PubMed Health⌕ Search

Biomedical subjects

H Strobl

Publications and source records attributed to H Strobl.

61 records · Page 4Linked to original sources
PubMed1992

Induction of differentiation of human mast cells from bone marrow and peripheral blood mononuclear cells by recombinant human stem cell factor/kit-ligand in long-term culture.

In the murine system, a number of cytokines (including interleukin-3 [IL-3], IL-4, and stem cell factor [SCF]) promote the growth of mast cells (MCs). However, so far little is known about factors controlling differentiation of human MCs. Recent data suggest that human MCs express receptors (R) for SCF. The aim of the present study was to investigate whether recombinant human (rh) SCF induces differentiation of human MCs from their precursor cells. For this purpose, bone marrow (BM; normal donors, n = 6) and peripheral blood (PB; normal donors, n = 11) mononuclear cells (MNC) were cultured in the presence of rhSCF, rhIL-3, rhIL-4, rhIL-9, recombinant human macrophage colony-stimulating factor (rhM-CSF), or control medium in long-term (8 weeks) suspension cultures. After 4 weeks, up to 5% of the MNC (BM and PB) cultured in the presence of rhSCF, but not in the presence of other cytokines, were found to exhibit the characteristics of MCs. These MCs expressed the YB5.B8-reactive domain of the SCF R as well as IgE R, as determined by combined toluidine blue/immunofluorescence staining. Myeloid antigens, likewise expressed on human basophils (ie, CD11b, CDw65, and Bsp-1), could not be detected on these cells. Furthermore, rhSCF, but not rhIL-3, rhIL-4, rhIL-9, or rhM-CSF, induced dose- and time-dependent increases in the formation of cellular tryptase (an MC-specific enzyme) (rhSCF [100 ng/mL], 1,308 +/- 679 ng/mL v control medium, 18 +/- 6 ng/mL tryptase on day 35 of PB cell cultures), as well as an increase in cellular histamine. After 6 to 8 weeks, when other mature hematopoietic cells decreased, MCs still could be detected in culture, with up to 40% of all cells being MCs. To test whether rhSCF also activates tissue MCs, we performed histamine release experiments (dispersed tissue; lung, n = 3; uterus, n = 3). SCF was found to enhance (by up to 3.4-fold) the capacity of the MCs to release histamine upon cross-linkage of IgE R with anti-IgE. Together, these observations suggest that rhSCF induces in vitro differentiation of human MCs from their BM and PB precursor cells in long-term culture and upregulates MC releasability.

Antibodies, Monoclonal↗
PubMed1992

Antigenic analysis of human haemopoietic progenitor cells expressing the growth factor receptor c-kit.

The cell surface molecule encoded by the protooncogene c-kit has recently been identified as the receptor for a growth factor variously termed stem cell factor (SCF), mast cell growth factor or steel factor. Using the c-kit antibody 17F11 we analysed, in triple staining experiments, the surface molecule profile and scatter characteristics of c-kit+CD34+ human haemopoietic progenitor cells. In 10 normal bone marrow samples we found 19-51% of CD34+ bone marrow progenitor cells to coexpress c-kit. These c-kit+CD34+ bone marrow cells turned out to represent a phenotypically heterogeneous population. A considerable proportion coexpressed CD33 (52 +/- 23%), and/or CD71 (62 +/- 26) antigens, marker molecules previously shown to be expressed by committed in vitro colony forming cells but not by their precursors. In line with a relatively differentiated phenotype c-kit+CD34+ cells also gave rise to on average higher forward and right-angle light scattering signals. The proportions of CD38 and/or HLA-D expressing cells were similar in the c-kit+ and in the c-kit- subsets of CD34+ progenitor cells. Coexpression of CD19 was found to be less frequent in the c-kit+ (4 +/- 5%) as compared to the c-kit- (17 +/- 14%) fraction of CD34+ cells. CD7+ CD34+ bone marrow cells were hardly detectable and their numbers too low to allow further subdivision in c-kit+ and c-kit- subsets.

Antigens, CD↗
PubMed1991

IL-4 regulates c-kit proto-oncogene product expression in human mast and myeloid progenitor cells.

The c-kit proto-oncogene encodes the receptor for a novel hemopoietic cytokine, termed stem cell factor (SCF) or mast cell growth factor (MGF) according to its stimulating spectrum. The human receptor for SCF/MGF is expressed in a subset of normal bone marrow progenitor cells, in leukemic myeloid cells, and in mast cells. In the present study, the effects of recombinant human growth regulators (IL-1 through -9, granulocyte-macrophage/granulocyte/macrophage-CSF, IFN, and TNF) on c-kit proto-oncogene product expression were analyzed by indirect immunofluorescence, by using the anti-SCF/MGFR mAb YB5.B8, and Northern blot analyses, by using a c-kit oligonucleotide probe. Of all cytokines tested, IL-4 was found to down-regulate expression of YB5.B8 Ag in the human mast cell line HMC-1 (maximum inhibition, 51.05 +/- 16.36% mean fluorescence intensity of control; p less than 0.02), as well as in primary leukemic myeloid cells. IL-4 was also found to down-regulate expression of YB5.B8 Ag in normal enriched bone marrow progenitor cells. The effects of IL-4 on expression of YB8.B8 Ag in myeloid/mast cell progenitors was dose and time dependent (maximum effects observed on days 2 and/or 4, by using 50 U/ml of rIL-4) and could be neutralized by using anti-IL-4 mAb. Moreover, IL-4 was found to down-regulate expression of c-kit mRNA in leukemic myeloid cells as well as in HMC-1 cells. Together, these observations identify IL-4 as a regulator of c-kit proto-oncogene product expression in the human system. The effects of IL-4 on human hemopoietic progenitor cells and mast cells may be mediated in part through regulation of SCF/MGFR expression.

Antibodies, Monoclonal↗
PubMedDate not supplied

Monitoring of hematopoietic recovery after autologous stem cell transplantation by analysis of G alpha 16 mRNA and CD34 surface glycoprotein.

The hematopoiesis-specific G protein alpha subunit G alpha16 was shown to be expressed in early normal and malignant hematopoietic cell lines and has been suggested to play an important role in signal transduction of hematopoiesis. We previously demonstrated a strict correlation of G alpha16 mRNA and CD34 antigen expression in peripheral blood stem cells (PBSC). In PBSC mobilization, both markers are detectable at the time of hematopoietic recovery and progenitor cell release. In this study the possible use of G alpha16 determination in peripheral blood samples for monitoring patients undergoing stem cell transplantation was investigated. Normal peripheral blood is negative for G alpha16 expression. In all five patients G alpha16 mRNA expression appeared shortly before the time of blood cell recovery. When tested together with CD34 (three cases) a pattern different from CD34 antigen expression was found, reflecting a different mechanism of action. In two cases with different time points of leukocyte and platelet recovery G alpha16 mRNA was detected at both time points but not in the interval, thus suggesting a role of G alpha16 in multipotent precursor cells. CD34 mRNA tested in three patients was not detected at any time; this argues for different regulation of CD34 and G alpha16 mRNA. G alpha16 may be used as an indicator of hematopoietic recovery after autologous stem cell transplantation, suggesting that there are cell type-specific G protein-mediated signal transduction pathways of early hematopoiesis.

Adult↗
PubMedDate not supplied

Myeloid cell-associated lysosomal proteins as flow cytometry markers for leukocyte lineage classification.

Lysosomal proteins including myeloperoxidase (MPO), lysozyme (LZ), CD68 and lactoferrin (LF), represent classical immunohistology marker molecules. Additionally, flow cytometry can be used to detect and quantify their expression at the single cell level in phenotypically defined leukocyte subsets. Recent results demonstrated that expression densities of these intracellular proteins vary among myeloid cell subsets, thus enabling insights into novel subset biology and development. Additionally, whole blood staining protocols allow detection of lysosomal proteins in infrequent leukocyte subsets such as circulating CD34+ hematopoietic progenitors and dendritic cells (DC). Thus, information on leukocyte subset distribution and aberrant phenotypes might be gained for diagnositic purposes. Finally, FACS detection of MPO and LZ proved to be of high value for the lineage diagnosis of acute leukemias.

Antigens, CD↗
PubMedDate not supplied

Relationship between MDR1 gene and surface markers in acute myeloid leukemia.

The MDR1 gene is of prognostic significance in acute myeloid leukemia (AML). The relationship of this gene to surface markers largely remains unclear. Therefore, we have studied the association of MDR1 gene expression with the expression of specific surface markers in AML. MDR1 RNA expression of leukemic cells was determined by slot blot analysis. Expression of P-glycoprotein and surface markers (CD7, CD13, CD19, CD34, HLA-DR, TdT, blood group H) was assessed by immunocytochemistry. MDR1 RNA (n = 79) and P-glycoprotein (n = 52) expression were detected in 63% and 63% of the patients, respectively. CD7, CD13, CD19, CD34, HLA-DR, TdT and blood group H were positive in 17%, 84%, 0%, 51%, 82%, 11% and 11% of the patients. MDR1 RNA or P-glycoprotein expression were not associated with the expression of either CD7, CD13, CD19, CD34, TdT or blood group H. However, P-glycoprotein expression was more frequent in HLA-DR positive than in HLA-DR negative patients (47% versus 10%, p = 0,04). Consistent with the latter finding, patients with intermediate or high MDR1 RNA expression expressed HLA-DR more frequently than patients with negative or weak MDR1 RNA expression (96% versus 76%, p = 0,03). In conclusion, MDR1 gene expression of AML cells was independent of surface markers except HLA-DR.

ATP Binding Cassette Transporter, Subfamily B, Mem↗