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

G-CSF inhibits LFA-1-mediated CD4+ T cell functions by inhibiting Lck and ZAP-70

In this study, we showed that G-CSF mobilization increased the frequency of T cells, specifically CD3⁺CD4⁺ T cells. G-CSF mobilization decreased the secretion of inflammatory cytokines of CD4⁺ T cells through the LFA-1/ICAM-1 signaling pathway, whereas it did not alter the TH1/TH2 ratio. We found that G-CSF mobilization inhibited LFA-1-mediated CD4⁺ T cell polarization and motility. In vitro, G-CSF stimulation also attenuated the polarization and adhesiveness of CD4⁺ T cells through the LFA-1/ICAM-1 interaction. Further investigation revealed that G-CSF mobilization suppressed LFA-1 signaling by down-regulating Lck and ZAP-70 expression in CD4⁺ T cells, similar results was also confirmed by in-vitro studies. These findings suggested that G-CSF directly suppressed LFA-1-mediated CD4⁺ T cell functions through the down-regulation of Lck and ZAP-70. The immunosuppressive effect of G-CSF mobilization deepened our understanding about peripheral blood hematopoietic stem cell transplantation. LFA-1/ICMA-1 pathway may become a potential target for graft-versus-host disease prophylaxis.

Granulocyte colony-stimulating factor therapy is associated with a reduced incidence of acute rejection episodes or allograft vasculopathy in heart transplant recipients

BACKGROUND

We evaluated the potential effects of granulocyte colony-simulating factor (G- CSF) on the incidence of rejection and allograft vasculopathy in heart transplant recipients.

METHODS

Of 247 patients undergoing heart transplantation from 2000 to 2007, 52 (21%) developed leukopenia (white blood cell [WBC] <2.5 × 10(9) cells/L) in the absence of active infection, rejection, or malignancy. In 24 (46%) patients a clinical decision was made to treat the leukopenia with G-CSF (G-CSF group), and 28 (54%) Patients received no G-CSF (non-GCSF group). Patients followed up for 1 year after the period of leukopenia were assessed for allograft vasculopathy and acute rejection incidence.

RESULTS

At baseline, the G-CSF group and the non-GCSF group did not differ in age, gender, race, heart failure etiology, creatinine, left ventricular ejection fraction (LVEF) or immunosupressive regimen. During 1-year follow-up there were no deaths in the G-CSF group, and 1 death in the non-GCSF group (P = .34). The incidence of rejection or progressive allograft vasculopathy was lower in the G-CSF group when compared with the non-GCSF group (2 [8%] vs 15 [53%]; P < .01). Multivariate analysis identified both prior rejection episodes and G-CSF therapy as factors associated with the combined end-point of rejection or progressive allograft vasculopathy (odds ratio [OR] = 7.89 [1.67-37.2] and OR = 0.09 [0.02-0.52], respectively).

CONCLUSIONS

G-CSF therapy appears to be associated with a decreased incidence of acute rejection episodes or allograft vasculopathy in heart transplant recipients, suggesting a potential immunomodulatory effect of G-CSF.

Effects of recombinant human granulocyte colony-stimulating factor on central and peripheral T lymphocyte reconstitution after sublethal irradiation in mice

Granulocyte colony-stimulating factor (G-CSF) is one of the most critical cytokines used for the treatment of acute radiation syndrome (ARS). In addition to the hematopoietic effects of G-CSF on the differentiation and proliferation of myeloid progenitor cells, G-CSF is also known to have immunomodulatory effects. The aim of the present study was to investigate whether G-CSF could accelerate central and peripheral T lymphocyte recovery after a sublethal dose of irradiation. Female BALB/c mice were subjected to 6 Gy of total body irradiation and then were treated with either 100 μg/kg G-CSF or an equal volume of PBS once daily for 14 days. Percentages of thymocyte subpopulations including CD4 - CD8 - , CD4 + CD8 + , CD4 + CD8- and CD4 - CD8+ T cells, peripheral CD3 + , CD4+ and CD8+ cells were analyzed by flow cytometry. Recent thymic emigrants (RTEs) were assessed by real-time polymerase chain reaction (PCR) using primers specific to the 257-bp T cell receptor rearrangement excision circles (sjTRECs). The proliferative capacity of splenic mononuclear cells upon exposure to ConA was measured by using the Cell Count Kit-8 (CCK-8). G-CSF treatment promoted thymocyte regeneration, accelerated the recovery of CD4 + CD8+ cells and increased the frequency of thymocyte sjTRECs. These effects were more prominent at early time points (Day 28) after irradiation. G-CSF also increased the rate of recovery of peripheral CD3 + , CD4+ and CD8+ cells and shortened the period of severe lymphopenia following irradiation. G-CSF also increased the splenic mononuclear cell mitotic responsiveness to ConA more than control-treated cells. Our results show that G-CSF accelerates T cell recovery through both thymic-dependent and thymic-independent pathways, which could be used to increase the rate of immune reconstitution after sublethal irradiation.

Cellular mechanism for granulocyte-colony stimulating factor in the prevention of graft-versus-host disease in combined bone marrow and peripheral blood transplantation for hematological malignancies: the composition in collection

Despite improvements in transplant immunology and clinical and supportive care, acute graft-versus-host disease (aGVHD) remains a clinical challenge and a major cause of morbidity and mortality for patients after allogeneic hematopoietic stem cell transplantation (HSCT). Many ways have been used to prevent and treat aGVHD, however, long-term survival remains poor. The key to improve aGVHD outcomes may, in fact, rest upon successful initial therapy. The HLA-matched HSCT was limited by the shortage of suitable donors. Unmanipulated haploidentical/mismatched related transplantation with combined granulocyte-colony stimulating factor (G-CSF)-mobilized peripheral blood stem cells and G-CSF-mobilized bone marrow as a stronger aGVHD inhibition and graft-versus-leukemia effect, has been developed as an alternative transplantation strategy for patients with hematologic malignancies for the advantage of immediate donor availability, ability to select the best of many relatives, controlled graft composition and immediate access to donor-derived cellular therapies if required after transplantation. G-CSF is a potent hematopoietic cytokine, which is produced by fibroblasts, monocytes, and endothelial cells. G-CSF regulates production of neutrophils within the bone marrow and affects neutrophil progenitor proliferation, maturation and is also involved in mobilization of granulocytes, stem and progenitor cells, which has an important role in this transplantation. In this article, we review the possible mechanism for this combined G-CSF-mobilized HSCT in the prevention of aGVHD. Monocytes, T cells, Tregs cells, DC, adhesive molecule, NK cell/KIR ligand mismatching and mesenchymal stem cells may be involved in this transplantation.

Immunomodulation: the role of hematopoietic cytokines

Hematopoietic cytokines have been used primarily as supportive care for patients undergoing cytotoxic chemotherapy or hematopoietic progenitor mobilization. Although the commonly used agents, granulocyte colony-stimulating factor and granulocytemacrophage colony-stimulating factor (GM-CSF), have been used interchangeably, it is clear that they have different effects on immune function and immune priming. GM-CSF has been used for some time as a vaccine adjuvant agent because of its activity on monocytes and dendritic cells. In order to capitalize on the immune activation effects of GM-CSF, numerous groups have transduced the GM-CSF gene into tumor cells in an effort to recruit local inflammatory cells and cytokines to the site of vaccination. Additionally, GM-CSF alone has been demonstrated to have activity for patients with high-risk melanoma and hormone-refractory prostate cancer. This article discusses some of the immune enhancing and suppressive activities of the hematopoietic cytokines, with particular focus on the immunomodulatory effects of GM-CSF, both in the context of single-agent therapy for solid tumors as well as in the context of dendritic cell modulation during therapy for hematopoietic malignancies.

G-CSF downregulates natural killer cell-mediated cytotoxicity in donors for hematopoietic SCT

In G-CSF-mobilized hematopoietic SCT (HSCT), natural killer (NK) cells have a critical role in GVHD and GVL effects. However, regulation of NK cell response to G-CSF remains unclear. This study assayed G-CSF effects in both HSCT donors and NK-92MI cells. The donors who received G-CSF had significantly decreased NK cell cytotoxicity. Levels of phosphatidylinositol 3-kinase (PI3K) and phosphorylated (p)-Akt, but not mammalian target of rapamycin (mTOR), were downregulated in NK cells from G-CSF-injected donors. G-CSF also decreased cytotoxicity without affecting viability and NF-κB of NK-92MI cells. PI3K and p-ERK expression were also decreased in G-CSF-treated NK-92MI cells, and their inhibitors, wortmannin and PD98059, respectively, both enhanced the downregulation of cytotoxicity. These effects were accompanied by decreased expression of a cytotoxicity-related gene, triosephosphate isomerase (TPI). Wortmannin, but not PD98059, enhanced the downregulation of TPI in G-CSF-treated NK-92MI cells, indicating a correlation between PI3K and TPI. We conclude that G-CSF-impaired NK cell cytotoxicity may accompany PI3K/Akt signaling. The effect is transient and NK cells may recover after G-CSF clearance, suggesting that G-CSF-mobilized HSCT may benefit both acute GVHD prevention and late-phase GVL promotion in HSCT recipients.

Granulocyte-colony stimulating factor drives the in vitro differentiation of human dendritic cells that induce anergy in naïve T cells

G-CSF is a modulator of T-cell and DC functions. Previous reports show that monocytes from G-CSF-treated (post-G) healthy donors differentiate into tolerogenic DC in vitro in the presence of autologous serum, containing high levels of IL-10 and IFN-α, and in turn induce type 1 Treg (Tr1) cells. However, the direct effect of G-CSF on DC differentiation was not investigated. Here, we show that monocytes differentiated in the presence of exogenous G-CSF (G-DC) remain CD14(+) CD1a(-) , but acquire a DC-like morphology, express CD83 and CD86 and low levels of the tolerogenic markers Ig-like transcript (ILT)4 and HLA-G. G-DC spontaneously produce IL-10 and, upon stimulation, low levels of IL-12. G-DC display low stimulatory capacity and induce anergy in naïve T cells, but do not confer suppressive function. Therefore, in vitro differentiation of monocyte-derived DC in the presence of G-CSF can replicate some but not all features of post-G DC. These findings indicate that the tolerogenic properties of G-CSF do not exclusively reside in its direct effect on DC, which in turn induce T-cell anergy, but also in its ability to generate a tolerogenic milieu in vivo, which is necessary for Tr1 cell induction and cannot be replicated in vitro.

Immune mobilization of autologous blood progenitor cells: direct influence on the cellular subsets collected

BACKGROUND AIMS

A phase I trial examined the ability of immunotherapy to mobilize progenitor and activated T cells.

METHODS

Interleukin (IL)-2 was administered subcutaneously for 11 days, with granulocyte (G)-colony-stimulating factor (CSF) (5 mcg/kg/day) and granulocyte-macrophage (GM)-CSF (7.5 mcg/kg/day) added for the last 5 days. Leukapheresis was initiated on day 11. Thirteen patients were treated (myeloma n = 11, non-Hodgkin's lymphoma n = 2).

RESULTS

Toxicities were minimal. IL-2 was stopped in two patients because of capillary leak (n = 1) and diarrhea (n = 1). Each patient required 2.5 leukaphereses (median; range 1-3) to collect 3.2 x 10⁶ CD34+ cells/kg (median; range 1.9-6.6 x 10⁶/kg). Immune mobilization increased the number of CD3+ CD8+ T cells (P = 0.002), CD56+ natural killer (NK) cells (P = 0.0001), CD8+ CD56+ T cells (P = 0.002) and CD4+ CD25+ cells (P = 0.0001) compared with cancer patients mobilized with G-CSF alone. There was increased lysis of myeloma cells after 7 days (P = 0.03) or 11 days (P = 0.02). The maximum tolerated dose of IL-2 was 1 x 10⁶ IU/m²/day.

CONCLUSIONS

Immune mobilization is well tolerated with normal subsequent marrow engraftment. As cells within the graft influence lymphocyte recovery, an increased number of functional lymphocytes may result in more rapid immune reconstitution.

Increased adenosine triphosphate production by peripheral blood CD4+ cells in patients with hematologic malignancies treated with stem cell mobilization agents

Hematopoietic stem cell (HSC) transplantation is an important therapeutic option for patients with hematologic malignancies. To explore the immunomodulatory effects of HSC mobilization agents, we studied the function and phenotype of CD4(+) T cells from 16 adult patients with hematologic malignancies undergoing HSC mobilization treatment for autologous transplantation. Immune cell function was determined using the Immuknow (Cylex) assay by measuring the amount of adenosine triphosphate (ATP) produced by CD4(+) cells from whole blood. ATP activity measured in G-CSF-treated patients was significantly higher than that measured in healthy individuals or "nonmobilized" patients. In patients treated with G-CSF, CD4(+) T cells were predominantly CD25(low)FOXP3(low), consistent with an activated phenotype. However, T-cell depletion did not abrogate ATP production in blood samples from G-CSF-treated patients, indicating that CD4(+) myeloid cells contributed to the increased ATP levels observed in these patients. There was a significant correlation between ATP activity and patient survival, suggesting that efficient activation of CD4(+) cells during mobilization treatment predicts a low risk of disease relapse. Monitoring immune cell reactivity using the Immuknow assay may assist in the clinical management of patients with hematologic malignancies and optimization of HSC mobilization protocols.

Leukemia-associated minor histocompatibility antigen discovery using T-cell clones isolated by in vitro stimulation of naive CD8+ T cells

T-cell immunotherapy that targets minor histocompatibility (H) antigens presented selectively by recipient hematopoietic cells, including leukemia, could prevent and treat leukemic relapse after hematopoietic cell transplantation without causing graft-versus-host disease. To provide immunotherapy that can be applied to a majority of transplantation recipients, it is necessary to identify leukemia-associated minor H antigens that result from gene polymorphisms that are balanced in the population and presented by common human leukocyte antigen alleles. Current approaches for deriving minor H antigen-specific T cells, which provide essential reagents for the molecular identification and characterization of the polymorphic genes that encode the antigens, rely on in vivo priming and are often unsuccessful. We show that minor H antigen-specific cytotoxic T lymphocyte precursors are found predominantly in the naive CD8(+) T-cell subset and provide an efficient strategy for in vitro priming of native T cells to generate T cells to a broad diversity of minor H antigens presented with common human leukocyte antigen alleles. We used this approach to derive a panel of stable cytotoxic T lymphocyte clones for discovery of genes that encode minor H antigens and identify a novel antigen expressed on acute myeloid leukemia stem cells and minimally in graft-versus-host disease target tissues.

Ortho-quinones of benzene and estrogens induce hyperproliferation of human peripheral blood mononuclear cells

Benzene is a known leukemogen. It has been hypothesized that benzene and natural estrogens initiate cancer by forming ortho-quinones (catechol quinones) that react with DNA in cells. These quinones form depurinating DNA adducts that generate the mutations leading to cancer. This study examined whether the treatment of normal human peripheral blood mononuclear cells with the ortho-quinones of benzene or estradiol would form DNA adducts and elicit an alteration in the proliferation of these cells. Both estradiol-3,4-quinone and benzene ortho-quinone formed depurinating DNA adducts and significantly increased the mitogen-induced proliferation of normal blood mononuclear cells. Immunophenotyping of the estradiol-3,4-quinone-treated blood cells indicated that monocyte/macrophage, natural killer and T-cells were particularly prone to hyperproliferation. Thus, DNA damage induced by the ortho-quinones of benzene and estradiol may promote the growth of human blood mononuclear cells, including those that appear in large numbers in leukemia and lymphoma.

Functional regulatory T cells are collected in stem cell autografts by mobilization with high-dose cyclophosphamide and granulocyte colony-stimulating factor

High-dose cyclophosphamide (Cy) and G-CSF are widely used to mobilize hemopoietic stem cells for treating patients with high-dose chemotherapy and autologous stem cell transplantation (ASCT). Because lymphocyte count in the graft collected after Cy-G-CSF treatment is an independent survival factor after ASCT for patients with multiple myeloma, our purpose was to study how Cy-G-CSF treatment affects the phenotype and function of T cells in patients with multiple myeloma. Cy induced a 3-fold decrease of T cell counts with a slow and partial T cell recovery of one-third at the time of hemopoietic stem cell collection. Cy-G-CSF treatment did not affect the relative ratios of central memory, effector memory, and late effector CD4+ or CD8+ T cells, but a decrease in the percentage of naive CD4+ cells was observed. The percentages of CD25+ cells increased 2- to 3-fold in CD4+ and CD8+ T cells, the former including both activated CD25low and CD25high cells. CD4+CD25high cells were regulatory T cells (Treg) that expressed high levels of FOXP3, CTLA-4, and GITR and displayed in vitro suppressive properties. The recovery of Treg absolute counts after Cy-G-CSF treatment was higher than the recovery of other lymphocyte subpopulations. In conclusion, Cy-G-CSF treatment induces a severe T cell count decrease without deleting Treg, which are potent inhibitors of antitumor response. The present data encourage novel therapeutic strategies to improve T cell recovery following ASCT while limiting Treg expansion.

Immunomodulatory effects of human recombinant granulocyte-macrophage colony-stimulating factor (rhuGM-CSF): evidence of antitumour activity

Human recombinant granulocyte-macrophage colony-stimulating factor (rhuGM-CSF) is traditionally used as supportive care for patients undergoing cytotoxic chemotherapy or haematopoietic cell progenitor mobilisation. Emerging evidence suggests rhuGM-CSF, through activity on monocytes and dendritic cells, acts as a potent modulator of immune responses and has the ability to recruit inflammatory cells and cytokines to local and systemic sites of infection. The immunomodulatory effects of rhuGM-CSF suggest the potential to enhance innate and acquired immune responses against tumour-related antigens. Enhancement of innate antitumour immunity, especially in the context of minimal residual disease, is of central importance and presents the potential for meaningful contributions to long-term disease survival. This article discusses the immunomodulatory effects of rhuGM-CSF in the context of single-agent therapy in solid tumours, as well as combination therapy in lymphoma. In addition, dendritic cell modulation with rhuGM-CSF in haematopoietic progenitor grafts and rhuGM-CSF-transduced tumour vaccines will be discussed.

Granulocyte colony-stimulating factor: a novel mediator of T cell tolerance

In recent years, several investigators have unraveled a previously unrecognized role for G-CSF in the regulation of T cell and dendritic cell functions. The experimental evidence in favor of G-CSF-mediated immune regulation includes the ability to switch T cell cytokine secretion profile to Th2 responses and the promotion of regulatory T cell and tolerogenic dendritic cell differentiation. Interestingly, G-CSF is beneficial in animals for the prevention and/or treatment of immune-mediated diseases, e.g., graft-vs-host disease, multiple sclerosis, systemic lupus erythematosus, inflammatory bowel disease, and diabetes, suggesting a potential role in human autoimmune diseases. This review summarizes the growing body of evidence that supports a critical role for G-CSF as a novel mediator of T cell tolerance.

rhG-CSF does not affect the phenotype of adult donor peripheral blood NK cells

Considerable evidence in preclinical models as well as in human transplantation now suggests that donor-derived natural killer (NK) cells can contribute to alloimmune recognition of recipient residual tumour cells. This makes the NK cell population an attractive target for in vitro or in vivo manipulations, in order to improve the antitumour effect of allogeneic transplantation. However, conditions in which allogeneic donor cells are collected vary; several reports have emphasised the different phenotypic and functional properties of T cells derived from marrow, cord blood or mobilised peripheral blood grafts; others have demonstrated different clinical outcomes following blood or marrow transplantation after myeloablative conditioning regimens. NK cells have been examined in this setting; the availability of new tools to study the expression of a variety of surface antigens that are involved in the control of NK cell activity offered us an opportunity to extensively characterise the phenotypic properties of NK cells from donors, before and after administration of pharmacological doses of rhG-CSF used for haematopoietic progenitor mobilisation. Our study suggests that rhG-CSF does not reproducibly alter blood NK cell phenotype in normal individuals, and thus that donor-derived cells are fully equipped to exert their potential antitumour effect.

Prognostic factors of chronic graft-versus-host disease after allogeneic blood stem-cell transplantation

Allogeneic hematopoietic stem cells in peripheral blood transplantation (alloPBSCT) or bone marrow transplantation (alloBMT) have different biological characteristics which may affect differently prognostic factors for incidence and severity of chronic graft-versus-host disease (cGVHD). To determine the prognostic factors of cGVHD in patients receiving alloPBSCT, data on 87 patients who survived at least 100 days after matched related donor myeloablative transplantation were analyzed. Factors significantly associated with higher incidence of cGVHD after alloPBSCT included CMV-positive donor, acute skin GVHD, and diagnoses other than lymphoma. Factors predictive for poor survival following cGVHD diagnosis included platelet count < 100,000/mm3 and history of acute liver GVHD. Acute liver GVHD and etoposide in the preparative regimen significantly increased risk of death due to cGVHD after alloPBSCT. All alloPBSCT multivariate models were fit to an independent cohort of comparable matched related donor alloBMT patients (n=75). After alloBMT, only acute skin GVHD and diagnoses other than lymphoma retained prognostic significance for predicting cGVHD. Low platelet count was the only variable predictive for poor survival in cGVHD patients after alloBMT. Acute liver GVHD was the only factor that retained prognostic significance for risk of death due to cGVHD after alloBMT. These data suggest there are some cGVHD prognostic factors that may be unique to recipients of alloPBSCT. More studies are needed to determine whether cGVHD prognostic systems should be used interchangeably in patient populations receiving different stem-cell products.

Phenotype and function of human natural killer cells purified by using a clinical-scale immunomagnetic method

Infection, disease relapse, graft failure, and graft-versus-host disease (GVHD) are significant adverse events associated with allogeneic bone marrow transplantation. Donor natural killer (NK) cells may be an ideal cell type for prevention or treatment of all these adverse events. Therefore, we investigated the phenotype and function of human NK cells purified by using a clinical-scale immunomagnetic method. We found that the NK cell purification procedures did not adversely affect the expression of killer cell immunoglobulin-like receptors, adhesion molecules, intracellular cytokines, perforin, and granzyme B. Purified NK cells had extensive proliferative capacity and potent antitumor activity when assessed using an immunodeficient mouse model. While all mice transplanted with unpurified mononuclear cells developed GVHD, none of the mice transplanted with purified NK cells did. NK cells were highly susceptible to lysis by antithymocyte globulin (ATG), whereas G-CSF had a minimal effect on their natural cytotoxicity. These results support future clinical investigation of the use of purified NK cells for adoptive immunotherapy in the absence of ATG.

Immune restoration following hematopoietic stem cell transplantation: an evolving target

Hematopoietic stem cell transplantation (HSCT) is the definitive cure for many malignant and nonmalignant diseases. However, delays in immune reconstitution (IR) following HSCT significantly limit the success of transplantation and increase the risk for infection and disease relapse in the transplant recipient. Therefore, ways to measure and to manipulate immune recovery following HSCT are emerging and their success depends directly upon an enhanced understanding for the underlying mechanisms responsible for reconstituted immunity and hematopoiesis. Recent discoveries in the activation, function, and regulation of dendritic cell (DC), natural killer (NK) cell, and T-lymphocyte subtypes have been critical in developing immunotherapies used to prevent graft-versus-host disease and to enhance graft-versus-leukemia. For example, regulatory T cells that induce tolerance and NK receptor-tumor ligand disparities that result in tumor lysis are being used to minimize GVHD and tumor burden, respectively. Furthermore, expansion and modulation of immune effector cells are being used to augment hematopoietic and immune recovery and to decrease transplant-related toxicity in the transplant recipient. Specifically, DC expansion and incorporation into antitumor and anti-microbial vaccines is fast approaching application into clinical trials. This paper will review our current understanding for IR following HSCT and the novel ways in which to restore immune function and decrease transplant-related toxicity in the transplant recipient.

Selective activation of STAT3 in human monocytes stimulated by G-CSF: implication in inhibition of LPS-induced TNF-alpha production

Lipopolysaccharide (LPS) induced tumor necrosis factor (TNF)-alpha production in human monocytes, which was dependent on activation of extracellular signal-regulated kinase (ERK), p38, c-Jun NH(2)-terminal kinase (JNK), and nuclear factor (NF)-kappa B. LPS-induced TNF-alpha production was inhibited by granulocyte colony-stimulating factor (G-CSF) and interleukin (IL)-10. G-CSF, like IL-10, exerted the inhibitory effect even when simultaneously added with LPS. Among the signaling pathways, signal transducer and activator of transcription 3 (STAT3) was selectively activated in monocytes stimulated by G-CSF or IL-10. G-CSF-mediated inhibition of LPS-induced TNF-alpha production as well as G-CSF-induced STAT3 phosphorylation and suppressor of cytokine signaling 3 mRNA expression were prevented by pretreatment of monocytes with AG-490, an inhibitor of Janus kinase 2. G-CSF did not affect LPS-induced activation of ERK, p38, JNK, and NF-kappa B, indicating that G-CSF affects the pathway downstream or independently of these signaling molecules. G-CSF-induced, but not IL-10-induced, STAT3 phosphorylation was attenuated in the presence of LPS. These findings suggest that G-CSF, like IL-10, inhibits LPS-induced TNF-alpha production in human monocytes through selective activation of STAT3, and the immunomodulation observed in vivo by G-CSF administration may be partly ascribed to the direct effect of G-CSF on monocyte functions.

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.

Blood versus marrow hematopoietic allogeneic graft

Allogeneic G-CSF-mobilized blood cell transplantation (BCT), an alternative to allogeneic bone marrow transplantation (BMT), is associated with enhanced engraftment and accelerated hematopoietic recovery. In addition, immune reconstitution and overall alloreactivity after BCT versus BMT differ significantly. Indeed, despite an increased number of donor T cells infused, the incidence of acute graft-versus-host disease (GvHD) after BCT appears to remain identical or lesser than after BMT. On the other hand, a higher risk of chronic GvHD has been reported after BCT. In a SFGM phase III trial, 101 patients with early leukemia and an HLA-matched sibling donor randomly received a BCT or BMT. BCT was associated with a higher number of infused CD34+ cells, accelerated platelet and neutrophil reconstitution, fewer platelet transfusions and similar acute GvHD incidence. However, chronic GvHD occurred more frequently after BCT. With a median follow-up of 20 months, relapse, survival and leukemia-free survival were not different. In the course of this study, immune parameters related to the graft as well as to early reconstitution were prospectively examined. T cells subsets, B cells, NK cells and monocytes numbers were significantly higher in BC grafts (versus BM). T cells in BC grafts were less activated than in BM grafts. Frequency of IFN-gamma, IL-2- and TNF-alpha-secreting cells and single-cell IFN-gamma production potential was reduced in BC graft. One month after BCT, blood T-cell counts were 3-fold higher than after BMT. Moreover, post-BCT T cells were less activated and counts correlated with the number of T cells infused with the graft, which was not the case after BMT. Several acute hemolysis episodes, resulting from anti-A and/or -B donor-derived Ab directed at Ag present on recipient red blood cells (minor ABO mismatch), have been described after BCT. Recipients indeed exhibited significantly increased anti-A and/or -B Ab titers after BCT, particularly in the setting of a "minor" ABO mismatch. Furthermore, the frequency of anti-HLA Ab early after BCT was significantly increased (despite the reduction in platelet transfusion requirements). The higher number of activated B cells and/or CD4 T cells and monocytes in a BCT graft and/or the higher number of circulating CD4 T- and B-cells after BCT could be associated with the enhanced alloAb production. G-CSF-induced TH2 cytokine profile of the T cells present in the graft could also be contributive. Recent studies have determined that BC grafts contained a higher number of type 2 dendritic cells (DC2), themselves associated with high frequencies of TH2 CD4+ cells. Since chronic GvHD is associated with the occurrence of Ab-mediated auto-immune-like syndromes, it is tempting to speculate that a higher incidence of chronic GvHD may result from these findings. In conclusion, BCT results in clinically relevant distinct hematopoietic and immune reconstitution patterns.

Granulocyte colony stimulation factor (G-CSF) suppresses interleukin (IL)-12 and/or IL-2 induced interferon (IFN)-γproduction and cytotoxicity of decidual mononuclear cells

PROBLEM

The placenta is one of the few non-hematopoietic tissues to express granulocyte colony stimulation factor (G-CSF). Placental G-CSF production is considered to be one of the major causes of granulocytosis during pregnancy although its physiological role in pregnancy has not yet been examined.

METHOD OF STUDY

The effects of G-CSF on interleukin (IL)-2 and/or IL-12 induced interferon (IFN)-gamma production of magnetic cell sorting (MACS) sorted decidual lymphocytes was examined by enzyme-linked immunosorbent spot-forming cell assay (ELISPOT). The effect of G-CSF on cytotoxicity of decidual lymphocytes against the choriocarcinoma cell line JEG-3 was examined by lactate dehydrogenase (LDH) release assay.

RESULTS

As previously reported by us, IL-2 and/or IL-12 activated decidual mononuclear cells were capable of killing choriocarcinoma cells. We observed that G-CSF abolished IFN-gamma production and cytotoxicity of decidual mononuclear cells and MACS sorted CD56+ cells.

CONCLUSIONS

In addition to its well-known trophic effects on hematopoiesis, our results suggest about new roles of G-CSF in reproductive immunology.

Factors affecting antibody levels after allogeneic hematopoietic cell transplantation

To obtain insight into the mechanism(s) of posttransplantation humoral immunodeficiency, we evaluated factors affecting serum antibody levels against polio, tetanus, Haemophilus influenzae, and Streptococcus pneumoniae in 87 patients. Patients with hematologic malignancies were randomized to receive marrow versus blood stem cells, which contain approximately 10 times more lymphocytes than marrow. Blood stem cell recipients did not have higher antibody levels than marrow recipients. Recipient pretransplantation antibody levels were correlated with the posttransplantation levels, especially in the first 6 months after transplantation when the correlation coefficients typically exceeded 0.6. Donor pretransplantation antibody levels had less of a correlation with posttransplantation levels in the recipient. Patient or donor age, total body irradiation, and graft-versus-host disease or its treatment appeared to have no effect. In conclusion, antibody levels in the first year after transplantation are affected primarily by pretransplantation antibody levels in the recipient and, to a lesser degree, in the donor. These findings suggest that immunization of the recipient and the donor before transplantation may be more effective in improving antibody immunity after transplantation than manipulating graft-versus-host disease, changing conditioning, or increasing the number of lymphocytes in the graft.

The therapy of myelofibrosis: targeting pathogenesis

Myelofibrosis with myeloid metaplasia (MMM) encompasses the diagnoses of agnogenic myeloid metaplasia (idiopathic myelofibrosis), as well as the advanced phases of polycythemia vera and essential thrombocythemia (post polycythemic and post thrombocythemia myeloid metaplasia, respectively). MMM is a clonal, hematopoietic stem cell disorder in which neither the pathogenesis, nor a broadly applicable effective therapy have been described. Clinically, these patients experience progressive marrow replacement by fibrotic tissue, ineffective hematopoiesis, problematic cytopenia's, significant hepato-splenomegaly, extramedullary hematopoiesis, profound constitutional symptoms, and a risk of blastic transformation. Historically, therapies have been targeted at palliating symptoms (i.e. splenectomy, transfusions, hydroxyurea, erythropoietin, androgens, localized radiotherapy). Stem cell transplantation appears promising, but is often toxic and not broadly applicable due to co-morbidities and age of MMM patients. Non-myeloablative approaches to conditioning may broaden the applicability of stem cell transplantation in MMM, yet results to date are preliminary. Although a definitive molecular abnormality responsible for the pathogenesis of MMM has not been described, much has been learned about the aberrant expression of pro-fibrotic cytokines and the presence of increased angiogenesis in MMM. These pathogenetic insights have led to a series of pilot clinical trials with therapeutic agents targeting aberrantly expressed cytokines (and possibly angiogenesis) including Thalidomide (alone or in combination), Etanercept, and STI-571. Amongst these later agents Thalidomide has demonstrated the most promise (palliating disease associated cytopenia's), whereas the TNF-alpha inhibitor Etanercept has aided with MMM associated constitutional symptoms. Although these later trials have been helpful in a subset of patients, no agent to date has led to solid complete responses in MMM across the spectrum of disease manifestations. Further insights into the pathogenetic mechanisms responsible for myeloproliferation (aberrant cell signaling pathways, apoptotic resistance, other) are necessary to guide selection and testing of the expanding number of novel anti-neoplastic agents in chronic myeloid disorders and MMM.

Induction of a hypercoagulability state and endothelial cell activation by granulocyte colony-stimulating factor in peripheral blood stem cell donors

In June, 1997, we initiated a prospective study to analyze the effect of granulocyte colony-stimulating factor (G-CSF) on coagulation system in peripheral blood stem cells (PBSC) donors following G-CSF administration. Since, 25 consecutively healthy donors received G-CSF (filgrastim) to mobilize and collect PBSC and 20 donors were finally included in the study. Blood samples were collected immediately before starting G-CSF and prior to PBSC collection to analyze the following parameters: prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, hypercoagulability markers (D-dimer, TAT complex, F1 + 2), natural anticoagulants (antithrombin, protein C, protein S), endothelial activation markers [von Willebrand factor antigen (vWF:Ag) and angiotensin converting enzyme (ACE)], and resistance to activated protein C. We found a significant increase in F1 + 2 and D-dimer while a significant decrease of antithrombin and protein C activity was evidenced. Regarding endothelial cell activation markers, a significant increase of vWF:Ag with a slightly significant decrease of ACE were also observed. Therefore, in PBSC donors receiving G-CSF our results reveal activation of both coagulation and endothelial cells that could favor the developing of thrombotic events. In consequence, a careful monitoring should be considered in those cases with risk factors for thrombosis.

Clinical and scientific advances in the Philadelphia-chromosome negative chronic myeloproliferative disorders

The chronic myeloproliferative disorders are clonal hematopoietic stem cell disorders and include chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), and agnogenic myeloid metaplasia (AMM). These diseases are characterized by clonal expansion of the myeloid compartment, increased marrow angiogenesis, and varying risks for blastic transformation. A clear molecular abnormality exists (t(9;22) leading to the fusion of BCR-Abl) only for CML, which led to effective targeted therapy (STI-571). Since no similar pathogenetic mechanism has been discovered for the t(9;22) negative chronic myeloproliferative disorders, their respective diagnosis is currently based on a variety of rather cumbersome diagnostic criteria. Polycythemia vera is distinguished from reactive erythrocytosis through erythropoietin independent growth of erythroid progenitors in vitro, suppressed levels of endogenous erythropoietin, possible overexpression of PRV-1 (polycythemia rubra vera-1), decreased c-Mpl expression on megakaryocytes, as well as overexpression of bcl-xL, and potentially aberrant activity of the Jak-Stat pathway. ET is defined by thrombocytosis and is distinguished from reactive states by decreased megakaryocyte c-Mpl expression, and a propensity for thrombosis. AMM has been associated with a variety of observations including increased concentrations of pro-fibrotic cytokines, increased angiogenesis, and myeloid expansion. AMM is often indistinguishable clinically and prognostically from the advanced phases of other CMPD (specifically post-polycythemic and post-thrombocythemia myeloid metaplasia), all of which are subentities of a diagnosis of myelofibrosis with myeloid metaplasia (MMM). The management of CMPD patients is quite varied given the broad range of disease severity and survival observed. The role of stem cell transplantation is limited by the age and comorbidities encountered in CMPD patients. Since no broadly applicable therapy effects the mortality of the CMPD, management currently focuses on the prevention/palliation of disease morbidity (i.e. vascular complications, pruritus, organomegaly, constitutional symptoms). Palliative strategies which currently focus on non-specific myelosuppresion, will hopefully be soon replaced by targeted therapies as insight into pathogenetic mechanisms of these diseases evolves.