Receptor Gamma Chain Research Articles

No Evidence That Soluble TACI Induces Signalling via Membrane-Expressed BAFF and APRIL in Myeloid Cells

Myeloid cells express the TNF family ligands BAFF/BLyS and APRIL, which exert their effects on B cells at different stages of differentiation via the receptors BAFFR, TACI (Transmembrane Activator and CAML-Interactor) and/or BCMA (B Cell Maturation Antigen). BAFF and APRIL are proteins expressed at the cell membrane, with both extracellular and intracellular domains. Therefore, receptor/ligand engagement may also result in signals in ligand-expressing cells via so-called “reverse signalling”. In order to understand how TACI-Fc (atacicept) technically may mediate immune stimulation instead of suppression, we investigated its potential to activate reverse signalling through BAFF and APRIL. BAFFR-Fc and TACI-Fc, but not Fn14-Fc, reproducibly stimulated the ERK and other signalling pathways in bone marrow-derived mouse macrophages. However, these effects were independent of BAFF or APRIL since the same activation profile was observed with BAFF- or APRIL-deficient cells. Instead, cell activation correlated with the presence of high molecular mass forms of BAFFR-Fc and TACI-Fc and was strongly impaired in macrophages deficient for Fc receptor gamma chain. Moreover, a TACI-Fc defective for Fc receptor binding elicited no detectable signal. Although these results do not formally rule out the existence of BAFF or APRIL reverse signalling (via pathways not tested in this study), they provide no evidence in support of reverse signalling and point to the importance of using appropriate specificity controls when working with Fc receptor-expressing myeloid cells.

Human T cells depend on functional calcineurin, tumour necrosis factor-α and CD80/CD86 for expansion and activation in mice

Dysregulated T cells are a hallmark of several autoimmune and inflammatory diseases; thus, models to study human T cells in vivo are advantageous, but limited by lacking insight into human T cell functionality in mice. Using non-obese diabetic (NOD), severe combined immunodeficient (SCID) or recombination activating gene-1 (RAG1)(-/-) and interleukin-2 receptor gamma-chain (IL-2Rγ)(-/-) mice reconstituted with human peripheral blood mononuclear cells (PBMCs), we have studied the mechanisms of human T cell expansion and activation in mice. Injection of human PBMCs into mice caused consistent xeno-engraftment with polyclonal expansion and activation of functional human T cells and production of human cytokines. Human T cell expansion coincided with development of a graft-versus-host disease (GVHD)-like condition observed as weight loss, multi-organ immune infiltration and liver damage. CD8(+) T cells alone were sufficient for expansion and required for disease development; in contrast, CD4(+) T cells alone expanded but did not induce acute disease and, rather, exerted regulatory capacity through CD25(+)CD4(+) T cells. Using various anti-inflammatory compounds, we demonstrated that several T cell-activation pathways controlled T cell expansion and disease development, including calcineurin-, tumour necrosis factor-α and co-stimulatory signalling via the CD80/CD86 pathway, indicating the diverse modes of action used by human T cells during expansion and activation in mice as well as the pharmacological relevance of this model. Overall, these data provide insight into the mechanisms used by human T cells during expansion and activation in mice, and we speculate that PBMC-injected mice may be useful to study intrinsic human T cell functions in vivo and to test T cell-targeting compounds.

Tofacitinib: Janus Bifrons in Ulcerative Colitis Treatment

Tofacitinib: Janus Bifrons in Ulcerative Colitis Treatment

Potent in vitro and in vivo activity of sorafenib in multiple myeloma: induction of cell death, CD138‐downregulation and inhibition of migration through actin depolymerization

Despite considerable advances, multiple myeloma (MM) remains incurable and the development of novel therapies targeting the interplay between plasma cells (PCs) and their bone marrow (BM) microenvironment remains essential. We investigated the effect of various agents in vitro on the proliferation, phenotype, morphology, actin polymerization and migration of MM cells and, in vivo, the tumour growth of L363-bearing non-obese diabetic severe combined immunodeficient mice with a deficient interleukin-2 receptor gamma chain (NSG). In vitro, we observed a dose-dependent cytotoxicity with bortezomib and sorafenib. Using RPMI8226 cells co-expressing histone 2B-mCherry and cytochrome c-GFP, bortezomib- and sorafenib-induced apoptosis was confirmed, and both agents combined showed synergism. Sorafenib induced CD138-downregulation and abolished CXCL12-induced actin polymerization. L363 cells expressed CCR4 and CCR5 and migrated to their common ligand CCL5. Chemotaxis to BM stroma cells was notable and significantly reduced by sorafenib. Downregulation of phospho-ERK appeared relevant for the inhibition of actin polymerization and chemotaxis. Sorafenib alone, and combined with bortezomib, showed substantial antitumour activity in L363-bearing NSG. Correspondingly, sorafenib induced clinical responses in MM-/AL-amyloidosis patients. We conclude that, in addition to the cytotoxic and anti-angiogenic effects of sorafenib, blocking of MM cell migration and homing represent promising mechanisms to interrupt the interplay between PCs and their supportive microenvironment.

Peripheral T-Cell Lymphoma with Aberrant Expression of CD19, CD20, and CD79a: Case Report and Literature Review

A case of lymphoma of T-cell derivation with aberrant expression of three B-cell lineage markers (CD19, CD20, and CD79a), which was diagnosed on a left axillary excision, is described. Immunohistochemical studies and flow cytometry analysis demonstrated neoplastic cells expressing CD3, CD19, CD20, and CD79a with absence of CD4, CD8, CD10, CD30, CD34, CD56, CD68, TDT, MPO, PAX-5, and surface immunoglobulin. Gene rearrangement studies performed on paraffin blocks demonstrated monoclonal T-cell receptor gamma chain rearrangement with no evidence of clonal heavy chain rearrangement. The neoplastic cells were negative for Epstein-Barr virus (EBV) or Human Herpes Virus 8 (HHV-8). At the time of diagnosis, the PET scan demonstrated hypermetabolic neoplastic cells involving the left axilla, bilateral internal jugular areas, mediastinum, right hilum, bilateral lungs, and spleen. However, bone marrow biopsy performed for hemolytic anemia revealed normocellular bone marrow with trilineage maturation. The patient had no evidence of immunodeficiency or infection with EBV or HHV-8. This is the first reported case of a mature T-cell lymphoma with aberrant expression of three B-cell lineage markers. The current report also highlights the need for molecular gene rearrangement studies to determine the precise lineage of ambiguous neoplastic clones.

Anayisis of Chromosomal Alterations by Array-Based Comparative Genomic Hybridization in 25 Patients with Sézary Syndrome.

AbstractAbstract 2714Sézary Syndrome (SS) is an aggressive type of cutaneous CD4+ T-cell lymphoma characterized by erythroderma, generalized lymphadenopathy and presence of malignant T cells in peripheral blood. Patients with SS have a generally poor median survival (2–4 years), with allogeneic stem cell transplantation as the only curative treatment option. Genome-wide analysis of chromosomal alterations represents a current powerful tool to investigate pathophysiology in hematological malignancies, possibly leading to development of new therapeutic agents. A recent important study reported gain of 17q22–25 and 8q22–24, as well as loss of 17p13 and 10q25 as characteristic genomic aberrations in SS.In this study, by array-based comparative genomic hybridization (a-CGH), we aimed to further explore genomic alterations in 25 patients with Sézary Syndrome (SS) referred to our Institution. The patient series included 11 males and 14 females, with a median age of 65 years (range 29 to 85). At diagnosis, 3 patients were in stage IIIB, 18 in stage IVA1 and 4 in stage IVA2. Flow cytometry analysis unveiled typical CD4+/CD7±/CD26- lymphocytic immunophenotype, while molecular analysis showed clonal rearrangement of T-cell receptor beta and/or gamma chains in all patients. At the time of blood samples collection, 21% of patients were untreated. Among treated ones, photopheresis alone was used in 37% whereas all the others received also chemotherapy-based therapies. Lymphocyte count was higher than 3000/mcL in 75% of patients, higher than 6000/mcL in 46% and higher than 9000/mcL in 25%. Elevated LDH levels were observed in 29%.Genomic DNA was isolated from peripheral blood mononuclear cells of 10 patients and from CD4+/CD14− cells of 15 patients, selected by an immunomagnetic method. Quantity and quality of all gDNA samples were assessed using UV- VIS spectrophotometry and agarose gel electrophoresis. Genome-wide array-based comparative genomic hybridization (aCGH) was performed using the Agilent Human Genome CGH Microarray Kit 4×44K. Copy number profiles from CGH arrays were compared using Integrative Genome Viewer.Most frequently observed recurrent copy number alterations involved gains in chromosomes 7, 8 and 17 and losses in chromosome 10, 17 and 19. In particular, chromosomal gains involved 7q11.21-7q11.23 in 32% of patients, 7q21.3-7q22.1 in 36%, 8q24.2-8q24.3 in 44% (with amplification of the MYC oncogene in 36%), while chromosomal losses involved 10p11.22 in 44% of patients, 10q11.22–21.1 in 48%, 10q23.3 (harbouring the PTEN tumor suppressor gene) in 40%, 10q24 (involving NFkB2 gene) in 56%, 10q25.1-q26.3 in 56%, and 19p13.3 (involving the cell growth/apoptosis regulating GADD45B gene) in 32%. With regard to chromosome 17, we observed loss of region 17p13.1 (containing the TP53 gene) in 60% of cases, whereas a gain in 17q21 (harbouring genes coding for STAT3, STAT5A e STAT5B) was documented in 64% of patients. Worth mentioning, 52% of cases showed both losses in the p arm and gains in the q arm within chromosome 17.In summary, our results partially confirmed those previously reported with regard to alterations in chromosomes 7, 8, 10 and 17, resulting in amplification of oncogenes and deletion of tumor suppressor genes. We also observed genome alterations associated with activation of the signal transduction JAK/STAT pathway, possibly involved in SS malignant phenotype. Further genome alterations emerged in this study, such as those in chromosome 7 and 19, are also worth investigating for their possible pathophysiological meanings. Disclosures:No relevant conflicts of interest to declare.

Lupus nephritis class I accompanied by tubulointerstitial nephritis with marked T-lymphocyte infiltration in an HTLV-1 positive patient.

We herein describe the case of a 40-year-old Japanese male who was admitted to our hospital because of a continuous remittent fever lasting 1month. He fulfilled the items of the classification criteria for the diagnosis of systemic lupus erythematosus (SLE). The administration of 20mg per day of oral prednisolone completely diminished his clinical symptoms. However, his renal biopsy performed 1day after the admission showed marked pathognomonic characteristics. Not only did his glomeruli show class I lupus nephritis with mesangial depositions of IgG, IgA, C3, and C1q, but also tubulointerstitial nephritis with marked T-lymphocyte infiltration. These infiltrated T cells partly had nuclear atypia. The patient was positive for human T cell leukemia virus type 1 (HTLV-1) antibodies. Furthermore, clonal rearrangements of T cell receptor-gamma chain gene was detected in the DNA extracted from his kidney sections by the polymerase chain reaction (PCR) method. A second renal biopsy 6months after the prednisolone treatment showed that the infiltrating T lymphocytes had markedly diminished. This is the first case report of lupus nephritis class I with tubulointerstitial nephritis, which might include oncogenic T lymphocytes, in an HTLV-1 positive patient.

Miniature Swine Expressing Human CD47 to Enhance Bone Marrow Engraftment in Non-Human Primates

Background: Tolerance induction via bone marrow chimerism has been successfully applied to small and large allogeneic models. However, in xenogenic models (pig-to-primate) host macrophages participate in the clearance of porcine bone marrow cells when transplanted into baboons, hindering the ability to achieve mixed chimerism. CD47 interacts with SIRPa receptors on macrophages to inhibit their activation, but this interaction is species-specific. Recent experiments indicate that expression of human CD47 on porcine cells can inhibit phagocytosis by primate macrophages. We report the generation of hCD47 transgenic miniature swine as potential pig-to-primate bone marrow donors. Methods: We constructed a knock-in vector for expression of the human CD47 gene from EF1a promoter with concomitant disruption of the a-1,3-galactosyltransferase (GalT) locus. Selectable targeted cells, with loss of gal epitope and gain of hCD47 expression were generated by transfecting GalT heterozygous fibroblast cells. Somatic cell cloned embryos were generated using Chromatin Transfer technology and transferred into recipient sows at Minitube International Center for Biotechnology. Two early trimester pregnancies were terminated for fetal collection and analysis. Established secondary fetal fibroblasts were then used for a second embryo reconstruction and transfer. Results: RT-PCR and Fluorescent Activated Cell Scan (FACS) analysis of fetal fibroblast lines showed that all fetuses expressed hCD47 and were GalT null. Further, genomic PCR of fetal DNA confirmed proper transgenic locus structure in the cloned fetuses. Transfer of embryos reconstructed using transgenic fetal fibroblasts has resulted in the birth of two healthy transgenic piglets to date. The newborn transgenic piglets also had the desired phenotype; GalT null and hCD47 expression on all peripheral white blood cell lineages. Colony forming unit assay (CFU) analysis of transgenic piglets also confirmed the expression of hCD47 in bone marrow progenitor cells. Also, in preliminary transplant experiments of ckit+ bone marrow progenitors from transgenic piglets in NOD scid IL2 receptor gamma chain knockout mice (NSG) we could detect porcine cells that were hCD47 positive in the peripheral blood and bone marrow of the recipients. Conclusion: We have been able to successfully generate the first transgenic piglets with widespread expression of the human CD47 gene. The animals appear to be healthy and have normal development. Initial transplant experiments in NSG mice recipients show that hCD47 is advantageous for porcine cells to engraft in the bone marrow.

Large Granular Lymphocytic Leukemia: A Treatable Form of Refractory Celiac Disease

Large granular lymphocyte leukemia (LGL) is characterized by clonal expansion of CD3+ T cells or CD3(-) natural killer cells and frequently is associated with autoimmune diseases. We describe 2 patients with celiac disease who no longer responded to gluten-free diets after they developed T-cell LGL, with intestinal localization of malignant lymphocytes. Flow cytometry phenotyping of isolated intestinal intraepithelial and lamina propria cells eliminated type II refractory celiac disease, identifying large-sized CD8(+)CD57(+) T cells. Treatment with a combination of cyclosporine and methotrexate restored the patients' sensitivity to gluten-free diets. LGL therefore might be a cause of refractory celiac disease that is sensitive to immunosuppressive therapy.

Macrophage impairment produced by Fc receptor gamma deficiency plays a principal role in the development of lipoprotein glomerulopathy in concert with apoE abnormalities

To obtain a clear understanding of the pathogenesis of lipoprotein glomerulopathy (LPG), we studied the role of the deficiency of Fc receptor gamma chain (FcRγ) for the development of LPG in concert with apolipoprotein E (apoE) abnormalities. We generated apoE and FcRγ double-knockout (FcRγ/apoE-KO) mice, and subsequently introduced several kinds of human recombinant apoE genes. At 21 days after infection, the mice were sacrificed and histologically examined. Peritoneal macrophages were evaluated for their response to modified lipids. In the FcRγ/apoE-KO mice, the human apoE3-injected mice showed the most drastic LPG-like changes, as well as prominent hypertriglyceridemia. Meanwhile, relative to the human apoE3-injected mice, the FcRγ/apoE-KO mice showed greater lipoprotein deposition and less macrophage infiltration into the mesangial area. Moreover, the peritoneal macrophages in the apoE/FcRγ-KO mice were impaired in lipid uptake and secretion of the cytokines monocyte chemotactic protein-1 and regulated upon activation, normal T-cell expressed and secreted, after the uptake of oxidized low-density lipoprotein. These results suggest that the impairment of macrophage function resulting from FcRγ deficiency plays a principal role in the development of LPG in the presence of apoE abnormalities.

Il2rg Gene-Targeted Severe Combined Immunodeficiency Pigs

A porcine model of severe combined immunodeficiency (SCID) promises to facilitate human cancer studies, the humanization of tissue for xenotransplantation, and the evaluation of stem cells for clinical therapy, but SCID pigs have not been described. We report here the generation and preliminary evaluation of a porcine SCID model. Fibroblasts containing a targeted disruption of the X-linked interleukin-2 receptor gamma chain gene, Il2rg, were used as donors to generate cloned pigs by serial nuclear transfer. Germline transmission of the Il2rg deletion produced healthy Il2rg(+/-) females, while Il2rg(-/Y) males were athymic and exhibited markedly impaired immunoglobulin and T and NK cell production, robustly recapitulating human SCID. Following allogeneic bone marrow transplantation, donor cells stably integrated in Il2rg(-/Y) heterozygotes and reconstituted the Il2rg(-/Y) lymphoid lineage. The SCID pigs described here represent a step toward the comprehensive evaluation of preclinical cellular regenerative strategies.

Reinventing mesenchymal stromal cells

The life-saving impact of chemotherapy and radiation has been as remarkable and momentous as any advance in the history of medicine. This becomes even more signifi cant when we remind ourselves that 50 years ago nearly all leukemias, lymphomas and aggressive solid tumors were fatal, and that nearly everything in oncology before the 20th century was a placebo. However, unintended collateral damage by chemotherapy and radiation to healthy tissues of patients has limited the benefi cial impact of these successes in oncology and in the related fi eld of hematopoietic cell transplantation (HCT). HCT has been a life-saving treatment for many patients with malignant as well as non-malignant, yet equally lethal, diseases and conditions, such as bone marrow failure (e.g. acquired idiopathic severe aplastic anemia, osteopetrosis, Fanconi anemia and dyskeratosis congenita), hemoglobinopathies (e.g. sickle cells disease and thalassemia), immunodefi ciencies (e.g. X-linked defi ciency in the common cytokine receptor gamma chain), and lysosomal (e.g. mucopolysaccharidosis type I – Hurler syndrome), peroxisomal (e.g. childhood cerebral adrenoleukodystrophy) and extracellular matrix (e.g. severe forms of epidermolysis bullosa) disorders (1,2). To limit tissue toxicity, in principle at least two major, but not mutually exclusive, approaches are possible: targeted therapy of cancer (e.g. Ph (Philadelphia (chromosome)) leukemia treatment with anti-BCR-ABL (Breakpoint Cluster Region-Abelson (gene)) antibody) (3) and targeted conditioning for HCT (e.g. immunoablation of hematopoietic stem cells with anti-c-kit antibody) (4); or injury protection and enhancement of tissue repair. During the last decade, the most popular cells for the latter concept have been mesenchymal stromal cells (MSC) (5). Their function in vivo is not well defi ned, but they are likely to be critical for a number of physiologic processes. One example is a support for blood-forming cells in the bone marrow hematopoietic niche, where they are ‘ a drugstore ’ , supplying neighboring cells with growth factors, adhesion molecules and homing cytokines. MSC can function as immune modulator cells and are being used extensively for the prevention and treatment of graft-versus-host disease, the main immune complication of HCT. Also, MSC home preferentially to sites of injury and, in several pre-clinical models and clinical trials of organ damage (e.g. heart, lung, kidney, pancreas, intestine, bone and skin), have been shown to mediate tissue healing. Contrary to original expectations, donor MSC do not appear to replace the damaged cells, but rather use paracrine mediators to recruit the recipients ’ cells into a regenerative microenvironment, which in turn limits apoptosis, promotes angiogenesis, and aids in productive tissue repair (6). Two recent reports in Cytotherapy explore this regenerative capability of human MSC in mice treated with high doses of radiation or chemotherapy. Di et al. (7) asked whether chemotherapy-induced injury in mice could be alleviated by infusion of MSC from human cord blood. They treated mice with doxorubicin, a chemotherapy medication associated with a stereotypical toxicity profi le in bone marrow, heart and intestines. Infusion of MSC not only decreased the degree of damage in these organs, but also increased overall survival in mice that had Cytotherapy, 2012; 14: 388–390

Highly activated and expanded natural killer cells for multiple myeloma immunotherapy

Patients with gene expression profiling-defined high-risk myeloma in relapse have poor outcomes with current therapies. We tested whether natural killer cells expanded by co-culture with K562 cells transfected with 41BBL and membrane-bound interleukin-15 could kill myeloma cells with a high-risk gene expression profile in vitro and in a unique model which recapitulates human myeloma. OPM2 and high-risk primary myeloma tumors were grown in human fetal bone implanted into non-obese diabetic severe combined immunodeficiency mice with a deficient interleukin-2 receptor gamma chain. These mice are devoid of endogenous natural killer and T-cell activity and were used to determine whether adoptively transferred expanded natural killer cells could inhibit myeloma growth and myeloma-associated bone destruction. Natural killer cells from healthy donors and myeloma patients expanded a median of 804- and 351-fold, respectively, without significant T-cell expansion. Expanded natural killer cells killed both allogeneic and autologous primary myeloma cells avidly via a perforin-mediated mechanism in which the activating receptor NKG2D, natural cytotoxicity receptors, and DNAX-accessory molecule-1 played a central role. Adoptive transfer of expanded natural killer cells inhibited the growth of established OPM2 and high-risk primary myeloma tumors grown in the murine model. The transferred, expanded natural killer cells proliferated in vivo in an interleukin-2 dose-dependent fashion, persisted up to 4 weeks, were readily detectable in the human bone, inhibited myeloma growth and protected bone from myeloma-induced osteolysis. These studies provide the rationale for testing expanded natural killer cells in humans.

Angioimmunoblastic T‐cell lymphoma with hyperplastic germinal centres (pattern 1) shows superior survival to patterns 2 and 3: a meta‐analysis of 56 cases

Angioimmunoblastic T-cell lymphoma (AITL) may present in patterns 1, 2 or 3, representing those with hyperplastic, regressed or effaced germinal centres (GCs), respectively, but the prognostic utility of this subclassification has not been previously validated. Twenty-five cases of AITL were reviewed immunohistologically and with in-situ hybridization for Epstein-Barr virus-encoded RNA and polymerase chain reaction for T-cell receptor gamma and immunoglobulin heavy chain clonality and followed for up to 120 months. Four cases had conventional hyperplastic GCs, two had floral GCs, and one had progressively transformed GCs, consistent with pattern 1 and one additional case had hyalinized GCs, consistent with pattern 2. The remaining 17 (pattern 3) cases lacked morphologically discernible GCs. The Kaplan-Meier survival distribution of pattern 1 cases (5-year survival 83%) was superior to that of pattern 2 and 3 cases [5-year-survival 36% (P = 0.0417)] only when combined with the 31 cases, seven of which were pattern 1, that Attygalle et al. had followed for up to 247 months and previously published. Furthermore, the development of B-lineage (classical Hodgkin or diffuse large-cell) lymphoma was associated exclusively with pattern 3 (P = 0.0057). Pattern 1 represents an indolent phase/grade of AITL, unassociated with the development of secondary B-lineage lymphoma and uninfluenced by treatment regimen.

Neuropathy in a patient with lymphocytic thrombophilic arteritis

A 35-year-old Lebanese woman presented with a 3-year history of persistent, localized livedo racemosa over her feet, distal legs and forearms that was associated with the development of lower limb sensorimotor neuropathy. Investigations revealed the patient was heterozygous for prothrombin gene mutation and was also found to have a T-cell receptor gamma chain gene rearrangement. Histological examination revealed a mid-lower dermal medium vessel lymphocytic vasculitis with prominent fibrinoid ring within its wall. These findings are consistent with a recently described condition known as lymphocytic thrombophilic arteritis. This has so far been considered to be a benign clinical condition not associated with extra cutaneous manifestations. The novel findings in the present case are the associated sensorimotor neuropathy and the characteristic fibrin ring appears to be intramural rather intraluminal in location. The findings of a T cell gene rearrangement and a prothrombin gene mutation suggest that both immunological and thrombophilic factors might contribute to the development of this condition.

Distinct Human Cell Populations Produce Rapidly Detectable Levels of Neutrophils and Platelets in NOD/SCID-IL-2Receptor Gamma Chain Null Mice Transgenically Engineered to Produce Human Myeloid Growth Factors

Abstract 1892Cord blood (CB) is becoming an increasingly utilized source of cells for cancer patients who are eligible for therapies that require a transplant to rescue them from toxic side effects on their own hematopoietic cells but lack a suitable HLA-matched donor. This strategy is now routinely used in children, but delayed neutrophil and platelet recovery remain unsolved problems and these problems are exacerbated in adults. To address this issue, we first surveyed the variability in 8 individual CB harvests of parameters routinely used to predict the utility of CB units as transplants (i.e., CD34+ and in vitro myeloid clonogenic progenitor cell frequencies). In addition, we compared their 3-week outputs of CD33/15/66+ cells (neutrophils and monocytes) in the marrow and CD41a+ platelets in the blood of sublethally irradiated NSG mice after the IV transplantation of ∼104 CD34+ cells. These latter assessments were based on ongoing experiments in our lab demonstrating that, at this transplant dose, the outputs measured are linearly related to the number of CD34+ cells injected and detect transplantable progenitor cell types that are biologically distinct from cells with longer term repopulating activity. The results showed variation between CBs in all parameters, a marked lack of correlation between %CD34+ cells or % total CFCs in initial cells and %CD41a+ cells regenerated at 3 weeks/104 CD34+ cells transplanted (R=-0.28 and 0.35, respectively), and a weak correlation between the %CD33/15/66+ cells regenerated at 3 weeks/104 CD34+ cells transplanted and %CD34+ cells or % total CFCs in the initial CB cells (R values of 0.46–0.64). However, although engraftment of primitive human cells in NSG mice appears highly efficient, terminal differentiation of the myeloid lineages in these mice is poor. One possible explanation for this deficiency in mature cell output is that several of the murine growth factors responsible for regulating the production and release of these cells into the circulation in mice are not cross-reactive on human cells. We therefore hypothesized that engineering NSG mice to produce the human counterparts might significantly improve the detection of short term repopulating human cells whose maximum clone size might be limiting in NSG mice. Three potential relevant factors are IL-3, GM-CSF and Steel factor. We therefore backcrossed a line of transgenic NS mice we had created to express human IL-3, GM-CSF and Steel factor onto the NSG strain to produce homozygous NSG mice expressing all 3 of these human factors (NSG-3GS mice). We then compared these NSG-3GS mice with NSG mice in terms of their ability to stimulate the production within 3 weeks of human neutrophil-monocytes and platelets from intravenously transplanted CD34+ cells isolated from pooled CB harvests. The results showed that the levels of neutrophils and monocytes generated in the marrow of the NSG-3GS mice were elevated to levels of >50% of the marrow in 90% of the mice, even at the lowest number of CD34+ cells transplanted. Human neutrophils and monocytes were also elevated in the blood of the NSG-3GS mice where, despite the observed “saturation” of the marrow, there was a linear dose-response in the number of human neutrophils and monocytes present in the blood with increasing CD34+ cells infused. These findings are consistent with the reported activities of these molecules in vitro and in patients suggesting their physiological relevance in this murine xenograft model. We next utilized this assay to characterize the cells responsible for the neutrophil/monocyte and platelet repopulating activities detected in NSG-3GS mice. Preliminary assessment of the CD34+CD45RA- population on the basis of CD123 (IL-3 receptor alpha chain) expression indicates that the CD123+ fraction is enriched for short term (3-week) neutrophil/monocyte repopulating activity, while the CD123- fraction is enriched for short term (3-week) platelet repopulating activity. In summary, NSG-3GS mice significantly enhance the output of human cells with short term human myeloid repopulating ability thereby enabling neutrophil/monocyte outputs as well as platelet outputs to be assessed by analysis of peripheral blood samples. We have also used this tool to obtain evidence that these two outputs are derived from distinct cell types. Direct quantification of these may add to future predictions of graft quality. Disclosures:No relevant conflicts of interest to declare.

Gene Transfer to Hematopoietic Stem/Progenitor Cells As a Novel Approach for Immunotherapy Against B-Lineage Malignancies: In Vivo Xenograft Model,

Abstract 4168Chimeric Antigen Receptors (CAR) against CD19 have been shown to direct T cells to specifically target B-lineage malignant cells in animal models and clinical trials, with efficient tumor cell lysis. But, there has been insufficient persistence of effector cells, limiting the clinical efficacy. We propose gene transfer to hematopoietic stem/progenitor cells (HSPC) as a novel approach to ensure persistent production of effector cells targeting B-lineage malignant cells, exponentially increasing the number of effectors that may be generated against tumor cells. Experiments were performed using NOD-SCID-IL2 receptor gamma chain null (NSG) mice engrafted with human CD34+ HSPCs transduced with lentiviral vectors carrying first and second generations of CD19-specific CAR. There was efficient and stable transduction with 1–2 copies of CAR/cell as determined by qPCR. Differentiation of modified HSPC in vivo was not impaired by gene transfer, as observed in vitro. Results of in vivo studies showed that CAR-transduced human HSPC successfully differentiated into all lineages, with CAR-expressing T, NK and myeloid cells populating bone marrow, spleen and peripheral blood. The human CD19+ B cell populations normally formed in the xenografted NSG mice were significantly reduced when the transplanted HSPC were transduced with the anti-CD19 CAR, demonstrating in vivo biological activity. Cells harvested from bone marrow and spleen of mice engrafted with modified HSPC lysed CD19-positive cell targets ex vivo. Leukemic challenges of engrafted mice are in progress. Our results provide evidence for the feasibility and efficacy of the modification of HSPC with CAR as a protocol for generation of effector cells for immunotherapy against B-lineage malignancies. Disclosures:No relevant conflicts of interest to declare.

Somatic Gene Therapy for X-Linked Severe Combined Immunodeficiency Using a Self-Inactivating Modified Gammaretroviral Vector Results in An Improved Preclinical Safety Profile and Early Clinical Efficacy in a Human Patient

Abstract 164▪FN2▪This icon denotes a clinically relevant abstractSomatic gene therapy for X-linked severe combined immunodeficiency (X-SCID) using a MLV-based gammaretroviral vector expressing the IL-2 receptor gamma chain (MFG-γc) resulted in excellent immunologic reconstitution but also in insertional oncogenesis. In 5/20 treated children, T cell leukemia developed, with insertional activation of LMO2 proto-oncogene in 4 of the 5. We reasoned that replacing the virus-derived promoter and enhancer elements with a weaker cellular promoter would result in improved safety yet retain efficacy. We therefore generated the pSRS11.EFS.IL2RG.pre* self-inactivating (SIN) gammaretroviral vector in which expression of γc is controlled by an intronless EF1-α promoter, in a MLV vector devoid of the LTR U3 (enhancer/promoter) region. In preclinical studies we determined ‘relative safety’ using several surrogate assays. In a reporter assay, the pSRS11.EFS.IL2RG.pre* vector when inserted into the oncogenic LMO2 locus induced LMO2 expression 6–90-fold less than the parent MFG vector (MFG-γc). pSRS11.EFS.IL2RG.pre* had lower activity in a murine in vitro immortalization assay (0.2 clones per 10e5 cells, fitness score 0.00007), compared to MFG-γc (0.54 clones per 10e5 cells, fitness score 0.00025). Peripheral blood and bone marrow from C57BL6 mice transplanted with murine bone marrow transduced with pSRS11.EFS.IL2RG.pre* and followed in primary recipients over 4 months and in secondary recipients over 1 year in vivo showed no evidence of vector associated leukemias. Deep sequencing demonstrated 8 of 3621 insertions into the MDS-associated gene Evi1 in mice transplanted with MFG-γc-transduced cells while there were none (0 of 2690 insertions into Evi1) in mice transplanted with pSRS11.EFS.IL2RG.pre* vector transduced cells (P=0.025). In preclinical efficacy studies, circulating T and B lymphocytes were detectable in the peripheral blood of 7/7 γc-deficient mice transplanted with pSRS11.EFS.IL2RG.pre* transduced cells while 4/4 mice repopulated with SFFV-eGFP transduced cells remained alymphoid. Experimental animals were sacrificed approximately five months post-transplant for analysis of immune reconstitution. Flow cytometric analysis of the spleens and bone marrow revealed restoration of mature B220+IgM+ B cells and NK cell populations in all mice transplanted with pSRS11.EFS.IL2RG.pre* transduced cells. CD4+ and CD8+ T cells were also detected in both tissues and in thymi recovered from transplanted animals. T cells in these mice proliferated in response to mitogenic stimuli. Immunoglobulin subclasses IgG1 and IgG2a detected in the plasma from pSRS11.EFS.IL2RG.pre* reconstituted mice also indicated restored B cell function in these animals. Human preclinical studies also supported the correction of XSCID cellular defects using this vector. Based on these data, a multi-institutional phase I/II trial was initiated with the pSRS11.EFS.IL2RG.pre* vector using an identical clinical protocol as in the previous X-SCID trials, to determine efficacy and safety compared with the MFG-γc vector. The first patient was treated in December 2010. Six months post-gene therapy, he has attained CD3 T cell count of >800, normal proliferation to mitogens, and normal NK cell numbers. He has cleared medically-resistant oral ulcers, and a rotavirus infection acquired post-gene therapy. Nearly all of the circulating T cells (86%) and 41% of his NK cells express γc, albeit at modestly lower density than normal, as expected. However, the early kinetics of T cell reconstitution was comparable to several subjects treated with MFG-γc. These data suggest that the improved safety profile demonstrated with numerous surrogate preclinical studies is associated with efficacious transgene expression and functional immune recovery in the initial human patient treated. Disclosures:Off Label Use: CliniMACS for selection of CD34+ hematopoietic cells. Baum:Patent office: Patents & Royalties.

The frequency of dual TCR-PCR clonality in granulomatous disorders

A granulomatous infiltrate in association with cutaneous T-cell lymphoma is uncommon. The diagnosis of mycosis fungoides can be difficult in the setting of an exuberant granulomatous infiltrate that obscures the neoplastic lymphoid infiltrate, thereby mimicking a granulomatous dermatitis. Therefore, the clinical context and supplemental molecular analysis, such as the demonstration of a monoclonal T-cell population, may assist in diagnosis. Monoclonal T-cell populations have been reported in association with inflammatory conditions and serve as a diagnostic pitfall. The frequency of T-cell clonality in association with granulomatous dermatitides has not yet been established. We identified 29 patients with granulomatous dermatitis who had biopsies at two distinct body sites. Results were correlated with clinical follow up and with clonal T-cell receptor-gamma chain rearrangement as detected by polymerase chain reaction-based analysis (dual TCR-PCR). Clinical follow up was obtained in 17 of 29 cases (58.6%). Twenty-five of 29 cases of granulomatous dermatitis lacked T-cell monoclonality. Three cases of granuloma annulare contained a T-cell clone in one of the two biopsies. One case of necrobiotic xanthogranuloma showed an identical T-cell clone in multiple biopsies. The use of dual TCR-PCR analysis, that is, T-cell clonality analysis in biopsy specimens from two different sites, serves as an adjunct to assist in distinguishing granulomatous inflammatory reactions from granulomatous T-cell lymphoma, including granulomatous mycosis fungoides. The occasional finding of a T-cell clone in a granulomatous dermatitis underscores the importance of clinicopathological correlation in daily diagnosis.

Follicular variant of peripheral T-cell lymphoma mimicking follicular lymphoma: A case report with a review of the Literature

Peripheral T-cell lymphoma (PTCL) with a follicular growth pattern is very rare. Herein, a case of follicular variant of PTCL in a 50-year-old man who complained of tonsillar and generalized lymph node swelling is reported. The resected tonsil revealed a vague nodular growth pattern of atypical cells, medium to large in size, with abundant pale cytoplasm. The lymphoma cells were CD3(+) CD4(+) CD5(+) CD8(-) CD10(+) CD56(-) CD57(-) BCL6(+) PD-1(+) CXCL13(+) and were associated with a meshwork of CD21(+) follicular dendritic cells. Molecular studies revealed clonal rearrangement of the T-cell receptor gamma chain gene but not of the immunoglobulin gene. Cytogenetic analysis disclosed a complex abnormality in 18 of 20 cells with the exclusion of t(5; 9). These findings suggest that the present case is a follicular variant of PTCL derived from follicular T-helper cells.