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B Torok-Storb

Publications and source records attributed to B Torok-Storb.

At least 37 records · Page 2Linked to original sources
PubMed1998

Impaired induction of the CD28-responsive complex in granulocyte colony-stimulating factor mobilized CD4 T cells.

Use of the CD28/B7 costimulatory signal for T-cell activation was analyzed in granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood mononuclear cells (G-PBMCs) and in peripheral blood mononuclear cells obtained before administration of G-CSF (preG-PBMCs). CTLA4Ig inhibition of OKT3-stimulated proliferation was significantly lower in G-PBMCs compared with preG-PBMCs (39.9% +/- 5.6% and 72.2% +/- 5.4%, respectively; P < .001). Furthermore, as shown in electrophoretic mobility-shift assays, the inducible level of the T-cell transcription factor CD28 responsive complex (CD28RC) was suppressed in CD4 cells derived from G-PBMC. However, depletion of CD14 cells from G-PBMCs restored CD28RC induction to normal levels. Taken together, these findings suggest that the large number of CD14 monocytes in G-PBMCs may limit T-cell responsiveness by suppressing the induction of the CD28RC.

Abatacept↗
PubMed1998

The human homolog of rat Jagged1 expressed by marrow stroma inhibits differentiation of 32D cells through interaction with Notch1.

A cDNA clone encoding the human homolog of rat Jagged1 was isolated from normal human marrow. Analyses of human stromal cell lines indicate that this gene, designated hJagged1, is expressed by marrow stromal cells typified by the cell line HS-27a, which supports the long-term maintenance of hematopoietic progenitor cells. G-CSF-induced differentiation of 32D cells expressing Notch1 was inhibited by coculturing with HS-27a. A peptide corresponding to the Delta/Serrate/LAG-2 domain of hJagged1 and supernatants from COS cells expressing a soluble form of the extracellular portion of hJagged1 were able to mimic this effect. These observations suggest that hJagged1 may function as a ligand for Notch1 and play a role in mediating cell fate decisions during hematopoiesis.

Adult↗
PubMed1998

Ex vivo expansion of immature 4-hydroperoxycyclophosphamide-resistant progenitor cells from G-CSF-mobilized peripheral blood.

The application of ex vivo expansion to cell products pharmacologically purged in vitro may provide sufficient numbers of cells for rapid engraftment in a product with reduced tumor burden. To pursue this possibility we evaluated the effect of 4-hydroperoxycyclophosphamide (4-HC) treatment on granulocyte colony-stimulating factor-mobilized peripheral blood stem cells (G-PBSC) and their subsequent expansion potential. A small number of G-PBSC CD34+ cells are resistant to 4-HC and are phenotypically and functionally immature. 4-HC-resistant G-PBSC cells are CD34+ bright, CD38+/-, DR(lo), CD13(lo), CD33-, CD71-, and rhodamine dull. In six experiments, treating G-PBSC with 60 microg/mL of 4-HC at 37 degrees C for 30 minutes reduced the number of colony-forming units (CFUs) per 5000 CD34+ cells by 96.3% (from 1333 +/- 137 to 46.5 +/- 11). This purging also reduced the frequency of 5-week long-term culture initiating cells (LTC-ICs) from 1/39 (range 1/27 to 1/62) to <1/1680 (range 1/1180 to 1/2420). Ex vivo expansion cultures were used to compare the proliferative potential of treated and untreated CD34+ cells. These cells were cultured with either the HS-5 stromal cell line serum-deprived conditioned media supplemented with 10 ng/mL kit ligand (HS-5CM/KL) or a recombinant growth factor mix (GFmix) containing 10 ng/mL each of interleukin (IL)-1, IL-3, IL-6, KL, granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and 3 U/mL of erythropoietin. Culturing untreated CD34+ G-PBSC with 10% HS-5CM/KL increased total nucleated cells by 460-fold after 15 days. Progenitors, which were measured as CFUs, also increased by 47-fold over the same period. More significantly, culturing the 4-HC-treated CD34+ cells with HS-5/KL increased CFUs 98-fold and the nucleated cells increased 4573-fold. The absolute number of CFUs present after expansion of the 4-HC-resistant cells with HS-5CM/KL was threefold higher than that detected before purging and significantly higher than that obtained with GFmix. These data indicate that G-PBSC contain a very immature pool of cells not detectable using the 5-week LTC-IC assay, but have extremely high proliferative potential. Additionally, pharmacological purging of G-PBSC greatly reduces mature cells while retaining an immature population. Also significant is the finding that supernatant from the HS-5 bone marrow stromal cell line plus KL can fully regenerate progenitors from the 4-HC-resistant CD34+ G-PBSC.

Antigens, CD34↗
PubMed1997

Association of specific cytomegalovirus genotypes with death from myelosuppression after marrow transplantation.

A retrospective analysis of cytomegalovirus (CMV) genotype was conducted on 281 CMV isolates obtained from marrow transplant recipients. The genotyping was based on sequence variations in the gene encoding envelope glycoprotein B (gB) as detected by restriction analysis of polymerase chain reaction (PCR)-amplified gB DNA. Among all isolates studied, the distribution of gB types 1-4 was 48.4%, 16.4%, 24.6%, and 8.2%, respectively, with only 2.5% of all isolates containing more than one gB type. The association of gB types with acute graft-versus-host-disease (GVHD) and death related to myelosuppression was examined using appropriate multivariable regression models. Covariables in addition to gB type included underlying disease type, donor-recipient HLA matching, donor CMV serostatus, and age as a continuous variable. Death associated with myelosuppression occurred in 2.9% or 4 of 136 patients with gB1, 0% or 0 of 46 patients with gB2, 21.7% or 15 of 69 patients with gB3, and 17.4% or four of 23 patients with gB4. The significant association of CMV gB type with death due to myelosuppression was maintained in a multivariable analysis (P < .001). In addition, the data also suggested that gB types 3 and 4 may be associated with a reduced hazard of grades II to IV acute GVHD.

Adult↗
PubMed1997

Suppression of alloantigen-induced T-cell proliferation by CD14+ cells derived from granulocyte colony-stimulating factor-mobilized peripheral blood mononuclear cells.

The proliferative responsiveness of granulocyte colony-stimulating factor (G-CSF)-mobilized blood was studied in uni-directional mixed leukocyte cultures. Unfractionated mononuclear cells from mobilized blood obtained by leukapheresis at day 4 after initiation of G-CSF (G-PBMC) were hyporesponsive (31.5% +/- 9.2% response, P = .003) compared to mononuclear cells obtained from the peripheral blood before administration of G-CSF (preG-PBMC). There was great variability among donors when purified preG- and G-CD4 cells were compared. In eight of 10 donors, G-CD4 cells were equally responsive or moderately hyporesponsive; in two of 10 donors, G-CD4 cells were more strikingly hyporesponsive. CD14 cells derived from leukapheresis products (G-CD14 cells) suppressed alloantigen-induced proliferation by 48.6% +/- 7.5% when added to preG-PBMC or preG-CD4 cells at responder-CD14 ratios of 2:1 (P < .001). Suppression was evident (14.4% +/- 5.0%) even at responder-CD14 ratios of 8:1 and was largely contact-independent. PreG- and G-CD14 cells had equivalent potency in suppressing proliferative responses. Given that G-CSF-mobilized blood cell grafts contain 50-fold more CD14 cells and only 10-fold more T cells than marrow, we propose that suppression of donor T cells by the large proportion of monocytes present in leukapheresis products could contribute to the unexpectedly low incidence and severity of graft-versus-host disease after peripheral blood stem cell transplantation.

Cell Communication↗
PubMed1997

Extrinsic control of stem cell fate: practical considerations.

Decades of experimental data suggest that hematopoietic stem cells can remain quiescent, divide, differentiate or die and further, that these cell fate decisions are determined by extracellular signals provided by the hematopoietic microenvironment (ME). Given the importance of the ME for regulating hematopoiesis, it is imperative that transplanted stem cells migrate efficiently and home to appropriate niches where they can receive regulatory signals. Currently the rapid engraftment seen after transplantation of cytokine-mobilized blood-derived stem cells would suggest that these cells are well-equipped for homing. More recent concerns have now been raised by the possibility that in vitro expansion of these stem cells may diminish their ability to engraft. One possible explanation for this is that expansion protocols may alter adhesion molecule expression and consequently homing. Data presented in this report indicate that expression of adhesion molecules is altered following in vitro exposure to recombinant cytokines, and that various combinations of cytokines differentially modulate adhesion molecule expression.

Animals↗
PubMed1997

Phenotype and engraftment potential of cytokine-mobilized peripheral blood mononuclear cells.

Cytokine-mobilized peripheral blood stem cell products are increasingly used for hematopoietic reconstitution after myeloablative therapy. Favorable engraftment kinetics, the ease of harvest, and the large number of CD34+ cells obtained that allow for graft manipulations (ie, tumor cell or T-cell depletion) have made this stem cell source an attractive alternative to marrow. More recent data suggest that in addition to the increased number of CD34 cells, there may be also qualitative differences between leukapheresis products and marrow. In the allogeneic transplantation setting, the one log more T cells contained in granulocyte colony-stimulating factor-mobilized peripheral blood mononuclear cells compared with marrow has not translated into more severe graft-versus-host disease, indicating possible differences in T-cell or accessory-cell function. Whether such differences will compromise graft-versus-leukemia effects and disease-free survival remains to be seen. Nevertheless, it is reasonable to speculate that cytokine-mobilized peripheral blood products may eventually replace marrow as a source for hematopoietic stem cells. However, each new mobilization strategy needs to be evaluated carefully, as comparable increases in CD34 cell numbers may not necessarily affect the same, as yet underlined, qualitative changes that make this product so attractive.

Bone Marrow↗
PubMed1997

Differential modulation of adhesion markers with ex vivo expansion of human umbilical CD34+ progenitor cells.

The effect of different expansion protocols on the expression levels of CD49dw/CD29 (VLA-4), CD11a/CD18 (LFA-1), CD31 (PECAM-1), CD44, and CD34 was determined after cord blood CD34+ cells were cultured for defined periods with the following: 1) A growth factor mix (GFmix) containing interleukin (IL)-1, IL-3, IL-6, kit ligand (KL), G-CSF, GM-CSF, and erythropoietin (Epo); 2) IL-3 + KL; and 3) HS-5 (a human stromal cell line supernatant) + KL. Before culturing, cord blood CD34+ cells (> 95% purity) were 94 +/- 5% CD31+, 98 +/- 1% CD44+, 66 +/- 29% VLA-4+, and 68 +/- 18% LFA-1+ (mean +/- SEM). Immunophenotyping and morphological examination of pre- and post-cultured cells indicated that GFmix preferentially supported erythroid development, while IL-3+KL and HS-5+KL preferentially supported myeloid development. Similar to what other investigators have reported, there was an absolute increase in CD34+ cell numbers as well as clonogenic precursors with ex vivo expansion. However, the majority of clonogenic precursors post-expansion expressed CD34 antigen at reduced levels. Examination of adhesion molecules indicated that a majority of cells cultured with GFmix expressed PECAM-1 and LFA-1 at undetectable levels, but PECAM-1 and LFA-1 levels remained essentially unchanged when cells were cultured with IL-3+KL and HS-5+KL. Overall VLA-4 expression levels slightly increased and CD44 expression levels were more heterogeneous with ex vivo expansion. Nevertheless, LFA-1, VLA-4, PECAM-1, and CD44 expression levels remained essentially unchanged on cultured progeny retaining a CD34 phenotype, independent of the culture system used. Together these results indicate that differential modulation of adhesion markers occur with different culture conditions, yet adhesion receptor expression levels on progeny cells retaining a CD34 phenotype are essentially maintained independent of the culture conditions. And although there is an absolute increase in CD34+ cells after ex vivo expansion, a majority of clonogenic precursors have reduced levels of CD34 antigen.

Antigens, CD↗
PubMed1996

Mortality hazard functions as related to neutropenia at different times after marrow transplantation.

We characterized the relationship between severe neutropenia and risk of death in 2,276 patients after marrow transplantation to define objective and clinically relevant criteria that could be used to judge the timing and potential value of interventions designed to improve survival in patients with delayed initial engraftment. Proportional hazard models were used to estimate the relative risk of death before day 100 among patients alive on any given day with an absolute neutrophil count (ANC) less than 100/microL compared with those alive on the same day with an ANC > or = 100/microL. Between day 10 and 14, the risk ratio remained close to 1.0, indicating that the risk of death before day 100 for patients with an ANC less than 100/microL was similar to that for patients with an ANC > or = 100/microL. Between day 15, when 38% of patients had an ANC less than 100/microL, and day 26, when 3.8% of patients had an ANC less than 100/microL, the risk ratio showed an overall upward trend, indicating that patients with an ANC less than 100/microL had a higher risk of death before day 100 than those with an ANC > or = 100/microL. Thereafter, the risk ratio fluctuated between 2.01 and 5.78, indicating consistently higher risks of mortality in patients with severe neutropenia. However, allogeneic and autologous transplant recipients each had distinctive risk ratio patterns. These results could be helpful in deciding the appropriate timing for treatment given to improve graft function after marrow transplantation.

Adolescent↗
PubMed1996

Normal human peripheral blood mononuclear cells mobilized with granulocyte colony-stimulating factor have increased osteoclastogenic potential compared to nonmobilized blood.

Single-cell suspensions of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood mononuclear cells (G-PBMC) cultured in alpha minimal essential medium (alphaMEM) containing 10% fetal bovine serum formed multicellular aggregates within 24 hours. In six separate experiments, formation of aggregates appeared to be dependent on cell density per surface area, so that 5.8 +/- 1.3 aggregates formed per 1 x 10(5) cells when G-PBMC were cultured at densities greater than or equal to 1 x 10(5) cells/cm2. The frequency of aggregate formation was less than 1 per 10(5) cells when G-PBMC were cultured at densities less than 1 x 10(5) cells/cm2. Once formed, aggregates became adherent within 72 hours, and then, over the course of 21 days, released CD3/CD4/CD25-positive cells into the supernatant. This T-cell production peaked between days 7 and 14, reaching a total of 1,269 +/- 125.9 cells released per aggregate by day 21. Between days 14 and 21, the aggregates also generated macroscopic clusters of adherent mononuclear and giant multinucleated cells that stained positive for tartrate-resistant acid phosphatase (TRAP). At 4 weeks, the macroscopic foci coalesced into monolayers. Multinucleated TRAP-positive cells were distinguished from macrophage polykaryons by the absence of CD14 expression and the presence of osteoclast-specific membrane receptors for calcitonin and alphavbeta3-vitronectin. The osteoclast nature of these cells was further demonstrated by their ability to form resorption lacunae on dentine slices. Comparable osteoclast formation was not detected in cultures of normal marrow or normal nonmobilized peripheral blood.

Acid Phosphatase↗
PubMed1996

CD14+ cells in granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood mononuclear cells induce secretion of interleukin-6 and G-CSF by marrow stroma.

The ability of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood mononuclear cells (G-PBMCs) to induce secretion of cytokines in primary long-term marrow cultures (LTC) or in the human marrow stromal cell line HS23 was compared with that of marrow mononuclear cells. Equal numbers of G-PBMCs or marrow mononuclear cells were added to stromal cultures, supernatants were harvested at day 4 and levels of interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-2, IL-6, G-CSF, and tumor necrosis factor alpha (TNF alpha) were determined. G-PBMCs induced 21.4-fold higher levels of IL-6 and 12.5-fold higher levels of G-CSF in LTC cocultures compared with marrow mononuclear cells and induced 20.6-fold more IL-6 and 6.3-fold more G-CSF when added to HS23 cells. Experiments using sorted populations of CD20+, CD3+, and CD14+ cells showed that CD14+ cells within G-PBMCs were responsible for triggering the production of IL-6 and G-CSF. The effect did not require cell-cell contact and was inhibited when neutralizing antibodies to IL-1 alpha and IL-1 beta were used in combination. In these experiments, the greater stimulating ability of G-PBMCs is most likely attributable to the greater number of CD14+ cells in G-PBMCs (26.1+% +/- 2.3%) compared with marrow (2.5% +/- 0.8%), because equal numbers of CD14+ cells sorted from marrow and G-PBMCs showed comparable ability to induce IL-6 and G-CSF when placed directly on stromal cells.

Bone Marrow↗
PubMed1996

Transplantation of allogeneic peripheral blood stem cells mobilized by recombinant human granulocyte colony stimulating factor.

Recombinant G-CSF has been given to over 150 normal donors for the collection of allogeneic or syngeneic peripheral blood stem cells (PBSC). G-CSF was found to be well-tolerated with mild-moderate bone pain, edema and mild thrombocytopenia being the observed side effects. To date, approximately 90 unmodified primary PBSC transplants from HLA-identical related donors have been performed with engraftment that is, in general, considerably more rapid than marrow. Acute graft-versus-host-disease (GVHD), grades II-IV occurred in 47% of patients and grades III-IV in 17%. Despite the infusion of one to two logs more T cells, these results are not remarkably different than would be expected with marrow transplantation. There have also been successful reports of using G-CSF mobilized allogeneic PBSC following second transplants for graft rejection or relapse. Allogeneic PBSC have been infused without reconditioning for correction of graft failure and unmodified or CD34 selected PBSC have also been given with marrow to augment the dose of hematopoietic cells. Further studies are needed to define the role of allogeneic PBSC for transplantation, refine PBSC mobilization and collection techniques and to evaluate the long-term effects of cytokines in normal donors.

Animals↗
PubMed1995

Identification of a novel DNA sequence differentially expressed between normal human CD34+CD38hi and CD34+CD38lo marrow cells.

We have applied the recently developed differential display method to extend the molecular characterization of the less mature CD34+CD38lo bone marrow progenitors in comparison with the CD34+CD38hi cells to better understand their functional differences. Immunomagnetic enrichment of CD34+ cells followed by flow cytometry was used to isolate CD34+CD38lo and CD34+CD38hi cells from human organ donor bone marrow. A limited set of the poly A+ RNA sequences present in these two cell populations was amplified by a combination of reverse transcription with an anchored oligo dT-based primer and polymerase chain reaction with the same oligo dT primer and arbitrary decamers. A radioactive tracer allowed these sequences to be displayed as a series of bands on a denaturing polyacrylamide gel. Eight bands were chosen that appeared in multiple displays to represent gene sequences differentially expressed between CD34+CD38hi and CD34+CD38lo cells. Comparison of the sequences with public DNA sequence databases available identified one sequence as myeloperoxidase. Two other clones matched sequence fragments of unknown function, whereas the remaining five are novel sequences not present in existing databases. The relative level of expression of all of the sequences was tested by an independent reverse transcriptase-polymerase chain reaction with sequence-specific oligonucleotide primers. The lower level of myeloperoxidase mRNA in CD34+CD38lo cells was confirmed, as was the higher expression of the novel sequence 345. Sequence 345 expression is highest in CD34+CD38- cells and decreases with increased CD38 expression. It is expressed in negligible amounts in hematopoietic cell lines and other sources of human tissue, suggesting it may have a functional role in normal hematopoiesis.

ADP-ribosyl Cyclase↗
PubMed1995

Benign marrow progenitors are enriched in the CD34+/HLA-DRlo population but not in the CD34+/CD38lo population in chronic myeloid leukemia: an analysis using interphase fluorescence in situ hybridization.

Fluorescence in situ hybridization (FISH) was used to discriminate between benign and malignant cells in sorted populations of chronic myelogenous leukemia (CML) marrow. FISH has the advantage of allowing for a cell by cell analysis of the breakpoint cluster region (BCR) gene rearrangement immediately after flow sorting in nondividing G0/G1 cells that are potentially transcriptionally inactive. We initially selected CD34+ cells with very low expression of the activation antigen CD38 as a candidate phenotype for an immature and hypothetically more benign cell population, but found no enrichment for Ph negativity in that subtype. In five CML samples, 55% +/- 3.3% (mean +/- SE) of CD34+/CD38hi cells had the BCR gene rearrangement, similar to 57% +/- 3.7% seen in the CD34+/CD38lo population. In contrast, subsequent experiments (n = 4) determined that the CD34+/HLA-DRlo population in CML marrow does contain an increased proportion of benign cells: 15% +/- 1% of the CD34+/DRlo cells were BCR rearranged, compared with 52% +/- 5.8% of the CD34+/DRhi cells (P = .001). Our results indicate that benign progenitors in CML are enriched within the CD34+ cells with low DR antigen expression, but not low CD38 expression. One possible interpretation of these observations is that low CD38 antigen expression is not as useful as low HLA-DR expression for isolating immature cells.

ADP-ribosyl Cyclase↗
PubMed1995

Cell cycle and functional differences between CD34+/CD38hi and CD34+/38lo human marrow cells after in vitro cytokine exposure.

The proliferation kinetics and clonogenic activity of CD34+/38hi (CD38hi) and CD34+/38lo (CD38lo) human marrow cells were measured before and after culturing the cells in vitro over a 6-day period in serum-deprived medium containing recombinant growth factors (interleukin-1 [IL-1], IL-3, IL-6, granulocyte colony-stimulating factor [G-CSF], granulocyte-macrophage [GM]-CSF, kit ligand, and erythropoietin). Before in vitro culture, 3% +/- 3% of the CD38lo and 13% +/- 2% of the CD38hi cells were in the S-phase of the cell cycle. The clonogenic activity of CD38hi cells was twofold greater than that of the CD38lo cells, as measured by colony-forming units (CFU) in short-term assays. However, CD38hi cells contained fewer pre-CFU than did the CD38lo cells, generating only 3 +/- 2 colonies per 1,000 cells after 4 weeks of culture on competent stromal layers, compared with 107 +/- 46 colonies per 1,000 cells from the CD38lo population. CD38hi and CD38lo cells exhibited distinctly different responses when cultured in serum-deprived medium supplemented with recombinant growth factors. After culturing cells for 24 hours, CD38lo cells essentially remained a noncycling population with only 5.1% +/- 3.0% of the cells cycling, whereas 44.2% +/- 6.9% of the CD38hi cells were in DNA synthesis. Gradually CD38lo cells were recruited into cycle, such that by 72 hours, approximately 28% of the CD38lo cells were in S-phase. However, during 6 days of culture, the percentage of cycling CD38lo cells never exceeded the proliferative response observed for CD38hi cells. Phenotype analysis conducted at day 6 indicated that 86% of the CD38hi population were no longer phenotypically CD34+/38hi, while 60% of CD38lo cells maintained a CD34+/38lo phenotype. Long-term cultures initiated with 6-day in vitro-expanded CD38lo cells showed approximately a twofold decrease in clonogenic activity attributable to a loss of erythroid precursors and a decrease in GM colonies. Thus, a proportion of CD38lo cells capable of generating CFU was maintained even after exposure to growth factors.

ADP-ribosyl Cyclase↗