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Biomedical subjects

S B Krantz

Publications and source records attributed to S B Krantz.

At least 55 records · Page 3Linked to original sources
PubMed1992

Case report: granulocyte colony-stimulating factor overcomes severe neutropenia of large granular lymphocytosis.

Large granular lymphocytosis (LGL) is characterized by enhanced proliferation of T lymphocytes that have antibody-dependent cell-mediated cytotoxicity or natural killer cell activity and that often produce severe cytopenias, including neutropenia. When a 68-year-old man with seropositive rheumatoid arthritis and severe neutropenia was examined, he was found to have LGL with a T cell gene rearrangement, indicating the presence of a clonal population of T lymphocytes. The patient was admitted with a fever of 102 degrees F and a nonhealing ulcer over the right tibia. When the infection did not respond to intravenous antibiotics, granulocyte colony-stimulating factor (GCSF) therapy was started at 5 micrograms/kg subcutaneously each day. The neutrophil count promptly increased and the patient subsequently defervesced and was able to have a skin graft placed, which healed without difficulty. GCSF, which is known to be an effective therapeutic agent for neutropenia associated with chemotherapy and bone marrow transplantation, also was a very valuable treatment for the life-threatening neutropenia of LGL.

Aged↗
PubMed1991

Human burst-forming units-erythroid need direct interaction with stem cell factor for further development.

To understand the factors that regulate the early growth and development of immature erythroid progenitor cells, the burst-forming units-erythroid (BFU-E), it is necessary to have both highly purified target cells and a medium free of serum. When highly purified human blood BFU-E were cultured in a serum-free medium adequate for the growth of later erythroid progenitors, BFU-E would not grow even with the addition of recombinant human interleukin-3 (rIL-3), known to be essential for these cells. However, the addition of recombinant human stem cell factor (rSCF), which supports germ cell and pluripotential stem cell growth, stimulated BFU-E to grow equally well in serum-free as in serum-containing medium. Limiting dilution studies showed that rSCF acts directly on the BFU-E that do not require accessory cells for growth. Furthermore, rSCF was necessary for BFU-E development during the initial 7 days of culture, until these cells reached the stage of the late progenitors, the colony-forming units-erythroid (CFU-E). These studies indicate that early erythropoiesis is dependent on the direct action of SCF that not only affects early stem cells but is continually necessary for the further development of committed erythroid progenitor cells until the CFU-E stage of maturation.

Cell Division↗
PubMed1991

Inhibition of human erythroid colony-forming units by gamma interferon can be corrected by recombinant human erythropoietin.

Tumor necrosis factor (TNF), interleukin-1 (IL-1), and gamma interferon (gamma IFN) inhibit erythropoiesis in vivo and in vitro, and have been implicated in the pathogenesis of the anemia of chronic disease. Anemia in patients with rheumatoid arthritis and in animals exposed chronically to IL-1 and TNF can be corrected by the administration of recombinant erythropoietin (Epo). We exposed highly purified human erythroid colony-forming units (CFU-E) cultured from peripheral blood burst-forming units-erythroid (BFU-E) and unpurified human marrow CFU-E to recombinant human gamma IFN and showed inhibition of colony formation in vitro. This inhibition was reversed by increased concentrations of Epo. The mechanisms by which this effect occurs are unknown at present. Epo may cause a downregulation of gamma IFN receptor expression on CFU-E or, alternatively, gamma IFN may cause a downregulation of Epo receptor expression. A full understanding of these mechanisms awaits a more complete comprehension of the regulation of erythropoiesis; however, the effect of Epo in vitro is similar to its ability to correct the anemia of chronic disease in vivo.

Bone Marrow Cells↗
PubMed1991

Abundance and stability of erythropoietin receptor mRNA in mouse erythroid progenitor cells.

The abundance and stability of erythropoietin (EPO) receptor mRNA was measured in Friend virus-infected mouse splenic erythroblast (FVA) cells. FVA cells correspond to the colony-forming unit-erythroid (CFU-E) and cluster-forming unit-erythroid stages of differentiation and they mature in vitro into reticulocytes during 45 to 60 hours of culture. After 20 hours, there was a rapid decline in the EPO receptor mRNA level through the 45-hour culture period. Levels of actin and beta-globin mRNAs were monitored as two representative proteins that are actively synthesized in early versus late stages of terminal erythroid differentiation. A general decrease of actin mRNA level was apparent, whereas globin mRNA levels increased throughout the culture period. The greatest decrease in both EPO receptor and actin mRNA was observed when the cell population was at the stage of basophilic and polychromatophilic erythroblasts. The half-life for EPO receptor mRNA was approximately 75 minutes, as determined using the transcriptional inhibitor actinomycin D. The half-life measured at several times during the 48-hour culture period remained constant. These results indicate that EPO receptor mRNA must be transcribed continuously until late in the maturation process of FVA cells in order to maintain the levels seen by Northern analysis. The number of copies of EPO receptor mRNA at 0 hours was determined to be 25 copies per cell. This low number and the decline of EPO receptor mRNA correlate with the low receptor numbers on FVA cells, as well as the decline of binding sites with cell maturation.

Actins↗
PubMed1991

Pharmacologic doses of recombinant human erythropoietin in the treatment of myelodysplastic syndromes.

Twenty patients with myelodysplastic syndromes (MDS) entered a randomized, placebo-controlled, double-blind trial designed to evaluate the efficacy and toxicity of high doses of recombinant human erythropoietin (rhEPO). Patients completing the trial were eligible to receive rhEPO as part of an open-label study. Eighteen patients were transfusion dependent; 10 had refractory anemia (RA), and 10 had refractory anemia with ringed sideroblasts (RARS). A response to rhEPO was defined as an increase in hematocrit of 4 percentage points or more over baseline, or the elimination of all transfusions with the hematocrit stable at the baseline level. In the double-blind trial, 1 patient (12.5%) receiving rhEPO responded, as compared with no responses in the placebo group. Overall, responses occurred in 4 of 17 patients (24%) receiving rhEPO at a dose of 1,200 to 1,600 U/kg intravenously (IV) twice weekly. Changes in granulocyte or platelet counts were not observed. Despite the administration of high doses of rhEPO, toxicity attributable to rhEPO was not observed in either the double-blind or open-label study. Response to rhEPO was not significantly related to age, gender, type of MDS, time since diagnosis, time since initiation of transfusion therapy, or baseline serum EPO. These studies indicate that rhEPO can be administered safely in very high doses to patients with MDS and that 24% of these patients will respond with increased erythropoiesis.

Adult↗
PubMed1991

Purification of human marrow progenitor cells and demonstration of the direct action of macrophage colony-stimulating factor on colony-forming unit-macrophage.

To facilitate the investigation of the direct interaction between hematopoietic progenitors and colony-stimulating factors, we have developed a method to purify human marrow progenitor cells. Using density centrifugation, negative panning with concanavalin A coated plates, positive selection of CD34-positive cells with immunomagnetic microspheres, overnight adherence to a plastic dish, negative selection with a panel of monoclonal antibodies, and density centrifugation, human marrow progenitor cells were purified from 1.5% to 53.2%, a 42-fold purification, with a 4.8% yield. The purified cells consisted of 38% erythroid, 9% colony forming unit-granulocyte (CFU-G), 29% CFU-macrophage (CFU-M), 12% CFU-eosinophil/basophil (CFU-Eo/Ba), and 4% CFU-mix. The purified cells cultured in serum-free fibrin clots with recombinant human macrophage colony-stimulating factor (rM-CSF) for 14 days developed a pure population of CFU-M colonies. An appearance of CFU-M colonies was present after the addition of 1 U/mL of rM-CSF and the maximum stimulation was found at 100 U/mL. When the purified cells were cultured in serum-free medium with rM-CSF in a limiting dilution assay and the percentage of nonresponder wells for CFU-M colonies was plotted against cell concentration, serum-free cultures yielded a straight line through the origin, indicating that CFU-M development did not depend on accessory cells and that rM-CSF acted directly on the CFU-M.

Antigens, CD↗
PubMed1991

Erythropoietin.

Explore the source record for details and available documents.

Animals↗
PubMed1991

Photoaffinity labeling of the erythropoietin receptor and its identification in a ligand-free form.

Pure human recombinant erythropoietin (EP) was acylated through a primary amino residue with a cross-linking reagent, N-[[3-[[4-[(p-azido-m-[125I]iodophenyl)azo]benzoyl]amino] propanoyl]oxy]-succinimide (Denny-Jaffe reagent), which is photoreactive and cleavable at the azo residue. The resulting conjugated hormone (DJ-EP) was purified from unmodified EP by reverse-phase high-pressure liquid chromatography and maintained its capacity to bind to receptors for EP on erythroid progenitor cells. The receptor for EP was previously identified as two related proteins of 100 and 85 kDa molecular mass by chemical cross-linking to 125I-EP. Recently, D'Andrea and co-workers [(1989) Cell 57, 277-285] cloned a cDNA that codes for a protein of 55-66 kDa, which is thought to be the EP receptor. In this report, cross-linking to the receptor through the monofunctional DJ-EP labeled the same 140- and 125-kDa molecular mass bands (100- and 85-kDa proteins) cross-linked with 125I-EP and disuccinimidyl suberate. Furthermore, cleavage of the azo bond of the DJ-EP receptor complex by sodium dithionite (80 degrees C, 5 min) demonstrated that proteins of 105 and 90 kDa were labeled in ligand-free form by DJ-EP. This result demonstrates that artifactual cross-linking of multiple proteins or other artifacts of cross-linking do not explain the difference in molecular mass of the EP receptor identified by cross-linking and the receptor identified by expression cloning.

Acylation↗
PubMed1991

Transitional change of colony stimulating factor requirements for erythroid progenitors.

The course of the differentiation and proliferation of the human erythroid burst-forming units (BFU-E) to colony-forming units (CFU-E) was directly investigated using a combination of highly purified BFU-E, a liquid culture system, and the following clonal assay. Highly purified human blood BFU-E with a purity of 45-79% were cultured in liquid medium with recombinant human erythropoietin (rEP) and recombinant human interleukin-3 (rIL-3) to generate more differentiated erythroid progenitors. The cultured cells were collected daily for investigating the morphology, the increment in the number of cells and the clonality. Ninety percent of purified BFU-E required not only rEP but also rIL-3 for clonal development. By 7 days of liquid culture, the total cell number increased 237 +/- 20-fold above the starting cells, while erythroid progenitors increased 156 +/- 74-fold. As the incubation time in liquid culture increased, the cells continuously differentiated in morphology. Replating experiments with rEP combined with or without rIL-3 showed the following: 1) The number of erythroblasts that were part of erythroid colonies decreased with accompanying erythroid progenitor differentiation and proliferation. 2) As the incubation time in liquid culture increased, erythroid progenitors had a graded loss of their dependency on rIL-3 and a complete loss of dependency was observed after 3 days of liquid culture. At that time 85% of the erythroid progenitors gave rise to colonies of more than 100 erythroblasts which were equivalent to mature BFU-E. These studies provide a quantitative assessment of the loss of IL-3 dependency by BFU-E and indicate that the size of the generated erythroid colonies and their IL-3 requirement correlate with the erythroid differentiated state.

Adult↗
PubMed1991

Treatment of refractory pure red cell aplasia with cyclosporine A: disappearance of IgG inhibitor associated with clinical response.

Remissions were obtained in 6/9 evaluable patients with pure red cell asplasia (PRCA) refractory to other immunosuppressive agents who were treated with cyclosporine A (CsA). Four of these patients have remained in continuous remission off all treatment for 4-19 months. Another patient who stopped CsA abruptly relapsed, but responded to reinstitution of therapy. The sixth patient died of a cerebrovascular accident while in remission on a low dose of CsA. Acute side effects were minimal and were responsive to dose reduction. One patient developed a lymphoma while in an unmaintained remission, and one patient who did not respond to CsA was found to have a lymphoma approximately a year after stopping treatment. In vitro studies of autologous erythroid progenitors in a patient with an IgG inhibitor of erythropoiesis showed a reduction of autoantibody associated with the response to CsA. The antigen to which this inhibitor is directed was expressed only during the marrow erythroid burst-forming unit (BFU-E) period of erythroid differentiation. CsA can induce sustained remissions in cases of PRCA refractory to other multiple agents, and these remissions may be associated with a reduction in autoantibody to erythroid progenitor cells. Further studies of patients with PRCA who respond to CsA may lead to an improved understanding of this disorder.

Adolescent↗
PubMed1991

Erythropoietin response to anemia as a function of age.

The erythropoietin (EPO) response to anemia was assessed for 244 subjects aged 1-64 years (mean 45.2 years) and 121 subjects aged 65-94 years (mean 68.3 years). Subjects included non-anemic individuals as well as those with anemia of various etiologies, excluding renal disease and pregnancy. Significant inverse correlations between serum immunoreactive EPO and hematocrit were noted for both groups. Regression lines failed to show a significantly lower slope or y-intercept for older compared to younger subjects. EPO levels were not significantly lower for older compared to younger subjects when controlled for hematocrit level. These results suggest that the EPO response to anemia in older subjects is similar to that of younger subjects.

Adolescent↗
PubMed1991

Polycythemia vera blood burst-forming units-erythroid are hypersensitive to interleukin-3.

Because polycythemia vera (PV) is a clonal hematopoietic stem cell disease with a trilineage hyperplasia, and interleukin-3 (IL-3) stimulates trilineage hematopoiesis, we have studied the response of highly purified PV blood burst-forming units-erythroid (BFU-E) to recombinant human IL-3 (rIL-3). Whereas the growth of normal blood BFU-E in vitro rapidly declined by 40 and 60% after 24 and 48 h of incubation without 50 U/ml of rIL-3, the growth of PV BFU-E declined by only 10 and 30% under the same conditions, demonstrating a reduced dependence on rIL-3. A reduced dependence of PV BFU-E on recombinant human erythropoietin (rEP) was also present. Dose-response experiments showed a 117-fold increase in PV BFU-E sensitivity to rIL-3, and a 6.5-fold increase in sensitivity to rEP, compared to normal BFU-E, whereas blood BFU-E from patients with secondary polycythemia responded like normal BFU-E. Endogenous erythroid colony (EEC) formation, which is independent of the addition of rEP, was reduced by 50% after erythroid colony-forming cells were generated from PV BFU-E in vitro without rIL-3 for 3 d, whereas rEP-stimulated erythroid colonies were unaffected. These studies demonstrate a striking hypersensitivity of PV blood BFU-E to rIL-3, which may be the major factor in the pathogenesis of increased erythropoiesis without increased EP concentrations.

Dose-Response Relationship, Drug↗
PubMed1991

Quantitation of insulin-like growth factor-I binding to highly purified human erythroid colony-forming units.

A method has been developed by which erythroid colony-forming units (CFU-E) may be obtained from human blood in sufficient number and purity for quantitative studies of growth factor binding. Studies in serum-free medium have shown that CFU-E require the addition of only two growth factors, erythropoietin (EP) and insulin-like growth factor-I (IGF-I), for growth and differentiation. The IGF-I may be replaced by higher (100-fold) concentrations of insulin. Incubation of CFU-E with 125I recombinant human IGF-I (rhIGF-I) at 4 degrees C has demonstrated specific binding that is directly proportional to the cell concentration. Competition with unlabeled rhIGF-I markedly decreased binding, whereas other growth factors such as granulocyte-monocyte colony-stimulating factor (GM-CSF), interleukin 3 (IL-3), and epidermal growth factor (EGF) had no significant effect on the binding of [125I]rhIGF-I. The binding was saturable at an [125I]rhIGF-I concentration of 10 ng/ml (1.2 nM). Scatchard analysis revealed two classes of IGF-I receptors present on the CFU-E cell surface: a low-affinity class of 549 receptors with Kd = 0.44 nM and a high-affinity class of 341 receptors with Kd = 0.04 nM.

Erythroid Precursor Cells↗
PubMed1991

Use of recombinant human erythropoietin to enhance autologous blood donation in a patient with multiple red cell allo-antibodies and the anemia of chronic disease.

We treated a patient with alcohol-induced cirrhosis, intractable pain from a defective hip prosthesis, and multiple red cell allo-antibodies with recombinant human erythropoietin (EPO) in order to facilitate collection of blood for autologous transfusion during an elective total hip revision. This patient had experienced a delayed transfusion reaction 4 months earlier after receiving least incompatible packed red cells for gastrointestinal bleeding. His blood could not be crossmatched because of the development of multiple antibodies to homologous blood given during previous surgery and several episodes of gastrointestinal hemorrhage. Following initiation of EPO therapy, there was a prompt and persistent increase in the reticulocyte count from a baseline of 1.6% to a maximum of 8.6%. This was accompanied by maintenance of the hematocrit between 32% and 38.5% despite withdrawal of seven units of autologous blood over the 45-day treatment period. Poor venous access and availability of blood bank personnel, not hematocrit level, were the limiting factors that determined how frequently blood could be collected. We conclude that EPO stimulated erythropoiesis in this patient with underlying anemia of chronic disease and facilitated harvest of autologous blood for elective surgery.

Aged↗
PubMed1990

Purification of human blood burst-forming units-erythroid and demonstration of the evolution of erythropoietin receptors.

To facilitate the direct study of the molecular events that control the development of human burst-forming units-erythroid (BFU-E), we have developed a method to purify BFU-E from peripheral blood. Using density centrifugation, rosetting with a mixture of neuraminidase-treated and IgG-coated sheep erythrocytes, positive panning with anti-My10 monoclonal antibody, overnight adherence to plastic dishes, negative panning with monoclonal antibodies, and density centrifugation, human blood BFU-E were purified from 0.04% to 56.6%, a 1,400-fold purification with a 13% yield. More than 90% of purified BFU-E were recombinant interleukin-3 (rIL-3) dependent, which survived for 48 h with rIL-3 in the absence of recombinant erythropoietin (rEP), and 80% gave rise to erythroid bursts of more than 500 hemoglobinized cells. rEP dependency was not evident until after 72 h of incubation in vitro. The purified cells (day 1) were incubated with rIL-3 and rEP in liquid culture for 24 (day 2), 48 (day 3), and 72 (day 4) h and then were transferred into semisolid cultures and incubated until day 15. The size of the erythroid colonies observed in semisolid cultures decreased continuously in association with the incubation time of day 1 purified cells in liquid cultures. The first appearance of colony-forming units-erythroid (CFU-E) that gave rise to colonies of 8 to 49 cells was observed after 72 h of incubation of day 1 cells in the liquid culture. 125I-rEP was incubated for 5 h at 37 degrees C with purified cells (day 1) or with the cells that had been incubated in liquid culture for an additional 24-72 h, and the presence of erythropoietin (EP) receptors was investigated using autoradiography. Specific binding of 125I-rEP was detected in 19 +/- 7% of the initial day 1 BFU-E. The percentage of 125I-rEP-binding to erythroid progenitor cells and the amount of binding continuously increased as day 1 BFU-E matured. 125I-rEP specific binding was observed with all of the erythroid progenitor cells that had been incubated in liquid culture for 72 h. These data demonstrate that primitive BFU-E have a much lower number of EP receptors than CFU-E and develop an increased concentration of EP receptors in association with their maturation and loss of proliferative capacity.

Adult↗
PubMed1990

Erythropoietin: receptors and clinical use in rheumatoid arthritis.

Erythropoietin (Epo) receptors have been delineated using radioiodinated recombinant erythropoietin (rEpo) and highly purified murine and human erythroid colony-forming units (CFU-e). The murine CFU-e had 950 receptors/cell. One-third had a Kd of 0.09 nM while two-thirds had a Kd of 0.57 nM. Human CFU-e had 1,050 receptors/cell. Two hundred had a Kd of 0.10 nM and 850 had a Kd of 0.57 nM. 125I-rEpo was rapidly internalized and degraded by the CFU-e. Cross-linking of 125I-rEpo to human Epo receptors demonstrated two proteins of 100 and 90 kDa and proteolytic peptide mapping of each protein showed identical fragments indicating that they are very similar. rEpo was also used to treat patients with the anemia of rheumatoid arthritis, and one case is presented in which the patient's hematocrit rose from 32.5% to 44% in eight weeks. When the rEpo was discontinued, the hematocrit fell back to 33%.

Aged↗
PubMed1990

Multicenter study of recombinant human erythropoietin in correction of anemia in rheumatoid arthritis.

PURPOSE: To administer recombinant erythropoietin to patients with rheumatoid arthritis who had significant anemia, while monitoring hematologic and rheumatologic clinical responses as well as potential toxicity. PATIENTS AND METHODS: Seventeen patients with rheumatoid arthritis from five rheumatology care settings were studied. The patients had initial hematocrits of 34% or less and stable clinical status, and were not being treated with second-line drugs or corticosteroids. An 8-week randomized double-blind study involving various dosages of recombinant erythropoietin, as well as placebo, was followed by a 24-week open-label study in which dosage could be titrated to achieve a normal hematocrit. RESULTS: In the 8-week randomized study, four of 13 patients who received injections of recombinant erythropoietin showed a hematologic response, arbitrarily defined as at least a 6-unit increase in hematocrit. None of four placebo-treated patients showed a meaningful hematologic response. All 11 patients who completed the subsequent 24-week open-label study reached a normal hematocrit level at some time during the study, and 10 of 11 showed an increase of hematocrit 6 units or greater. At least one adjustment, i.e., an increase, decrease, or omission of the erythropoietin dosage, was required in all patients to maintain the hematocrit at a target range of 35% for women or 40% for men. Meaningful changes were not seen in patients' capacity to perform activities of daily living or pain levels during either the 8-week randomized study or the 24-week open-label study. No adverse effects were associated with recombinant erythropoietin therapy. CONCLUSION: Patients with rheumatoid arthritis showed excellent hematologic responses to recombinant erythropoietin, without toxicity, during careful monitoring for appropriate dosage adjustment, although a meaningful change in rheumatologic clinical status was not seen.

Activities of Daily Living↗