Natural Killer (NK) Cells Are Functionally Abnormal and NK Cell Progenitors Are Diminished in Granulocyte Colony-Stimulating Factor–Mobilized Peripheral Blood Progenitor Cell Collections

In vivo G-CSF treatment activates the GR-SOCS1 axis to suppress IFN-γ secretion by natural killer cells

Natural killer (NK) cells are lymphocytes that are involved in controlling tumors or microbial infections through the production of interferon gamma (IFN-γ). Granulocyte colony-stimulating factor (G-CSF) inhibits IFN-γ secretion by NK cells, but the mechanism underlying this effect remains unclear. Here, by comparing the multi-omics profiles of human NK cells before and after in vivo G-CSF treatment, we identify a pathway that is activated in response to G-CSF treatment, which suppresses IFN-γ secretion in NK cells. Specifically, glucocorticoid receptors (GRs) activated by G-CSF inhibit secretion of IFN-γ by promoting interactions between SOCS1 promoters and enhancers, as well as increasing the expression of SOCS1. Experiments in mice confirm that G-CSF treatment significantly downregulates IFN-γ secretion and upregulates GR and SOCS1 expression in NK cells. In addition, GR blockade by the antagonist RU486 significantly reverses the effects of G-CSF, demonstrating that GRs upregulate SOCS1 and inhibit the production of IFN-γ by NK cells.

Hematopoietic cell transplantation donor-derived memory-like NK cells functionally persist after transfer into patients with leukemia

Natural killer (NK) cells are innate lymphoid cells that eliminate cancer cells, produce cytokines, and are being investigated as a nascent cellular immunotherapy. Impaired NK cell function, expansion, and persistence remain key challenges for optimal clinical translation. One promising strategy to overcome these challenges is cytokine-induced memory-like (ML) differentiation, whereby NK cells acquire enhanced antitumor function after stimulation with interleukin-12 (IL-12), IL-15, and IL-18. Here, reduced-intensity conditioning (RIC) for HLA-haploidentical hematopoietic cell transplantation (HCT) was augmented with same-donor ML NK cells on day +7 and 3 weeks of N-803 (IL-15 superagonist) to treat patients with relapsed/refractory acute myeloid leukemia (AML) in a clinical trial (NCT02782546). In 15 patients, donor ML NK cells were well tolerated, and 87% of patients achieved a composite complete response at day +28, which corresponded with clearing high-risk mutations, including TP53 variants. NK cells were the major blood lymphocytes for 2 months after HCT with 1104-fold expansion (over 1 to 2 weeks). Phenotypic and transcriptional analyses identified donor ML NK cells as distinct from conventional NK cells and showed that ML NK cells persisted for over 2 months. ML NK cells expressed CD16, CD57, and high granzyme B and perforin, along with a unique transcription factor profile. ML NK cells differentiated in patients had enhanced ex vivo function compared to conventional NK cells from both patients and healthy donors. Overall, same-donor ML NK cell therapy with 3 weeks of N-803 support safely augmented RIC haplo-HCT for AML.

Perturbed NK Cell Homeostasis Associated with Disease Severity in Chronic Neutropenia

Neutrophils have been suggested to play a critical role in terminal differentiation of NK cells. Whether this is a direct effect or a consequence of global immune changes with effects on NK cell homeostasis remains unknown. Here, we used high-resolution flow- and mass cytometry to examine NK cell repertoires in 64 patients with neutropenia and 27 healthy age- and gender-matched donors. A subgroup of patients with chronic neutropenia showed severely disrupted NK cell homeostasis manifested as increased frequencies of CD56bright NK cells and a lack of mature CD56dim NK cells. These immature NK cell repertoires were characterized by expression of proliferation/exhaustion markers Ki-67, Tim-3 and TIGIT and displayed blunted tumor target cell responses. Systems-level immune mapping revealed that the changes in immunophenotypes were confined to NK cells, leaving T cell differentiation intact. RNA sequencing of NK cells from these patients showed upregulation of a network of genes, including TNFSF9, CENPF, MKI67 and TOP2A, associated with apoptosis and the cell cycle, different from conventional CD56bright signatures. Profiling of 249 plasma proteins showed a coordinated enrichment of pathways related to apoptosis and cell turnover, which correlated with immature NK cell repertoires. Notably, most of these patients exhibited severe-grade neutropenia, suggesting that the profoundly altered NK cell homeostasis was connected to the severity of their underlying etiology. Hence, although our data suggests that neutrophils are dispensable for NK cell development and differentiation, some patients displayed a specific gap in the NK repertoire, associated with poor cytotoxic function and more severe disease manifestations.

Non-invasive and label-free identification of human natural killer cell subclasses by biophysical single-cell features in microfluidic flow

Natural killer (NK) cells are indicated as favorite candidates for innovative therapeutic treatment and are divided into two subclasses: immature regulatory NK CD56^bright and mature cytotoxic NK CD56^dim. Therefore, the ability to discriminate CD56^dim from CD56^bright could be very useful because of their higher cytotoxicity. Nowadays, NK cell classification is routinely performed by cytometric analysis based on surface receptor expression. Here, we present an in-flow, label-free and non-invasive biophysical analysis of NK cells through a combination of light scattering and machine learning (ML) for NK cell subclass classification. In this respect, to identify relevant biophysical cell features, we stimulated NK cells with interleukine-15 inducing a subclass transition from CD56^bright to CD56^dim. We trained our ML algorithm with sorted NK cell subclasses (≥86% accuracy). Next, we applied our NK cell classification algorithm to cells stimulated over time, to investigate the transition of CD56^bright to CD56^dim and their biophysical feature changes. Finally, we tested our approach on several proband samples, highlighting the potential of our measurement approach. We show a label-free way for the robust identification of NK cell subclasses based on biophysical features, which can be applied in both cell biology and cell therapy.

Planned Granulocyte Colony-Stimulating Factor Adversely Impacts Survival after Allogeneic Hematopoietic Cell Transplantation Performed with Thymoglobulin for Myeloid Malignancy

The in vivo depletion of recipient and donor T lymphocytes using antithymocyte globulin (ATG; Thymoglobulin) is widely adopted in allogeneic hematopoietic stem cell transplantation (HCT) to reduce the incidence of both graft failure and graft-versus-host disease (GVHD). However, excess toxicity to donor lymphocytes may hamper immune reconstitution, compromising antitumor effects and increasing infection. Granulocyte-colony stimulating factor (G-CSF) administered early after HCT may increase ATG-mediated lymphotoxicity. This study aimed to investigate the effect of an interaction between ATG and post-transplantation granulocyte colony-stimulating factor (G-CSF) on allogeneic HCT outcomes, using the Center for International Blood and Marrow Transplant Research (CIBMTR) registry. We studied patients age ≥18 years with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS) who received Thymoglobulin-containing preparative regimens for HLA-matched sibling/unrelated or mismatched unrelated donor HCT between 2010 and 2018. The effect of planned G-CSF that was started between pretransplantation day 3 and post-transplantation day 12 was studied in comparison with transplantations that did not include G-CSF. Cox regression models were built to identify risk factors associated with outcomes at 1 year after transplantation. A total of 874 patients met the study eligibility criteria, of whom 459 (53%) received planned G-CSF. HCT with planned G-CSF was associated with a significantly increased risk for nonrelapse mortality (NRM) (hazard ratio [HR] 2.03; P <.0001; 21% versus 12%) compared to HCT without G-CSF. The 6-month incidence of viral infection was higher with G-CSF (56% versus 47%; P = .007), with a particular increase in Epstein-Barr virus infections (19% versus 11%; P = .002). The observed higher NRM with planned G-CSF led to lower overall survival (HR, 1.52; P = .0005; 61% versus 72%). There was no difference in GVHD risk between the treatment groups. We performed 2 subgroup analyses showing that our findings held true in patients age ≥50 years and in centers where G-CSF was used in some, but not all, patients. In allogeneic peripheral blood HCT performed with Thymoglobulin for AML and MDS, G-CSF administered early post-transplantation resulted in a 2-fold increase in NRM and a 10% absolute decrement in survival. The use of planned G-CSF in the early post-transplantation period should be carefully considered on an individual patient basis, weighing any perceived benefits against these risks.

Enhancing a Natural Killer: Modification of NK Cells for Cancer Immunotherapy

Natural killer (NK) cells are potent innate immune system effector lymphocytes armed with multiple mechanisms for killing cancer cells. Given the dynamic roles of NK cells in tumor surveillance, they are fast becoming a next-generation tool for adoptive immunotherapy. Many strategies are being employed to increase their number and improve their ability to overcome cancer resistance and the immunosuppressive tumor microenvironment. These include the use of cytokines and synthetic compounds to bolster propagation and killing capacity, targeting immune-function checkpoints, addition of chimeric antigen receptors (CARs) to provide cancer specificity and genetic ablation of inhibitory molecules. The next generation of NK cell products will ideally be readily available as an “off-the-shelf” product and stem cell derived to enable potentially unlimited supply. However, several considerations regarding NK cell source, genetic modification and scale up first need addressing. Understanding NK cell biology and interaction within specific tumor contexts will help identify necessary NK cell modifications and relevant choice of NK cell source. Further enhancement of manufacturing processes will allow for off-the-shelf NK cell immunotherapies to become key components of multifaceted therapeutic strategies for cancer.

Exploring the NK cell platform for cancer immunotherapy

Natural killer (NK) cells are cytotoxic lymphocytes of the innate immune system that are capable of killing virally infected and/or cancerous cells. Nearly 20 years ago, NK cell-mediated immunotherapy emerged as a safe and effective treatment approach for patients with advanced-stage leukaemia. Subsequently, the field of NK cell-based cancer therapy has grown exponentially and currently constitutes a major area of immunotherapy innovation. In general, the development of NK cell-directed therapies has two main focal points: optimizing the source of therapeutic NK cells for adoptive transfer and enhancing NK cell cytotoxicity and persistence in vivo. A wide variety of sources of therapeutic NK cells are currently being tested clinically, including haploidentical NK cells, umbilical cord blood NK cells, stem cell-derived NK cells, NK cell lines, adaptive NK cells, cytokine-induced memory-like NK cells and chimeric antigen receptor NK cells. A plethora of methods to augment the cytotoxicity and longevity of NK cells are also under clinical investigation, including cytokine-based agents, NK cell-engager molecules and immune-checkpoint inhibitors. In this Review, we highlight the variety of ways in which diverse NK cell products and their auxiliary therapeutics are being leveraged to target human cancers. We also identify future avenues for NK cell therapy research.

Directed Differentiation of Mobilized Hematopoietic Stem and Progenitor Cells into Functional NK cells with Enhanced Antitumor Activity

Obtaining sufficient numbers of functional natural killer (NK) cells is crucial for the success of NK-cell-based adoptive immunotherapies. While expansion from peripheral blood (PB) is the current method of choice, ex vivo generation of NK cells from hematopoietic stem and progenitor cells (HSCs) may constitute an attractive alternative. Thereby, HSCs mobilized into peripheral blood (PB-CD34⁺) represent a valuable starting material, but the rather poor and donor-dependent differentiation of isolated PB-CD34⁺ cells into NK cells observed in earlier studies still represents a major hurdle. Here, we report a refined approach based on ex vivo culture of PB-CD34⁺ cells with optimized cytokine cocktails that reliably generates functionally mature NK cells, as assessed by analyzing NK-cell-associated surface markers and cytotoxicity. To further enhance NK cell expansion, we generated K562 feeder cells co-expressing 4-1BB ligand and membrane-anchored IL-15 and IL-21. Co-culture of PB-derived NK cells and NK cells that were ex-vivo-differentiated from HSCs with these feeder cells dramatically improved NK cell expansion, and fully compensated for donor-to-donor variability observed during only cytokine-based propagation. Our findings suggest mobilized PB-CD34⁺ cells expanded and differentiated according to this two-step protocol as a promising source for the generation of allogeneic NK cells for adoptive cancer immunotherapy.

Improving Clinical Manufacturing of IL-15 Activated Cytokine-Induced Killer (CIK) Cells

Cytokine-induced killer (CIK) cells are an immunotherapeutic approach to combat relapse following allogeneic hematopoietic stem cell transplantation (HSCT) in acute leukemia or myelodysplastic syndrome (MDS) patients. Prompt and sequential administration of escalating cell doses improves the efficacy of CIK cell therapy without exacerbating graft vs. host disease (GVHD). This study addresses manufacturing-related issues and aimed to develop a time-, personal- and cost-saving good manufacturing process (GMP)-compliant protocol for the generation of ready-for-use therapeutic CIK cell doses starting from one unstimulated donor-derived peripheral blood (PB) or leukocytapheresis (LP) products. Culture medium with or without the addition of either AB serum, fresh frozen plasma (FFP) or platelet lysate (PL) was used for culture. Fresh and cryopreserved CIK cells were compared regarding expansion rate, viability, phenotype, and ability to inhibit leukemia growth. Cell numbers increased by a median factor of 10-fold in the presence of FFP, PL, or AB serum, whereas cultivation in FFP/PL-free or AB serum-free medium failed to promote adequate CIK cell proliferation (p < 0.01) needed to provide clinical doses of 1 × 10⁶ T cells/kG, 5 × 10⁶ T cells/kG, 1 × 10⁷ T cells/kG, and 1 × 10⁸ T cells/kG recipient body weight. CIK cells consisting of T cells, T- natural killer (T-NK) cells and a minor fraction of NK cells were not significantly modified by different medium supplements. Moreover, neither cytotoxic potential against leukemic THP-1 cells nor cell activation shown by CD25 expression were significantly influenced. Moreover, overnight and long-term cryopreservation had no significant effect on the composition of CIK cells, their phenotype or cytotoxic potential. A viability of almost 93% (range: 89–96) and 89.3% (range: 84–94) was obtained after freeze-thawing procedure and long-term storage, respectively, whereas viability was 96% (range: 90-97) in fresh CIK cells. Altogether, GMP-complaint CIK cell generation from an unstimulated donor-derived PB or LP products was feasible. Introducing FFP, which is easily accessible, into CIK cell cultures was time- and cost-saving without loss of viability and potency in a 10-12 day batch culture. The feasibility of cryopreservation enabled storage and delivery of sequential highly effective ready-for-use CIK cell doses and therefore reduced the number of manufacturing cycles.

Effect of the in vivo application of granulocyte colony-stimulating factor on NK cells in bone marrow and peripheral blood

Granulocyte colony‐stimulating factor (G‐CSF) has been widely used in the field of allogeneic haematopoietic stem cell transplantation (allo‐HSCT) for priming donor stem cells from the bone marrow (BM) to peripheral blood (PB) to collect stem cells more conveniently. Donor‐derived natural killer (NK) cells have important antitumour functions and immune regulatory roles post‐allo‐HSCT. The aim of this study was to evaluate the effect of G‐CSF on donors' NK cells in BM and PB. The percentage of NK cells among nuclear cells and lymphocyte was significantly decreased and led to increased ratio of T and NK cells in BM and PB post‐G‐CSF in vivo application. Relative expansion of CD56^briNK cells led to a decreased ratio of CD56^dim and CD56^briNK subsets in BM and PB post‐G‐CSF in vivo application. The expression of CD62L, CD54, CD94, NKP30 and CXCR4 on NK cells was significantly increased in PB after G‐CSF treatment. G‐CSF treatment decreased the IFN‐γ‐secreting NK population (NK1) dramatically in BM and PB, but increased the IL‐13‐secreting NK (NK2), TGF‐β‐secreting NK (NK3) and IL‐10‐secreting NK (NKr) populations significantly in BM. Clinical data demonstrated that higher doses of NK1 infused into the allograft correlated with an increased incidence of chronic graft‐vs‐host disease post‐transplantation. Taken together, our results show that the in vivo application of G‐CSF can modulate NK subpopulations, leading to an increased ratio of T and NK cells and decreased ratio of CD56^dim and CD56^briNK cells as well as decreased NK1 populations in both PB and BM.

Modification of NK cell subset repartition and functions in granulocyte colony-stimulating factor-mobilized leukapheresis after expansion with IL-15

The ability of natural killer (NK) cells to kill tumor cells without antigen recognition makes them appealing as an adoptive immunotherapy. However, NK cells are not routinely used in the context of leukemic relapse after hematopoietic stem cell transplantation. Patients who experience relapse can be treated with donor lymphocyte infusions (DLI) based on small-cell fractions frozen at the time of transplantation. Since peripheral blood stem cells (PBSCs) are increasingly used as a stem cell source and as a source of cells for DLI, we aimed to evaluate the impact of G-SCF mobilization on NK cell phenotype, subset repartition, and functionality. Immunomagnetically isolated NK cells from healthy donor blood, donor PBSCs, and patient PBSCs were expanded for 14 days with IL-15. The expansion capacity, phenotype, and functions (cytokine secretion and cytotoxicity) of NK cell subsets based on CD56 and CD16 expression were then evaluated. Mobilized sources showed a significant decrease of CD56^brightCD16⁺ NK cells (28 versus 74%), whereas a significant increase (64 versus 15%) of CD56^brightCD16^- NK cells was observed in comparison with peripheral blood. Patient-mobilized NK cells showed a significantly decreased cytotoxicity, and antibody-dependent cell cytototoxicity (ADCC) was also observed to a lesser extent in NK cells from healthy donor PBSC. G-CSF-mobilized NK cell TNF-α and IFN-γ secretion was impaired at day 0 compared to healthy donors but was progressively restored after culture. In conclusion, expansion of NK cells from G-CSF-mobilized sources may progressively improve their functionality.

Anti-G-CSF treatment induces protective tumor immunity in mouse colon cancer by promoting protective NK cell, macrophage and T cell responses

Granulocyte colony-stimulating factor (G-CSF) is a cytokine that is highly expressed in human and mouse colorectal cancers (CRC). We previously reported that G-CSF stimulated human CRC cell growth and migration, therefore in this study we sought to examine the therapeutic potential of anti-G-CSF treatment for CRC. G-CSF is known to mobilize neutrophils, however its impact on other immune cells has not been well examined. Here, we investigated the effects of therapeutic anti-G-CSF treatment on CRC growth and anti-tumor immune responses. C57BL/6 mice treated with azoxymethane/dextran sodium sulfate (AOM/DSS) to induce neoplasms were administered anti-G-CSF or isotype control antibodies three times a week for three weeks. Animals treated with anti-G-CSF antibodies had a marked decrease in neoplasm number and size compared to the isotype control group. Colon neutrophil and macrophage frequency were unchanged, but the number of macrophages producing IL-10 were decreased while IL-12 producing macrophages were increased. NK cells were substantially increased in colons of anti-G-CSF treated mice, along with IFNγ producing CD4(+) and CD8(+) T cells. These studies are the first to indicate a crucial role for G-CSF inhibition in promoting protective anti-tumor immunity, and suggest that anti-G-CSF treatment is a potential therapeutic approach for CRC.

Revving up Natural Killer Cells and Cytokine-Induced Killer Cells Against Hematological Malignancies

Natural killer (NK) cells belong to innate immunity and exhibit cytolytic activity against infectious pathogens and tumor cells. NK-cell function is finely tuned by receptors that transduce inhibitory or activating signals, such as killer immunoglobulin-like receptors, NK Group 2 member D (NKG2D), NKG2A/CD94, NKp46, and others, and recognize both foreign and self-antigens expressed by NK-susceptible targets. Recent insights into NK-cell developmental intermediates have translated into a more accurate definition of culture conditions for the in vitro generation and propagation of human NK cells. In this respect, interleukin (IL)-15 and IL-21 are instrumental in driving NK-cell differentiation and maturation, and hold great promise for the design of optimal NK-cell culture protocols. Cytokine-induced killer (CIK) cells possess phenotypic and functional hallmarks of both T cells and NK cells. Similar to T cells, they express CD3 and are expandable in culture, while not requiring functional priming for in vivo activity, like NK cells. CIK cells may offer some advantages over other cell therapy products, including ease of in vitro propagation and no need for exogenous administration of IL-2 for in vivo priming. NK cells and CIK cells can be expanded using a variety of clinical-grade approaches, before their infusion into patients with cancer. Herein, we discuss GMP-compliant strategies to isolate and expand human NK and CIK cells for immunotherapy purposes, focusing on clinical trials of adoptive transfer to patients with hematological malignancies.

Tracking in vivo dynamics of NK cells transferred in patients undergoing stem cell transplantation

Haploidentical stem cell transplantation (haploSCT) offers an alternative treatment option for advanced leukemia patients lacking a HLA-compatible donor. Transfer of NK cells represents a promising therapeutic option in combination with SCT, as NK cells can promote graft versus leukemia with low risk of GVH disease. In this study, we show results from a phase I/II trial in which 24 acute myeloid leukemia patients underwent haploSCT in combination with early transfer of unmodified NK cells and observed a promising 2-year overall survival rate of 37%. By performing immunomonitoring and subsequent principal component analysis, we tracked donor NK-cell dynamics in the patients and distinguished between NK cells reconstituting from CD34(+) precursors, giving rise over time to a continuum of multiple differentiation stages, and adoptively transferred NK cells. Transferred NK cells displayed a mature phenotype and proliferated in vivo during the early days after haploSCT even in the absence of exogenous IL-2 administration. Moreover, we identified the NK-cell phenotype associated with in vivo expansion. Thus, our study indicates a promising path for adoptive transfer of unmodified NK cells in the treatment of high-risk acute myeloid leukemia.

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.

Neutrophil depletion impairs natural killer cell maturation, function, and homeostasis

Neutropenia in mice and humans results in the generation of NK cells with an immature and hyporesponsive phenotype.

Natural killer (NK) cells are bone marrow (BM)–derived granular lymphocytes involved in immune defense against microbial infections and tumors. In an N-ethyl N-nitrosourea (ENU) mutagenesis strategy, we identified a mouse mutant with impaired NK cell reactivity both in vitro and in vivo. Dissection of this phenotype showed that mature neutrophils were required both in the BM and in the periphery for proper NK cell development. In mice lacking neutrophils, NK cells displayed hyperproliferation and poor survival and were blocked at an immature stage associated with hyporesponsiveness. The role of neutrophils as key regulators of NK cell functions was confirmed in patients with severe congenital neutropenia and autoimmune neutropenia. In addition to their direct antimicrobial activity, mature neutrophils are thus endowed with immunoregulatory functions that are conserved across species. These findings reveal novel types of cooperation between cells of the innate immune system and prompt examination of NK cell functional deficiency in patients suffering from neutropenia-associated diseases.

Thymic function after allogeneic stem cell transplantation is dependent on graft source and predictive of long term survival

T-cell deficiency after allogeneic stem cell transplantation (ASCT) is common and has major impact on clinical outcome. In this retrospective study 210 patients were analyzed with regards to levels of T-cell receptor excision circles (TRECs) during the first 24 months after transplantation. We could for the first time show a significant correlation between the use of bone marrow grafts and higher TREC levels >6 months post-ASCT (p<0.001). Treatment with anti-thymocyte globulin was correlated with lower TREC levels ≤6 months post-ASCT (p<0.001). Patients with TREC levels above median at 3 months had a superior overall survival, 80% vs. 56% (p=0.002), and lower transplantation-related mortality, 7% vs. 21% (p=0.01). We conclude that graft source and conditioning regimen may have a significant effect on T-cell reconstitution after ASCT and can thus affect outcome. These results strongly support the use of TREC measurement as part of the standard repertoire of immunological monitoring after ASCT.

Bone marrow may be the preferable graft source in recipients homozygous for HLA-C group 2 ligands for inhibitory killer Ig-like receptors

HLA class I molecules participate in natural killer cell regulation by acting as ligands for inhibitory killer cell Ig-like receptors (KIRs). One individual may express one or more inhibitory KIR lacking the corresponding HLA ligand. The role of this 'missing KIR ligand' constellation in hematopoietic SCT (HSCT) remains controversial and depends on incompletely defined transplant variables. We have retrospectively analyzed the effects of missing HLA-C group 1/2 and Bw4 KIR ligands in the recipients on the outcome in 382 HSCT, comparing 118 BMT to 264 PBSC transplants (PBSCT). In the multivariate Cox analysis of PBSCT, poor PFS was observed in homozygous HLA-C group 2 (C2/2) recipients (risk ratio (RR), 1.59; P=0.026). In contrast, C2 homozygosity was not unfavorable after BMT (RR, 0.68; P=0.16). C2 homozygous recipients (n=68) had better PFS after BMT than after PBSCT (RR, 0.17; P=0.001), due to fewer relapses (RR, 0.27; P=0.018). Missing Bw4 favorably influenced PFS after BMT (RR, 0.56; P=0.04), but not after PBSCT. These data suggest opposite effects of missing KIR ligands in BMT vs PBSCT. Larger studies are required to reassess whether BMT should be preferred to PBSCT as an option for C2/C2 recipients.

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.

Persistence of lymphocyte function perturbations after granulocyte-colony-stimulating factor mobilization and cytapheresis in normal peripheral blood stem cell donors

BACKGROUND

The short-term effects of granulocyte-colony-stimulating factor (G-CSF) have been extensively studied, but recent reports of G-CSF-induced genetic perturbations raised concerns regarding its long-term safety. In this respect, duration of G-CSF-induced perturbations has been less studied than short-term effects and needs to be evaluated.

STUDY DESIGN AND METHODS

G-CSF mobilization-induced immunologic alterations were prospectively analyzed in a cohort of 24 healthy donors. Blood samples were taken before G-CSF administration; at the time of administration; and at 1, 3, 6, and 12 months and analyzed for blood cell counts and in vitro cytokines (interleukin [IL]-2, -8, and -10) and immunoglobulin production, quantified in the culture supernatant of peripheral blood mononuclear cells (PBMNCs) after, respectively, phytohemagglutinin and pokeweed mitogen stimulation.

RESULTS

Platelet, granulocyte, monocyte, B, and dendritic blood cell counts as well as the IL-2, -8, and -10 secretion by PBMNCs, perturbed at the time of G-CSF mobilization, returned to baseline values at 1 month, with T-cell and natural killer cell counts recovering at 3 months. In vitro immunoglobulin production was increased up to 6 months after mobilization.

CONCLUSION

Although assessment of the potential long-term risk of G-CSF administration will require prolonged observation of larger cohorts, our data show that the duration of immunologic perturbations may be more persistent than previously anticipated, especially for B-cell functional alterations. Most perturbations remain, however, transient with a return to baseline values within 1 year.

Biology and clinical effects of natural killer cells in allogeneic transplantation

PURPOSE OF REVIEW

Following allogeneic hematopoietic cell transplantation, donor-derived natural killer (NK) cells target recipient hematopoietic cells, resulting in an antileukemia effect and a lower incidence of graft rejection. NK cells do not mediate and may diminish graft versus host disease. Here we review the determinants of NK cell alloreactivity and their implications for adoptive NK cell therapy.

RECENT FINDINGS

NK cell alloreactivity has been defined by the absence of recipient MHC class I ligands for donor inhibitory killer immunoglobulin-like receptor (KIR) receptors, as predicted by a number of algorithms. Recently, the role of activating NK receptors and their cognate ligands has received more attention. The beneficial clinical effect of NK-cell alloreactivity has not been uniformly demonstrated, likely reflecting differences in conditioning regimens, graft components and posttransplant immune suppression. Investigations of NK cell phenotype and function after transplantation have helped demonstrate which NK cell subsets mediate the graft versus leukemia effect. These advances have proceeded in parallel with increasing facility in GMP-grade bulk purification and administration of NK cell preparations.

SUMMARY

NK cells are a heterogeneous population of lymphocytes with diverse patterns of target-cell recognition and effector function. Further clinical and functional correlations will help maximize their potential for clinical benefit.

Good manufacturing practices production of natural killer cells for immunotherapy: a six-year single-institution experience

BACKGROUND

Natural killer (NK) cells, a subset of lymphocytes and part of the innate immune system, play a crucial role in defense against cancer and viral infection. Herein is a report on the experience of clinical-scale, good manufacturing practices (GMPs) production of NK cells to treat advanced cancer.

STUDY DESIGN AND METHODS

Two types of NK cell enrichments were performed on nonmobilized peripheral blood mononuclear cell apheresis collections with a cell selection system (CliniMACS, Miltenyi): CD3 cell depletion to enrich for NK cells and CD3 cell depletion followed by CD56 cell selection to obtain a more pure NK cell product. After overnight incubation with interleukin-2 (IL-2), cells were washed, resuspended in 5 percent human serum albumin, and then released for infusion.

RESULTS

A total of 70 NK cell therapy products have been manufactured for patient infusion since 2000. For the CD3 cell-depleted NK cell products, the mean purity, recovery, and viability were 38, 79, and 86 percent, respectively. For the CD3 cell-depleted/CD56 cell-enriched NK cell products, the mean purity, recovery, and viability were 90, 19, and 85 percent, respectively. Gram stain, sterility, and endotoxin testing were all within acceptable limits for established lot release. Compared to the resting processed cells, IL-2 activation significantly increased the function of cells in cytotoxicity assays.

CONCLUSION

Clinical-scale production of NK cells is efficient and can be performed under GMPs. The purified NK cell product results in high NK cell purity with minimal contamination by T cells, monocytes, and B cells, but it requires more time for processing and results in a lower NK cell recovery when compared to NK cell enrichment with CD3 cell depletion alone. Additional laboratory studies and results from clinical trials will identify the best source and type of NK cell product.

Peripheral blood mobilization of different lymphocyte and dendritic cell subsets with the use of intermediate doses of G-CSF in patients with non-Hodgkin's lymphoma and multiple myeloma

Between June 2003 and November 2004, we collected mobilized peripheral blood units from 29 patients with non-Hodgkin's lymphoma and multiple myeloma for autologous peripheral blood stem cell transplantation. They received granulocyte colony-stimulating factor (G-CSF) (16 micro g/kg/day) for a total of 5 days. Immediately before and 3 h after the fourth and fifth dose of G-CSF, we performed flow cytometry analysis to quantify: T cells (CD3+CD4+, CD3+CD8+), B cells (CD19+), NK cells (CD3-CD16+CD56+), NKT cells (CD3+CD16+CD56+), type 1 dendritic cells (DC1) (lin-HLA-DR+CD11c+), type 2 dendritic cells (DC2) (lin-HLA-DR+CD123+), regulatory T cells (Tregs) (CD4+CD25+), and activated T cells (CD3+HLA-DR+). All cell subsets were mobilized after G-CSF treatment with the exception of B, NK, and NKT lymphocytes. The median number of Treg cells before and after G-CSF was statistically different (29+/-14.9x10(6)/l vs 70.1+/-46.1x10(6)/l, P<0.02). DCs were mobilized significantly with a 5.9-fold increase in DC2 (15.1+/-30.3x10(6)/l vs 89.8+/-81.0x10(6)/l, P<0.02) and a 2.6-fold increase for DC1 (41+/-42.5x10(6)/l vs 109.5+/-58.0x10(6)/l, P<0.04). Patients received a mean of 3.1+/-1.2x10(7)/kg NK cells, 1.3+/-0.9x10(7)/kg NKT cells, 0.41+/-0.29x10(7)/kg DC1, 0.2+/-0.22x10(7)/kg DC2, and 1.8+/-1.9x10(7)/kg Tregs. In conclusion, intermediate doses of G-CSF induce mobilization of different lymphocyte subsets, with the exception of B, NK, and NKT cells. The mobilization of certain suppressive populations (DC2 and Treg) could be in theory deleterious, at least in patients with cancer.

Clinical relevance of NK, NKT, and dendritic cell dose in patients receiving G-CSF-mobilized peripheral blood allogeneic stem cell transplantation

To analyze the relationship between the cellular composition of peripheral blood allografts and clinical outcome, we performed a prospective study in 45 adult patients who underwent allogeneic peripheral blood hematopoietic stem cell transplantation (HSCT) from a histocompatibility leukocyte antigen identical sibling donor for different hematological malignancies. The dose of CD34+, CD3+, CD4+, CD8+, and CD19+ lymphocytes, natural killer (NK) cells, natural killer T (NKT) cells, type 1 and type 2 dendritic cells (DC1 and DC2), as well as regulatory T (Treg) lymphocytes was analyzed. All patients were conditioned with busulphan and cyclophosphamide (BuCy2) +/- VP-16 and received a short course of methotrexate and cyclosporin-A as graft-versus-host disease (GVHD) prophylaxis. Acute GVHD (aGVHD) was present in 9 of 43 (21%) patients, and chronic GVHD (cGVHD) developed in 18 of 39 (46%) patients. There was a significantly higher incidence of aGVHD in patients receiving more than 6x10(6)/kg CD34+ cells. In univariate analysis, variables associated with better survival were as follows: a dose of less than 1.5x10(7)/kg NKT cells and less than 1.7x10(6)/kg DC2 for disease-free survival (DFS), and a dose of less than 3x10(7)/kg NK cells, less than 1.5x10(7)/kg NKT cells, less than 3x10(6)/kg DC1, and less than 1.7x10(6)/kg DC2 for overall survival (OS). In the Cox regression analysis, the dose of NKT cells was the only variable associated with better DFS, while the doses of NK, NKT, and CD34+ cells (less than 8x10(6)/kg) were associated with better OS. In conclusion, different circulating cell populations, other than CD34+ cells, are also of relevance in predicting the clinical outcome after allogeneic peripheral blood HSCT.

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.

Granulocyte and granulocyte-macrophage colony-stimulating factors in allografts: Uses, misuses, misconceptions, and future applications

Despite more than 10 years experience using growth factors after allogeneic stem cell transplantation (ASCT), their state in this has not been elucidated. Most studies show that they accelerate myeloid recovery, regardless of whether they are instituted on day 0 or day 10 after transplant. However, this does not correlate with an improvement in the outcome. One disadvantage is that granulocyte colony-stimulating factor (G-CSF) prophylaxis is associated with slower platelet engraftment due to an increase in platelet aggregation. There is also no agreement as regards the value of G-CSF given as prophylaxis after ASCT, the effects on graft-vs-host disease (GVHD), and the survival rate. A large retrospective study from Europe showed that patients with acute leukemia who received bone marrow from HLA-identical siblings and were treated with G-CSF ran a higher risk of acute and chronic GVHD and transplant-related mortality, while the survival and the leukemia-free survival rates were reduced. In contrast, a meta-analysis of 18 small studies showed no evidence of an increase in acute and chronic GVHD, using G-CSF as prophylaxis after ASCT. Two studies from the Center for International Blood and Marrow Transplant Research showed contradictory data. When G-CSF is given to the recipient as prophylaxis, the levels of soluble interleukin-2 receptor-alpha increase, which aggravates GVHD. When it is given to the donor, G-CSF polarizes T cells to produce T-helper cell-2 cytokines, which reduce GVHD after transplantation. G-CSF has no effect on relapse. Available findings suggest that there is no indication to use G-CSF as prophylaxis after ASCT.

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.

Suppression of natural killer cells in the presence of CD34+ blood progenitor cells and peripheral blood lymphocytes

Abstract Mobilization of CD34 + peripheral blood progenitor cells (PBPCs) with granulocyte-colony stimulating factor (G-CSF) may induce functional alterations in peripheral blood lymphocyte (PBL) subsets. We and others have shown that natural killer (NK) cells from PBPC collections are less expandable in vitro than those obtained during steady-state hematopoiesis. We show here that the extent of this proliferation deficit is related to the number of circulating CD34 + cells in vivo at the time of PBPC apheresis. Likewise, addition of autologous CD34 + cells to unseparated PBL reduced the expansion of the NK-cell subset by 22.2% +/- 6.0% (n = 10; P <.005). In contrast, when using purified NK cells, their proliferation remained unimpaired by autologous CD34 + cells. Supernatants from CD34 + cells cultured with autologous PBLs had an inhibitory effect on proliferation of purified NK cells (n = 16; P =.03), indicating that an interaction between CD34 + cells and lymphocytes is essential for the suppressive effect on NK cells. To investigate the role of T cells in this interaction, intracellular cytokines were determined in T cells cultured for 7 days with or without autologous CD34 + cells. When cultured with CD34 + cells, the frequency of IL-2-producing CD4 + and CD8 + T cells was reduced by 19% and 24%, respectively, compared with T cells cultured alone (n = 7; P =.016). Interferon-gamma-producing T cells were slightly reduced ( P = not statistically significant [ns]). Finally, the influence of T cells and NK cells on the recovery of myeloid colony-forming cells (CFU-GMs) from purified CD34 + cells was examined. In the presence of T cells, 16% +/- 6% of the input CFU-GM recovered after 7 days, compared with 5% +/- 4% in the presence of NK cells (n = 5; P = ns). Our findings point to an inhibition of NK-cell proliferation mediated by an interaction of CD34 + cells and T cells occurring during PBPC mobilization with G-CSF.

Granulocyte colony-stimulating factor modulates alpha-galactosylceramide-responsive human Valpha24+Vbeta11+NKT cells

Despite more than a 10-fold increase in T cell numbers in G-CSF-mobilized peripheral blood stem cell (PBSC) grafts, incidence and severity of acute graft-vs-host disease (GVHD) are comparable to bone marrow transplantation. As CD1d-restricted, Valpha24+Vbeta11+ NKT cells have pivotal immune regulatory functions and may influence GVHD, we aimed to determine whether G-CSF has any effects on human NKT cells. In this study, we examined the frequency and absolute numbers of peripheral blood NKT cells in healthy stem cell donors (n = 8) before and following G-CSF (filgrastim) treatment. Effects of in vivo and in vitro G-CSF on NKT cell cytokine expression profiles and on responsiveness of NKT cell subpopulations to specific stimulation by alpha-galactosylceramide (alpha-GalCer) were assessed. Contrary to the effects on conventional T cells, the absolute number of peripheral blood NKT cells was unaffected by G-CSF administration. Furthermore, responsiveness of NKT cells to alpha-GalCer stimulation was significantly decreased (p < 0.05) following exposure to G-CSF in vivo. This hyporesponsiveness was predominantly due to a direct effect on NKT cells, with a lesser contribution from G-CSF-mediated changes in APC. G-CSF administration resulted in polarization of NKT cells toward a Th2, IL-4-secreting phenotype following alpha-GalCer stimulation and preferential expansion of the CD4+ NKT cell subset. We conclude that G-CSF has previously unrecognized differential effects in vivo on NKT cells and conventional MHC-restricted T cells, and effects on NKT cells may contribute to the lower than expected incidence of GVHD following allogeneic peripheral blood stem cell transplantation.

G-CSF-mobilized CD34+ cells cultured in interleukin-2 and stem cell factor generate a phenotypically novel monocyte

To study the early stages of development from stem cells of the CD56+ cell population [which includes natural killer (NK) cells], granulocyte-colony stimulating factor-mobilized peripheral blood CD34+ cells from healthy donors were sorted to >99% purity and cultured in the presence of stem cell factor and interleukin (IL)-2. After 3 weeks in culture, the majority of cells acquired CD33, with or without human leukocyte antigen-DR and CD14. In 20 stem cell donors tested, 8.7 +/- 8.8% of cells were CD56+. Two major CD56+ subsets were identified: CD56(bright), mainly CD33- cells (7+/-10%, n=11) with large, granular lymphocyte morphology, and CD56dim, mainly CD33+ (2.5+/-2, n=11) cells with macrophage morphology. The CD56bright population had cytoplasmic granzyme A but lacked killer inhibitory receptor, suggesting they were immature NK cells. The CD56dim, CD33+, population lacked NK markers. They may represent a minor subset of normal monocytes at a developmental stage comparable with the rare CD56+ CD33+ hybrid myeloid/NK cell leukemia. Consistent with a monocyte nature, CD56dimCD33+ proliferated and produced a variety of cytokines upon lipopolysaccharide stimulation, including IL-8, IL-6, monocyte chemoattractant protein-1, and macrophage-derived chemokine but not interferon-gamma. In a short-term cytotoxicity assay, they failed to kill but powerfully inhibited the proliferation of the NK-resistant cell line P815. The generation of CD56+ cells was negatively regulated by hyaluronic acid and IL-4, indicating that extracellular matrix may play an important role in the commitment of CD34+ cells into CD56 myeloid and lymphoid lineages.

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.

Functional significance of the activation-associated receptors CD25 and CD69 on human NK-cells and NK-like T-cells

The application of autologous ex-vivo expanded cytotoxic lymphocytes to cancer patients may help to control minimal residual disease. However, the number of effector cells and the resulting antitumoral activity that can be generated in vitro are remarkably variable. Thus, we separately assessed the proliferative and cytotoxic potential of CD56+ CD3- natural killer (NK) and CD56+ CD3+ T-cells in relation to their expression of CD25, CD69, and CD16 in vitro. Two-week lymphocyte cultures from peripheral blood (n = 51) and from G-CSF-mobilized progenitor cell harvests (n = 11) were performed repeatedly from 14 women with breast cancer throughout conventional- and high-dose chemotherapy. A large proportion of CD25+ cells on day 7 of the culture predicted high expandability (r = 0.69, p < 0.00001), while elevated expression of CD69 predicted augmented cytotoxicity (r = 0.72; p = 0.00001) and low expandability (r = -0.69, p < 0.00001). CD25 and CD69 expression were inversely correlated (r = -0.8, p < 0.0001). CD16 expression was not suited to predict functional properties. Additionally, NK-cells were sorted by FACS according to CD25 versus CD69 expression. In a [3H]thymidine incorporation assay the CD25+ NK-cell fraction exhibited a higher proliferation rate than did the CD69+ fraction in all of three experiments. Together, our data suggest that CD69 is a useful marker for cytotoxic activity of NK cells, whereas proliferative potential is indicated by CD25 expression. These findings should help optimizing the ex-vivo generation of large numbers of cytotoxic effector cells for immunotherapy.

Mirimostim (macrophage colony-stimulating factor; M-CSF) improves chemotherapy-induced impaired natural killer cell activity, Th1/Th2 balance, and granulocyte function

The purpose of this study was to clarify the effects of mirimostim (macrophage colony-stimulating factor; M-CSF) on immunological functions after chemotherapy. The percentage of natural killer (NK) cells in peripheral blood mononuclear cells (PBMCs), NK cell activity, T-helper cell 1/T-helper cell 2 (Th1/Th2) ratio, and superoxide anion production by granulocytes (granulocyte function) were measured as immunological parameters before and after chemotherapy in 44 patients with primary ovarian cancer who received at least three consecutive courses of postoperative chemotherapy. Patients were observed during the first course of chemotherapy, and 39 patients who presented grade III or IV neutropenia were entered into this study and randomly allocated to an M-CSF-administered group (group 1; 19 patients) and a non-M-CSF-administered group (group 2; 20 patients) for the second course. For the third course, a crossover trial was conducted. In the observation period, chemotherapy significantly impaired the immunological parameters. In particular, those parameters were significantly decreased at day 14 compared to the level before chemotherapy. The values of the parameters of group 1 were significantly higher than those of group 2. In the course of chemotherapy during which M-CSF was administered, 19 of the 39 patients presented grade IV neutropenia, and received granulocyte colony-stimulating factor (G-CSF) between days 7 and 14. We compared the changes of those immunological parameters in the M-CSF alone group and the M-CSF + G-CSF group, and found that the concomitant use of G-CSF did not further improve the parameters. These results indicate that chemotherapy markedly impaired the immunological functions, and that the administration of M-CSF significantly improved the impaired immunological functions.

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.

Differential STAT3, STAT5, and NF-kappaB activation in human hematopoietic progenitors by endogenous interleukin-15: implications in the expression of functional molecules

Different forms of interleukin-15 (IL-15) have been identified and shown to elicit different transduction pathways whose impact on hematopoiesis is poorly understood. We demonstrated herein that hematopoietic CD34+ cells constitutively produced endogenous secreted IL-15 (ES-IL-15) that activated different transcription factors and controlled the expression of several functional proteins, depending on the progenitor source. Thus, nuclear factor-kappa B (NF-kappa B) was activated in bone marrow (BM) and cord blood (CB) progenitors, whereas signal transducer and activator of transcription 3 (STAT3) and STAT5 activation was restricted to peripheral granulocyte-colony-stimulating factor (G-CSF)-mobilized and BM progenitors, respectively. ES-IL-15 acts through autocrine/paracrine loops controlled by high-affinity receptors involving IL-15 receptor alpha (IL-15Ralpha). Furthermore, ES-IL-15 was found to differentially control the expression of several functional molecules important for hematopoietic differentiation. Indeed, in BM precursors, neutralizing anti-IL-15 monoclonal antibody (mAb) inhibits the expression of the gamma c chain and of the chemokine stromal derived factor-1 (SDF-1) but had no effect on vascular cell adhesion molecule 1 (VCAM-1) and beta1 integrin adhesion molecule expression. Conversely, in CB progenitors, anti-IL-15 mAb inhibited VCAM-1 and beta1 integrin expression without affecting gammac chain expression and, most important, up-regulated SDF-1 expression. In conclusion, unprimed human hematopoietic CD34+ cells secrete cell-unbound IL-15, which activates through autocrine/paracrine loop distinct signaling pathways, depending on the progenitor source, thereby influencing the expression of several molecules important in the control of hematopoiesis.

Enhanced antileukemic activity of allogeneic peripheral blood progenitor cell transplants following donor treatment with the combination of granulocyte colony-stimulating factor (G-CSF) and stem cell factor (SCF) in a murine transplantation model

Allogeneic peripheral blood progenitor cells (PBPCs) have mostly been mobilized by granulocyte colony-stimulating factor (G-CSF). There is neither clinical nor experimental data available addressing the question if other hematopoietic growth factors or combinations thereof might influence engraftment, graft-versus-host disease (GvHD), and graft-versus-leukemia (GvL) effects after allogeneic peripheral blood progenitor cell transplantation (PBPCT). We used a murine model to investigate these parameters after transplantation of PBPCs mobilized with G-CSF and SCF either alone or in combination. Treatment of splenectomized DBA and Balb/c mice with 250 microg/kg/day G-CSF for 5 days resulted in an increase of CFU-gm from 0 to 53/microl. The highest progenitor cell numbers (147/microl) were observed after treatment with 100 microg/kg/day SCF administered in conjunction with G-SCF. No differences were detected with regard to the number of T cells (CD3+), T cell subsets (CD4+, CD8+), B cells (CD19+) and NK cells (NK1.1+) in PBPC grafts mobilized by G-CSF plus SCF compared to those mobilized with G-CSF alone. The antileukemic activity of syngeneic and MHC-identical allogeneic PBPC grafts was investigated in lethally irradiated Balb/c mice bearing the B-lymphatic leukemia cell line A20. In this model, PBPCs mobilized by G-CSF plus SCF exerted a significantly higher antileukemic activity compared to grafts mobilized by G-CSF alone (94 vs 71% freedom from leukemia at day 100, P<0.05). The antileukemic effect was lowest after BMT (38% freedom from leukemia). Since significant differences in the incidence of lethal GvHD were not observed, improved GVL-activity resulted in superior overall survival. Our data demonstrate that the utilization of specific hematopoietic growth factors not only improve the yield of hematopoietic progenitor cells but can also significantly enhance the immunotherapeutic potential of allografts.

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.

Allogeneic hematopoietic stem cell transplantation

More than 30 years have passed since the first clinical application of allogeneic bone marrow transplantation to treat hematological diseases. In recent years, the availability of peripheral blood and cord blood as additional sources of stem cells other than bone marrow has expanded the applicability of hematopoietic stem cell transplantation. In addition to differences in stem cell content, immune cells in the grafts from the three sources are different in quality and quantity. As a consequence, transplants from different sources have different kinetics of hematological recovery. Stem cell sources also influence risks for developing graft-versus-host disease. In this paper, we review recently reported results of thus diversified allogeneic hematopoietic, stem cell transplantation.

Detection of a functional hybrid receptor gammac/GM-CSFRbeta in human hematopoietic CD34+ cells

A functional hybrid receptor associating the common gamma chain (gammac) with the granulocyte/macrophage colony-stimulating factor receptor beta (GM-CSFRbeta) chain is found in mobilized human peripheral blood (MPB) CD34+ hematopoietic progenitors, SCF/Flt3-L primed cord blood (CB) precursors (CBPr CD34+/CD56-), and CD34+ myeloid cell lines, but not in normal natural killer (NK) cells, the cytolytic NK-L cell line or nonhematopoietic cells. We demonstrated, using CD34+ TF1beta cells, which express an interleukin (IL)-15Ralpha/beta/gammac receptor, that within the hybrid receptor, the GM-CSFRbeta chain inhibits the IL-15-triggered gammac/JAK3-specific signaling controlling TF1beta cell proliferation. However, the gammac chain is part of a functional GM-CSFR, activating GM-CSF-dependent STAT5 nuclear translocation and the proliferation of TF1beta cells. The hybrid receptor is functional in normal hematopoietic progenitors in which both subunits control STAT5 activation. Finally, the parental TF1 cell line, which lacks the IL-15Rbeta chain, nevertheless expresses both a functional hybrid receptor that controls JAK3 phosphorylation and a novel IL-15alpha/gammac/TRAF2 complex that triggers nuclear factor kappaB activation. The lineage-dependent distribution and function of these receptors suggest that they are involved in hematopoiesis because they modify transduction pathways that play a major role in the differentiation of hematopoietic progenitors.

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.

Dendritic cells for NK/LAK activation: rationale for multicellular immunotherapy in neuroblastoma patients

Natural killer (NK)/lymphokine-activated killer (LAK) cell-based immunotherapy could be beneficial against major histocompatibility complex class I-negative tumor residual disease such as neuroblastoma (NB), provided that interleukin 2 (IL-2) or surrogate nontoxic NK cell stimulatory factors could sustain NK cell activation and survival in vivo. Here we show that human monocyte-derived dendritic cells (MD-DCs) promote potent NK/LAK effector functions and long-term survival, circumventing the need for IL-2. This study demonstrates (1) the feasibility of differentiating granulocyte colony-stimulating factor-mobilized hematopoietic peripheral blood stem cells (PBSCs) into high numbers of functional MD-DCs and NK/LAK cells in a series of 12 children with stage 4 neuroblastoma (NB); (2) potent DC-mediated NK cell activation in autologous settings; (3) the reciprocal capacity of NK/LAK cells to turn immature DCs into maturing cells electively capable of triggering NK cell functions; and (4) the unique capacity of maturing DCs to sustain NK cell survival, superior to that achieved in IL-2. These data show a reciprocal interaction between DCs and NK/LAK cells, leading to the amplification of NK cell effector functions, and support the implementation of DC/NK cell-based immunotherapy for purging the graft and/or controlling minimal residual disease after autologous stem cell transplantation.

Late G-CSF after allogeneic bone marrow or peripheral blood stem cell transplantation: a prospective controlled trial

Granulocyte colony-stimulating factor (G-CSF) is widely used to accelerate neutrophil recovery after allogeneic BMT or PBSC transplantation. The optimal time to start G-CSF treatment is not known. Forty-two patients undergoing allogeneic BMT or PBSC transplantation for hematological malignancies received G-CSF either on day 6 or on day 9 post transplant. The time to hematological recovery was monitored and the two groups were compared with respect to peritransplant morbidity and mortality. Recovery of the neutrophil counts to >0.1 x 10(9)/l, > 0.5 x 10(9)/l and >1.0 x 10(9)/l were not significantly different in either group. There was no difference in recovery of red blood cell and platelet counts and no difference between the two groups with respect to the number of febrile days or number of days on antibiotic treatment. Documented bacterial, viral or fungal infections did not occur more often when G-CSF treatment was started on day 9. Delaying treatment with G-CSF resulted in a significant reduction in the length of treatment from 13 to 10 days (23.1% reduction). Reducing the length of the treatment by 3 days lowered the costs by 395.40 Euro per patient. Delaying G-CSF treatment and starting on day 9 after BMT or PBSC transplantation is safe and results in a clear economic benefit.

Effect of coadministration of M-CSF and IFN-alpha on NK1.1+ cells in mice

The purpose of this study was to evaluate the effect of coadministration of macrophage colony-stimulating factor (M-CSF) and interferon-alpha (IFN-alpha) on NK1.1(+) cells in mice. Administration of M-CSF, but not IFN-alpha, increased the number of NK1.1(+) cells and CD11b(+) cells in spleen and blood. Coadministration of the two agents induced a greater increase in NK1.1(+) cells than did administration of M-CSF alone. Administration of M-CSF or IFN-alpha augmented the clearance activity of Yac-1 cells in lung, and coadministration of these agents further augmented this effect. The combination of M-CSF and IFN-alpha effectively reduced the formation of tumor nodules in lung and liver in an experimental metastasis model using B16 melanoma. The combination of M-CSF and IFN-alpha induced the increase and activation of NK1.1(+) cells more than either agent alone. These effects may contribute to the antimetastatic reaction by NK1.1(+) cells in vivo.

The BCR/ABL transgene causes abnormal NK cell differentiation and can be found in circulating NK cells of advanced phase chronic myelogenous leukemia patients

NK cells from the blood of chronic myelogenous leukemia (CML) patients are progressively decreased in number as the disease progresses from chronic phase to blast crisis. We hypothesize that BCR/ABL may be directly responsible by interfering with NK cell differentiation. CD34(+)HLA-DR(+) cells from CML patients were studied for their capacity to differentiate into NK cells. The NK cell cloning frequency was significantly decreased from CML CD34(+)HLA-DR(+) cells compared with cells from normal donors, yet CD34(+)HLA-DR(+) cells gave rise to BCR/ABL(+) NK cells in some patients. This finding prompted us to further investigate circulating NK cells from the blood of CML patients. CD56(+)CD3(-) NK cells were sorted from CML patients and examined by fluorescence in situ hybridization (FISH). In contrast to chronic phase CML, significant numbers of NK cells from advanced phase CML patients were BCR/ABL(+), whereas T cells were always BCR/ABL(-) regardless of the disease stage. To test the effects of BCR/ABL as the sole genetic abnormality, BCR/ABL was transduced into umbilical cord blood CD34(+) cells, and NK development was studied. p210-enhanced green fluorescence protein-transduced cells gave rise to significantly decreased numbers of NK cells compared with enhanced green fluorescence protein transduction alone. In addition, the extrinsic addition of BCR/ABL-transduced autologous CD34(+) cells suppressed the NK cell differentiation of normal umbilical cord blood CD34(+)CD38(-) cells. This study provides the first evidence that BCR/ABL is responsible for the altered differentiation of NK cells and that the NK cell lineage can be involved with the malignant clone in advanced stage CML.