Increased glycocalicin index and normal thrombopoietin levels in patients with idiopathic thrombocytopenic purpura with a decreased rate of platelet production.

Platelet kinetic studies in idiopathic thrombocytopenic purpura (ITP) have shown that in a subgroup of patients a shortened mean platelet life (MPL) is associated with a decreased platelet production rate (PPR). Other methods of studying certain aspects of thrombocytopoiesis are the plasma concentrations of thrombopoietin and glycocalicin.

Stem cell factor synergistically enhances thrombopoietin-induced STAT5 signaling in megakaryocyte progenitors through JAK2 and Src kinase.

Stem cell factor (SCF) has a potent synergistic effect during megakaryopoiesis when administered in combination with the major megakaryocytic cytokine, thrombopoietin (TPO). In this study we analyzed the underlying mechanisms with regard to STAT5 activity. TPO stimulation of MO7e cells resulted in STAT5 transactivation, which could be enhanced 1.

Increased peripheral platelet destruction and caspase-3-independent programmed cell death of bone marrow megakaryocytes in myelodysplastic patients.

To investigate underlying mechanisms of thrombocytopenia in myelodysplastic syndrome (MDS), radiolabeled platelet studies were performed in 30 MDS patients with platelet counts less than 100 x 10(9)/L. Furthermore, plasma thrombopoietin and glycocalicin index (a parameter of platelet or megakaryocyte destruction) were determined. Mean platelet life (MPL), corrected for the degree of thrombocytopenia, was reduced in 15 of 30 patients (4.

Ultrastructural study shows morphologic features of apoptosis and para-apoptosis in megakaryocytes from patients with idiopathic thrombocytopenic purpura.

To investigate whether altered megakaryocyte morphology contributes to reduced platelet production in idiopathic thrombocytopenic purpura (ITP), ultrastructural analysis of megakaryocytes was performed in 11 ITP patients. Ultrastructural abnormalities compatible with (para-)apoptosis were present in 78% +/- 14% of ITP megakaryocytes, which could be reversed by in vivo treatment with prednisone and intravenous immunoglobulin. Immunohistochemistry of bone marrow biopsies of ITP patients with extensive apoptosis showed an increased number of megakaryocytes with activated caspase-3 compared with normal (28% +/- 4% versus 0%).

In vitro megakaryocyte expansion in patients with delayed platelet engraftment after autologous stem cell transplantation.

Increasing the number of megakaryocytic cells in stem cell transplants by ex vivo expansion culture may provide an approach to accelerate platelet engraftment after high-dose chemotherapy. However, it is unknown if a relationship exists between the expansion potential of progenitor cells and the time to platelet engraftment in vivo. Therefore, we questioned if those patients who potentially would benefit most from expanded cell supplements are able to generate megakaryocytic cells efficiently in vitro.

An inhibitor of PI3-K differentially affects proliferation and IL-6 protein secretion in normal and leukemic myeloid cells depending on the stage of differentiation.

In this study, we examined the involvement of the phosphatidylinositol 3-kinase (PI3-K) and p70S6 kinase signal transduction pathway in the interleukin-1(IL-1)-mediated proliferation and cytokine production by normal and leukemic myeloid cells. Total AML blast populations, early progenitor (CD34(+)/CD36(-)) cells, and more differentiated (CD34(-)/CD36(+)) cells were treated with the PI3-K inhibitor Ly294002 and p70S6K inhibitor rapamycin. The effects on proliferation, IL-6 protein secretion, and intracellular signaling cascades were determined and compared with normal CD34(+) cells and monocytes.

Differential effects of interleukin-3 and interleukin-1 on the proliferation and interleukin-6 protein secretion of acute myeloid leukemic cells; the involvement of ERK, p38 and STAT5.

In the present study we examined whether the p38 and extracellular signal-regulated kinase (ERK) signal transduction pathways are involved in the interleukin-3 (IL-3)- or interleukin-1 (IL-1)-mediated proliferation and cytokine production of acute myeloid leukemic (AML) cells. The IL-3- and IL-1-mediated proliferation were both inhibited by the specific p38 and MEK1 inhibitors SB203580 and PD98059, respectively. Specificity of these inhibitors was demonstrated by in vitro kinase assays.

A dual function for p38 MAP kinase in hematopoietic cells: involvement in apoptosis and cell activation.

In the present study we examined in more detail the dual role of the c-JUN N-terminal kinase (JNK) and p38 stress-activated protein kinase pathways in mediating apoptosis or cellular activation in hematopoietic cells. Growth factor deprivation of the erythroleukemic cell line TF-1 led to apoptosis which was associated with an enhanced activity of JNK and p38 and immediate dephosphorylation of the extracellular signal-regulated kinases (ERKs). Enhanced activity of p38 and JNK was not only observed during apoptosis but also in TF-1 cells stimulated with IL-1.

Interleukin-15 differentially enhances the expression of interferon-gamma and interleukin-4 in activated human (CD4+) T lymphocytes.

In this study interleukin (IL)-15 was examined for its ability to modulate the expression of interferon-gamma (IFN-gamma) and IL-4 in activated human T lymphocytes. The effect of IL-15 was compared with IL-2 and IL-7, cytokines all known to use the IL-2 receptor gammaC chain. The results demonstrate that the extent of upregulation of IFN-gamma and IL-4 mRNA was dependent on the applied cytokine (IL-2>IL-15>IL-7) and on the stimulatory signal.

Beta-adrenoceptor-mediated inhibition of IFN-gamma, IL-3, and GM-CSF mRNA accumulation in activated human T lymphocytes is solely mediated by the beta2-adrenoceptor subtype.

Cytokine gene expression in T lymphocytes is a strictly regulated process, involving both stimulatory and inhibitory signals. beta-Adrenoceptor (betaAR) agonists are widely used in the treatment of asthma and are able to induce an inhibitory signal on immunological responses after binding to their specific receptors. In this study, the characterization of betaAR subtype(s) (beta1, beta2, and beta3) involved in the regulation of interleukin (IL)-3, IL-4, granulocyte-macrophage colony-stimulating factor (GM-CSF), and interferon-gamma (IFN-gamma) mRNA accumulation was studied by using various betaAR agonists and antagonists.

The supportive effects of erythropoietin and mast cell growth factor on CD34+/CD36- sorted bone marrow cells of myelodysplasia patients.

In the present study, we analyzed the capacity of CD34+/CD36- sorted bone marrow cells of myelodysplasia patients (n = 4) to differentiate along the erythroid lineage in the presence of erythropoietin (Epo) and mast cell growth factor (MGF). Two subgroups could be identified. In 6 patients, a normal number of burst-forming units-erythroid (BFU-Es) were cultured from CD34+/CD36- sorted cells.

Divergent effects of IL-10 and IL-4 on the proliferation and growth factor secretion by acute myeloblastic leukemic cells.

The effects of interleukin-10 (IL-10) and IL-4 were studied on the spontaneous and IL-1, IL-3, and Granulocyte-Colony Stimulating Factor (G-CSF) supported proliferation of acute myeloid leukemic cells. IL-10 inhibited the spontaneous proliferation in 1 out of 12 (1/12) cases while the IL-1 stimulated the tritiated thymidine (3H-TdR) uptake was suppressed in 2/12 cases as a result of IL-10 administration. In the presence of G-CSF, IL-10 affected 3H-TdR uptake in 2/12 and no distinct changes were observed in the presence of IL-3.

The spontaneous expression of interleukin-1 beta and interleukin-6 is associated with spontaneous expression of AP-1 and NF-kappa B transcription factor in acute myeloblastic leukemia cells.

The nature of the spontaneous expression of cytokines that is observed in blasts of some AML patients is unclear. We studied whether or not the spontaneous expression of IL-1 beta and IL-6 is due to an increased transcription rate of the cytokine gene and associated with a spontaneous expression of two transcription factors that play an important role in IL-1 beta and IL-6 gene transcription, namely activator protein-1 (AP-1) and nuclear factor-kappa B (NF-kappa B). In eight of the 19 AML patients a spontaneous expression of IL-1 beta mRNA was observed, whereas IL-6 mRNA was expressed in seven of the cases.

The effects of IL-1 and IL-4 on the Epo-independent erythroid progenitor in polycythaemia vera.

Human recombinant interleukin-1 (IL-1) was studied for its effects on the erythroid progenitors from normal subjects and from patients with polycythaemia vera (PV). No supportive effect of IL-1 was noticed on the normal, erythropoietin (Epo) dependent, erythroid burst-forming unit (BFU-E) using peripheral blood or bone marrow. In contrast, the Epo-independent BFU-E from peripheral blood of PV patients could be stimulated significantly.

Effect of ultrafilterable platinum concentration on cisplatin and carboplatin cytotoxicity in human tumor and bone marrow cells in vitro.

The importance of the ultrafilterable platinum (fPt) fraction of cisplatin (CDDP) and carboplatin (CBDCA) for cytotoxicity and myelotoxicity was studied in vitro. By incubating CDDP or CBDCA with fetal calf serum (FCS) various fractions of fPt were prepared and determined by atomic absorption spectroscopy. A relation of % fPt fraction and incubation time (h) of 87e-0.

Interleukin-4-mediated inhibition of C-Fos mRNA expression: role of the lipoxygenase directed pathway.

Interleukin-4 inhibits several monocyte functions like A23187-induced expression of cytokines and c-fos and c-jun proto-oncogene mRNA expression. In an attempt to elucidate the mechanism by which this inhibitive effect is mediated, we compared the effect of IL-4 on A23187-induced c-fos and c-jun mRNA expression in conjunction with inhibitors that selectively inhibit the cyclooxygenase dependent (indomethacin) and lipoxygenase dependent (NDGA) pathway of arachidonic acid (AA) metabolism. NDGA inhibited A23187-induced c-fos mRNA expression by a similar magnitude as IL-4, whereas the effect of indomethacin was only minor.

Differential regulation of M-CSF and IL-6 gene expression in monocytic cells.

Using the human monocytic cell line Mono Mac 6 we studied the involvement of Ca2+, protein kinase A (PKA), and protein kinase C (PKC) dependent pathways in the regulation of M-CSF and IL-6 gene expression. The results demonstrate that on activation with the calcium ionophore A23187 both M-CSF and IL-6 mRNA are induced after 3 and 6 h respectively. Co-stimulation with A23187 plus PMA resulted in an up-regulation of M-CSF mRNA and a down-regulation of IL-6 mRNA.

Interleukin-4 mRNA and protein in activated human T cells are enhanced by interleukin-7.

We studied the effect of the stroma-derived cytokine interleukin-7 (IL-7) on the expression of IL-4 in human T cells at mRNA and protein level. The results demonstrate that IL-7 did not induce IL-4 mRNA in resting T cells. However, concanavalin A (con A)-induced IL-4 mRNA expression was enhanced by costimulation with con A plus IL-7.

Recombinant human mast cell growth factor supports erythroid colony formation in polycythemia vera in the presence and absence of erythropoietin and serum.

The effect of mast cell growth factor (MGF) was studied on erythropoietin (Epo)-dependent and Epo-independent ("spontaneous") erythroid colony formation in patients with polycythemia vera (PV). MGF stimulated both Epo-dependent and Epo-independent erythroid colony formation from PV peripheral blood progenitor cells in vitro at a dose similar to normal erythroid progenitor. In addition, evidence was obtained that the stimulating effect of MGF was a direct effect on the erythroid progenitor and independent of serum.

Interferon-gamma enhances the LPS-induced G-CSF gene expression in human adherent monocytes, which is regulated at transcriptional and posttranscriptional levels.

Human adherent monocytes were studied with regard to the expression of granulocyte colony-stimulating factor (G-CSF) at mRNA and protein levels in response to lipopolysaccharide (LPS) and gamma-interferon (IFN-gamma) stimulation. Monocytes did not express G-CSF transcripts in response to IFN-gamma treatment. In contrast, monocytes exposed to IFN-gamma plus LPS showed a dose-dependent increase in G-CSF mRNA accumulation and protein secretion compared to LPS-stimulated monocytes.

IL-7 enhances the expression of IL-3 and granulocyte-macrophage-CSF mRNA in activated human T cells by post-transcriptional mechanisms.

The stromal derived growth factor IL-7 was studied for its ability to modulate cytokine expression in human T cells. IL-7 alone did not induce IL-3 or granulocyte-macrophage-CSF (GM-CSF) mRNA. However, IL-7 enhanced the Con A-induced IL-3 and GM-CSF mRNA accumulation in a dose-dependent way.

The release of endotoxin from antibiotic-treated Escherichia coli and the production of tumour necrosis factor by human monocytes.

The influence of antibiotic-induced release of endotoxin from in-vitro grown Escherichia coli on the production of tumour necrosis factor-alpha (TNF) by human monocytes was studied. Antibiotics tested were: cefuroxime (7.5 and 75 mg/L); ceftazidime (10 and 100 mg/L); aztreonam (10 and 100 mg/L); imipenem (10 and 100 mg/L); and tobramycin (8 mg/L).

Interleukin-4 inhibits the lipopolysaccharide-induced expression of c-jun and c-fos messenger RNA and activator protein-1 binding activity in human monocytes.

We studied the effect of interleukin-4 (IL-4) on the lipopolysaccharide (LPS) induction of two immediate early genes c-fos and c-jun. These genes encode proteins that form the dimeric complex activator protein-1 (AP-1), which is active as a transcriptional factor. Maximal accumulation of either c-fos and c-jun messenger RNA (mRNA) occurred 30 minutes after LPS addition.

Transcriptional and posttranscriptional regulation of the interleukin-4 and interleukin-3 genes in human T cells.

Human T cells were studied with regard to the regulation of interleukin-4 (IL-4) and IL-3 gene expression. IL-4 and IL-3 mRNA were undetectable in unstimulated T cells. On activation with the lectin concanavalin A (Con A), both IL-4 and IL-3 mRNA were expressed.