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T Olofsson

Publications and source records attributed to T Olofsson.

At least 37 records · Page 2Linked to original sources
PubMed1997

Altered expression of the retinoblastoma tumor-suppressor gene in leukemic cell lines inhibits induction of differentiation but not G1-accumulation.

The retinoblastoma tumor-suppressor gene, RB, has been implicated in tumor suppression, in regulation of the cell cycle, and in mediating cell differentiation. RB is necessary for hematopoiesis in mice, and aberrant RB-expression is associated with the progress and prognosis of leukemia. We have used antisense oligonucleotides, established clones stably expressing an antisense RB construct, and also established clones over expressing the retinoblastoma protein (pRb) to study the role of RB expression in monocytic differentiation induced by all-trans retinoic acid (ATRA) or 1-alpha-25-dihyroxycholecalciferol (Vit D3) in the monoblastic cell line U-937 and erythroid differentiation induced by transforming growth factor beta1 (TGFbeta1) and hemin in the erythroleukemic cell line K562. A reduction in pRb production in antisense RB-transfected U-937 clones was shown. Antisense oligonucleotides as well as expression of the antisense RB construct suppressed differentiation responses to ATRA or Vit D3, as judged by the capability to reduce nitro blue tetrazolium, by the appearance of monocyte-related cell surface antigens and by morphologic criteria. K562 cells showed decreased differentiation response to TGFbeta1, but not to hemin, when incubated with antisense oligonucleotides. U-937 antisense RB-transfected cells were also suppressed in their ability to upregulate levels of hypophosphorylated pRb when induced to differentiate. Although U-937 cells incubated with antisense oligonucleotides and clones expressing the antisense RB construct were hampered in their ability to differentiate on incubation with ATRA or Vit D3, the induced G0/G1-accumulation was similar to differentiating control cells treated with ATRA or Vit D3. Intriguingly, U-937 clones overexpressing RB were also inhibited in their differentiation response to ATRA or Vit D3 but not inhibited in their ability to respond with G0/G1 accumulation when induced with these substances. The results indicate that pRb plays a role in induced differentiation of U-937 cells as well as K562 cells involving mechanisms that, at least partially, are distinct from those inducing G1 accumulation.

Animals↗
PubMed1997

Clonal CD5-positive B lymphocytes in myelodysplastic syndrome with systemic vasculitis and trisomy 8.

Bone marrow and peripheral blood from a myelodysplastic syndrome (MDS) patient with trisomy 8 and associated systemic vasculitis was investigated for clonal lymphoid lineage involvement using simultaneous metaphase and interphase fluorescence in situ hybridization (FISH) and immunocytochemistry with antibodies against CD13 (granulocytic), glycophorin A (GPA, erythroid), and the lymphocytic antigens CD3. CD5, CD20, and CD22. Trisomy 8 was detected in 55% of CD13+, 40% of GPA+, 6% of CD5+, and 5% of CD20/22+, but not in CD3+ cells. In a complementary experiment using interphase FISH on bone marrow cells sorted by flow cytometry, 13% of CD5/CD19 double-positive cells (76% purity) were found to be trisomic. The results indicate the existence of a small CD5-positive B-lymphoid clone as part of the MDS process in this patient. Since CD5/19-positive cells have been proposed to be autoantibody producing, this finding might be a clue to the pathogenesis underlying the propensity for MDS patients to develop immune-mediated complications.

B-Lymphocytes↗
PubMed1997

Bernard-Soulier syndrome Karlstad: Trp 498-->Stop mutation resulting in a truncated glycoprotein Ib alpha that contains part of the transmembranous domain.

In Bernard-Soulier syndrome, a hereditary bleeding disorder, the platelets are deficient in the glycoprotein (GP) Ib-IX-V complex, a major receptor for the von Willebrand factor. The components of the complex are encoded by separate genes. Patients with this syndrome have a variable expression level of the receptor protein on platelets depending on the specific genetic abnormality. We describe a patient with life-long bleeding symptoms, who is homozygous for a unique stop mutation. Trp 498-->Stop in the GPIb alpha gene, resulting in a truncated GPIb alpha polypeptide chain. In contrast to previously reported truncated forms of GPIb alpha, this form contains a portion of the transmembranous domain as well as the juxtamembranous cysteines engaged in a disulphide bond with GPIb beta. Flow cytometry with GPIb alpha antibodies demonstrated the presence of GPIb on the patient's platelets, although in reduced amounts compared to normal controls. GPIX was similarly detectable. Immunoblotting demonstrated that the patient synthesized a truncated GPIb alpha of the expected size of 130 K, which was, however, sensitive to proteolysis. These studies show that GPIb alpha lacking the intracytoplasmic tail can be expressed at the platelet surface provided elements of the transmembranous domain are present.

Aged↗
PubMed1996

Expression of the p53 tumor suppressor gene induces differentiation and promotes induction of differentiation by 1,25-dihydroxycholecalciferol in leukemic U-937 cells.

Leukemic U-937 cells, which lack normal p53, were stably transfected with a temperature-sensitive mutant of p53 to investigate the consequences for growth and differentiation. On induction of wild-type p53 activity at the permissive temperature, some of these cells underwent maturation as judged by the capacity for oxidative burst and the appearance of monocyte related cell surface molecules. Moreover, wild-type p53-expressing cells were more sensitive than p53-negative control cells to induction of differentiation by 1,25-dihydroxycholecalciferol; a twofold to fourfold increase of the fraction of cells showing signs of terminal maturation was observed when wild-type p53-expressing cells were incubated with 1,25-dihydroxycholecalciferol at concentrations that only slightly affected control cells. Whereas wild-type p53 activity per se induced maturation of certain cells, other underwent cell death judging from the reduced capability to exclude trypan blue and the appearance of fragmented DNA in flow cytometric analysis. The p53-induced cell death could be inhibited by incubation with 1,25-dihydroxy-cholecalciferol, but not all-trans retinoic acid. Thus, 1,25-dihydroxycholecalciferol, seemed to increase the survival of wild-type p53-expressing cells and to cooperate with wild-type p53 to induce differentiation. The data imply that p53-mediated maturation in U-937 cells depends on optimal regulation of signals for differentiation, survival and proliferation, and suggest a role for p53 in the differentiation induction of leukemic cells.

Apoptosis↗
PubMed1996

Cytokine regulation of GM-CSF and G-CSF secretion by human umbilical cord vein endothelial cells (HUVEC).

The cytokine regulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) and G-CSF secretion by human umbilical cord vein endothelial cells (HUVEC) using quantitative immunoassays was studied. Unstimulated HUVEC produced no CSF. Interleukin 1 (IL-1), TNF and lipopolysaccharides (LPS) had stimulatory effects, with IL-1 being the most potent. GM-CSF and G-CSF secretion followed the same pattern, except that more GM-CSF was secreted. Exposure to stimuli for 30 min induced secretion, and detectable amounts in supernatants were found after 4 h incubation. CSF secretion was strictly regulated by the presence of a stimulus in a concentration dependent manner, and there were no signs of any endogenous downregulatory mechanism. No other cytokine tested had any stimulatory effect of its own. However, addition of IL-3 to stimulated HUVEC enhanced both GM-CSF and G-CSF secretion in a dose-dependent manner. In addition, TNF, and to a lesser degree LPS, enhanced IL-1-induced secretion. The only cytokine with a prominent downregulatory effect was IFN-gamma. IL-4 and IL-10, which downregulate CSF secretion by monocytes, had only minor effects.

Cells, Cultured↗
PubMed1996

Effects of immunosuppressive drugs and antibiotics on GM-CSF and G-CSF secretion in vitro by monocytes, T lymphocytes and endothelial cells.

We studied the effects of eight antibiotics, cyclosporin and corticosteroids on the in vitro secretion of GM-CSF and G-CSF by monocytes. T lymphocytes and endothelial cells. The aim was to evaluate a possible mechanism for these drugs in the delay of haemopoietic recovery after high-dose chemotherapy or bone marrow transplantation. Corticosteroids were prominent inhibitors of GM-CSF secretion by monocytes and T lymphocytes, but not by endothelial cells. In contrast, G-CSF secretion by monocytes was unchanged whereas that of endothelial cells was enhanced in the presence of corticosteroids. Cyclosporin efficiently down-regulated GM-CSF secretion by T lymphocytes and had also a minor effect on CSF secretion by endothelial cells, whereas monocyte secretion was unaffected. Stimulated T lymphocytes derived from patients under treatment with cyclosporin had impaired capacity to secrete GM-CSF compared to controls. Among the antibiotics, cephalosporins inhibited GM-CSF secretion by T lymphocytes, and GM- and G-CSF secretion by endothelial cells. Ciprofloxacin and sulphmethoxazole had minor effects on GM-CSF secretion by T lymphocytes and endothelial cells. No antibiotic significantly influenced GM-CSF secretion by monocytes.

Adrenal Cortex Hormones↗
PubMed1995

Aggressive course of primary plasma cell leukemia with unusual morphological and cytogenetic features.

A case of aggressive plasma cell leukemia with unusual morphological and cytogenetic features is reported. A 65-year-old man was admitted to hospital due to anemia, thrombocytopenia, and renal insufficiency. Bone marrow examination and peripheral blood smear revealed a large number of pleomorphic cells with convoluted and multilobulated nuclei. Immunohistochemistry of the bone marrow biopsy was negative for anti-keratin antibodies CAM.5.2 and AE1/AE3, but positive for EMA. The immunophenotypic features of these cells were suggestive of plasma cell origin with positivity for CD38, CD56, CD9, and CD44 and a weak positivity for CD71 and CD45 (40% of the cells), while all other markers of hematopoietic origin were negative. Furthermore, a serum protein electrophoresis showed a monoclonal component type IgG-kappa of 70 g/l. The cytogenetic analysis demonstrated a hypotetraploid clone with multiple numerical and structural abnormalities. Although some of the aberrations found are associated with plasma cell malignancies--e.g., structural rearrangement of chromosome 1, del(6q), and monosomy 13--the karyotypic complexity in the present case is unusual. The course of the disease was very aggressive, and the patient died 3 days after admission.

Aged↗
PubMed1993

Specific binding and uptake of extracellular nicotinamide in human leukemic K-562 cells.

Extracellular nicotinamide is well recognized as the primary precursor to the cellular synthesis of NAD. NAD is a pivotal molecule in regulating the energy and redox potentials of cells via synthesis of ATP and NAD(P)/NAD(P)H ratios. NAD turnover in cells is very rapid due to NAD catabolism via ADP-ribosylation reactions. These facts suggest that the cellular uptake and transport of nicotinamide may not be a passive process but a highly regulated cellular event. We have utilized radiometric procedures to characterize the uptake of [14C]nicotinamide in human leukemic K-562 cells. At physiologically relevant doses of nicotinamide (< 100 microM), the uptake was saturable with a Km of 2.3 +/- 1.0 microM and a Vmax of about 1.5 +/- 0.5 pmol/10(6) cells/min. Kinetic studies revealed that nicotinamide was first taken up intracellularly and then immediately converted to NAD and 1-methyl nicotinamide. All of the nicotinamide taken up into the cell was bound tightly to plasma membranes (25,000 g pellet) with Kd values between 3.2 and 12.7 microM and a Bmax of 1.56 pmol/10(6) cells. The specificity of nicotinamide binding was demonstrated by competitive inhibition experiments using NAD analogs, nicotinamide derivatives, and agonists or antagonists of plasma membrane receptors. We conclude that there is specific binding of nicotinamide, followed by intracellular uptake and immediate synthesis to NAD.

Binding, Competitive↗
PubMed1993

Flow cytometric clonal excess analysis of peripheral blood, routine handling, and pitfalls in interpretation.

Clonal excess (CE) analysis by flow cytometry is a convenient method to detect minimal involvement of peripheral blood and bone marrow by B-cell lymphoma. The method is based on evaluation of the congruity between kappa and lambda light chain distributions within a normal B-cell population. By using the Kolmogorov-Smirnov method for evaluation of histogram identity, the maximum difference (D value) between distributions is calculated. However, variable adsorption of cytophilic plasma immunoglobulin (Ig) to CD16 positive cells, T-cell subsets, and the B cells themselves may cause incongruity between the light chain distributions that might simulate or disguise a true clonal excess and thus create major pitfalls in the interpretation of the CE analysis. These phenomena are observed both in normal blood donors and in patients with non-Hodgkin's lymphoma. In the present report we describe: (1) how freezing of the isolated mononuclear cells before immunostaining effectively removes most of the adsorbed cytophilic Ig, (2) how by exclusion of the CD16 positive population further resolution of the relevant histogram shape is obtained to avoid false interpretations of incongruity, and (3) how adsorption of Ig to B-cells creates a typical pattern of "reciprocal labeling" that can be mistaken for a clonal excess. Based on our observations we argue against an uncritical use of normal D values for definition of clonal excess and advocate an analytic evaluation of the kappa and lambda overlay distribution by dual immunofluorescence, either by excluding CD16 positive cells or by including only B cells, to reveal the nature of the different deviations.

Cell Separation↗
PubMed1992

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) secretion by adherent monocytes measured by quantitative immunoassays.

The kinetics of GM-CSF and G-CSF secretion by purified adherent human monocytes were studied by quantitative immunoassays. Interleukin-1 (IL-1); 4-40 ng/ml and E. coli lipopolysaccharide (LPS); 0.1-1.00 ng/ml, were the most effective stimuli and induced dose-dependent secretion of both GM-CSF and G-CSF. Secretion of newly synthesized CSF was detectable 3-6 hours after stimulation and continued for approximately 24 h. Twenty minutes pulse exposure to LPS was sufficient to induce half maximum secretion of GM-CSF, and after 24-36 h the adherent monocytes could not be restimulated. Neither GM-CSF nor TNF could down-regulate the secretion of GM-CSF. IL-3 induced a minor secretion of GM-CSF whereas TNF, G-CSF, M-CSF and IFN-gamma were unable to induce GM-CSF secretion. In addition to LPS and IL-1, GM-CSF and to a minor degree TNF induced G-CSF secretion. Enriched T lymphocytes secreted GM-CSF, but not G-CSF, after stimulation with PHA or staphylococcal enterotoxin A (SEA), whereas LPS and IL-1 were without stimulatory effects. We also noted that enriched T lymphocytes added to LPS-stimulated adherent monocytes at ratios of 1:10 or more inhibited, in a dose-dependent fashion, GM-CSF secretion by 13-55%. These findings add new quantitative data on CSF secretion by human monocytes.

Cell Adhesion↗
PubMed1991

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) in serum during induction treatment of acute leukaemia.

Granulocyte-macrophage colony stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) are increasingly used to stimulate granulopoiesis in neutropenic patients but in most cases without any knowledge of the endogenous CSF-levels. With the purpose to define serum levels of GM-CSF and G-CSF during induction chemotherapy and haematological reconstitution in patients with acute leukaemia we have used enzyme-linked immunosorbent assay (ELISA) techniques to measure these growth factors in 18 patients with acute myeloid leukaemia (AML) and eight patients with acute lymphoblastic or undifferentiated leukaemia (ALL/AUL). G-CSF above 0.05 ng/ml was detected in 54% of the analysed AML samples, median 0.29 (range 0.05-2.80) ng/ml; and in 40% of analysed ALL/AUL samples, median 0.09 (range 0.05-3.00) ng/ml. In patients with AML there was a clear correlation between an elevated serum concentration of G-CSF and documented infections. On the other hand, 15/18 of the patients with acute myeloid leukaemia and 8/8 patients with ALL/AUL had non-detectable levels of GM-CSF (less than 0.10 ng/ml). Two patients had measurable levels of GM-CSF in all samples, median 0.71 (range 0.26-1.18) ng/ml and in these patients the levels successively decreased during and after chemotherapy and did not increase in response to infections. In normals detectable levels of GM-CSF were found in 2/35 individuals and G-CSF in 0/10 individuals.

Acute Disease↗
PubMed1991

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) in serum in bone marrow transplanted patients.

Colony-stimulating factors (CSF) are being increasingly used to accelerate hematopoietic recovery after bone marrow transplantation. To study the endogenous serum levels of CSF in bone marrow transplanted patients we have used immunoassays measuring granulocyte-macrophage colony-stimulating factor (GM-CSF) with a sensitivity of 0.10 ng/ml and granulocyte colony-stimulating factor (G-CSF) with a sensitivity of 0.05 ng/ml. Serum samples, taken from the conditioning treatment until engraftment, were analysed in 13 patients receiving allogeneic transplants and in eight patients receiving autologous transplants. Ten patients had acute myeloid leukemia, seven acute lymphoblastic leukemia, one acute undifferentiated leukemia, two non-Hodgkin's lymphoma and one multiple myeloma. Samples were taken 1-2 times before transplantation and 1-2 times per week after transplantation (median of 46 days in allotransplant recipients and 32 days in autotransplant recipients); 17% of the allogeneic transplanted patients and 35% of the autologous transplanted patients had detectable levels of G-CSF. In both types of transplantation the G-CSF concentrations were low: median 0.06 (range 0.05-0.14) and 0.08 (range 0.05-0.40) ng/ml respectively. GM-CSF was detected only in one analysed sample in all patients. There was no evidence of increased CSF levels related to engraftment or documented infections.

Acute Disease↗
PubMed1990

Tumor associated myelopoiesis inhibiting factors.

The best characterized hemopoietic growth inhibitors in myeloid leukemias are leukemia associated inhibitor (LAI) and leukemia inhibitory activity (LIA). Both are normal cell products overproduced in leukemia. LIA is identical to acid isoferritin and LAI is not identical to LIA. They act in different ways to inhibit normal stem cell growth. The over-production of these putative normal regulators may explain the suppression of normal hemopoiesis typical of myeloid leukemias. Modulation of the production and the action of LAI and LIA therefore have potential therapeutic value in leukemia.

Bone Marrow↗
PubMed1989

Cell-mediated inhibition of granulopoiesis in vitro in patients with acute myeloid leukemia in remission.

We investigated the in vitro granulopoiesis in 11 patients with acute myeloid leukemia (AML) in complete remission 3-80 months after diagnosis (median 8.5 months). 3 of the patients had subnormal levels of bone marrow-derived CFU-GM. 6 of 10 patients tested had defective recloning capacity of d-7 CFU-GM, suggesting a stem cell defect. Most patients (7/11) showed an increased colony growth of bone marrow-derived CFU-GM after T-cell depletion by E-rosetting, while readdition of isolated autologous T cells to T-cell depleted marrow caused a dose-dependent inhibition of colony formation; bone marrow T cells were more effective in this inhibition than peripheral blood T cells. Experiments using cells depleted of either CD4- or CD8-positive cells and CD4/CD8-enriched cell populations showed that both CD4- and CD8-positive cells had the capacity to inhibit colony growth. Long-term culture of bone marrow cells in suspension showed that the production of CFU-GM declined at about the same rate as in normal controls. Our findings suggest that there are persisting stem cell defects in patients with AML in remission and that the cell growth regulatory systems may be altered. These abnormalities could possibly be an effect of residual damage to the hematopoietic system caused by intensive chemotherapy.

Bone Marrow↗