Allogeneic Mixed Lymphocyte Culture Research Articles

Cord Blood-Derived Multipotent Stem Cells Ameliorate in Vitro/in Vivo Alloreactive Responses, and This Effect Is Associated with Exosomal Microvesicles in Vitro

Human cord blood derived-multipotent stem cells (CB-SCs) have been found to have immunomodulatory capabilities that can result in inhibition of immune activation. Clinically, when used to interact with apheresed peripheral blood mononuclear cells (PBMCs) before reinfusion, they can counteract inflammation and restore immune balance in patients with autoimmune diseases, including alopecia areata and type 1 diabetes. The present study aimed to explore the potential application of CB-SCs to control donor alloreactive responses involved in allogeneic hematopoietic cell transplantation, which often results in acute graft-versus-host disease (GVHD). Phenotypically, we demonstrated that CB-SCs express CD45, CD11b, and CD9 markers on the cell surface; express Oct3/4, a transcription factor for embryonic stem cells; are negative for CD3, CD14, and CD34 expression; and have low expression of HLA-DR. In an allogeneic mixed lymphocyte culture (MLC) using human CD4 T cell enriched PBMCs and allogeneic myeloid derived dendritic cells, direct coculture with CB-SCs decreased CD4 T cell proliferation and activation, as evidenced by a marked decrease in the expression of the late activation markers CD25 and HLA-DR and a reduction of the PKH26 cell proliferation membrane lipophilic marker. Cytokine profiling of MLC supernatants revealed decreased concentrations of inflammatory proteins, including IFN-γ, IL-17, IL-13, IL-2, IL-6, and MIP1-α, along with marked increases in IL-1RA, IP-10, and MCP-1 concentrations in the presence of CB-SCs. Furthermore, transwell MLC experiments revealed that a soluble component was partially responsible for the immunomodulatory effects of CB-SCs. In this regard, exosomal microvesicles (EVs) positive for CD9, CD63, and CD81 were found in CB-SC-derived, ultrafiltered, and ultracentrifuged culture supernatants. CB-SC-EVs inhibited T cell proliferation in allogeneic MLC, suggesting a potential mode of action in allogeneic responses. Finally, CB-SCs were evaluated for their cellular therapy potential in vivo and found to ameliorate the development of GVHD responses in a xenogeneic human PBMC-induced NSG mouse model. Taken together, our results indicate that CB-SCs can directly and indirectly attenuate alloreactive CD4 T cell activation and proliferation in vitro with a potentially related EV mode of action and may have potential as a cellular therapy to control donor T cell-mediated GVHD responses in vivo.

Siplizumab Induces NK Cell Fratricide Through Antibody-Dependent Cell-Mediated Cytotoxicity.

The glycoprotein CD2 is expressed on T and NK cells and contributes to cell-cell conjugation, agonistic signaling and actin cytoskeleton rearrangement. CD2 has previously been shown to have an important function in natural NK cell cytotoxicity but to be expendable in antibody-mediated cytotoxicity. Siplizumab is a monoclonal anti-CD2 IgG1 antibody that is currently undergoing clinical trials in the field of transplantation. This study investigated the effect of CD2 binding and Fc γ receptor binding by siplizumab (Fc-active) and Fc-silent anti-CD2 monoclonal antibodies in allogeneic mixed lymphocyte reaction and autologous lymphocyte culture. Further, induction of NK cell fratricide and inhibition of natural cytotoxicity as well as antibody-dependent cytotoxicity by these agents were assessed. Blockade of CD2 via monoclonal antibodies in the absence of Fc γ receptor binding inhibited NK cell activation in allogeneic mixed lymphocyte reaction. In contrast, siplizumab increased NK cell activation in both mixed lymphocyte reaction and autologous lymphocyte culture due to FcγRIIIA binding. However, experiments using purified NK cells did not show an inhibitory effect of CD2 blockade on natural cytotoxicity or antibody-dependent cytotoxicity. Lastly, it was shown that siplizumab induces NK cell fratricide. Concluding, siplizumab is a promising biopharmaceutical drug candidate for depletion of T and NK cells with minimal off-target effects.

Influenza infection directly alters innate IL-23 and IL-12p70 and subsequent IL-17A and IFN-γ responses to pneumococcus in vitro in human monocytes.

It is well accepted that influenza A virus predisposes individuals to often more severe superinfections with Streptococcus pneumonia. However, the mechanisms that lead to this synergy are not clearly understood. Recent data suggests that competent Th17 immunity is crucial to clearance and protection from invasive pneumococcal disease of the lung. We demonstrate that early influenza infection significantly reduced levels of pneumococcus driven IL-12p70, IL-23 and IL-27 in human monocytes with significant impairment of IL-17A and IFN-γ in HKSP-treated allogeneic mixed lymphocyte cultures. We also provide evidence to suggest that the hemagglutinin component of the virus is at least partially responsible for this downward pressure on IL-17 responses but surprisingly this suppression occurs despite robust IL-23 levels in hemagglutinin-treated monocyte cultures. This study demonstrates that influenza can directly affect the immunological pathways that promote appropriate responses to Streptococcus pneumonia in human immune cells.ImportanceInfluenza virus is highly contagious and poses substantial public health problems due to its strong association with morbidity and mortality. Approximately 250,000–500,000 deaths are caused by seasonal influenza virus annually, and this figure increases during periods of pandemic infections. Most of these deaths are due to secondary bacterial pneumonia. Influenza-bacterial superinfection can result in hospitalisation and/or death of both patients with pre-existing lung disease or previously healthy individuals. The importance of our research is in determining that influenza and its component haemagglutinin has a direct effect on the classic pneumococcus induced pathways to IL-17A in our human ex vivo model.Our understanding of the mechanism which leaves people exposed to influenza infection during superinfection remain unresolved. This paper demonstrates that early infection of monocytes inhibits an arm of immunity crucial to bacterial clearance. Understanding this mechanism may provide alternative interventions in the case of superinfection with antimicrobial resistant strains of bacteria.

Induction of a Regulatory Phenotype in CD3+ CD4+ HLA-DR+ T Cells after Allogeneic Mixed Lymphocyte Culture; Indications of Both Contact-Dependent and -Independent Activation.

Although the observation of major histocompatibility complex II (MHCII) receptors on T cells is longstanding, the explanation for this occurrence remains enigmatic. Reports of an inducible, endogenous expression exist, as do studies demonstrating a protein acquisition from other cells by mechanisms including vesicle transfer. Irrespective of origin, the presence of the human MHCII isotype, human leukocyte antigen DR (HLA-DR), potentially identifies a regulatory T cell population. Using an allogeneic mixed lymphocyte culture (MLC) to induce an antigen-specific immune response, the role of antigen-presenting cells (APCs) for the presence of HLA-DR on cluster of differentiation 3(CD3)+ CD4+ T cells was evaluated. Moreover, a functional phenotype was established for these T cells. It was demonstrated that APCs were essential for HLA-DR on CD3+ CD4+ T cells. Additionally, a regulatory T cell phenotype was induced in CD3+ CD4+ HLA-DR+ responder T cells with an expression of CD25, CTLA-4, CD62L, PD-1, and TNFRII. This phenotype was induced both with and without physical T cell:APC contact, which could reveal novel indications about its functionality. To further investigate contact-independent communication, a phenotype of the small cell-derived vesicles from the MLCs was determined. Yet heterogeneous, this vesicle phenotype displayed contact-dependent differences, providing clues about their intended function in cellular communication.

Liver Transplantation for Hepatic Graft-Versus-Host-Disease: A United Network for Organ Sharing (UNOS) Database Study

rabbit anti-human CD83 antibodies prevented GVHD in mouse and human preclinical alloHCT models. A second generation human mAb 3C12C has been evaluated as a novel therapeutic (Seldon et al, in prep) and its ability to deplete activated DC and preserve protective T cell responses was investigated. Methods: Control human IgG1 (trastazumab) and 3C12C mAb were tested in human peripheral blood mononuclear cell (PBMC) cultures and in allogeneic mixed lymphocyte cultures (alloMLC) for their ability to deplete DC. The antibody was tested in a human xenogeneic TBI and anti-NK conditioned SCID mouse model of GVHD. Survival, clinical scoring and histology were used to document the effect of 3C12C compared to the control mAb. Flow cytometry and immunohistology were used to investigate CD83 induction and the effect of 3C12C on human DC and T cell biology. Results: 3C12C but not the control mAb reduced the number of CD83+ DC in PBMC cultures. The 3C12C mAb reduced T cell proliferation in the alloMLC but did not affect Cytomegalovirus specific CD8+ T cell numbers. Human cells were identified in the liver, lung, spleen and gut of the control mAb treated PBMC transplanted mice, which developed histological GVHD d+8-13. Human DC were activated by d+2 and expressed the CMRF-44 activation marker plus CD83, CD80 and CD86. Treatment with 3C12CmAb eliminated CD83+ CMRF44+ DC early post-transplant and reduced T cell activation in terms of CD25, CD69 and CD137 and cytokine expression but maintained Treg cells. Conclusion: A potential therapeutic human anti-CD83 mAb appears to induce significant immunosuppression, associated with the depletion of CMRF-44+ activated DC, whilst preserving T cell numbers.

Hypomethylating Agent Azacitidine Induces FoxP3 Negative HLA-G Expressing Immunoregulatory T Cells

The major obstacles in using FOXP3+ T regulatory cells as T-cell based immunotherapy against GVHD after allogeneic hematopoietic cell transplantation are their low numbers in the circulation and the lack of specific cell surface markers for efficient purification. DNA methylation has been considered to play a role in the regulation of T-cell effector function and cytokine gene expression, indicating a promising role of hypomethylating agents for immunomodulation. Recently it was shown that in-vitro treatment of conventional T-cells with hypomethylating agent azacitidine (aza) induced FoxP3 expression and converted CD4+CD25- cells into immunosuppressive T-cells the suppressor function of which is independent of FOXP3 expression (Choi et al Blood 116:129;2010), suggesting that aza induced suppressor function depends on the modification of other hypomethylated genes. Human leukocyte antigen-G (HLA-G) is a non-classical HLA class I molecule, shown to exert immunoregulatory functions, the expression of which is epigenetically regulated. In this study we investigated whether hypomethylating agent aza can induce HLA-G+ immunoregulatory T cells. We used CD3+ T cells from peripheral blood of healthy individuals isolated by MACS negative selection. T cells were stimulated with anti-CD3+ plus anti-CD28+ coated magnetic beads and then were treated for 72 hours with aza (0.5-15 mM) in the presence of 50U/ml inteleukin-2 (IL-2). Detailed phenotypical characterization of in-vitro aza treated cells was performed with flow cytomentry. Aza-induced FACS sorted HLA-G+ T cells, were irradiated and then used as third party cells in allogeneic mixed lymphocyte cultures (MLC). For the analysis of the in-vivo effect of aza on HLA-G expression, peripheral blood of patients with myelodysplastic syndrome (MDS) was obtained at baseline and after Vidaza treatment. In-vitro treatment of CD3+ T cells with aza increases the percentage of HLA-G+ cells, with maximum induction at a concentration of aza 7.5 mM in comparison to control (aza-0mM) (n=4, 9,11±0,6% vs 0,76±0,74%, p<0,0001). However optimum aza concentration for the maximum HLA-G induction with the lowest toxicity in CD3 T cells was determined at 5 mM (HLA-G+:6,88±3,9%, p=0,0022). Aza treatment increases the percentage of CD4+CD25highFoxP3+ cells in culture. Maximum HLA-G induction was observed on CD4+CD25+ population (n=2, 9,21±5,5%). Aza treatment of FACS-sorted CD4+CD25negHLA-Gneg cells induced CD4lowCD25+HLA-G positive cells, revealing that aza induced HLA-G positive cells are not the result of a selectively expanded proexisting HLA-G+ population. Strickingly aza induced CD4lowCD25+HLA-G+ are FoxP3 negative. Aza induced HLA-G+ cells showed suppressive function (20% inhibition of proliferation) in allo MLCs, whereas HLA-G- selected cells had no effect.The percentage of peripheral blood HLA-G+ lymphocytes of healthy donors was 1,33±0,36% (n=4) in comparison to MDS patients which was 2,08±0,99% (n=2). In accordance to the in- vitro studies, preliminary data from MDS patients under Vidaza show up to 10 fold increase in CD4+CD25highHLA-G+ cells on day 28 post treatment. In conclusion, aza induces de-novo HLA-G expression on CD4+ T cells in-vitro and in-vivo. By using hypomethylating agent aza in-vitro, we generated a CD4lowHLA-G+ FoxP3neg immunoregulatory population, that is highly possible to be the aza induced FoxP3 independent T regulatory population.This strategy may provide an easy methodology to generate ex-vivo immunoregulatory T cells for adoptive immunotherapy. Disclosures: No relevant conflicts of interest to declare.

Inhibiting cardiac allograft rejection with interleukin-35 therapy combined with decitabine treatment in mice

BackgroundRegulatory T (Treg) cells play a pivotal role in the maintenance of transplantation tolerance. It is of great interest to induce allograft tolerance mediated by regulatory CD4+CD25+ T cells. MethodsHere we investigated the effect of hydrodynamic IL-35-expressing plasmid injection in combination with a methyltransferase inhibitor (decitabine) on immune function and transplantation tolerance in mice. ResultsWe showed that IL-35 and decitabine stimulated the proliferation of CD4+CD25+ Tregs and suppressed CD8+ T cell proliferation in an allogenic mixed lymphocyte culture in vitro. IL-35 gene therapy and decitabine administration prolonged the survival of the transplanted heart in the heterotopic abdominal heart transplantation model in mice. ConclusionsThe possible mechanism through which IL-35 and decitabine treatment increased the survival of graft tissues is to enhance the proliferation of CD4+CD25+ Treg cells and suppress the generation and function of effector T cells. Thus, IL-35 gene therapy combined with decitabine provides a novel approach to induce transplantation tolerance.

<i>In vitro</i> activity and function of B7-H4-Ig fusion protein

B7-H4 has been shown to inhibit T cell proliferation, cytokine production and cell cycle in vitro. B7-H4 deficient mice develop exacerbated disease in the mouse models of Rheumatoid Arthritis (RA), Type 1 Diabetes (T1D) and Experimental Autoimmune Encephalomyelitis (EAE). On the other hand, B7-H4-Ig fusion protein has been documented to assuage the symptoms in mouse models of RA, T1D, and multiple sclerosis in vivo. In the present study, B7-H4-Ig bound to the majority of human peripheral blood monocytes and NK cells, but not to either normal or activated T cells. B7-H4-Ig fusion protein was assayed for its effects in allogeneic mixed lymphocyte culture (MLC) systems. Soluble B7- H4-Ig had no significant effect in the MLC, but with a tendency to promote allogeneic response. Immobilized, but not soluble B7-H4-Ig inhibited plastic bound anti-CD3 mediated activation of T cells. This inhibition however was largely due to B7-H4-Ig mediated displacement of anti-CD3 antibody from the plastic plate. Finally, B7-H4-Ig had no effect on the cytotoxicity mediated by NK and LAK cells in PBMC. Our findings thus caution against the interpretation of suppressive effect observed solely in plate-bound anti-CD3 mediated T cell co-stimulation in vitro.

Inhibition of IL-32 activation by α-1 antitrypsin suppresses alloreactivity and increases survival in an allogeneic murine marrow transplantation model

AbstractInterleukin (IL)–32 was originally identified in natural killer cells and IL-2–activated human T lymphocytes. As T cells are activated in allogeneic transplantation, we determined the role of IL-32 in human mixed lymphocyte cultures (MLCs) and GVHD. In allogeneic MLCs, IL-32 increased two-fold in responding T cells, accompanied by five-fold increases of TNFα, IL-6, and IL-8. After allogeneic hematopoietic cell transplantation, IL-32 mRNA levels in blood leukocytes were statistically significantly higher in patients with acute GVHD (n = 10) than in serial samples from patients who did not develop acute GVHD (n = 5; P = .02). No significant changes in IL-32 levels were present in patients with treated (n = 14) or untreated (n = 8) chronic GVHD, compared with healthy controls (n = 8; P = .5, and P = .74, respectively). As IL-32 is activated by proteinase-3 (PR3), we determined the effect of the serine protease inhibitor α-1 antitrypsin (AAT) on IL-32 levels and showed suppression of IL-32 and T-lymphocyte proliferation in MLCs. In an MHC-minor antigen disparate murine transplant model, preconditioning and postconditioning treatment with AAT resulted in attenuation or prevention of GVHD and superior survival compared with albumin-treated controls (80% vs 44%; P = .04). These findings suggest that AAT modulates immune and inflammatory functions and may represent a novel approach to prevent or treat GVHD.

Expansion of CD4+CD25+ regulatory T cells from cord blood CD4+ cells using the common γ-chain cytokines (IL-2 and IL-15) and rapamycin

Rapamycin has important roles in the modulation of regulatory T cells. We tried to expand CD4(+)CD25(+) regulatory T cells (Treg cells) from umbilical cord blood (CB) CD4-positive cells using interleukin (IL)-15 or IL-2 with transforming growth factor (TGF)-β and rapamycin. We were able to obtain more than 500-fold expansion of CD4(+)CD25(+) cells from CB CD4(+) cells using IL-15 and TGF-β with rapamycin. These expanded CD4(+)CD25(+) cells expressed forkhead box P3 (FoxP3) mRNA at a level about 100-fold higher and could suppress allogeneic mixed lymphocyte culture (MLC) by more than 50%. Early after rapamycin stimulation, CB CD4(+) cells showed increased expression of FoxP3 and a serine/threonine kinase Pim2 and sustained expression of negative phosphoinositide 3-kinase regulator phosphatase and tensin homolog deleted on chromosome 10 (PTEN). On the other hand, CD4(+)CD25(+) cells expanded with rapamycin for 8 days showed much higher levels of FoxP3 mRNA expression and decreased expression of PTEN. A comparison of IL-15 stimulation and IL-2 stimulation showed slightly higher efficiency of IL-15 for expansion of CD4(+)CD25(+) cells, and for FoxP3 expression, IL-15 also showed significantly higher efficacy for inhibition of MLC. The combination of the common γ-chain cytokine IL-15, TGF-β, and rapamycin may be a useful means for expanding Treg cells. Pim2 expression early after stimulation with rapamycin may be important for conferring rapamycin resistance for growth of Treg cells. IL-15 is not less useful than IL-2 for expansion of Treg cells.

Interleukin-32, α1 Anti-Trypsin (AAT-1) and Graft-Versus-Host-Disease

AbstractAbstract 522Graft-versus-host disease (GVHD) is an important complication of allogeneic hematopoietic cell transplantation (HCT). The role of various cell populations, cytokines and chemokines, present pre and post-transplantation, in the development of GVHD has been studied extensively.We investigated the potential role of Interleukin (IL)-32 in alloreactivity and GVHD. IL-32 is the protein product of the NK4 transcript first reported in IL-2 activated T lymphocytes and natural killer cells. IL-32 has pro-inflammatory and pro-apoptotic properties and induces expression of TNF-α in several cell targets. We used one-way mixed lymphocyte cultures (MLC) as a simple in vitro model of GVHD to determine IL-32 expression upon alloactivation. The α and γ isforms of (IL)-32 protein were 2-fold upregulated in allogeneic MLC compared to autologous controls (n=4, p=0.037). Concurrently, the concentrations of TNF-α, IL-6 and IL-8 in the allogeneic MLC supernatants were, as expected, upregulated significantly. This finding led us to evaluate IL-32 expression as a potential marker for GVHD after allogeneic HCT in 45 patients with either active acute GVHD or chronic GVHD, and 16 patients who did not show clinical evidence of GVHD. IL-32 mRNA levels in peripheral blood unsorted white blood cells, correlated with acute GVHD (RT-PCR values expressed as mean +/− SEM of the ratio of expression of IL-32/GUS-B = 1.01, p=0.011, vs control values IL-32/GUS-B = 0.23) but not with chronic GVHD, (IL-32/GUS-B = 0.26, p=0.16) (Figure 1). As the serine protease neutrophil proteinase 3 (PR3) has been shown to serve as activator of IL-32, and to process several inflammatory cytokines, including IL-32, TNF-α and IL-8, we postulated that the addition of the serine protease inhibitor α-1 anti-trypsin (AAT), would interfere with the processing of IL-32 by PR3, and as a result would lead to decreased proliferation of cells in MLC, and reduced cytokine production. To test this hypothesis, MLCs were treated with AAT at concentrations of 1–20 ug/ml and expression of IL-32 and PR3 were determined. In MLCs treated with AAT at the optimal concentration of 5 ug/ml, added to cultures on alternate days for a period of 7 days T lymphocyte proliferation was suppressed when compared to vehicle-treated MLC, (mean CPM=33.000 versus CPM=67.000; p=0.012). Concurrently there was a 2.5 fold decrease in IL-32 and PR3 protein levels (n=4, p=0.023). CONCLUSION: IL-32 is upregulated in patients with acute GVHD. Determination of IL-32 in patients with suspected GVHD may support the diagnosis and the decision to treat.AAT interferred with T cell activation and the release of cytokines, including IL-32, suggesting that administration of AAT may have therapeutic potential in patients with acute GVHD. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Human UCB CD133+ Cell Infusion In NOD-SCID Mice with Acute Hind Limb Ischemia Improves Reperfusion of An Ischemic Bed

AbstractAbstract 4697Clinical trials have shown intracoronary or intramuscular injections of hematopoietic stem cells (HSC) ameliorate vascular ischemia. HSCs are isolated from bone marrow (BM), umbilical cord blood (UCB), and adult peripheral blood (AB). Critical limb ischemia patients, injected with autologous HSC into ischemic tissue had improved perfusion and reduced amputations. However, autologous HSC effectiveness declines with age. We hypothesized that UCB CD133+ HSCs' are more efficacious than autologous HSC at revascularization for an ischemic bed.Immune reactive surface antigens on UCB CD133+ cells were determined using multi-parameter flow cytometry. UCB CD133+ allogeneic immune responses from 72 h co-cultures were analyzed using a mixed lymphocyte culture (MLR) proliferation assays, and induced cytokine production found using TH1(inflammatory)/TH2(anti-inflammatory) cytometric bead assays (CBA) (BD Biosciences (San Jose, CA). In vivo studies were done using NOD/SCID mice treated with low-dose irradiation (200cGy) then femoral ligation. Study mice were divided into 3 treatment groups and underwent intracoronary infusions of; 1×106 UCB CD133+, 0.5×106 UCB mononuclear cells (MNCs), or EGM media alone. Day 3 post-ligation and cell infusion, quadriceps from 3 mice in each group were harvested, total RNA isolated using Trizol™ and RNA for each treatment group pooled. Pooled RNA was converted to cDNA then assayed using mouse ABI Affymetrix™ Gene chip. Computational pathway analyzes were run for significant transcriptome changes. Gene array data was confirmed on select genes using quantitative reverse transcriptase real time PCR (qPCR). Treated mice were followed for ischemic bed reperfusion by Laser Doppler imaging for 28 days post-ligation. UCB CD133+ cells express MHC class I and II, but lack CD80 and CD86. Allogeneic MLR assays using UCB and AB MNCs showed UCB CD133+ cells were stimulatory to MNC proliferation. The MNCs alloresponse to UCB CD133+ cells produced high concentration of interleukin 4 (IL-4) and IL-10 indicative of a TH2 response. These results show allogeneic UCB CD133+ cells induce a TH2 immune response due to an absence of co-stimulation of immune cells. To verify whether the results are recapitulated in vivo, we treated acute limb ischemia in NOD/SCID mice with human UCB CD133+ cells and monitored revascularization by blood flow and Affymetrix mouse gene array. Computational analysis of Affymetrix mouse gene arrays from comparing all 3 treatment protocols indicated that ischemic quadriceps treated with UCB CD133+ cells exhibited a significant enrichment of anti-angiogeneic, chemotaxic, cytokine, and immune response genes. UCB CD133+ treated mice had increase expression of anti-inflammatory, and anti-angiogeneic genes versus controls. Conversely media and UCB MNC treated mice had equal to or higher pro-inflammatory gene expression. The anti-inflammatory gene response was confirmed for 2 of the 3 genes, arginase 1, CXCL7, and tumor growth factor beta binding protein 2 (TGFβBP2) comparing CD133+ treated mice to UCB MNC treated mice. TGFβBP2 was not observed to change in vivo. UCB CD133+ cells treated mice also had improved blood perfusion of the ischemic bed at 28 days post-ligation versus control protocols. The in vivo mouse model supports the in vitro observation, but demonstrates improved reperfusion over controls.Currently there are 2 non-exclusive hypotheses for the function of CD133+ cells in revascularization. First the CD133+ cells integrate and differentiate into new vascular endothelial cells and the second is that the CD133+ cells augment revascularization via a paracrine effect which does not require integration into the host tissue. In vitro studies suggest that UCB CD133+ cells promote an allogeneic TH2 type response because of a lack of co-stimulatory immune surface antigens, resulting in high concentrations of IL-4 and IL-10. This skewed TH2 response inhibits inflammation, the subsequent tissue damage, and may augment revascularization. Although these studies cannot exclude a role for UCB CD133+ cellular integration, results support the paracrine hypothesis as infusion of selected CD133+ cells appears to promote an anti-inflammatory, anti-angiogenic profile at day 3 post-ligation and at 1 month improved reperfusion compared with non-selected MNC. Disclosures:No relevant conflicts of interest to declare.

EUS-Guided Antitumor Therapy for Pancreatic Tumors

Endoscopic ultrasound (EUS) is a very useful modality for the diagnosis and staging of pancreatic masses. With the advent of EUS-guided fine-needle aspiration technology, this modality has made a tremendous leap from imaging modality to histologic diagnosis and therapeutic intervention. EUS offers high-resolution images of and unparalleled access to the pancreas. After locating the tip of the echoendoscope in the duodenum or stomach, several drugs or local treatment modalities can be delivered directly into the pancreas. EUS-guided ethanol lavage with/without paclitaxel injection has been tested for the treatment of cystic tumors of the pancreas, with complete resolution of cystic tumor being observed in up to 70-80% of patients. Ethanol injection is also performed for the management of solid neuroendocrine tumors of the pancreas. Various type of EUS-guided injection have also been investigated for the treatment of pancreatic cancer. An activated allogenic mixed lymphocyte culture (Cytoimplant) was injected in patients with advanced pancreatic cancer. A replication-deficient adenovirus vector carrying the tumor necrosis factor-alpha gene was also delivered intratumorally by EUS. ONYX-015 is an oncolytic attenuated adenovirus that exhibits replication preferentially in malignant cells, causing cell death, and this has also been injected into pancreatic cancers under EUS guidance. EUS-guided local ablation therapies such as radiofrequency ablation, photodynamic therapy, and brachytherapy are also under investigation. EUS-guided fine-needle injection for various solid or cystic lesions is a rapidly expanding field. This article reviews the various applications of EUS for the treatment of pancreatic tumors.

Human Fibroblasts Share Immunosuppressive Properties with Bone Marrow Mesenchymal Stem Cells

Bone marrow mesenchymal stem cells (BM-MSCs) and adipose tissue-derived stem cells share immunosuppressive capacities, suggesting that the latter could be a general property of stromal cells. To check this hypothesis, we compared human BM-MSC and fibroblasts for their in vitro multi-potentiality, expandability and their immunomodulatory properties under normalized optimized culture conditions. We report that, unlike BM-MSCs, fibroblasts cannot differentiate in vitro into adipocytes and osteoblasts and differ from BM-MSCs by the expression of membrane CD106, CD10 and CD26 and by the expression of collagen VII mRNA. Like BM-MSCs, fibroblasts are unable to provoke in vitro allogeneic reactions, but strongly suppress lymphocyte proliferation induced by allogeneic mixed lymphocyte culture (MLC) or mitogens. We show that fibroblasts' immunosuppressive capacity is independent from prostaglandin E2, IL-10 and the tryptophan catabolising enzyme indoleamine 2,3-dioxygenase and is not abrogated after the depletion of CD8+ T lymphocytes, NK cells and monocytes. Finally, fibroblasts and BM-MSCs act at an early stage through blockage of lymphocyte activation, as demonstrated by down-regulation of GZMB (granzyme B) and IL2RA (CD25) expression.

The Role of Human Leukocyte Antigen G in Inducing Immune Tolerance After Allogeneic Hematopoietic Stem Cell Transplantation.

Abstract 4478▪ Background and ObjectiveAllogeneic hematopoietic stem cell transplantation (allo-HSCT) is now applied widely for the treatment of hematological or non-hematological malignancies, aplastic anemia and hereditary diseases. Recently, a protocol for haploidentical allo-HSCT that combines granulocyte-colony stimulating factor (G-CSF) primed bone marrow (G-BM) and peripheral blood stem cells (G-PBSC) without in vitro T-cell depletion received great success. But the mechanism of G-CSF inducing immunotolerance in haploidentical-HSCT has not yet been clarified. Human leucocyte antigen G (HLA-G) is a nonclassical HLA class I molecule, the tolerogenic role of HLA-G is highly supported in pregnancy immunization, tumor immune escape and organ transplant. Because HLA-G closely related to immunotolerance, we investigate the role of HLA-G in inducing immune tolerance after allo-HSCT and the effects of G-CSF on the expression and secretion level of HLA-G. MethodsFlow cytometry was used to detect the expression of membrane-bound HLA-G (mHLA-G) on donor peripheral blood cells (PBC) or bone marrow (BM) cells. The levels of soluble HLA-G (sHLA-G) in the plasma and bone marrow fluid were determined by enzyme-linked immunosorbent assay (ELISA). In vitro, the expression and secretion level of HLA-G in bone marrow mononuclear cells (BMMCs) and peripheral blood mononuclear cells (PBMCs) after G-CSF stimulated were detected by flow cytometry and ELISA, respectively; Separated T lymphocytes which expressed high level of HLA-G were cultured with allogeneic T lymphocytes and relative response index (RPI) was measured with MTT assay; Furthermore, separated T lymphocytes were cultured with allogeneic BMMCs and the levels of IFN-γ and IL-10 in culture supernatant were determined by ELISA. ResultsThe mean level of mHLA-G after G-CSF mobilization in the PBC or BM cells was significantly higher than that before G-CSF mobilization (P<0.05). The level of mHLA-G or sHLA-G in BM cells was higher than that in PBC after G-CSF mobilization (P<0.05). The level of mHLA-G or sHLA-G in BMMCs or PBSCs which were stimulated by G-CSF was higher than that of the controls (P<0.05), and the level of HLA-G in BMMCs was higher than that in PBSCs. HLA-G predominant expressed in CD3+ T cells; The results of allogeneic mixed lymphocyte culture revealed that immunological function of the separated T lymphocytes which expressed high level of HLA-G was inhibited (RPI: 54.3%). The separated T lymphocytes co-cultured with allogeneic BMMCs, the levels of IFN-γ and IL-10 in culture supernatant were significantly higher than the controls (P<0.05). ConclusionsHLA-G is rich in G-BM that might be interpret G-BM could induce better immunotolerance than G-PBSC. The G-CSF could regulate HLA-G expression and secretion directly. The mechanism of G-CSF inducing immunotolerance might be related to the inhibition of allogeneic T cell reactivity and the increase of IFN-γ and IL-10 secretion through HLA-G. Disclosures:No relevant conflicts of interest to declare.

Loci controlling lymphocyte production of interferon γ after alloantigen stimulation in vitro and their co-localization with genes controlling lymphocyte infiltration of tumors and tumor susceptibility

Low infiltration of lymphocytes into cancers is associated with poor prognosis, but the reasons why some patients exhibit a low and others a high infiltration of tumors are unknown. Previously we mapped four loci (Lynf1–Lynf4) controlling lymphocyte infiltration of mouse lung tumors. These loci do not encode any of the molecules that are involved in traffic of lymphocytes. Here we report a genetic relationship between these loci and the control of production of IFNγ in allogeneic mixed lymphocyte cultures (MLC). We found that IFNγ production by lymphocytes of O20/A mice is lower than by lymphocytes of OcB-9/Dem mice (both H2 pz) stimulated in MLC by irradiated splenocytes of C57BL/10SnPh (H2 b) or BALB/cHeA (H2 d) mice, or by ConA. IFNγ production in MLCs of individual (O20 × OcB-9)F2 mice stimulated by irradiated C57BL/10 splenocytes and genotyped for microsatellite markers revealed four IFNγ-controlling loci (Cypr4-Cypr7), each of which is closely linked with one of the four Lynf loci and with a cluster of susceptibility genes for different tumors. This suggests that inherited differences in certain lymphocyte responses may modify their propensity to infiltrate tumors and their capacity to affect tumor growth.

Mesenchymal Stems Cells and Regulatory T Cells Inhibit Alloantigen Mediated Graft-Versus-Host Reaction but Also Impair Graft-Versus-Tumor Reactions Targeting Tumor Associated Antigens

Graft-versus-host disease (GvHD) is a common and potentially life-threatening complication after allogeneic hematopoietic stem cell transplantation (HSCT). It is mediated by donor immune cells reacting against alloantigens presented by host or donor derived professional antigen presenting cells or expressed on host tissue. In addition, donor derived T-cells contribute to the beneficial graft-versus-tumor (GvT) reaction targeting minor histocompatibility antigens and, as previously demonstrated (Stelljes et al., Blood 2004; 104:1210-6), tumor associated antigens (TAAs). Several publications have shown that regulatory T-cells (Tregs) and mesenchymal stem cells (MSCs) can be used to prevent or treat GvHD. Since both cell populations react in a largely unspecific manner on alloantigen mediated immune responses, it remains a matter of debate whether intervention with these cell populations might interfere with GvT reactions directed against TAAs. In order to investigate the effects of MSCs and Tregs on GvHD and tumor specific GvT reactions, we used a murine parent-into-F1 transplant model. After total body irradiation with 9 Gy F1[BALB/c × C57BL/6] (CB6F1) mice were transplanted with parental bone marrow and splenocytes from C57BL/6 (B6) or BALB/c donors, respectively. Following transplantation, CB6F1 recipients received either three doses of 1×106 MSCs of B6 or BALB/c origin s.c. within the first two weeks or 1×106 Tregs together with the transplant. To evaluate TAA specific GvT effects, transplanted recipients were inoculated with tumor cells sharing the MHC background of the donor strain. GvHD score and tumor size were monitored every other day. Treatment with unstimulated MSCs of B6 origin had only marginal effects on GvHD intensity. In contrast, mice treated with unstimulated MSCs of BALB/c origin or BL/6 MSCs stimulated in vitro with supernatant of allogeneic mixed lymphocyte cultures, showed no signs of GvHD like weight loss or skin damage. TAA specific GvT reactions were significantly impaired by MSCs of either origin resulting in markedly increased tumor growth. Analysis of in vivo primed T cells 25 days after transplantation by IFN-γ ELIspot assay revealed significantly reduced TAA specific T-cells in recipients treated with MSCs as compared to transplanted tumor bearing control animals. In our experimental setting, Tregs also reduced GvHD compared with transplanted controls. Again, specific immune responses targeting TAAs were also abolished. In conclusion, cellular immune modulation using MSCs or Tregs might be effective to modulate GvHD. However, both strategies clearly impair tumor specific GvT reactions in our experimental setting suggesting that these interventions might bear the risk of higher relapse rates after allogeneic HSCT. The different effects on GvHD by stimulated and unstimulated MSCs of B6 or BALB/c origin are being explored.

Identification and Characterization of Canine Dendritic Cells Generated In Vivo

Emerging evidence suggests that host dendritic cells (DC) initiate and regulate graft-versus-host and graft-versus-tumor reactions after allogeneic hematopoietic cell transplantation (HCT). Even though decades of experimentation in the preclinical canine HCT model have substantially improved our understanding of the biology and safety of HCT in human patients, the in vivo phenotype of potent antigen-presenting cells in dogs is poorly defined. Therefore, peripheral blood leukocytes were obtained from dogs treated with recombinant human Flt3-ligand and phenotypically distinct cell populations, including putative DC, were purified by 4-color flow-cytometry and tested for their stimulatory potential in allogeneic mixed lymphocyte cultures (MLC). Cells characterized by surface expression of CD11c and HLA-DR, and absence of expression of CD14 and DM5, a marker of mature granulocytes, were found to be highly potent stimulators in allogeneic MLC. In contrast, all other immunophenotypically different cell populations tested had either weak or absent allostimulatory potential. Transmission electron microscopy of CD11c +/HLA-DR +/CD14 −/DM5 − cells revealed the morphology similar to that described for DC in humans and ex vivo-generated canine DC, including long cytoplasmic extensions, discrete lysosomes, and an abundant Golgi apparatus and endoplasmatic reticulum. In summary, CD11c +/HLA-DR +/CD14 −/DM5 − cells obtained from canine peripheral blood have functional and morphologic characteristics similar to those of human myeloid DC.

Expansion of natural killer cell receptor (CD94/NKG2A)–expressing cytolytic CD8 T cells and CD4 +CD25 + regulatory T cells from the same cord blood unit

Cord blood contains a significant number of precursor cells that differentiate to cytotoxic effector cells and immunoregulatory cells. We tried to expand inhibitory natural killer cell receptor CD94-expressing CD8 T cells with cytolytic activity and CD4(+)CD25(+) regulatory T cells from the same cord cell unit. Cytotoxic CD94-expressing CD8 T cells were expanded from CD4-depleted cord blood using an immobilized anti-CD3 monoclonal antibody and a cytokine and also CD4(+)CD25(+) regulatory T cells were expanded from a CD4-enriched fraction derived from the same cord blood unit using anti-CD3/CD28 monoclonal antibody-coated Dynabeads and cytokines. We were able to obtain a more than 1000-fold expansion of CD94-expressing CD8 T cells and a more than 50-fold expansion of CD4(+)CD25(+) cells from the same cord blood unit. These expanded CD4(+)CD25(+) cells expressed FoxP3 mRNA at a level about 100-fold higher than that in isolated CD25(-) cells and could suppress allogeneic mixed lymphocyte culture by >80% (effector cells: CD4(+)CD25(+) cells = 2:1). Cytolytic activities of purified CD94-expressing cells detected by a 4-hour (51)Cr release assay against K562 were >60%. Coculture of CD94-expressing cells with expanded CD4(+)CD25(+) cells did not have any effect on cytolytic activities of purified CD94-expressing cells against K562 cells. These expanded cytolytic CD94-expressing CD8 cells might be able to induce a graft-vs-leukemia effect without enhancing graft-vs-host disease, and CD4(+)CD25(+) cells might be able to suppress allogeneic responses, including graft-vs-host disease and graft rejection after cord blood transplantation.

Expansion of Inhibitory NK Receptor (CD94/NKG2A)-Expressing Cytolytic CD8 T Cells and CD4+CD25+ Regulatory T Cells from the Same Cord Blood.

It has recently been shown that inhibitory natural killer cell receptors (NKRs) on not only NK cells but also on T cells negatively regulate NK cell and T cell functions through their binding to MHC class I molecules. The C-type lectin superfamily inhibitory NKR CD94/NKG2A heterodimer recognizes an HLA-E that preferably bound to a peptide derived from the signal sequences of most HLA class I. Therefore, CD94-expressing cells can monitor the global status of HLA class I on the tumor and leukemic cells and induce cytolytic attack without inhibitory signal against HLA class I decreased target cells resulting induction of graft-versus-leukemia (GVL) effect but does not attack normal cells with HLA class I expression resulting no enhancement of graft-versus-host disease (GVHD). On the other hand, CD4+ CD25+ regulatory T cells (Treg) contribute to suppress allogeneic immune responses and prevent transplant rejection and GVHD. In this study, we tried to expand CD94-expressing T cells and Treg cells from the same cord blood cells and then investigated their cytolytic characteristics and immunoregulatory function in order to develop a potential strategy of cell therapy for hematological malignancy.After CD4 enrichment by negative selection using magnetic cell sorting (MACS) (Miltenyi Biotec)(CD4-enriched fraction) from cord blood, CD4+ CD25+ cells were isolated by positive selection with anti-CD25 magnetic microbeads. We could get more than 1,000 fold expansion of CD94-expressing CD8 T cells from CD4-depleted fraction after 8 days culture with immobilized anti-CD3 monoclonal antibody (mAb) (1 μg/mL) and IL-15 (5 ng/mL). Isolated CD4+ CD25+ cells were cultured with anti-CD3/CD28 mAb-coated dynabeads and IL-15 (5 ng/mL) and we could get about 50 fold expansion of Treg cells for 8 days. These expanded Treg cells could suppress allogeneic mixed lymphocyte culture more than 80% (effector cells: Treg cells= 2:1) and expressed FoxP3 mRNA about 100 fold compared with isolated CD25-negative cells. Cytolytic activities of purified CD94-expressing cells (CD94 > 90%) detected by 4 hours 51Cr release assay against K562 were 68.8 ± 16.8 % (n=5). Coculture of CD94-expressing cells with expanded Treg cells (CD94-expressing cell: Treg cells= 1:1, preincubation 4 hours) did not have any effect on cytolytic activities of purified CD94-expressing cells against K562 cells (66.1 ± 19.8 %, n=5). CD94-expressing CD8 T cells with cytolytic activity could be expanded from CD4-deplted fractions and Treg cells with immunosuppressive activity and increased expression level of FoxP3 mRNA could be expanded from CD4-enriched fractions of the same cord blood. Expanded these cytolytic CD94-expressing CD8 cells might be able to induce GVL effect without enhancing GVHD and Treg cells might be able to suppress allogeneic response including GVHD and graft rejection. Therefore, this strategy may be useful to differentiate lymphocytes in cord blood to two different kinds of effector cells exhibiting cytolytic or immunoreguratoly characters.