clinicopathological study was conducted on 351 bone marrow trephine biopsies derived from 124 patients with chronic myeloid leukemia (CML) at standardized endpoints before and after allogeneic bone marrow transplantation (BMT). The purpose was to investigate quantitative changes of the nucleated erythroid precursor cell population and other associated features such as resident bone marrow macrophages and myelofibrosis and to elucidate their relevance on engraftment parameters. Monoclonal antibodies were applied for the identification of erythroid precursors and the labeling of mature macrophages; argyrophilic (reticulin-collagen) fibers were demonstrated by a silver impregnation technique. Following morphometric analysis of the pregraft bone marrow specimens statistical evaluation was in line with an adverse correlation between early to moderate reticulin fibrosis and amount of erythropoiesis. Moreover, a significant relationship was calculable between numbers of erythroid precursors and CD68+ macrophages. After myelo-ablative therapy and BMT a pronounced decrease in cellularity and in the quantity of erythropoiesis was found. Comparable with the pregraft samples, a significant association between erythroid precursors and macrophages could be determined in the regenerating donor bone marrow. A pretransplant relevant reduction of the red cell lineage and a manifest (reticulin) myelofibrosis indicating an advanced stage of disease were accompanied by a significant delay to reach transfusion independence. This result was further supported by comparable findings in trephine biopsies performed in the early post-transplant period (second month after BMT). Corresponding examinations revealed an enhancement of fiber density and a decrease in erythropoiesis in those patients who did not conform with the usually accepted criteria for successful engraftment. In conclusion, compelling evidence has been produced that a significantly reduced amount of erythroid precursors, which is usually associated with myelofibrosis in the pretransplant bone marrow, exerts an impairment to undisturbed hematopoietic reconstitution. Moreover, a close spatial and numerical relationship between the erythroid lineage and resident (mature) macrophages is observable, in particular in the state of regeneration after BMT.

Effects of chemotherapy (busulfan-hydroxyurea) and interferon-alfa on bone marrow morphologic features in chronic myelogenous leukemia. Histochemical and morphometric study on sequential trephine biopsy specimens with special emphasis on dynamic features

We performed a retrospective clinicopathologic study on sequential biopsy specimens from 90 patients with Philadelphia chromosome-positive chronic myelogenous leukemia to study therapy-specific effects of busulfan (28 patients), hydroxyurea (32 patients), and interferon-alfa (IFN-alfa; 30 patients). Bone marrow specimens were evaluated by morphometry after silver impregnation and staining with monoclonal antibodies to identify reticulin fibers, nucleated erythroid precursors, megakaryocytes, and macrophages. To compute dynamics of histopathology implicating corresponding changes in time, relevant indices were calculated. Quantification of megakaryocytopoiesis and its precursor cell population showed a significant increase in the IFN-alfa and busulfan groups compared with the hydroxyurea group. These changes were associated with a development of myelofibrosis during therapy. Although a significant increase in fiber density was detectable in the busulfan group, the progression index proved to be twice as high after IFN-alfa therapy. In contrast, a considerable number of patients displayed a regression of myelofibrosis after hydroxyurea treatment. The general association of the megakaryocyte lineage with myelofibrosis was in line with experimental findings. The mature macrophage population and its activated subfraction revealed a marked proliferation (IFN-alfa group) during treatment. Growth and activation of macrophages may be compatible with their putative function during erythrocytopoietic regeneration and with stimulation of their phagocytic properties.

Resident bone marrow macrophages in idiopathic (primary) myelofibrosis (IMF): a histochemical and morphometric study on sequential trephine biopsies

A histochemical and morphometric study was performed on sequential bone marrow biopsies in 65 patients with idiopathic (primary) myelofibrosis (IMF) to quantify the resident-mature CD68+ macrophages and a peculiar, so-called activated subpopulation. Statistical analysis revealed no significant correlations between number of macrophages, density of argyrophilic fibers and degree of myeloid metaplasia. Our results are reflecting in vitro findings on cytokine release, macrophage activation and their complex functional associations with myelofibrotic matrix formation. Macrophage growth is assumed to be related to a number of putative pathomechanisms including abnormal (upregulated) cytokine expression (PDGF, TGF-beta, IL-1), enhancement and activation by CSF-1 (M-CSF) and possibly also phagocytic stimulation. The latter feature may be triggered by increased degradation of senescent megakaryocytes, frequently occurring as endstages of growth factors-releasing fibrogenetic megakaryopoiesis.

Immunohistochemical assessment of human bone marrow macrophages in hematologic disorders

Changes in bone marrow macrophages may be associated with abnormal hematopoiesis in various hematologic disorders. We immunohistochemically evaluated the density of macrophages in bone marrow trephine biopsies. In reactive erythroid hyperplasia (hemolytic anemia and megaloblastic anemia), the macrophages slightly increased in density, extending their cytoplasmic processes between hematopoietic cells. In erythroid hypoplasia (pure red cell aplasia), they became rounded and frequently had hemosiderin granules. There was no significant difference in the macrophage density in the hematopoietic area between erythroid hyperplasia and hypoplasia. The macrophages increased in density in myeloproliferative disorders (polycythemia vera, chronic myelogenous leukemia and primary thrombocythemia). In myelofibrosis, some macrophages became extremely elongated along the line of the fibroblastic cells. In contrast, in conditions in which myelopoietic activity is considerably impaired (aplastic anemia, acute leukemia and multiple myeloma), they significantly decreased in density. These results suggest that the morphologic change in bone marrow macrophages is associated with erythropoietic activity and that there is a correlation between macrophage density and myelopoietic activity.

Detection of the bcr/abl gene in bone marrow macrophages in CML and alterations during interferon therapy--a fluorescence in situ hybridization study on trephine biopsies

A fluorescence in situ hybridization (FISH) study was performed on trephine biopsies of the bone marrow in chronic myelogenous leukaemia (CML) to evaluate the bcr/abl translocation in macrophages before and during interferon (IFN) therapy. Mature macrophages and osteoclasts were identified by the monoclonal antibody PG-M1, which recognizes a fixative-resistant epitope of the CD68 molecule. In contrast to a control group, in 145 of 479 (30 per cent) macrophages of the CML bone marrow, a positive fusion signal was found, together with corresponding translocation sites in the surrounding myeloid cells. In patients following IFN treatment for approximately 12 months and with haematological/cytogenetic remission by clinical standards, this number was reduced to 10 of 136 (9 per cent) macrophages. In addition, the few multinucleated osteoclasts of the untreated CML bone marrow displayed positive translocation spots. This finding supports the hypothesis that stromal macrophages and osteoclasts are of haematogenic stem cell origin. Moreover, clinical remission and reduction of bcr/abl-positive macrophages under IFN therapy lend support to the hypothesis that the presence of malignant stromal macrophages may contribute to the selective expansion of leukaemic precursors and the suppression of normal haematopoiesis in CML.

A histomorphometric study of haematological disorders with respect to marrow fibrosis and osteosclerosis

A retrospective investigation of 75 EDTA-decalcified Jamshidi biopsies collected over a 2-year period at Aarhus University Hospital was performed. The biopsies originated from 75 patients suffering from idiopathic myelofibrosis, other chronic myeloproliferative disorders, or other conditions with known associations with bone marrow fibrosis. The relative volumes of trabecular and woven bone, as well as haematopoietic and non-haematopoietic tissue, were estimated histomorphometrically. The degree of fibrosis was estimated semiquantitatively. Finally, the thickness of trabecular osteons was estimated from the number of lamellae by counting. Patients with idiopathic myelofibrosis had statistically significantly more bone tissue than the other groups of patients. The osteosclerosis was primarily due to woven bone. Larger cancellous osteons also suggested a positive balance in bone remodelling. The amount of bone tissue showed furthermore a statistically significant increase through the groups of polycythaemia vera, essential thrombocythaemia, chronic myelogenous leukaemia and idiopathic myelofibrosis. Parallel to the increase in the amount of bone, an increase in the degree of marrow fibrosis was detected. The positive correlation between the amount of bone and the degree of marrow fibrosis was statistically highly significant (p=0.0008).

Enrichment of human bone marrow mononuclear phagocytes and characterization of macrophage subpopulations by immunoenzymatic double staining

In order to isolate and enrich bone marrow mononuclear phagocytes, we performed magnetic-activated cell sorting using beads coupled to a monoclonal antibody directed against the monocyte/macrophage surface molecule CD14. Colocalization of antigens in single cells was achieved by combining an alkaline phosphatase-anti-alkaline phosphatase and an avidin-biotin complex immunoassay, avoiding the use of peroxidase. Bone marrow macrophages were first labelled by the monoclonal antibody PG-M1 (anti-CD68). Subsequently, cytoplasmic and/or surface double staining by the monoclonal antibodies against HLA-DR and Mac-2 antigen or the lectin GSA-I-B4 was carried out. Whereas HLA-DR was co-expressed by the great majority of PG-M1+ macrophages (84.9%+/-6.9%), only a subpopulation exhibited Mac-2 (69.9%+/-5.9%) antigen or galactoside structures detected by GSA-I-B4 (65.0%+/-6.7%). The latter result differed only slightly from the percentage of GSA-I-B4+ macrophages determined in a previous comparative immunomorphometrical study. Therefore, using our method of isolation and enrichment by magnetic-activated cell sorting, only a negligible portion of macrophages is apparently stimulated, as shown by GSA-I-B4 staining. This methodology seems to be a valuable tool for further studies on the monocyte-macrophage system.

Frequency of pseudo-Gaucher cells in diagnostic bone marrow biopsies from patients with Ph-positive chronic myeloid leukaemia

Pseudo-Gaucher cells (PGC) are a characteristic finding in Ph-positive CML, and prolongation of survival was observed when PGC were detected within the bone marrow. However, the conspicuous variation in the reported frequencies indicates the necessity for analysis of their natural occurrence in the bone marrow from untreated CML patients. A total of 833 diagnostic bone marrow biopsies from patients with Ph-positive CML were examined for PGC by 7 observers. Proof of PGC was based on systematic examination of Giemsa-stained slides with and without polarization at high magnification. Birefringence within the cytoplasm turned out to be highly specific for PGC. The risk of overlooking PGC was at least 80% when the number of these storing histiocytes was 70 per slide or less, and at least 50% when the total amount per slide was < or = 250. This high risk of failure explained the disagreement among the authors. An intensive investigation by at least two observers is mandatory if results are to be evaluated in research. Under the conditions used in this study, the natural frequency of PGC within the bone marrow from untreated patients with a Ph-positive CML is much higher than assumed to date, amounting to about 70%. On the basis of these findings, the prognostic importance of PGC in CML must be evaluated critically.

T lymphocytes, CD68-positive cells and vascularisation in thyroid carcinomas

Immunohistochemical detection and quantification of CD3- and CD45RO-positive lymphocytes and CD68-positive cells in 75 thyroid carcinomas of follicular cell origin revealed rising levels for these parameters associated with dedifferentiation. A parallel trend towards reduction of vascularisation, determined as CD31-positive blood vessels, with decreasing differentiation became evident, statistically only significant when well-differentiated follicular and anaplastic carcinomas were compared. Positive correlations could be demonstrated between the density of CD68-, CD3-, and CD45RO-positive cells as well as between the density of CD68-, and CD3-, and CD45RO-positive cells and vascularisation. These correlations were expected, as the interaction of CD68-positive cells and T lymphocytes results in the production of angiogenesis factors, ultimately leading to better vascularisation of the tumour. Nevertheless, the tumour cells themselves are variously capable of producing angiogenic substances. The obvious lack of positive correlation between the density of tumour-infiltrating cells determined in this study and vascularisation, despite reduced vascularisation in less differentiated tumours that contained increasing numbers of tumour-infiltrating cells, seems to be due to functional heterogeneity of morphologically similar tumours.

Assessment of inflammation in noninfectious chronic maxillary sinusitis

BACKGROUND AND AIM

Pathologic examination of the sinus mucosa and titration of inflammatory mediators in the sinus fluid were carried out to characterize inflammation in chronic sinusitis and determine whether patients with chronic allergic rhinitis (CAR) and sinusitis differ from patients with chronic nonallergic rhinitis (CNAR) and sinusitis.

METHODS

Nine control subjects (patients requiring ear, nose, and throat surgery not related to sinusitis), 12 patients with CAR and sinusitis, and 13 patients with CNAR and sinusitis were investigated. Eosinophil cationic protein, tryptase, myeloperoxidase, histamine, and prostaglandin D2 were measured in the sinus lavage fluids, and cells were enumerated. The cellular infiltrate was studied by immunohistochemistry with monoclonal antibodies against eosinophil cationic protein (eosinophils), tryptase (mast cells), neutrophil elastase (neutrophils), CD3 (lymphocytes), CD68 (macrophages), and proliferating cell nuclear antigens.

RESULTS

Neutrophils were not increased in sinusitis. In comparison with control subjects, patients with CAR and CNAR with sinusitis showed significant increases in eosinophils and macrophages in biopsy specimens and in eosinophil cationic protein in sinus lavage fluids. In comparison with patients with CNAR, patients with CAR had an increased number of intraepithelial mast cells and lymphocytes.

CONCLUSIONS

These findings suggest that patients with CNAR and sinusitis can be distinguished from patients with CAR and sinusitis, which resembles nonallergic rhinitis with eosinophilia syndrome.

Erythropoiesis in primary (idiopathic) osteomyelofibrosis: quantification, PCNA-reactivity, and prognostic impact

In 64 patients with primary (idiopathic) osteomyelofibrosis (OMF), a morphometric analysis has been performed on bone marrow trephine biopsies following sequential double-immunostaining with monoclonal antibodies against proliferating cell nuclear antigen (PCNA) and erythroid precursor cells (glycophorin C). The purpose of this study was to quantify erythropoiesis and its PCNA-staining capacity and, further, to determine the impact of these parameters for the development of anemia and for prognosis. In comparison with a control group (15 patients), a significant reduction in the number of erythro-normoblasts could be demonstrated, associated with an increase in PCNA-labelling. Moreover, significant correlations between the amount of nucleated erythroid marrow cells and degree of anemia (hemoglobin level, hematocrit, erythrocyte count) and survival could be calculated. Adverse relationships were assessed between number of erythroid cells, thrombocyte count, and spleen size, and also argyrophilic (reticulin/collagen) fiber density. These interactions were thought to reflect the biological behaviour of the disease process, i.e., the progression or extent of myeloid metaplasia. Our findings support ferrokinetic studies suggesting erythroid hypoplasia as one of the major causes of anemia in OMF. The remarkable high PCNA-labelling index of the macrocytic-megaloblastoid appearing erythropoiesis is probably caused by an overexpression of this marker protein. A comparative evaluation of Ki-67 antigen immunostaining in splenic tissue (myeloid metaplasia) and of the PCNA-labelling in pernicious anemia lend support to the assumption of an undue prolongation of the S-phase generated by secondary folate (hematinic) deficiency.

An immunohistochemical study of human pituicytes demonstrating frequent expression of MHC class II antigens and macrophage markers

Using a panel of antibodies (Abs) and a lectin, normal human adult pituicytes were studied in neurohypophyses obtained from 29 patients at autopsy. The pituicytes reacted frequently with Abs against major histocompatibility complex (MHC) class II antigens (Ags), macrophage markers (KP.1, PG.M1, LN-5), an anti-vimentin Ab and a biotinylated lectin Ricinus communis agglutinin (RCA-1). The number of pituicytes immunostained for these reagents varied, with the notable exception of vimentin. MHC class II Abs (LN-3, CR3.43)-positive pituicytes were numerous in approximately half. Microscopically, MHC class II Ag was found in pituicytes of various shapes, and were identified in macrophage-typed pituicytes by electron microscopic immunohistochemistry. Glial fibrillary acidic protein was found in only a small number of pituicytes and was absent in cells labeled with MHC class II Abs or macrophage markers. The results indicate that the immunophenotype of human pituicytes is distinct from other glial cells of the central nervous system, with a considerable number of cells expressing MHC class II Ags and macrophage markers.

Histological features of prognostic significance in CML--an immunohistochemical and morphometric study (multivariate regression analysis) on trephine biopsies of the bone marrow

To evaluate the prognostic significance of clinical as well as histological disease features at the time of diagnosis, an immunohistochemical and morphometric study was performed on bone marrow trephine biopsies in 130 patients with Ph(1+)-CML. For identification of all cell elements of the megakaryocytopoiesis we used the monoclonal antibody CD61 (Y2/51) and for the macrophages, the recently characterized antibody PG-M1. Density of argyrophilic fibers was determined per fat cell-free marrow area. Based on a multivariate analysis-derived risk model, the reproducibility of the prognostic score described by Sokal and co-workers was tested, particularly with regard to histological variables. Additionally, we calculated the disease-specific loss in life expectancy. Our prognostic model (Cox model) consisted of the variables: age, spleen size, peripheral erythro-normoblasts, pseudo-Gaucher cells, and fiber density. To assess the validity of this new CML score, a receiver-operating curve (ROC) of sensitivity and specificity was constructed. The improved prognostic efficiency of this newly developed risk model in predicting death within 3 years after diagnosis of CML was demonstrated in comparison with generally accepted staging systems. Immunohistochemistry revealed that not the total number of macrophages, but only the subfraction of pseudo-Gaucher cells exerted a significant impact on survival. Furthermore, it was feasible to calculate the number of atypical micromegakaryocytes and pro- and megakaryoblasts. This abnormal and immature cell population showed a significant correlation with fiber density and prognosis. Finally, the practical value of the Hannover classification was tested. This histological classification enabled a discrimination between two groups with different survival patterns, i.e., granulocyte and/or megakaryocyte-rich subtypes versus subtypes with increase in reticulin and collagen fibers.