Biomedical subjects

A Kessinger

Publications and source records attributed to A Kessinger.

At least 19 recordsLinked to original sources

PubMed2005

An ex vivo model of hematopoietic stem cell mobilization.

BACKGROUND: Mobilization of hematopoietic stem cells to the circulation facilitates their collection, thereby providing a non-marrow source of these cells for transplantation. Hematopoietic cytokine administration induces mobilization for most, but not all, donors. Because the underlying biology of mobilization is not well understood, improving the process on a rational basis is difficult. The design of an in vitro mobilization model was pursued to facilitate investigations of the process. METHODS: MS5 murine stromal cell line cells were grown to confluence on microporous transwell membranes. Murine femoral marrow plugs were placed on top of the prepared transwell membranes. The transwells were then seated in wells containing media and hematopoietic growth factors. Cells that were released from the marrow plugs over time and migrated through the stromal layer into the wells were assayed for stem cell/progenitor cell characteristics. RESULTS: Few or no GM-CSF (progenitors) were found in wells containing media alone or media plus mobilizing cytokines after 24 h. After 120 h, the numbers of cells in the cytokine-containing wells increased, as did the numbers of CD34(+) cells. Cells in the wells at the time progenitor cells were most frequent were shown to include side population (SP) hematopoietic stem cells. After 120 h in the presence of cytokines, cells pooled from the wells were transplanted to lethally irradiated mice. Eighty per cent of the transplanted mice survived 30 days or more, demonstrating that radioprotective stem cells were present in the wells. DISCUSSION: An ex vivo model has been designed that may aid investigations of the various steps of stem cell mobilization.

Animals↗

PubMed2003

The whys and hows of hematopoietic progenitor and stem cell mobilization.

Intentional mobilization of hematopoietic/stem cells into the circulation has improved the efficiency of their collection. Transplantation of mobilized blood stem cells to patients with marrow aplasia results in a faster pace of hematopoietic recovery than transplantation of marrow-derived stem cells. Autologous and allogeneic hematopoietic stem cell transplantation are increasingly performed with blood-derived cells. Donors of both autologous and allogeneic blood stem cells do not always respond well to therapies designed to produce mobilization. Autologous donors may respond poorly as a result of myelotoxic damage inflicted by prior antitumor therapy, but this explanation is not valid for allogeneic donors. The mechanism(s) involved in the process of mobilization are incompletely understood. Until these mechanisms are elucidated, methods to improve mobilization vigor on a rational basis will not be obvious. In the meanwhile, clinical observations may provide some hints regarding the whys and hows of mobilization and permit incremental improvements in this process.

Animals↗

PubMed2003

Occult tumor cells detected in autologous blood stem cell harvests have no impact on 5 year outcomes for breast cancer patients with 4-9 positive nodes treated with adjuvant high-dose therapy and stem cell transplantation.

Breast cancer cells have been detected in autologous blood stem cell collections of early stage breast cancer patients, but their clinical significance is undefined. From October 1993 to August 1998, 32 consecutive Stage II breast cancer patients with 4-9-positive nodes underwent stem cell apheresis. The patients were treated with cyclophosphamide 1.75 gm/m(2), etoposide 400 mg/m(2) and cisplatin 50 mg/m(2) daily for 3 days, followed by infusion of the autologous cells. Cytospins of cells from each apheresis collections and from an aliquot of three pooled collections were examined for cytokeratin expression using an immunocytochemical assay. The cells were considered positive for tumor if at least one cell with tumor morphology stained positively for cytokeratin. Negative aliquots were confirmed with RT-PCR. Six patients (19%) had positive collections. In total, 24 patients (75%) were disease free a median of 61 (30-86) months after transplant. Eight patients relapsed at a median of 17 (8-27) months after transplant. Four of the disease-free patients and two of the relapsed patients had positive apheresis collections. There was no significant correlation between the presence of detectable tumor cells in the graft product and outcome.

Adult↗

PubMed2003

The impact of escalating regulatory requirements on the conduct of clinical research.

A discussion of the impact of escalating regulatory requirements is provided, from the point of view of the administration of the institutional review board of an academic institution, and from clinical investigators who conduct studies at that same institution. Current and anticipated future issues are discussed.

Adverse Drug Reaction Reporting Systems↗

PubMed2003

Immunological and clinical effects of post-transplant G-CSF versus placebo in T-cell replete allogeneic blood transplant patients: results from a randomized double-blind study.

BACKGROUND: Immunological and clinical effects of post-transplant growth factor administration have not been well studied. This report describes the outcome and immune functions of a total of 50 HLA-matched related donor allogeneic blood stem-cell transplantation patients who received post-transplant G-CSF (10 microg/kg) or placebo. METHODS: Immune status, including number of lymphocyte subsets and their functions, and serum immunoglobulin levels and clinical status--including GvHD, rate of relapse, event-free survival, and overall survival--were determined in the patients enrolled in this study. RESULTS: Twenty-eight patients survived 1 year after transplant, and 15 patients had available results to compare immune function by randomization assignment. At 12 months post-transplant, immune parameters in G-CSF versus placebo groups showed no statistically significant differences in number of circulating lymphocyte subsets CD3, CD4, CD8, CD19 and CD56 in the two groups. There was no significant (NS) difference in immunoglobulin IgG, IgA and IgM levels, NK or LAK cell-mediated cytotoxicity levels, and mitogen-induced proliferation between post-transplant G-CSF and placebo group. In addition, the analyses of immune parameters at earlier time-points on Days 28, 100, 180, and 270 revealed that, except for LAK cytotoxicity at Day 100, there was no differences between the two groups. Fourteen of 26 patients are alive in the G-CSF arm and nine of 24 in the placebo arm. Median follow-up of surviving patients is 43 months. Four year overall and event-free survival in the G-CSF and the placebo group were 53% and 35% (NS), and 44% and 36% (NS) respectively. Bacterial or fungal infections were the cause of six of 12 deaths in the G-CSF arm (all bacterial) and of four of 15 deaths in the placebo arm (two deaths from Aspergillus) (P=0.26). Two patients relapsed in the G-CSF arm and three in the placebo arm. Four year cumulative incidences of relapse were 8% versus 13% in G-CSF versus placebo arms, respectively, (NS). Chronic GvHD developed in 14 of 19 100-day survivors after G-CSF (11 extensive stage), and in 17 of 20 (14 extensive stage) in the placebo arm. The 4-year cumulative incidence of chronic GvHD was 56% [95% confidence interval (CI) 24-88%] after G-CSF and 71% (95% CI 48-94%) after placebo; this difference was not statistically significant (log rank P=0.41). CONCLUSION: In summary, there were no significant immunological or alterations in clinical benefit of post-transplant G-CSF administration in T-replete allotransplant recipients.

Adult↗

PubMed2002

Pseudoautologous blood stem cell transplantation for refractory chronic graft-versus-host disease.

A female patient with AML received an allogeneic BMT from her brother. She experienced two relapses managed with chemotherapy and donor leukocyte infusions. The patient subsequently developed extensive therapy-refractory chronic GVHD. Pseudoautologous blood stem cell transplantation was performed as a salvage treatment for chronic GVHD. Her blood stem cells were easily mobilized with cyclophosphamide and G-CSF. The conditioning regimen was well tolerated and consisted of 200 mg/kg cyclophosphamide and horse-derived antithymocyte globulin. A total of 4.03 x 10(6)/kg CD34+ cells were infused and hematological recovery was rapid. Chronic GVHD improved with the ability to taper steroids. Nine months post transplantation the patient died from leukemia.

Adult↗

PubMed2002

Plasma from poorly mobilizing human subjects inhibits cytokine-induced murine blood stem-cell mobilization.

BACKGROUND: Cytokine-induced mobilization of hematopoietic stem/progenitor cells to the circulation facilitates efficient harvest of blood stem cells by leukapheresis. Up to 30% of autologous, and 10-20% of allogeneic blood stem-cell donors respond poorly to mobilizing cytokines and preliminary studies implicated a circulating inhibitor of mobilization. METHODS: In this study, plasma from 11 allogeneic and 23 autologous stem cell donors was assayed for inhibition of mobilization in mice. RESULTS: There were significant correlations between CD34(+) cells collected/kg human donor weight and spleen weight, CD34(+) CD45(+) cells, GMCFC and HPP-CFC per spleen in murine recipients of these plasma samples. Overall, there was a positive association between transforming growth factor beta (TGF-beta) levels and CD34(+) cells per liter of blood processed (LBP). However, when arbitrarily segregated into good versus poor mobilizers, based on less or greater than 15 million CD34(+) cells collected per LBP, the majority (64%) of normal donors were good mobilizers. The majority of the poor mobilizers (83%) were patients. For a subset of 12 individuals whose plasma strongly inhibited mobilization in the mouse, a significant positive correlation of the extent of inhibition with TGF-beta levels was found. For 11 individuals whose plasma, based on colony assays, enhanced mobilization when injected into mice, no correlation with TGF-beta levels was evident. DISCUSSION: Elevated plasma TGF-beta levels in some stem-cell donors may be associated with poor stem-cell mobilization. It remains to be determined whether elevation of TGF-beta levels is a cause of, or a compensatory response to, poor mobilization.

Animals↗

PubMed2002

The International Prognostic Factors Project score for advanced Hodgkin's disease is useful for predicting outcome of autologous hematopoietic stem cell transplantation.

BACKGROUND: The International Prognostic Factors Project on Advanced Hodgkin's Disease developed a seven-factor prognostic score consisting of serum albumin, hemoglobin, gender, stage, age, leukocytosis and lymphocytopenia for newly diagnosed Hodgkin's disease patients who receive chemotherapy. The purpose of this study was to determine whether this prognostic score would also be useful for Hodgkin's disease patients undergoing autologous hematopoietic stem cell transplantation. PATIENTS AND METHODS: We performed a retrospective review of 379 patients who had autologous transplants for Hodgkin's disease, at the University of Nebraska Medical Center between October 1984 and December 1999. Multivariate analysis was performed to determine whether the prognostic factors identified by the International Prognostic Factors Project adversely influenced event-free survival (EFS) or overall survival (OS). RESULTS: Low serum albumin, anemia, age and lymphocytopenia were associated with poorer EFS and OS. Gender, stage and leukocytosis were not associated with significantly poorer outcomes. Estimated 10-year EFS was 38%, 23% and 7% for patients with 0-1, 2-3 or > or =4 of the adverse prognostic characteristics identified by the International Prognostic Factors Project, respectively. CONCLUSIONS: The prognostic score for advanced disease is also useful for relapsed and refractory Hodgkin's disease patients undergoing high-dose therapy followed by autologous hematopoietic stem cell transplantation.

Adolescent↗

PubMed2001

Decreased immune functions of blood cells following mobilization with granulocyte colony-stimulating factor: association with donor characteristics.

In this study, mononuclear cells (MNCs) from granulocyte colony-stimulating factor (G-CSF)-mobilized blood stem cell (BSC) harvests from 104 healthy donors were analyzed for their immunological functions and compared with MNCs from 28 steady-state nonmobilized donors. The relationships between donor characteristics (age, gender, weight, and HLA type) and immune functions of the harvests were also analyzed. There was a significant (P <.01) decrease in natural killer and lymphokine-activated killer (LAK) cell-mediated cytotoxicity for G-CSF-mobilized effector cells compared with nonmobilized cells. Similarly, there was a significant (P <.005) decrease in both T-cell and B-cell mitogen response in G-CSF-mobilized cells compared with nonmobilized cells. There was dose-dependent inhibition of LAK cell-mediated cytotoxicity, but this effect was not seen with other immune function assays. Changes in immune function did not appear to be determined by frequency of cellular phenotypes or expression of effector function genes seen in a reverse-transcription polymerase chain reaction. There was a significant relationship between expression of certain HLA alleles (A1, A3, A24, B44, B62, DR15, DR17; all P <.01) and increased immune function, such as cytotoxicity and/or mitogen response. A decrease in immune function with the HLA-DR13 expression was also observed (P <.01). Since the G-CSF increases the number of MNCs, the increase in effector cells might compensate for decreased immune functions of these cells in vivo when transplanted into patients. These results suggest a decreased immune function in G-CSF-mobilized BSC harvests and warrant further studies to correlate these data with clinical outcome.

Adolescent↗

PubMed2001

Circulating factors may be responsible for murine strain-specific responses to mobilizing cytokines.

OBJECTIVE: To determine if circulating factors influence strain-specific responses to administration of hematopoietic stem-cell mobilizing cytokines, a murine model was employed. METHODS: Plasma aliquots from intact DBA2, Balb/c, and C57Bl/6 mice were injected into intact Balb/c mice prior to delivery of mobilizing cytokines. Control Balb/c mice were injected with mobilizing cytokines alone. Plasma from hemi-body irradiated Balb/c mice, known to inhibit mobilization, was also injected into Balb/c mice. Twenty-four hours later, spleen cells were harvested and assayed for granulocyte-macrophage colony-forming cells (GM-CFC) and high-proliferative-potential colony-forming cells (HPP-CFC). Simultaneously harvested blood aliquots were assayed for CD45(+)/CD34(+) cells using flow cytometric techniques. RESULTS: Mice receiving plasma from any source demonstrated significant inhibition of mobilization of HPP-CFC and GM-CFC to the spleen as compared to mobilized controls; for HPP-CFC, plasma from C57Bl/6 mice was more inhibitory than plasma from Balb/c (p = 0.001) or from DBA2 mice (p = 0.01), while for GM-CFC, plasma from C57Bl/6 mice was more inhibitory than Balb/c plasma but not more inhibitory than DBA2 plasma. Mice injected with plasma from previously irradiated Balb/c mice exhibited the expected HPP-CFC and GM-CFC mobilization inhibition, which was not statistically different from the inhibition seen in animals that received C57Bl/6 plasma. Mobilization of CD34(+)/CD45(+) cells to the blood also appeared to be inhibited by pretreatment with C57Bl/6 plasma, but not DBA2 plasma. CONCLUSION: These data suggest that strain-specific patterns of mobilization may be influenced by a circulating mobilization inhibitor(s).

Animals↗

PubMed2001

Progenitor and lymphoma cells in blood stem cell harvests: impact on survival following transplantation.

This study evaluated whether cytokine-induced blood stem cell mobilization also mobilized lymphoma cells and whether lymphoma cell mobilization affected outcome post autologous blood stem cell transplant. Blood stem cell collections from 26 non-Hodgkin's lymphoma (NHL) patients harvested during steady-state (non-mobilized) and from 35 NHL patients harvested after cytokine administration (mobilized) were studied. The harvests were cultured and molecularly evaluated for clonal markers of the primary lymphoma. All patients underwent high-dose chemotherapy and autologous transplantation. Graft products from mobilized patients were more likely to contain lymphoma than graft products from non-mobilized patients (37% vs 19%) but this difference was not significant (P = 0.16). In a multivariate analysis, lymphoma contamination was not associated with patient age, gender, tumor grade, prior radiotherapy, duration of prior chemotherapy, mononuclear cell count, or the number of aphereses performed to obtain the product. Heavily pre-treated patients were less likely to have lymphoma-contaminated harvests (P = 0.064). Lymphoma contamination was positively associated with the number of progenitor cells collected (P = 0.047). In multivariate analyses, the only significant independent predictor of lymphoma contamination was the number of mononuclear cells collected (P = 0.031). Lymphoma contamination of transplanted apheresis products had no apparent impact on event-free and overall survival.

Adult↗

PubMed2001

Elevated transforming growth factor beta levels in the plasma of cytokine-treated cancer patients and normal allogeneic stem cell donors.

BACKGROUND: Allogeneic blood stem-cell donors demonstrate more vigorous mobilization of CD34(+) cells to the circulation in response to cytokine administration than do autologous donors. Transforming growth factor (TGF-beta1) has been implicated as a mobilization inhibitor. A study was designed to determine whether plasma TGF-beta1 levels are elevated in cytokine-mobilized autologous cancer donors compared with cytokine-mobilized normal donors. METHODS: Plasma collected from 29 autologous cancer donors and 33 normal allogeneic stem-cell donors following administration of mobilizing cytokines just prior to the first collection was assayed for TGF-beta1 using a sandwich-type ELISA. Plasma from three volunteers not treated with cytokine was also analyzed. Comparisons were made using the Student's t test on log-transformed data. RESULTS: Average TGF-beta1 levels in the plasma of cancer patients were significantly higher than in allogeneic stem-cell donors (4.4 ng/mL versus 7.2 ng/mL; p = 0.038). The allogeneic donors required fewer collections to harvest greater numbers of CD34(+) cells and colony-forming unit granulocyte-macrophage (CFU-GM) than autologous donors. Plasma from three untreated volunteers had mean TGF-beta1 levels of 0.36 ng/mL, with all three levels below the 25th percentile for allogeneic donors and the 5th percentile for cancer patients. DISCUSSION: Cytokine administration was associated with increased plasma TGF-beta1 levels. The levels were higher in cancer patients being mobilized for stem-cell collection than in allogeneic blood stem-cell donors. These differences could underlie the increased number of apheresis procedures required to harvest autologous graft products from cancer patients.

Antigens, CD34↗

PubMed2001

Intensive immunoablation and autologous blood stem cell transplantation in patients with refractory rheumatoid arthritis: the University of Nebraska experience.

Two patients with severe rheumatoid arthritis (RA) were treated with high dose chemotherapy and autologous blood stem cell transplantation. Hematopoietic stem cells mobilized readily with cyclophosphamide and granulocyte-colony stimulating factor. Both patients achieved an American College of Rheumatology (ACR) 50% response before starting high dose therapy. The transplantation regimen included 200 mg/kg cyclophosphamide and 6 doses of equine antithymocyte globulin. Transplantation was well tolerated and both patients recovered neutrophils on day 7 post-transplant. At one month post-transplant both patients had an ACR response of 80%. Both individuals relapsed at 6 months and responded well to a combination of disease modifying antirheumatic drugs that was previously ineffective. At 12 months ACR responses were 80% and 60%, respectively. The first patient developed a flare at 18 months when she was found to be hypothyroid; she regained an 80% ACR response at 24 months with therapy of hypothyroidism. The second patient progressed relentlessly 15 months post-transplant. Immunological reconstitution showed a continuous inversion of the ratio of CD4 and CD8 lymphocytes with a predominant expansion of memory T cells.

Academic Medical Centers↗

PubMed2000

A randomized, double-blind trial of filgrastim (granulocyte colony-stimulating factor) versus placebo following allogeneic blood stem cell transplantation.

Blood stem cell transplantation (BSCT) results in rapid hematopoietic recovery in both the allogeneic and autologous transplant settings. Because of the large numbers of progenitor cells in mobilized blood, the administration of growth factors after transplantation may not provide further acceleration of hematopoietic recovery. A randomized, double-blind, placebo-controlled study was performed to determine the effects of filgrastim (granulocyte colony-stimulating factor; G-CSF) administration on hematopoietic recovery after allogeneic BSCT. Fifty-four patients with hematologic malignancies undergoing a related, HLA-matched allogeneic BSCT were randomly assigned to receive daily filgrastim at 10 microg/kg or placebo starting on the day of transplantation. A minimum of 3 x 10(6) CD34(+) cells/kg in the allograft was required for transplantation. All patients received a standard preparative regimen and a standard regimen for the prevention of graft-versus-host disease (GVHD). The median time to achieve an absolute neutrophil count greater than 0.5 x 10(9)/L was 11 days (range, 9-20 days) for patients who received filgrastim compared with 15 days (range, 10-22 days) for patients who received placebo (P =.0082). The median time to achieve a platelet count greater than 20 x 10(9)/L was 13 days (range, 8-35 days) for patients who received filgrastim compared with 15.5 days (range, 8-42 days) for patients who received placebo (P =.79). There were no significant differences for red blood cell transfusion independence, the incidence of acute GVHD, or 100-day mortality between the groups. The administration of filgrastim appears to be a safe and effective supportive-care measure following allogeneic BSCT.

Adolescent↗

PubMed2000

Central nervous system dysfunction as the first manifestation of multiple organ dysfunction syndrome in stem cell transplant patients.

Development of CNS dysfunction in the setting of hematopoietic stem cell transplant (HSCT) has been previously shown to predict for subsequent second organ dysfunction and death. In this paper, we describe the characteristics of this isolated CNS dysfunction, and its relationship to multiple organ dysfunction syndrome (MODS) after HSCT. Twenty-one of 186 patients undergoing HSCT developed CNS dysfunction as their first organ dysfunction a mean of 22.8 +/- 0.9 days after the start of the preparative regimen. Compared with 137 patients who developed no organ dysfunction, patients presenting with CNS dysfunction were more likely to have undergone allogeneic HSCT (P = 0.001) and to have received a total body irradiation-based regimen (P = 0.001), and were less likely to have been transplanted for lymphoma (P = 0.008). Patients who developed CNS dysfunction were more likely to die than those with no organ dysfunction (P < 0. 001). Of the 21 patients who developed CNS dysfunction, 48% resolved their dysfunction by a mean of 4.6 days later without progression to second organ dysfunction, and 90% of these patients survived to day 100. Fifty-two percent of patients with CNS dysfunction progressed to second organ dysfunction (pulmonary or hepatic) a mean of 5.5 days later, and only 36% survived to day 100 (P = 0.02). The patients who progressed to second organ dysfunction and those who did not were not different in terms of type of HSCT (allogeneic vs autologous), stem cell source (blood vs bone marrow), age, diagnosis or preparative regimen. Development of CNS dysfunction in the setting of HSCT, as with other organ dysfunctions (such as hepatic veno-occlusive disease), probably represents an early manifestation of a systemic disorder predisposing for MODS, increasing the risk of transplant-related mortality. Early systemic therapies directed at modulating this systemic disorder are probably indicated. Bone Marrow Transplantation (2000) 25, 79-83.

Adult↗

PubMed2000

Outcome of allogeneic stem cell transplantation for B cell chronic lymphocytic leukemia.

The objective of this study was to describe the outcome of allogeneic stem cell transplantation (alloSCT) in a series of patients with B cell chronic lymphocytic leukemia (B-CLL). Twenty-three B-CLL patients were transplanted between 1988 and 1997 using stem cells from a related (n = 20) or an unrelated donor (n = 3). The median age of the patients was 46 years, and the median number of prior chemotherapy regimens received was two. At transplantation, 14 patients had chemorefractory disease and 12 of these were refractory to fludarabine. The preparative regimens included total body irradiation (TBI) in 22 of the 23 cases. All patients received graft-versus-host disease (GVHD) prophylaxis with cyclosporine and methotrexate. Twenty patients (87%) achieved a complete remission (CR). The incidence of grade II-IV acute GVHD was 54%. Fourteen (61%) patients are alive and disease-free, including two with unrelated donors, at a median of 26 months (range, 9-115 months). Nine patients (39%) have died, one of whom had progressive B-CLL. The only favorable prognostic factor for failure-free survival (FFS) and overall survival (OS) after alloSCT was the use of a cyclophosphamide/TBI rather than an etoposide/cyclophosphamide/TBI regimen (P = 0.03). The projected 5-year FFS, OS, and relapse rates after alloSCT were 65% (95% CI, 48-88%), 62% (95% CI, 43-88%), and 5% (95%, CI 0-13%), respectively. These findings demonstrate the potential of high-dose therapy and alloSCT for inducing and maintaining a remission in patients with advanced or chemorefractory B-CLL. The low relapse rate may be due to an allogeneic graft-versus-leukemia effect.

Adult↗

PubMed2000

Immunological properties of mononuclear cells from blood stem cell harvests following mobilization with erythropoietin + G-CSF in cancer patients.

BACKGROUND: Although the recombinant granulocyte colony-stimulating factor (G-CSF) is a good CD34 cell mobilizer, the effects of G-CSF mobilization on the immune effector function of the individual is not always optimal. We studied the functional and phenotypic properties of peripheral blood stem cells (PBSC) collected from 15 cancer patients mobilized with G-CSF plus recombinant erythropoietin (EPO). METHODS: The patients received EPO (300 U/kg) and (G-CSF 1 microg/kg) per day as mobilizing cytokines and an autologous graft product was collected with at least daily apheresis procedures until a target number of CD34 cells and mononuclear cells were obtained. Mononuclear cells from the first four PBSC collections were tested for their natural killer (NK), activated NK and lymphokine activated killer (LAK) cytotoxicity in vitro against K562 and Raji tumor target cells. RESULTS: There was a significant increase in NK, activated NK and LAK cytotoxicity in EPO + G-CSF mobilized cells when compared to mononuclear cells from premobilization blood baseline values. Although there was no increase in CD3+ T cells, there was a significant increase in myeloid cells (CD14+), B-cells (CD20+) and NK cells (CD56+) following mobilization. There was no difference in T cell response to the mitogens PHA and Con-A, but there was an increase in B-cell response to PWM following mobilization. Thus, the combination of EPO + G-CSF not only mobilized hematopoietic precursor cells but also increased the number of immune effector cells in the PBSC collections.

Adult↗

PubMed2000

Blood stem cell transplantation: factors influencing cellular immunological reconstitution.

Recovery of immune function following stem cell transplantation is necessary for a good outcome. Immune recovery is facilitated by transplanting higher numbers of cells than neutrophil or platelet reconstitution requires. Estimates from studies in the allogeneic setting suggest the minimum stem cell dose to achieve optimal lymphocyte recovery is about 10(7) CD34+ cells/kg. Increasing the number of autologous stem cells infused potentially increases the risk of reinfusing tumor cells. Transplanted mature immune cells apparently have very limited early contribution to cellular immune recovery. Mobilizing cytokines permit collection of greater numbers of stem cells, but they also can polarize T cells with potentially significant consequences, for example, granulocyte colony-stimulating factor (G-CSF) decreases the antitumor cytotoxic effector functions of cells. Although this could be a disadvantage in the autologous setting, it might decrease graft versus host disease in the allogeneic setting. Thus, identification of cytokines, which alone or in combination provide the most potent mobilizing effect to permit the collection of the highest number of stem cells without inadvertent detrimental polarization of the responses of immune cells, and employment of cytokines posttransplantation, which direct differentiation of the stem cells along the most desirable pathways, for example, to generate antitumor immune responses, might improve immunological outcome. A future emphasis should be to better define the cytokines and target cell populations that provide optimal immune reconstitution rather than focusing solely on rapid hematological recovery. More complete immunological reconstitution in a greater proportion of patients should be accompanied by improvements in outcomes of blood stem cell transplantation.

Cytotoxicity Tests, Immunologic↗