Allogeneic Donor NK Cell Infusion and IL-2 for Patients with Refractory B-Cell Non-Hodgkin Lymphoma.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3036-3036
Author(s):  
Veronika Bachanova ◽  
Linda J. Burns ◽  
David H. McKenna ◽  
Julie Curtsinger ◽  
Sarah Cooley ◽  
...  
Keyword(s):  
B Cell ◽  
Nk Cells ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Cell Expansion ◽  
Nk Cell ◽  
Peripheral Blood Cells ◽  
Non Hodgkin Lymphoma ◽  
Pre Treatment

Abstract Abstract 3036 Poster Board II-1012 The potential role of allogeneic natural killer (NK) cells for therapy of refractory lymphoma is supported by the curative potential of allogeneic transplantation for lymphoid malignancies. Haploidentical donor derived NK cells may overcome Class I MHC Ag mediated inhibition and deliver an NK versus lymphoma effect. In a Phase II study we evaluated allogeneic NK cell infusions with Rituximab and IL-2 in a non-transplant setting to determine the expansion of NK cells in vivo and the clinical response in patients with refractory B-cell non-Hodgkin lymphoma (NHL). Six patients with advanced NHL received conditioning with Rituximab 375mg/m2 days -8,-1,+6,+15; Cyclophosphamide 60 mg/kg IV day -5; Fludarabine 25 mg/m2 IV days -6 through -2 as immunosupression to permit homeostatic expansion of allogeneic donor NK cells. Peripheral blood cells were obtained by lymphapheresis from unmobilized, HLA-haploidentical donors and selected for “killer immunoglobulin receptor” (KIR) ligand mismatch when available (3 out of 6 patients). Donor peripheral blood cells were enriched for NK cells with the Miltenyi CliniMACS device by depletion of T (CD3+) cells. The donor NK cells were then activated by overnight incubation with IL-2 (1,000 U/mL) and infused at a median nucleated cell dose of 2.27 ±0.4 × 107/kg. Subcutaneous IL-2 10×106 units (qod x 6 doses) was given to facilitate NK cell survival and expansion. All patients were evaluable for toxicity and efficacy. Patients tolerated the NK infusion well with only transient grade 1-2 toxicity and 5 received all 6 scheduled doses of IL-2. IL-2 activated donor NK cell products showed > 55% cytotoxicity against K562 targets. After IL-2 therapy, we observed a median absolute lymphocyte count of 980 ±440/μL. All cells were of recipient origin with no detectable donor NK cells. Importantly, in all patients the median number of host regulatory T cells (T regs phenotype CD4+Foxp3+CD127−) post treatment was significantly increased compared to pre-treatment (day 14 T regs: 134 ±141 cells/μL versus pre-treatment T regs: 24 ±12 cells/μL; P=0.06). To investigate the possibility of NK trafficking to affected lymph nodes, we performed fine needle aspiration of palpable tumor in 1 patient and demonstrated a low level of donor DNA by RFLP testing (2.5% donor chimerism). Simultaneous absence of NK cells in peripheral blood in the same patient suggested NK cell tissue homing to lymphoma-bearing nodes. Three patients achieved a partial remission (PR), one of whom proceeded to non-myeloablative cord blood allograft 2 month after NK cell infusion; two remain in partial remission after 1 and 4 months of follow-up. The trial failed to achieve prospective statistical parameters established to detect circulating NK cell expansion rate and will be modified. Conclusions This “proof of principle” study demonstrated lack of in vivo expansion of haploidentical NK cells in peripheral blood of patients with lymphoma. However, we identified host factors that interfered with NK cell expansion, including T reg proliferation and possibly inadequate immunosupression, and additionally, the finding of donor DNA in sites of tumor suggested donor NK cell localization to extravascular or tumor sites. Novel approaches to adoptive NK cell therapy trials should incorporate strategies to eliminate or prevent T reg expansion using alternate lymphodepleting regimens. Disclosures No relevant conflicts of interest to declare.

scholarly journals Preclinical Mechanistic Studies Investigating Neutrophil and Lymphoid Cell Depletion By IMGN529, a CD37-Targeting Antibody-Drug Conjugate (ADC)

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3119-3119 ◽  
Author(s):  
Jutta Deckert ◽  
Jose F. Ponte ◽  
Jennifer A. Coccia ◽  
Leanne Lanieri ◽  
Sharon Chicklas ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cell ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Peripheral Blood Cells ◽  
Employment Equity ◽  
Normal Human ◽  
Equity Ownership

Abstract CD37 is a surface antigen widely expressed on malignant B cells in non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL). In normal tissues, CD37 expression is restricted to lymphoid tissues and blood cells, with high levels of expression on B lymphocytes and low levels on non-B lymphoid and myeloid cells. IMGN529 is a CD37-targeting ADC currently in a Phase I clinical study in adult patients with relapsed or refractory NHL (NCT01534715). This ADC uniquely combines the intrinsic pro-apoptotic and immune effector activities of its anti-CD37 antibody component with the potent cytotoxic mechanism provided by targeted delivery of its maytansinoid payload, DM1. In the Phase I study, IMGN529 has demonstrated early evidence of clinical activity. A reduction in lymphocyte counts was also observed in the majority of patients after dosing, consistent with the proposed mechanism of action of a CD37-targeted therapy. However, in the initial dose-escalation phase, some patients experienced transient, early-onset neutropenia. To investigate the potential mechanisms of this transient neutropenia observed in patients, different pre-clinical models were considered and utilized to recapitulate clinical findings. In vitro studies with peripheral blood cells from normal human donors demonstrated that incubation with IMGN529 for 1 hour or 24 hours resulted in significant B-cell depletion with no apparent neutrophil depletion detected, similar to observations after rituximab treatment. In contrast, alemtuzumab treatment in vitro resulted in both B-cell and neutrophil depletion. This is consistent with the high level of CD37 expression on target B cells and the relatively low CD37 expression level on other blood cells. Analysis of cytokine release by normal human donor peripheral blood cells incubated with IMGN529 revealed increased levels of IL-8, CCL2 (MCP-1) and CCL4 (MIP-1β), but not IL-6 or TNF, to a similar extent as rituximab but less pronounced than alemtuzumab. An anti-murine CD37 antibody was identified to enable in vivo studies in a murine model and characterize CD37 expression on murine blood cells. Similar to the expression profile of CD37 in human peripheral blood cells, CD37 expression on murine peripheral blood cells was highest in B cells, with much lower expression seen on T cells and granulocytes. In vivo activity of the anti-muCD37 antibody and the corresponding ADC, with the same SMCC-DM1 linker-payload combination as IMGN529, was evaluated to discern antibody and payload-mediated events in comparison to the classic cytotoxic cyclophosphamide (CPA). Treatment of C57/B6 mice with 1-10 mg/kg of anti-muCD37 antibody or anti-muCD37 ADC resulted in a significant decrease in absolute lymphocyte counts (ALC) lasting greater than 7 days and a transient decrease in absolute neutrophil counts (ANC) lasting 1-2 days. A non-targeted control SMCC-DM1 ADC had no effect on ALC or ANC counts, suggesting the decrease is a CD37-mediated effect. In contrast, treatment with CPA resulted in an ALC decrease with similar kinetics but a more pronounced ANC decline. No impact on bone marrow lymphocyte, myeloid or erythroid precursor cell counts was observed in response to the anti-muCD37 antibody or anti-muCD37 ADC, whereas CPA treatment caused reduced cellularity with a decrease in the percentage of mature myeloid precursors and neutrophils in bone marrow. Elevated levels of CCL2 and CCL4 chemokines were detected in mouse plasma after anti-muCD37 ADC treatment, which may contribute to a redistribution of circulating neutrophils into peripheral tissues. Studies are currently underway to assess neutrophil distribution in murine tissues post anti-muCD37 ADC treatment. Current preclinical studies provide no clear evidence for direct IMGN529-mediated depletion of normal human neutrophils in the context of B-cell depletion in vitro. In vivo studies with an anti-muCD37 ADC recapitulate transient peripheral lymphopenia and neutropenia with no impact on bone marrow precursors observed, indicative of a different mechanism than classic chemotherapy-induced bone marrow myelosuppression. These preliminary results suggest a role for chemokine-mediated neutrophil redistribution following CD37 engagement, which is the subject of further studies. Disclosures Deckert: ImmunoGen, Inc.: Employment, Equity Ownership. Ponte:ImmunoGen, Inc.: Employment, Equity Ownership. Coccia:ImmunoGen, Inc.: Employment, Equity Ownership. Lanieri:ImmunoGen, Inc.: Employment, Equity Ownership. Chicklas:ImmunoGen, Inc.: Employment, Equity Ownership. Yi:ImmunoGen, Inc.: Employment, Equity Ownership. Watkins:ImmunoGen, Inc.: Employment, Equity Ownership. Ruiz-Soto:ImmunoGen, Inc.: Employment, Equity Ownership; sanofi: Employment. Romanelli:ImmunoGen, Inc.: Employment, Equity Ownership; sanofi: Employment. Lutz:ImmunoGen, Inc.: Employment, Equity Ownership.

Sustained Expansion of Human Natural Killer Cells for Leukemia Therapy.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3719-3719
Author(s):  
Hiroyuki Fujisaki ◽  
Harumi Kakuda ◽  
Chihaya Imai ◽  
Dario Campana
Keyword(s):  
Reverse Transcriptase ◽  
Nk Cells ◽  
Natural Killer ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Nk Cell ◽  
Leukemia Cell Line ◽  
Cell Transplant ◽  
Peripheral Blood Cells ◽  
Htert Expression

Natural killer (NK) cells are a promising tool for cell therapy of hematologic malignancies. They have potential for enhancing graft-versus-leukemia responses in recipients of hematopoietic stem cell transplant, and can also be used in a non-transplant setting, where haploidentical donor NK cells have been shown to expand in vivo. NK cells represent a small subset of peripheral blood cells. Hence, it can be problematic to obtain them in quantities sufficient to exert significant anti-leukemic activity in patients. We sought to identify culture conditions that would stimulate vigorous, sustained and specific expansion of CD56+ CD3− NK cells. NK cell proliferation was stimulated by contact with the K562 leukemia cell line transfected with two NK stimulatory molecules: membrane-bound interleukin 15 and 4-1BB ligand. Exposure of peripheral blood cells from 23 donors to irradiated K562-mb15-41BBL cells in the presence of 10 IU/mL interleukin-2 resulted in a median expansion of CD56+ CD3− cells of 22-fold (range, 9- to 87-fold) after only 7 days of culture; expansion of CD3+ T cells was negligible. After 14 days of culture, K562-mb15-41BBL cells were completely lysed by the NK cells and no further expansion occurred. However, further NK cell expansion could be achieved by addition of fresh K562-mb15-41BBL cells to the cultures. Using this method, NK cell expansions ranged from 2,000- to 98,000-fold (n = 4) after 65 days of culture. We noted that NK cells eventually became unresponsive to stimulation and underwent senescence after 2–5 months of culture. To determine whether NK cell senescence could be overcome by enforced expression of human telomerase reverse transcriptase (hTERT), we stimulated NK cells for 1 week with K562-mb15-41BBL cells and then transfected them using an MSCV retroviral vector and the hTERT gene (gift of Dr. J. Dome, St. Jude). hTERT expression and telomerase activity was demonstrated by reverse transcriptase-polymerase chain reaction and telomerase repeat amplification protocol assay. The cultures were then stimulated with periodic pulses of K562-mb15-41BBL cells. In 2 donors, enforced expression of hTERT overcame senescence: NK cells transfected with an empty vector died after 85 and 170 days of culture, whereas hTERT-NK cells continue to grow after more than 350 days of culture, while retaining a normal karyotype. hTERT-NK cells maintained their cytotoxicity against the NK-sensitive leukemic cell lines K562, KG1, U937, HL60 and Jurkat. They could be also be genetically modified to express anti-CD19 chimeric signaling receptors, thus becoming cytotoxic against NK-resistant CD19+ B-lineage acute lymphoblastic leukemia cells. Cytotoxicity against CD19+ targets was similar to that of NK cells transfected with the signaling receptor after only one week of culture. In conclusion, coculture of human peripheral blood mononuclear cells with pulses of irradiated K562-mb15-41BBL cells allows the generation of a large numbers of NK cells which have powerful anti-leukemic capacity and can be redirected to lyse NK-resistant target cells. Although senescence eventually ensues, this can be overcome by hTERT expression. The culture system described here has now been adapted to large scale expansion for clinical use.

In Vitro Preactivation of PBMCs with PM-mb21-41BBL Particles Stimulates in Vivo Expansion of NK Cells Under Low IL-2 in NSG Mice

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3842-3842
Author(s):  
Jeremiah L Oyer ◽  
Veethika Pandey ◽  
Robert Y Igarashi ◽  
Dominic A Colosimo ◽  
Melhem M. Solh ◽  
...  
Keyword(s):  
Cancer Treatment ◽  
Nk Cells ◽  
Peripheral Blood ◽  
Cell Expansion ◽  
Nk Cell ◽  
K562 Cells ◽  
High Dose ◽  
Nsg Mice

Abstract NK cell immunotherapy as a cancer treatment shows promise, but methods for consistent expansion of NK cells from a small fraction (~5%) of peripheral blood mononuclear cells (PBMCs) to therapeutically effective amounts are not widely accessible. Strategies that promote in vivo expansion rely on high-dose IL-2 in combination with lymphodepletion and suffer from severe treatment related toxicities as well as limited expansion. On the other hand, in vitro methods are available for robust NK cell expansion, but rely on prolonged in vitro co-culture with feeder cells that is costly and complex and requires high dose IL-2 (25,000-35,000 U) for persistence after injection into mice. An optimal NK cell expansion method would rely on “off the shelf” reagents, would not require long-term complex cultures, and would induce a rapid, sustained in vivo expansion of NK cells from unsorted PBMCs under low concentration of IL-2. We have developed a method to prepare particles from K562 cells engineered to express specific cytokines, and such particles stimulate NK cell expansion. Particles prepared using K562 cells expressing IL-21 and 41BBL (PM21 particles) cause highly specific expansion of cytotoxic NK cells from unsorted PBMCs that achieves 95% NK cells in ~14 days and ~10,000 fold expansion of NK in about 21 days. NK cell expansion is consistent using different preparations of PM-particles or leukocyte sources, and the PM-particles retain expansion efficacy with storage. The PM-mb21-41BBL particles were also used to stimulate in vivo NK cell expansion in NSG mice under ultralow IL-2 (1,000 units per injection, 3 injections per week, per mouse). Unsorted human PBMCs, either shortly pre-activated in culture for two days or not pre-activated, were injected (2 x 106 PBMCs per mice by i.p.) and human CD56+CD3- NK cells and other relevant hCD45+ lymphocytes were monitored in the peripheral blood over time and in tissues and fluids at the time of euthanization. In vivo NK cell expansion was observed in mice injected with PBMCs that were pre-activated with PM21 particles. The extent of NK cell expansion observed in the peripheral blood was in levels that would be relevant for clinical cancer treatment (>50,000 NK cells/mL of mouse blood 14 days post injection). In vivo NK cell expansion was further confirmed with analogous experiments using PBMCs that were stained with CellTrace Violet to monitor proliferation. Notably, NK cells were also found in spleen, bone marrow, lung, liver and brain. These results taken together provide proof of principle that PM-particle technology is effective for direct in vivo NK cell expansion from unsorted PBMCs under low dose IL-2. Disclosures No relevant conflicts of interest to declare.

Receptor Mediated Binding of the Fibrinolytic Components, Plasminogen and Urokinase, to Peripheral Blood Cells

1987 ◽  
Vol 58 (03) ◽  
pp. 936-942 ◽  
Author(s):  
Lindsey A Miles ◽  
Edward F Plow
Keyword(s):  
T Cells ◽  
B Cell ◽  
Peripheral Blood ◽  
Binding Sites ◽  
Blood Cells ◽  
High Capacity ◽  
Red Cells ◽  
Peripheral Blood Cells ◽  
Cellular Functions ◽  
Fibrinolytic Proteins

SummaryGlu-plasminogen binds to platelets; the monocytoid line, U937, and the human fetal fibroblast line, GM1380 bind both plasminogen and its activator, urokinase. This study assesses the interaction of these fibrinolytic proteins with circulating human blood cells. Plasminogen bound minimally to red cells but bound saturably and reversibly to monocytes, granulocytes and lymphocytes with apparent Kd values of 0.9-1.4 μM. The interactions were of high capacity with 1.6 to 49 × 105 sites/cell and involved the lysine binding sites of plasminogen. Both T cells and non-rosetting lymphocytes and two B cell lines saturably bound plasminogen. Urokinase bound saturably to gianulocytes, monocytes, non-rosetting lymphocytes and a B cell line, but minimally to T cells, platelets and red cells. Therefore, plasminogen binding sites of high capacity, of similar affinities, and with common recognition specificities are expressed by many peripheral blood cells. Urokinase receptors are also widely distributed, but less so than plasminogen binding sites. The binding ol plasminogen and/ or urokinase to these cells may lead to generation of cell- associated proteolytic activity which contributes to a variety of cellular functions.

scholarly journals Stem Cell Factor Enhances Interleukin-2–Mediated Expansion of Murine Natural Killer Cells In Vivo

Blood ◽  
1997 ◽  
Vol 90 (9) ◽  
pp. 3647-3653 ◽  
Author(s):  
Todd A. Fehniger ◽  
William E. Carson ◽  
Ewa Mrózek ◽  
Michael A. Caligiuri
Keyword(s):  
Nk Cells ◽  
Cell Expansion ◽  
Stem Cell Factor ◽  
Low Dose ◽  
Nk Cell ◽  
Interleukin 2 ◽  
Innate Immune ◽  
Ifn Γ

Abstract The administration of low dose interleukin-2 (IL-2) results in a selective expansion of natural killer (NK) cells in vivo, and promotes the differentiation of NK cells from hematopoietic precursor cells in vitro. We have previously shown that stem cell factor (SCF ), the ligand to the c-kit tyrosine kinase receptor, enhances IL-2–induced NK cell proliferation and differentiation in vitro. Here, we investigated the effects of SCF plus IL-2 delivered to mice in vivo. Eight-week-old C57BL/6 mice were treated with a continuous subcutaneous infusion of IL-2 (1 × 104 IU/d) plus a daily intraperitoneal dose of SCF (100 μg/kg/d), IL-2 alone, SCF alone, or vehicle alone for 8 weeks. The in vivo serum concentration of IL-2 ranged between 352 ± 12.0 pg/mL and 606 ± 9.0 pg/mL, achieving selective saturation of the high affinity IL-2 receptor, while the peak SCF serum concentration was 296 ± 13.09 ng/mL. Alone, the daily administration of SCF had no effect on the expansion of NK cells. The continuous infusion of IL-2 alone did result in a significant expansion of NK1.1+CD3− cells compared to mice treated with placebo or SCF. However, mice treated with both SCF and IL-2 showed an increase in the absolute number of NK cells that was more than twofold that seen with IL-2 alone, in the spleen (P ≤ .005), bone marrow (P ≤ .025), and blood (P < .05). NK cytotoxic activity against YAC-1 target cells was significantly higher for mice treated with SCF plus IL-2, compared to mice treated with IL-2 alone (P ≤ .0005). Interferon-γ (IFN-γ) production in cytokine-activated splenocytes was also greater for the SCF plus IL-2 group, over IL-2 treatment alone (P ≤ .01). The effect of SCF plus IL-2 on NK cell expansion was likely mediated via NK cell precursors, rather than mature NK cells. In summary, we provide the first evidence that SCF can significantly enhance expansion of functional NK cells induced by the prolonged administration of low dose IL-2 in vivo. Since the NK cell is a cytotoxic innate immune effector and a potent source of IFN-γ, this therapeutic strategy for NK cell expansion may serve to further enhance innate immune surveillance against malignant transformation and infection in the setting of cancer and/or immunodeficiency.

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

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 811
Author(s):  
Pranav Oberoi ◽  
Kathrina Kamenjarin ◽  
Jose Francisco Villena Ossa ◽  
Barbara Uherek ◽  
Halvard Bönig ◽  
...  
Keyword(s):  
Nk Cells ◽  
Progenitor Cells ◽  
Peripheral Blood ◽  
Cell Expansion ◽  
Nk Cell ◽  
Ex Vivo ◽  
Feeder Cells ◽  
Hematopoietic Stem ◽  
Cd34 Cells ◽  
Stem And Progenitor Cells

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.

Optimal NK Cell Expansion Depends on Accessory Cells, Synergy between Physiologic Concentrations of IL-2 and IL-15, and Umbilical Cord Blood (UCB) NK Cell Precursors Expand Better Than Adult NK Cells.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3642-3642 ◽  
Author(s):  
Purvi Gada ◽  
Michelle Gleason ◽  
Valarie McCullar ◽  
Philip B. McGlave ◽  
Jeffrey S. Miller
Keyword(s):  
T Cells ◽  
B Cells ◽  
Nk Cells ◽  
Cell Expansion ◽  
Nk Cell ◽  
High Dose ◽  
Unexpected Result ◽  
Accessory Cells

Abstract Allogeneic NK cells may play a therapeutic role in treating patients with AML. We have previously shown that high dose cyclophosphamide (120 mg/kg × 1 day) and fludarabine (125 mg/m2 × 5 days) can clear lymphoid space and induce a surge of endogenous IL-15 to expand haploidentical NK cells obtained from CD3-depleted lymphapheresis products from adult donors. In this initial study, 5 of 19 patients achieved remissions and in vivo NK cell expansion. Limitations of this therapy includeinability of NK cells to expand in most patients,development of PTLD (in one patient) andinadequate disease control.We hypothesized that contaminating T cells could compete for NK cell expansion, that B-cells may contribute to PTLD, and that a 2-step NK cell purification method using CD3 depletion followed by CD56 selection (CliniMacs) may overcome these problems. We tested this in 9 patients with advanced AML. The purified NK cells, activated with 1000 U/ml IL-2 (16–20 hours), were infused 48 hours after the last fludarabine dose. Patients then received subcutaneous IL-2 (10 MU) every other day × 6 doses to expand NK cells in vivo. None of the 9 pts treated on this protocol achieved remission or exhibited evidence of in vivo expansion. Several studies were designed to investigate this unexpected result. First, we found that the more extensive processing resulted in approximately 1/3 the NK cell recovery compared to CD3 depletion alone (38±% viable NK cells vs. 91±2% respectively). In addition, we questioned whether the contaminating B cells and monocytes that were removed in the 2-step depletion strategy had served a critical role in NK cell activation or expansion. Cytotoxicity assays performed against K562 targets showed that the killing was about 3-fold higher with the purified (CD3-CD56+) product compared the CD3-depleted product alone (P=0.001 at E:T of 6.6:1). Proliferation, measured by a 6-day thymidine assay, was higher in proportion to the higher NK cell content. The only difference between the two NK products was their expansion after 14 days of culture, where the CD3-depleted product, with contaminating B-cells and monocytes, gave rise to greater NK cell expansion (14 ±3-fold) compared to the 2-step purified product (4.5±0.9, n=6, P=0.005). If this finding holds true in vivo, the co-infusion of accessory cells may be required for NK cell expansion. We next developed in vitro assays using very low concentrations (0.5 ng/ml) of IL-2 and IL-15 to understand their role in expansion. IL-2 or IL-15 alone induced low proliferation and the combination was synergistic. Lastly, UCB, a rich source of NK cell precursors, was compared to adult NK cells. In a short term proliferation assay, CD56+ NK cells stimulated with IL-2 + IL-15 expanded better from adult donors (61274±12999, n=6) than from UCB (20827± 6959, n=5, P=0.026) but there was no difference after 14 days in expansion culture suggesting that the only difference is in kinetics. However, UCB depleted of T-cells (enriching for NK cell precursors) exhibited higher fold expansion over 14 days under different culture conditions conducive to NK cell progenitors. In conclusion, NK cell expansion in vitro depends on cell source, IL-2 and IL-15 (increased in vivo after lymphoid depleting chemotherapy) as well as accessory cells. The role of these factors to enhance in vivo expansion is under clinical investigation to further exploit the NK cell alloreactivity against AML targets.

Immunostimulatory Properties of the Human Ortholog of the GMCSF/IL2 Fusion Protein for Cell Based Therapy.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4894-4894
Author(s):  
Claudia Penafuerte Graduate ◽  
Jacques Galipeau
Keyword(s):  
Fusion Protein ◽  
Nk Cells ◽  
Cell Expansion ◽  
Cell Activation ◽  
Nk Cell ◽  
Ex Vivo ◽  
Potential Candidate ◽  
Activation Markers ◽  
Cell Based Therapy

Abstract NK cells constitute a potential candidate for cancer cell therapy because they express a diverse array of inhibitory and activating receptors, which recognize and kill infected or tumor cells without prior immune sensitization. However, autologous NK cell mediated adoptive immunotherapy is restricted due to insufficient cytolytic activity of NK cells from patient with aggressive malignancies. In contrast, the infusion of alloreactive NK cells has shown more successful outcomes in the treatment of cancer, but this approach also presents difficulties such as the high doses of cytokines required to induce NK cell expansion ex vivo, which may also sensitize NK cells to apoptosis. Therefore, a critical issue for NK cell based therapy is the use of appropriate growth factors or cytokines that promote NK cell expansion and activation. We have previously shown that a murine GM-CSF/IL-2 fusion protein (aka GIFT2) displays novel antitumor properties in vivo compared to both cytokines in combination regarding tumor site recruitment of macrophages and significant functional NK cell infiltration [Stagg et al., Cancer Research (December 2004)]. In the present work, we found that human GIFT2 will lead to a substantial two fold proliferation of human blood-derived NK cells which is significantly (p<0.05) superior to either IL2 or GMCSF single cytokine treatment or both cytokines combined at equimolar concentration. In addition, we observed that GIFT2 leads to robust expression of NK-cell activation markers CD69 and CD107a. In conclusion, the human GIFT2 fusokine is a novel and potent tool for ex vivo expansion of activated NK cells which may be of use in cell-based immunotherapy of cancer.

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