RESUMO
Trechini ground beetles include some of the most spectacular radiations of cave and endogean Coleoptera, but the origin of the subterranean taxa and their typical morphological adaptations (loss of eyes and wings, depigmentation, elongation of body and appendages) have never been studied in a formal phylogenetic framework. We provide here a molecular phylogeny of the Pyrenean subterranean Trechini based on a combination of mitochondrial (cox1, cyb, rrnL, tRNA-Leu, nad1) and nuclear (SSU, LSU) markers of 102 specimens of 90 species. We found all Pyrenean highly modified subterranean taxa to be monophyletic, to the exclusion of all epigean and all subterranean species from other geographical areas (Cantabrian and Iberian mountains, Alps). Within the Pyrenean subterranean clade the three genera (Geotrechus, Aphaenops and Hydraphaenops) were polyphyletic, indicating multiple origins of their special adaptations to different ways of life (endogean, troglobitic or living in deep fissures). Diversification followed a geographical pattern, with two main clades in the western and central-eastern Pyrenees respectively, and several smaller lineages of more restricted range. Based on a Bayesian relaxed-clock approach, and using as an approximation a standard mitochondrial mutation rate of 2.3% MY, we estimate the origin of the subterranean clade at ca. 10 MY. Cladogenetic events in the Pliocene and Pleistocene were almost exclusively within the same geographical area and involving species of the same morphological type.
Assuntos
Besouros/genética , Evolução Molecular , Filogenia , Algoritmos , Animais , Teorema de Bayes , Núcleo Celular/genética , Besouros/classificação , DNA Mitocondrial/genética , Meio Ambiente , França , Especiação Genética , Geografia , Alinhamento de Sequência , Análise de Sequência de DNA , EspanhaRESUMO
Friend virus induces a leukemia characterized by the proliferation of neoplastic hematopoietic cells believed to be erythroid precursors. In vitro studies were conducted with spleen cells from mice with terminal Firend leukemia in order to determine their capacity for leukocytic differentiation. Spleen cells were obtained from leukemic DBA/2 mice 1 to 2 days before anticipated death and cultured in the presence or absence of colony-stimulating activity (CSA). Growth in liquid culture in dissusion chambers was dependent on CSA and resulted in the generation of normally differentiated granulocytes and macrophages. Colony formation in agar was also dependent on CSA, and the cloning efficiency of leukemic spleen cells was found to be approximately 10 times normal. The colonies formed were composed of leukocytes, which appeared morphologically normal. Total in vitro colony-forming units per leukemic spleen exceeded normal by more than 300-fold, but cells elaborating CSA were decreased. Although it is uncertain whether the stem cells stimulated by CSA are "normal" or leukemic," it is clear that Friend leukemia has profound effects on the proliferation and differentiation of nonerythroid stem cells.
Assuntos
Granulócitos/patologia , Células-Tronco Hematopoéticas/patologia , Leucemia Experimental/patologia , Leucócitos/patologia , Animais , Diferenciação Celular , Células Clonais , Fatores Estimuladores de Colônias , Vírus da Leucemia Murina de Friend , Macrófagos/patologia , Camundongos , Camundongos Endogâmicos DBA , Baço/citologiaRESUMO
SIAH-1, the human homologue of the drosophila seven in absentia gene, is a p53-p21Waf-1 inducible gene. We report that stable transfection with SIAH-1 of the epithelial breast cancer cell line MCF-7 blocks its growth process. The transfectants show a redistribution of SIAH-1 protein within the nucleus, more specifically to the nuclear matrix, associated to dramatic changes in cell morphology and defective mitosis. Multinucleated giant cells (2-12 nuclei in more than 50% cells) were a most striking observation associated with tubulin spindle disorganization and defective cytokinesis. There were also present at high frequency abortive mitotic figures, DNA bridges and persistance of intercellular bridges and midbodies, along with an increased expression of p21Waf-1. These results indicate that the mechanism of growth arrest induced by SIAH-1 in MCF-7 cells involves disorganization of the mitotic program, mainly during nuclei separation and cytokinesis.
Assuntos
Divisão Celular/fisiologia , Mitose/fisiologia , Proteínas Nucleares/fisiologia , Apoptose , Inibidor de Quinase Dependente de Ciclina p21 , Ciclinas/genética , Expressão Gênica , Humanos , Proteínas Nucleares/genética , Células Tumorais Cultivadas , Ubiquitina-Proteína LigasesRESUMO
We studied peripheral blood lymphocytes (PBL) of eight B chronic lymphocytic leukemia (CLL) patients for the expression of the human leucocyte antigens, HLA-DR and HLA-DQ. Cell surface expression of HLA class II epitopes was analyzed by fluorescent activated cell sorter (FACS) using three monomorphic anti-HLA class II monoclonal antibodies (mAb) specific for DR (D1.12) and DQ (TU22, L2) and a polymorphic anti-DQ (G2A5). The DR and DQ molecules were characterized by two-dimensional gel electrophoresis (2D-PAGE) of the specific immunoprecipitates from biosynthetically labeled cells. DR, DQ specific probes were used to characterize the class II transcripts of the corresponding genes. The data obtained with immunofluorescence disclosed two distinct patterns of HLA class II expression leading to two cell surface phenotypes: (DR+DQ+) and (DR+DQ-). In all cases the cells expressed normal amounts of HLA-DR gene products in terms of mRNA. DR cell surface determinants were present in more than 80% of cells in every sample. By 2-D gel analysis DR proteins disclosed the normal classical pattern associating the alpha, beta, and invariant chain gamma with normal level of biosynthesis for alpha and gamma but decreased biosynthesis for one of the beta gene products. Moreover, the three chains demonstrated defect in glycosylation process. In half of the cases studied the cells lacked DQ molecules at the cell surface. DQ alpha and DQ beta transcripts were detected in all cases, although the amount was extremely low in one case. DQ proteins were variable in the DQ+ phenotype and absent in the DQ- one. Interestingly, TPA and rIFN gamma treatment could restore normal glycosylation process of the DR isotype and increase biosynthesis of DQ alpha and beta chains. Those combined results support the view that transcriptional, post-transcriptional, and posttranslational mechanisms underlie the heterogeneity of class II expression observed in CLL. Moreover, 2-D gel analysis may be an invaluable tool for the analysis of the biosynthetic process of class II molecules.
Assuntos
Antígenos de Superfície/análise , Antígenos HLA-DQ/análise , Antígenos HLA-DR/análise , Leucemia Linfocítica Crônica de Células B/imunologia , RNA Mensageiro/análise , Eletroforese em Gel de Poliacrilamida , Humanos , Interferon gama/farmacologia , Proteínas Recombinantes , Transcrição GênicaRESUMO
The kinetics of granulomonocyte colony forming cells have been studied in unfractionated normal human bone marrow by hydroxyurea suicide and in cells separated by velocity sedimentation. Sequential studies revealed two subpopulations of colony forming cells, having different sizes and different multiplication potentialities. There are large cells with a high suicide rate which develop small granulocyte and monocyte colonies during the first week of culture in semi-solid agar. Smaller cells develop larger colonies of granulocytes, monocytes and eosinophils between 2 and 3 weeks of culture. Only granulocyte progenitors have a substantial suicide rate in this small cell population. This population is also less responsive to stimulation than is the large cell class, which is a more highly differentiated progeny. The role of these different kinetics of colony forming cells is discussed in the context of the heterogeneity of the in vitro differentiation of neutrophil, monocyte and eosinophil lines.
Assuntos
Células da Medula Óssea , Divisão Celular/efeitos dos fármacos , Células-Tronco Hematopoéticas/citologia , Hidroxiureia/farmacologia , Agregação Celular , Contagem de Células , Separação Celular , Células Cultivadas , Meios de Cultura , Eosinófilos/fisiologia , Humanos , Macrófagos/fisiologia , Monócitos/fisiologia , Neutrófilos/fisiologiaRESUMO
The etiology of aplastic anemia is unknown. A stem cell lesion caused by a toxin, virus or microenvironment defect is the main hypothesis. An autoimmune origin has been recently suspected. In an attempt to demonstrate the autoimmune origin of the disease, 17 patients with severe aplastic anemia were treated with antilymphocyte globulin (ALG). Nine patients showed no improvement, developed infectious or hemorrhagic complications and died within 1 to 7 months. In contrast, eight patients had a prompt rise of granulocyte and reticulocyte counts. Although the hematological reconstitution is not complete, these eight patients are still alive between 11 months and 24 months after treatment. This study shows that ALG may have a beneficial effect in the treatment of patients with severe aplastic anemia.
Assuntos
Androgênios/uso terapêutico , Anemia Aplástica/terapia , Soro Antilinfocitário/uso terapêutico , Adolescente , Adulto , Anemia Aplástica/sangue , Anemia Aplástica/tratamento farmacológico , Anemia Aplástica/mortalidade , Células da Medula Óssea , Criança , Pré-Escolar , Ensaios Clínicos como Assunto , Ensaio de Unidades Formadoras de Colônias , Avaliação de Medicamentos , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The cellular composition of the granulocytic series in normal human bone marrow was studied in aspirates of different volume. An increase in the proportion of polymorphonuclears was observed in samples of more than 1 ml, thus indicating a dilution of bone marrow by peripheral blood. Certain data from the literature, referring to the differential count in the bone marrow granulocytic series, are discussed. The differences between these data can be explained by the dilution of bone marrow cells by mature granulocytes in blood.
Assuntos
Células da Medula Óssea , Leucócitos/citologia , Biópsia por Agulha , Contagem de Células , Humanos , Contagem de Leucócitos , MétodosRESUMO
The sera of 28 patients with aplastic anaemia were examined for their effect on granulocyte colony growth in soft agar. Normal sera did not affect colony growth, but 13 sera from patients with aplastic anaemia, three from multiparous women, and six from patients polytransfused for various disorders caused colony inhibition. This inhibition was not due to the presence of HLA antibodies in aplasia patients because some sera inhibited HLA compatible bone marrow, and polyspecific HLA antibodies were not found in all inhibitory sera. All patients who failed to show engraftment or who rejected their bone marrow graft within three weeks had serum inhibitory to normal bone marrow cell culture, but inhibition could not be demonstrated against autologous bone marrow cells in these patients with aplastic anaemia. The results show that patients with serum inhibitors have an increased risk of early graft rejection and suggest that this rejection is mediated by antibodies directed against bone marrow stem cells.
Assuntos
Anemia Aplástica/imunologia , Transplante de Medula Óssea , Rejeição de Enxerto , Adolescente , Adulto , Anemia Aplástica/terapia , Criança , Pré-Escolar , Ensaio de Unidades Formadoras de Colônias , Feminino , Antígenos HLA/imunologia , Humanos , Masculino , Fatores de Tempo , Transplante HomólogoRESUMO
Blood and bone marrow granulocyte colony forming units (CFUc) were assayed in 46 patients with aplastic anemia, and the serum was examined for its inhibitory action on normal CFUc growth. All patients showed a gross reduction in colonies and clusters in incidence and absolute number in the bone marrow and blood. Two proliferative abnormalities of CFUc in aplastic anaemia were identified: a significantly higher than normal cluster to colony ratio (P less than 0.05) and a higher than normal ratio of granulocytes to total aggregates in the bone marrow. Eleven out of 34 patients tested had serum inhibitory to normal CFUc. These patients were indistinguishable from the rest on haematological and CFUc culture characteristics, and no correlation between the results of CFUc assay and haematological severity was found. The results suggest that the CFUc is abnormal in aplastic anaemia, the reduction in pool size being related to a failure of self-renewal, but an immunological role in the pathogenesis of aplastic anaemia remains unproven. The close relationship of CFUc incidence to the percentage of granulocyte precursors in the marrow, together with the failure of the CFUc assay to predict clinical severity, limits the practical use of the assay to the confirmation of diagnosis in aplastic anaemia.
Assuntos
Anemia Aplástica/patologia , Medula Óssea/patologia , Adulto , Anemia Aplástica/sangue , Ensaio de Unidades Formadoras de Colônias , Feminino , Granulócitos/patologia , Inibidores do Crescimento/sangue , Células-Tronco Hematopoéticas/patologia , Humanos , MasculinoRESUMO
The inhibitory activity of peripheral blood lymphocytes on autologous bone marrow was studied in 27 patients with aplastic anaemia after treatment with androgen. Inhibitory activity was hard to assess in 10 patients studied during the first year of treatment. The colony count was too low to be certain of differences between the samples incubated with or without lymphocytes. Among the 17 patients who had more than 10 colonies per 2 x 10(5) mononuclear bone marrow cells, nine showed inhibitory activity by peripheral blood lymphocytes. After 12 months of androgen therapy each of these patients showing inhibitory activity of bone marrow colony forming cells by peripheral lymphocytes responded to antithymocyte globulin. None of nine patients with few colony forming cells or no inhibitory activity of lymphocytes responded to immunosuppression.
Assuntos
Anemia Aplástica/imunologia , Soro Antilinfocitário/uso terapêutico , Ensaio de Unidades Formadoras de Colônias , Linfócitos/imunologia , Adolescente , Corticosteroides/uso terapêutico , Adulto , Androgênios/uso terapêutico , Anemia Aplástica/patologia , Anemia Aplástica/terapia , Células Cultivadas , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Linfócitos T/imunologiaRESUMO
Using two-dimensional gel electrophoresis we have analyzed the pattern of phosphorylated proteins in HL-60 leukemia cells and changes associated with their differentiation into granulocyte and monocyte-like cells. In undifferentiated cells 18 spots with MW ranging from 110 to 17, kDa were individualized with high resolution and reproducibility. Myelocytic differentiation induced by dimethyl sulfoxide (DMSO) and retinoic acid (RA) resulted in a decrease of the overall phosphorylation, the disappearance of two proteins of 42 and 17 kDa, and the appearance of one new acidic protein of 46-48 kDa. These changes seem to be specifically related to this differentiation pathway since they are not found in two HL-60 subclones resistant to DMSO or RA-induced differentiation. Monocytic differentiation induced by 1,25-dihydroxyvitamin D3 [1,25 (OH)2D3] and the combination of RA + 1-B-D-arabinofuranosyl cytosine (Ara-C) was associated with the appearance of 2 proteins of 68 kDa and 2 proteins of 80 kDa located in the acidic region of the gel. The protein of 17 kDa, when disappeared completely in granulocytic-like cells was present in monocytic cells, this suggesting that its phosphorylation state may be involved in the control of the differentiation pathway of HL-60 cells. Data concerning the effect of phorbol myristate acetate (PMA) and histamine on the level of phosphorylation of various proteins in HL-60 cells have also been obtained and discussed. Our results show that the myelocytic and monocytic phenotypes are characterized by a specific pattern of phosphoproteins involving both phosphorylation and dephosphorylation reactions.
Assuntos
Granulócitos/citologia , Leucemia Mieloide Aguda/metabolismo , Monócitos/citologia , Proteínas/metabolismo , Calcitriol/farmacologia , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Citarabina/farmacologia , Dimetil Sulfóxido , Eletroforese em Gel de Poliacrilamida , Histamina/farmacologia , Humanos , Peso Molecular , Fosforilação , Acetato de Tetradecanoilforbol/farmacologia , Tretinoína/farmacologiaAssuntos
Divisão Celular , Eritropoese , Leucemia Mieloide/diagnóstico , Idoso , Medula Óssea/patologia , Células Cultivadas , Ensaio de Unidades Formadoras de Colônias , Humanos , Hidroxiureia/uso terapêutico , Cinética , Leucemia Mieloide/tratamento farmacológico , Leucemia Mieloide/fisiopatologia , PrognósticoRESUMO
Biosynthesis and molecular structure of major histocompatibility complex (MHC) class II antigens of DR2/DR7 hairy cells were analyzed by two-dimensional polyacrylamide-gel electrophoresis (2D-PAGE). Two anti-human Ia monoclonal antibodies (mAb) were used to immunoprecipitate DR and DR-linked DC/DS molecules. Monoclonal antibody VI 15 C recognizes DR (I-E-like) molecules and CA 2.06 precipitates DR and DR-linked DC/DS (I-A-like) molecules in DR7 allotypes. Studies were performed on a pure population of hairy cells before and after culture with phorbol ester: 12-O-tetradecanoyl phorbol-13-acetate (TPA), 5 azacytidine (5 Aza), sodium butyrate (NA-BU), and phytohemagglutinin (PHA-P). Before any treatment, hairy cells expressed and synthesized DR antigens: DR alpha and beta subunits appeared both qualitatively and quantitatively normal by 2D-PAGE profile. In contrast, the hairy cells failed to express and synthesized any DC/DS molecule. The lack of DC/DS molecular expression was restored after culture in presence of TPA, sodium butyrate, and 5 azacytidine, but not after PHA-P treatment. Differential molecular expression of MHC class II antigens in leukemic cells provides a model to define further discrete stages of hemopoietic differentiation and study the role of these molecules in the cellular interactions occurring during differentiation.
Assuntos
Azacitidina/farmacologia , Butiratos/farmacologia , Antígenos de Histocompatibilidade Classe II/imunologia , Leucemia de Células Pilosas/imunologia , Forbóis/farmacologia , Acetato de Tetradecanoilforbol/farmacologia , Anticorpos Monoclonais/imunologia , Células Cultivadas , Eletroforese em Gel de Poliacrilamida , Antígenos HLA-DQ , Antígenos HLA-DR , Heterozigoto , Antígenos de Histocompatibilidade Classe II/biossíntese , Homozigoto , Humanos , Leucemia de Células Pilosas/genéticaRESUMO
Granulopoiesis was studied simultaneously by three methods in normal subjects and in subjects with neutropenia of various aetiologies: in vitro labelling of autologous and homologous granulocytes for the study of peripheral kinetics, in vivo labelling with DF32P (di-isopropyl-flourophosphate 32P) or 75Se-selenomethionine, and bone marrow autoradiography after in vitro labelling with 3H-thymidine for the study of bone marrow granulopoiesis. Three main mechanisms of neutropenia can be distinguished: a) peripheral hyperdestruction, corpuscular or extra-corpuscular, and false leukopenias (change in the distribution of peripheral granulocytes from the circulating to the marginal granulocyte pool; b) quantitative bone marrow insufficiency without qualitative abnormality; c) qualitative abnormality in bone marrow granulopoiesis with cell death in either the maturation stage or the proliferative stage. There is no exact correlation between clinical and kinetic classifications, but most cases of post-infection chronic neutropenias and idiopathic neutropenias fall into the first two categories, and most cases of benzol intoxication and bone marrow insufficiency due to X-irradiation fall into the last category. Some of these last patients developed an acute myeloblastic leukaemia in the two following years and can be considered as preleukaemic states.
Assuntos
Agranulocitose/fisiopatologia , Hematopoese , Agranulocitose/etiologia , Medula Óssea/efeitos dos fármacos , Medula Óssea/metabolismo , Medula Óssea/efeitos da radiação , Células da Medula Óssea , Síndrome de Felty/complicações , Granulócitos/patologia , Humanos , Cinética , Neutropenia/etiologia , Neutropenia/fisiopatologia , Lesões por Radiação , Esplenomegalia/complicações , Tuberculose/complicações , Raios XRESUMO
Murine spleen cells were cultured in vitro to study the induction of committed granulopoietic stem cell (CFU-C) proliferation and maturation. Marbrook-type diffusion cultures were established with and without the addition of colony-stimulating activity (CSA) and harvested at intervals up to 14 days for viable and differential cell counts, [3H]TdR autoradiography, and quantitation of CFU-C by the agar plate method. Without CSA there was poor cell viability and little proliferative capacity. In CSA-stimulated cultures there was a prominent rise in viable cell counts and [3H]TdR labeling indices rose from a mean of 2% at 0 time to 47% after 5 days in vitro. CFU-C increased by 70-fold in these cultures. Peak numbers of CFU-C, immature cells, and [3H]TdR-labeled cells occurred at about 7 days. Thereafter, mature granulocytes and macrophages predominated in culture. Because the liquid spleen cell culture system begins in a resting state and undergoes a wave of proliferative activity in response to CSA, it can provide a useful model system for studying phenomena associated with stem cell activation and differentiation in vitro.
Assuntos
Granulócitos/fisiologia , Hematopoese , Leucócitos/fisiologia , Baço/fisiologia , Animais , Fatores Estimuladores de Colônias/farmacologia , Feminino , Técnicas In Vitro , Camundongos , Camundongos Endogâmicos DBA , Fagócitos/fisiologia , Fatores de TempoRESUMO
Granulopoiesis was studied in 20 cases of chronic granulocytopenia (adults and children; acquired and congenital). Bone marrow colony growth in methylcellulose culture was compared with the turnover-rate of blood granulocytes labelled with 51Cr and with the bone marrow granulocyte labelling index (L.I.) after "in vitro" flash labelling with 3H-thymidine (3H-TDR). There was a positive correlation between colony forming cells (C.F.C.) content and turnover rate and between C.F.C. content and bone marrow cellularity but there was no statistically valid correlation between C.F.C. content and labelling index. In patients with acquired granulocytopenia the colony counts were increased in cases with autoimmune destruction of neutrophils and in one patient during granulocytic regeneration. The C.F.C. numbers were low in cases with neutropenia associated with granulocyte hypoplasia but the prognosis was better in those cases with the highest colony count. On the other hand, colony counts were variable and had no prognostic value in cases of neutropenia secondary to a bone marrow abnormality in maturation or mutiplication, either acquired or congenital, as revealed by turnover studies and autoradiographic data.
Assuntos
Agranulocitose/patologia , Células da Medula Óssea , Medula Óssea , Granulócitos/patologia , Leucócitos/patologia , Adolescente , Adulto , Idoso , Agranulocitose/diagnóstico , Divisão Celular , Criança , Pré-Escolar , Técnicas de Cultura , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Neutropenia/congênito , PrognósticoRESUMO
90 patients with hemopoietic dysplasia (preleukemia) have been studied with iron kinetics for the mechanism of the anaemia, 23 patients had a bone marrow autoradiography and 18 a bone marrow culture in semi-solid medium. The death was caused in half the cases by acute myeloblastic leukaemia transformation (LAM) and in half the cases by complications of pancytopenia (infection, haemorrhage) or hemochromatosis. Three data give prognostic factors at short or long term: the bone marrow hypoplasia, no patient with major bone marrow hypoplasia (ratio of 59Fe fixation in liver and sacrum of more than 2) lived more than 2 years after the examination. The low labeling index of myeloblasts and promyelocytes, the mean LI is 0.20 patients having lived less than one year after the study and 0.35 for those who lived more than two years. The bone marrow culture of the macroclusters type, no patient whose bone marrow grew with macroclusters and no colonies survived more than 8 months after the study. These three data seem to be essential in the regular survey of the patients with hemopoïetic dysplasia.
Assuntos
Doenças Hematológicas/diagnóstico , Autorradiografia , Medula Óssea/análise , Células da Medula Óssea , Células Cultivadas , Humanos , Radioisótopos de Ferro , Cinética , PrognósticoRESUMO
The physiopathogeny of aplastic anemia is still unknown, it can be related to a stem cell defect or a microenvironment disease. An autoimmune origin is suspected but not as yet proved. To demonstrate the autoimmune origin of some cases of aplastic anemia, we have studied the effect of antilymphocyte globulin (ALG) on the hematopoiesis of aplastic patients by serial hematological and bone marrow investigation including blood counts, bone marrow cellularity, scanning with indium and technetium and granulocytic colonies in agar, 8 out of 17 patients had a response to ALG as shown by a rise of granulocytes and reticulocytes counts, increase of bone marrow cellularity and number of granulocytic colonies. This study tends to show that ALG has a stimulating effect on hematopoiesis in some cases of severe aplastic anemia.
Assuntos
Anemia Aplástica/terapia , Soro Antilinfocitário/uso terapêutico , Medula Óssea/patologia , Células-Tronco Hematopoéticas/patologia , Anemia Aplástica/patologia , Anemia Aplástica/fisiopatologia , Doenças Autoimunes , Diferenciação Celular , Granulócitos/citologia , HematopoeseRESUMO
Cell kinetics have been studied at several periods in a patient with typical cyclic neutropenia. Peripheral blood granulocyte labelling showed an increased destruction in the preleucopenic phase. Bone marrow colony-forming cells and blood leucocyte colony forming activity were normal or above the normal range. The major abnormalities were found in sequential studies of bone marrow proliferation measured by "in vitro" 3H-thymidine flash labelling. A fall in the labelling index of promyelocytes was observed in the second part of the cycle. Incubation of normal human bone marrow cells with patient's granulocytes showed a marked decrease in 3H-thymidine incorporation, compared with incubation with the same number of normal granulocytes. Human cyclic neutropenia seems to be due to a factor secreted by abnormal polymorphonuclears inhibiting myeloid proliferation.