Relationships between thrombopoiesis and erythropoiesis: with studies of the effects of preparations of thrombopoietin and erythropoietin

The effects of administration of partially purified human urinary erythropoietin and rabbit thrombopoietin, and of endogenously produced erythropoietin and thrombopoietin on both red cell and platelet production were examined in mice. Partially purified thrombopoietin was prepared from rabbit plasma by sequential fractionation with ammonium sulfate precipitation, and DEAE and Sephadex G-100 chromatography. Preparations of thrombopoietin and partially purified human urinary erythropoietin (NIH No. H-11-TaLSL) were administered subcutaneously to normal mice, and the rate of incorporation of selenomethionine-75 Se into platelets was measured as an index of thrombopoietic activity of the infused material. Erythropoietin and thrombopoietin were assayed for erythropoietic activity by measuring the rate of appearance of 59Fe in the red cells of posthypoxic polycythemic mice. Preparations containing thrombopoietin had barely measurable erythropoietic activity, and 7 units of partially purified erythropoietin had little thrombopoietic activity. When endogenous levels of erythropoietin were increased by hypoxia, platelet production was not enhanced. Similarly, increased levels of thrombopoietin, induced in response to thrombocytopenia produced by platelet antiserum, did not alter red cell production. These data suggest that physiologically increased levels of thrombopoietin do not stimulate erythropoiesis, and that physiologically increased levels of erythropoietn do not stimulate thrombopoiesis. However, currently available, partially purified preparations of erythropoietin and thrombopoietin may be capable of stimulating both platelet and red cell production if used in sufficient quantities.     

Obstruction of the outflow tract of the left ventricle by accessory mitral valve tissue

Among the causes of left ventricular outflow tract obstruction, accessory mitral valve tissue is one of the last described and least studied. At present echocardiography permits a complete exploration of the atrioventricular valves as well as left ventricular outflow tract. In this study we evaluate the information obtained in four patients with two-dimensional echocardiography and color-coded Doppler by both transthoracic and transesophageal approaches. The information was compared with catheterization results. In none of the three cases in which hemodynamic study was performed, diagnostic angiographic images of the anomaly were obtained. Transesophageal echocardiography gave additional information about the mitral valve and subvalvular apparatus, the site of accessory tissue implantation and associated lesions.     

Altered glycosaminoglycan production by HL-60 cells treated with 4- methylumbelliferyl-beta-D-xyloside

Glycosaminoglycans, mainly chondroitin 4-sulfate, are located in the primary granules of human myeloid cells. These polyanionic carbohydrates are believed to play an important role in leukocyte maturation and function. To study the effect of altered chondroitin sulfate metabolism on human promyelocytic leukemia cells, we have treated HL-60 cells with 4-methylumbelliferyl-beta-D-xyloside. beta-D- Xylosides initiate the synthesis of free chondroitin sulfate chains. Cytochemical studies of treated cells demonstrated a marked increase in cytoplasmic granules stained with cationic dyes. This was confirmed by radiolabeled precursor incorporation studies that demonstrated a 344% increase in 35S-sulfate uptake into glycosaminoglycans associated with the cells and a 39% increase in incorporation into glycosaminoglycans released into the media. Chromatographic analyses of these glycosaminoglycans from treated cells demonstrated that the newly formed chondroitin sulfate chains were not attached to protein core and were of shorter length, but of greater charge density than chondroitin sulfate produced by control cells. Thus, beta-D-xyloside appears to alter the protein linkage, chain length, and sulfation of chondroitin sulfate produced by HL-60 cells, and these changes are morphologically evident. These biochemically altered cells may provide important information concerning the role of these macromolecules in myeloid development.     

Developmental regulation of erythropoiesis by hematopoietic growth factors: analysis on populations of BFU-E from bone marrow, peripheral blood, and fetal liver

Fetal hematopoiesis is characterized by expanding erythropoiesis to support a continuously increasing RBC mass. To explore the basis for this anabolic, nonhomeostatic erythropoiesis, the proliferative effect of recombinant hematopoietic growth factors on highly enriched hematopoietic progenitor cells from fetal and adult tissues were compared. Fetal hepatic BFU-E, unlike adult bone marrow (BM) or peripheral blood (PB) BFU-E, were capable of proliferating in response to erythropoietin in the absence of added GM colony-stimulating factor (GM-CSF) or interleukin-3 (IL-3), and erythropoietin (Epo) directly stimulated the expansion of the fetal BFU-E pool in suspension culture. A murine monoclonal antibody (MoAb), Ep 3, was raised against enriched fetal liver progenitor cells, which detected all fetal BFU-E and which reacted with the erythropoietin-responsive, GM-CSF/IL-3-independent fraction of adult BM BFU-E and CFU-E. All adult PB BFU-E were Ep 3- but became Ep 3+ after stimulation with GM-CSF or IL-3. These data indicate that Epo plays a unique role in fetal hepatic erythropoiesis, stimulating proliferation of immature BFU-E in addition to promoting terminal differentiation of later erythroid progenitor cells. In addition, these results demonstrate a MoAb which detects all erythropoietin-responsive progenitor cells and distinguishes the BFU-E compartments in adult BM and PB.     

Effects of laser irradiation on human thrombus: Demonstration of a linear dissolution-dose relation between clot length and energy density

Because vascular thrombosis often accompanies arteriosclerotic disease in occluding blood vessels, the dissolution properties of laser irradiation were investigated and the energies needed to penetrate different lengths of thrombus were quantitated. Spectrophotometric studies show that the blood clot due to the presence of hemoglobin is well absorbed by argon laser energies, which emit blue-green wavelengths between 454 and 514 nm. Thus, laser energies transmitted directly from an argon-ion source produced vaporization and penetration of human thrombus in a linear dose-response fashion; the longer the thrombus, the greater the power intensity or time exposure necessary to penetrate the clot.     

Molecular analysis of T-cell receptor V beta chains of human T-cell chronic lymphocytic leukemia does not show intraclonal variability: implications for immunotherapy

Human T-cell chronic lymphocytic leukemia (T-cell CLL) is a heterogeneous disease characterized by a monoclonal malignant proliferation of T cells in which the T-cell receptors (TCRs) can be, when expressed, considered to be membrane tumor-specific antigens. Owing to the increasing number of available monoclonal antihuman TCR reagents, it could be of interest to evaluate the feasibility of anti- TCR treatment during T-cell CLL. To test the therapeutic potentiality of anti-TCR monoclonal antibodies, we first analyzed the intraclonal variability in two terminally ill patients suffering from TCR alpha beta-positive cell CLL bearing different immunophenotypes. The cDNA corresponding to the variable regions of the TCR beta chains originating from the malignant T cells were amplified, cloned into M13 phages, and sequenced. The sequence analysis of multiple independent clones showed no intraclonal variability, with no evidence for ongoing hypermutation in the V beta region genes. The relevance of these findings with regard to an anti-V beta therapy and the comparison with similar analysis during B-cell monoclonal lymphoproliferations are discussed.     

Lysis of human fibroblast colony-forming cells and endothelial cells by monoclonal antibody (6-19) and complement

The murine IgG2a monoclonal antibody 6-19 binds to a wide variety of nonhematopoietic cells including human marrow-derived stromal cells but does not bind to marrow or peripheral blood cells. We studied the effects of this antibody and rabbit complement on marrow cells. Fibroblast colonies were eliminated from light density marrow cells by a single incubation with monoclonal antibody 6-19 and complement. The growth and composition of granulocytic and erythroid colonies were unaffected. Specific complement mediated cytotoxicity of the antibody was confirmed on passaged human fibroblasts derived from marrow (more than 99.6% of fibroblasts are killed by a single treatment). Similar results were obtained with human umbilical cord endothelial cells. In addition, such treatment abolished the initiation of Dexter culture stroma. Incubation of bone marrow cell suspensions with this antibody and complement will allow the study of stroma-free marrow cells in long- term liquid cultures.     

The pathophysiology of pure red cell aplasia: implications for therapy

To determine the utility of marrow culture in defining the natural history and therapeutic response of pure red cell aplasia we have studied 37 patients. Patients were evaluated at the University of Washington before specific therapies (n = 21) or at the time of treatment failure in = 16). Evaluation included a medical and drug exposure history, a physical examination, a chest x-ray or computed tomography to rule out thymoma, lymphocyte immunophenotype studies, anti-nuclear antibody and rheumatoid factor determinations, marrow cytogenetics, and marrow progenitor cell cultures. Retrospective Southern analyses to detect human parvovirus B19 was performed in the 27 patients for whom sera was stored. Clinical follow-up was obtained to document therapeutic responses. Normal burst forming unit-erythroid (BFU-E) growth (>30 bursts/10(5) marrow mononuclear cells [MMNC]) in culture proved an outstanding predictor of clinical response, as 27 of 29 individuals with normal frequencies of erythroid bursts in culture responded to immunomodulating therapies (sensitivity 96%, specificity 78%, predictive value 93%, P = .0001 with two-tailed chi square analysis). Overall, 28 patients responded to either immunomodulating therapies or drug withdrawal. Twenty-four patients obtained a normal hematocrit (complete response [CR] and 4 additional patients became transfusion independent (partial response). Although responding patients often required several therapies, 20 of 24 (83%) patients who obtained a CR have sustained a normal hematocrit without maintenance therapy at the time of last follow-up (median 5 years). In contrast, of 8 patients with poor in vitro BFU-E growth (<6 bursts/10(5) MMNC), 7 failed to respond to any therapy and all died (median survival time 17 months). Our data suggest that in individuals, from whom BFU-E mature appropriately in culture, immunosuppressive drugs should be used sequentially until a CR is obtained and a durable remission is the expected outcome.     

Functional heterogeneity of B-CLL lymphocytes: dissociated responsiveness to growth factors and distinct requirements for a first activation signal

We studied the effects of B cell directed growth factors on B lymphocytes from 11 patients with chronic lymphocytic leukemia (B-CLL). B-CLL lymphocytes were costimulated with anti-mu antibody (Ab) and with three growth factor preparations: recombinant IL2, B cell growth factor (BCGF) (20 kiloDalton (kD) BCGF) and a high molecular weight BCGF (50 kD BCGF). IL2 was the more active factor (in six of 11 patients). The effect of IL2 was dependent on a costimulation with anti-mu Ab or occurred independently of anti-mu Ab, according to the patients. This pattern of reactivity did not correlate with the presence or absence of the IL2 receptor (IL2-R) molecule on fresh B-CLL lymphocytes. Five patients responded to the 20 kD BCGF. Although four of them were also strong responders to IL2, one strongly responded to the 20 kD BCGF and did not respond to IL2. Only one patient responded to the 50 kD BCGF. When an anti-IL2-R Ab was introduced into the culture, only the responsiveness to IL2 was abolished: thus both 20 kD and 50 kD BCGFs activate B-CLL lymphocytes independently of the IL2-R. These results show that several B cell directed growth factors can act independently to support the proliferation of B-CLL lymphocytes.