ALBERT

Description: Abstract 2024 Poster Board II-1 The combination of tumor-sensitizing drugs with NK cell infusion is beginning to emerge as a novel anti-tumor therapy. A growing body of in vitro studies show that drugs such as proteosome inhibitors, histone deacetylase inhibitors and thiazolidinediones are able to sensitize tumor cells but not their healthy counterparts to NK-mediated lysis. Drug induced NK-sensitization has shown promise in acute myeloid leukemias but no studies have yet proven this principle in acute lymphoblastic leukemia (ALL); a tumor phenotype reported to be relatively NK-resistant. The mechanisms underlying sensitization have not been fully identified but up regulation of ligands for TRAIL and the NK activating receptor NKG2D: MICA MICB and the UL16-binding proteins, may have a role. We set out to explore ALL susceptibility to NK cytotoxicity and whether this could be modulated by drug treatment. In contrast to published data, untreated ALL cell lines were positive for surface expression of MICB and ULBP2. Median fluorescence intensity ratios (mean ± SD; n = 6) for MICB detection on the cell lines 697, NALM-6, BV173 and SEM were: 3.2 ± 0.9; 3.8 ± 1.3; 4.0 ± 0.5; 2.5 ± 0.9, respectively and for ULBP-2: 2.3 ± 0.4; 55 ± 4.9; 2.9 ± 0.2; 1.8 ± 0.4, respectively. NALM-6 was also positive for ULBP1 (3.3 ± 0.6) while all were negative for MICA and ULBP3. Susceptibility of untreated ALL lines to NK mediated killing was assessed by chromium release assay using an IL-2 stimulated primary NK cell line. At effector to target ratio 40:1, specific release was 2.3% with cell line 697, 12% with NALM-6, 36% with BV173 and 63% with SEM. These results correlated with CD107a exposure in a degranulation assay using IL-2 stimulated peripheral blood lymphocytes: specific degranulation (% CD107a+ target with effector minus %CD107a+ effector alone) was 0.68% (697), 7.1% (NALM-6), 10% (BV173) and 17% (SEM). There was no correlation between baseline expression of NKG2DL and susceptibility to NK killing. Bortezomib, sodium valproate and troglitazone were added to cell cultures at sub-IC50 doses for 48 hours and compared with equimolar vehicle controls. Surface NKG2DL expression was measured by flow cytometry. On NALM-6 troglitazone treatment increased ULBP1 MFI by 2.0 ± 0.33 fold compared with vehicle control and increased percentage of ULBP1 positive cells by 39.6% (paired t-test: p=0.063). Sodium valproate increased MICA expression by 2.91 ± 1.18 fold and percentage of MICA positive cells by 12.3% (p=0.0382). On BV173, sodium valproate treatment increased ULBP2 MFI by 1.55 ± 0.07 fold and percentage of ULBP2 positive cells by 8.6% (p=0.04). There were no significant ligand changes after drug treatment on cell line 697. No NKG2DL changes were seen after Bortezomib treatment on any cell line. The functional significance of NKG2DL changes was assessed by CD107a degranulation assay. NALM-6 treated for 48 hours with drugs yielded the following fold increases in specific degranulation of NK cells compared to NALM-6 vehicle controls: 5.02 ± 5.98 for Bortezomib (mean ± SD), 2.4 ± 0.67 for Troglitazone and 1.44 ± 0.13 for Valproate. Levels of NK degranulation with 697 were very low (

Description: Abstract 3333 Poster Board III-221 Alemtuzumab (CAMPATH 1H) is a well established agent for effecting in vivo T cell depletion and prevention of GVHD in reduced intensity transplants. Many studies indicate that full dose alemtuzumab (100mg in 5 daily doses of 20mg) induces profound immunodeficiency, almost completely ablating GVHD in Fludarabine and Melphalan (FM) matched related donor (MRD) and matched unrelated donor (MUD) transplants. In contrast, FM conditioning alone exposes patients to a high burden of acute and chronic GVHD. Accordingly, many transplant centres have adopted policies of intermediate alemtuzumab dosing of 50mg or less. While the pharmacokinetics, rate of T cell engraftment and incidence of GVHD are well described using full dose alemtuzumab, much less is known about the in vivo action of alemtuzumab at intermediate doses. Methods We report our experience of alemtuzumab at 30mg (day -2) for MRD and 60mg (30mg day -4 and day -2) for MUD transplants, which was adopted as standard GVHD prophylaxis for FM transplantation at our centre in 2006. We avoided giving alemtuzumab on day -1, since there is a steep drop in alemtuzumab level in the first 24 hours after infusion and the timing of stem cell infusion may vary considerably, especially with unrelated donor grafts. From May 2006 to May 2009, 24 patients received MRD and 27 patients received MUD transplants. Post transplant serum samples were available from 19 MRD transplants and 15 MUD transplants at day +1. In addition, day +3 samples were identified from 10 patients previously transplanted with 100mg alemtuzumab, 10 MUD receiving 60mg and 10 MRD transplants receiving 30mg. All patients gave consent for clinical follow up and post transplant serum sampling for research purposes, according to protocols approved by the local research ethics committee of Northumberland and North Tyneside. Alemtuzumab concentration was measured by a validated flow cytometry assay, as previously described. Results The mean (SEM) alemtuzumab concentration (micrograms/ml) on day +1 was 2.9 (0.3) after 30mg and 4.6 (0.6) after 60mg (t test p

Description: Key Points Diverse patient groups with GATA2 mutation develop mononuclear cytopenia and elevated Flt3 ligand. Progressive cytopenias, rising Flt3 ligand, and terminal differentiation of lymphoid cells accompany clinical progression.

Description: Abstract 2045 The novel syndrome of Dendritic Cell, Monocyte, B and NK lymphocyte (DCML) deficiency has recently been characterised and found to be caused by mutations in the transcription factor GATA-2 (Dickinson et al. Blood 2011, Hsu et al. Blood 2011). In this report we describe a series of 10 patients and show that there is a high risk of death unless curative haematopoietic stem cell transplantation (HSCT) is performed. Our case series includes 10 patients; 4 sporadic cases and 6 cases from 2 pedigrees showing autosomal dominant inheritance. 7 patients died; of the 3 survivors, 2 were transplanted and show marked resolution of their disease with a follow up of 36 and 11 months, respectively. Causes of death in the patients who died include disseminated mycobacterium avium infection (2) H1N1 influenza (1) candidiasis (1) pulmonary alveolar proteinosis (2) and CMV pneumonitis (1). At least 8 patients had chronic HPV infection and 2 patients had autoimmune phenomena including inflammatory arthritis and erythema nodosum. One patient also developed lymphoma. All patients had monocytopenia and decreased B and NK cells with normal T cells at presentation. Haemoglobin, platelets and neutrophil counts were within normal ranges or mildly reduced. In 4 patients, near absolute dendritic cell (DC) deficiency and elevated Flt-3 ligand was also confirmed. BM aspirate showed dysplastic megakaryocytes and increased fibrosis in some instances. Macrophages were present in dermis, bone marrow and lung, epidermal Langerhans cells were largely preserved and plasma cells were found in inflammatory lesions by immunohistochemistry. GATA-2 mutation was confirmed by Sanger sequencing in all cases. Of the 2 patients treated with transplantation, the first patient presented aged 12 with disseminated BCG sepsis 6 months following BCG vaccination. Skin biopsy showed acid fast bacilli but no well-formed granulomata, and ongoing sepsis failed to respond to antitubercular therapy including addition of IFN gamma. The second patient presented to gynaecology services at the age of 20 with vulval intraepithelial neoplasia stage 3 (VIN3), and then to respiratory physicians a year later with breathlessness, productive cough, weight loss and night sweats; pulmonary alveolar proteinosis was diagnosed on biopsy. She continued to deteriorate despite whole lung lavage, and developed respiratory failure requiring 35% oxygen and nocturnal non-invasive ventilation (NIV). The patient's family history included two generations affected by haematological malignancy or respiratory illness in early adulthood, inherited in a fashion suggesting an autosomal dominant trait. Both patients underwent reduced intensity allogeneic haematopoietic stem cell transplantation with PBMC from unrelated adult donors (patient 1 – 10/12 HLA match; patient 2 – 9/12); transplant conditioning was with Fludarabine 150mg/m2, Melphalan 140mg/m2 and Alemtuzumab 60mg (patient 1), and Fludarabine 150mg/m2, Busulphan 6.4mg/kg, Alemtuzumab 60mg (patient 2). GVHD prophylaxis was with Ciclosporin and Mycophenolate Mofetil. Both transplants were uneventful. 32 months post-transplantation, patient 1 is well and off all medication. The monocyte count, lymphocyte subsets and immunoglobulins are normal and there were good responses to tetanus and HIB vaccinations. Chimerism shows 100% donor myeloid and B cells and 85% donor T cells. 9 months post-transplantation patient 2 has improved significantly and no longer requires oxygen or NIV. Lung function tests and radiology have significantly improved. Monocytes are in the normal range and chimerism shows 100% donor CD15 and 85% donor CD3. Follow-up continues with gynaecology for VIN3 associated with HPV16/18 infection. Neither patient has developed GVHD. Here we show that DCML deficiency caused by GATA-2 mutation incurs a high risk of mortality due to infection or respiratory failure unless treated by HSCT. Rapid correction of both immunodeficiency and pulmonary alveolar proteinosis is possible, even in the context of severe infection or respiratory failure, using reduced intensity conditioning. The absence of GVHD in both these cases, despite significant HLA-mismatching, may reflect the absence of recipient DC at transplantation. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 1341 Poster Board I-363 Introduction Graft versus host disease (GVHD) following haematopoietic stem cell transplantation is often first observed in the skin; a primary target organ of GVHD. GVH related tissue damage in the skin is mainly driven by infiltrating alloreactive cytotoxic effector T cells, facilitated by a cascade of cytokines and chemokines. Our recently published observations showed that addition of regulatory T cells (Treg) suppressed skin GVH tissue damage mediated by alloreactive CD8+ T cells in an in vitro human GVHD skin explant model [1]. The current study investigated the role of Treg in modulating effector T cell infiltration into skin, it's consequence on the severity of skin GVH histopathology and the possible changes of effector T cell production and expression of chemokines and chemokine receptors. Methods CD8+ T cells, monocyte derived dendritic cells (mDC) and natural Treg (CD4+CD2highFOXP3+) were generated as previously described [1]. In an in vitro human GVHD skin explant model, CD8+ T cells and ex vivo expanded Treg obtained from buffy coats were used as “donor” cells. mDC and skin biopsies obtained from HLA unmatched unrelated normal volunteers acted as “recipient” tissues. “Donor” CD8+ T cells primed with “recipient” mDC in the presence or absence of Treg were co-cultured with “recipient” skin. The severity of histopathological GVH skin damage was scored as grade 0 to grade IV using a clinically validated scoring system. The number of infiltrating CD8+ T cells in skin was evaluated using immunohistochemistry then correlated to the severity of skin GVH histopathology. The gene expression of selected chemokines and chemokine receptors in alloreactive CD8+ effector T cells was analysed using quantitative RT-PCR. The effector T cell expression of chemokine receptors was assessed using flow cytometry. The secretion of selected chemokines into the culture supernatants was quantified using BD cytometric bead array kit. Results The percentage of infiltrating effector T cells in skin was significantly associated with the severity of skin GVH histopathology (2.6±0.8, 12.6±3.1 and 27.2±2.7 for skin sections with GVH histopathology grade I, II and III-IV; p=0.017 and 0.021 respectively). The percentage of skin infiltrating CD8+ T cells was significantly reduced by the presence of Treg (24.8±3.7 vs 11.58±1.8, p=0.011, n=13) which correlated with Treg mediated suppression of skin GVH histopathology (p

Description: The human syndrome of dendritic cell, monocyte, B and natural killer lymphoid deficiency presents as a sporadic or autosomal dominant trait causing susceptibility to mycobacterial and other infections, predisposition to myelodysplasia and leukemia, and, in some cases, pulmonary alveolar proteinosis. Seeking a genetic cause, we sequenced the exomes of 4 unrelated persons, 3 with sporadic disease, looking for novel, heterozygous, and probably deleterious variants. A number of genes harbored novel variants in person, but only one gene, GATA2, was mutated in all 4 persons. Each person harbored a different mutation, but all were predicted to be highly deleterious and to cause loss or mutation of the C-terminal zinc finger domain. Because GATA2 is the only common mutated gene in 4 unrelated persons, it is highly probable to be the cause of dendritic cell, monocyte, B, and natural killer lymphoid deficiency. This disorder therefore constitutes a new genetic form of heritable immunodeficiency and leukemic transformation.