ALBERT

Description: A 150 m observation borehole was drilled in Abbey Arms Wood, Delamere, Cheshire, UK in order to explore the local hydrogeological conditions and to understand better the source of the high concentrations of arsenic in some of the local groundwaters. The borehole was located on an outcrop of the Helsby Sandstone Formation (part of the Sherwood Sandstone Group) and was cored into the underlying Wilmslow Sandstone Formation. The aquifers in the area are unconfined and give rise to low-Fe groundwaters with As concentrations in the 10-50 {micro}g l-1 range. The chemical composition of the sediments is quite uniform down to 150 m. The total arsenic content is in the range from 5 to 15 mg kg-1 and averaged 8 mg kg-1 (n = 60). There is no trend in sediment As concentration with depth, but pore water centrifuged from the core steadily increased in As concentration with depth. The As concentration ranges from 8 {micro}g l-1 at 10 m (unsaturated zone) to 30 {micro}g l-1 at 150 m. The source of the dissolved As remains unclear but the lack of evidence for discrete high-As minerals or zones of mineralization suggests that it is probably derived by desorption from rock-forming minerals in the sandstones, e.g. iron oxides. This may be in response to slightly higher pH (up to 8.0 at depth). If this trend applies throughout the area, restricting the screened interval for abstraction boreholes to the uppermost parts of the saturated zone may reduce As concentrations, but is likely to reduce yields and may also risk encountering groundwaters with high nitrate concentrations.

Description: ABSTRACT Threlkeld Knotts (ca 500 m asl) in the English Lake District has hitherto been considered to be a glacially-modified intrusion of microgranite. However, its surface features are incompatible with glacial modification; neither can these nor the subsurface structures revealed by ground-penetrating radar (GPR) be explained by postglacial subaerial processes acting on a glacially-modified microgranite intrusion. Here we reinterpret Threlkeld Knotts as a very large postglacial landslide involving the microgranite, with an estimated volume of about 4 x 10 7  m 3 . This interpretation is tested against published and recent information on the geology of the site, the glacial geomorphic history of the area and newly-acquired ground-penetrating radar data. More than 60 large post-LGM (Last Glacial Maximum) rock-slope failures have significantly modified the glaciated landscape of the Lake District; this is one of the largest. Recognition of this major landslide deposit in such a well-studied environment highlights the need to continuously re-examine landscapes in the light of increasing knowledge of geomorphic processes and with available technology in currently active or de-glaciating environments. Copyright © 2012 John Wiley & Sons, Ltd.

Description: Preventing Graft-versus-Host Disease (GvHD) without impairment of immune reconstitution is a major goal in HLA-mismatched hematopoietic stem cell transplantation (HSCT). Many experimental strategies to selectively destroy or remove alloreactive donor T cells after allostimulation prior to infusion have been explored. An alternative approach is costimulatory blockade (CSB) during ex vivo allostimulation of donor T cells, rendering allospecific T cells within the donor cell pool alloanergized (i.e hyporesponsive to subsequent alloantigenic challenge). Murine and human data suggest effective induction of alloanergy by ex vivo CSB may involve an active cell-mediated suppression process requiring the presence of CD4+ CD25+ regulatory T cells (Tregs). We conducted a pilot clinical study of haploidentical HSCT after allospecific CSB with anti-B7.1 and -B7.2 antibodies and measured reconstitution of Treg by intracellular flow cytometry. 5 patients (pts; 4 high risk acute lymphoblastic leukemia, one marrow failure) underwent cyclophosphamide/TBI-conditioned haploidentical HSCT with cyclosporine and methotrexate as GvHD prophylaxis. Donor bone marrow was incubated with irradiated recipient peripheral blood mononuclear cells and 10μg anti-B7.1/2 antibodies/106 cells for 48 hours to induce alloanergy, washed and infused. All pts engrafted. All evaluable patients had a marked relative increase in peripheral blood CD4+ FOXP3+ T cells at D+20-60 (Figure 1). CD4+ FOXP3+ cells were CD25+ CD45RO+ intracellular CTLA4+ CD127lo consistent with a memory Treg phenotype. Treg were predominantly negative for HLA DR differentiating them from activated T cells. Despite receiving high doses of mismatched donor T cells (median 1.8 (CD4) and 3.1 (CD8) x 107/kg) and all pts achieving 100% donor chimerism, only 2 pts developed acute GvHD, both Grade II, resolving after short courses of corticosteroids. All evaluable patients also had an increase in CD4+ T effector (Teff) cells with an activated phenotype (CD25+ HLA DR+ FOXP3-) at D+30-50. Pts had very rapid immune reconstitution (CD4, CD8, NK and CD8-CMV-tetramer+ cell numbers and immunoglobulin levels) and have had normal vaccination responses. 2 pts died, at D+35 (bacterial sepsis) and D+71 (multi-organ failure), both without GvHD. 3 pts survive (median follow up 5 years) with normal performance status with no chronic GvHD or disease relapse. Conditioning-related cytokine secretion may have led to reversal of anergy in vivo and expansion of alloreactive cells within the Teff cell population. The marked in vivo expansion of Treg may represent one mechanism of suppression of alloreactive Teff and subsequent immunological control of acute GvHD without impairing immune reconstitution in pts receiving HLA-mismatched donor T cells after ex vivo allospecific CSB. We are using a modification of this strategy in a clinical trial of delayed infusion of escalating doses of alloanergized donor T cells after CD34-selected haploidentical HSCT, to determine the optimal dose of alloanergized donor T cells that controls acute GvHD without impairment of immune reconstitution. Figure Figure

Description: We report the outcomes of 24 patients with high-risk hematologic malignancies or bone marrow failure (BMF) who received haploidentical bone marrow transplantation (BMT) after ex vivo induction of alloantigen-specific anergy in donor T cells by allostimulation in the presence of costimulatory blockade. Ninety-five percent of evaluable patients engrafted and achieved full donor chimerism. Despite receiving a median T-cell dose of 29 ×106/kg, only 5 of 21 evaluable patients developed grade C (n = 4) or D (n = 1) acute graft-versus-host disease (GVHD), with only one attributable death. Twelve patients died from treatment-related mortality (TRM). Patients reconstituted T-cell subsets and immunoglobulin levels rapidly with evidence of in vivo expansion of pathogen-specific T cells in the early posttransplantation period. Five patients reactivated cytomegalovirus (CMV), only one of whom required extended antiviral treatment. No deaths were attributable to CMV or other viral infections. Only 1 of 12 evaluable patients developed chronic GVHD. Eight patients survive disease-free with normal performance scores (median follow-up, 7 years). Thus, despite significant early TRM, ex vivo alloanergization can support administration of large numbers of haploidentical donor T cells, resulting in rapid immune reconstitution with very few viral infections. Surviving patients have excellent performance status and a low rate of chronic GVHD.

Description: Control of alloreactivity without loss of immunity to pathogens and tumor antigens remains the major challenge in allogeneic hematopoietic stem cell transplantation (AHSCT). One platform for achieving this objective has been based upon the methodologies of stimulating donor T cells with recipient alloantigens and destroying, removing, and/or inactivating alloreactive donor T-cells. We have previously reported a clinical trial employing ex vivo inactivation of alloreactive donor T cells via CTLA-4 immunoglobulin-mediated co-stimulatory blockade of CD28 signaling, which allowed large doses of HLA-mismatched T cells to be infused at the time of AHSCT without excess graft-versus-host disease (GvHD) and with no clinically significant late viral infections in surviving patients. We have now refined this approach, exposing donor peripheral blood mononuclear cells (PBMCs) to irradiated stimulator PBMCs in the presence of clinical grade humanized anti-B7.1 and anti-B7.2 monoclonal antibodies, blocking the delivery of positive co-stimulatory signals to (predominantly CD4+) alloantigen-specific donor T cells. This strategy reduces proliferative responses to irradiated stimulator PBMCs to less than 1% of those seen with untreated cultured responder cells in fully HLA mismatched healthy volunteer donor pairs. The proliferative capacity of responder cells to mitogenic anti-CD3 and -CD28 antibodies following alloantigen-specific co-stimulatory blockade is not impaired. In order to demonstrate the retention of antigen-specific responses in donor CD4+ cells following recipient alloantigen-specific co-stimulatory blockade, we used a highly sensitive 5-color flow cytometric intracellular cytokine secretion assay following stimulation of PBMCs with virus-infected cell lysates. Donors in whom viral lysate-specific CD4+ cells could be detected in untreated PBMCs retain approximately two-thirds of VZV, HSV and CMV-specific Th1 cytokine+ (IFN-γ/IL2) CD4+ cells after anti-B-7 mediated alloantigen-specific co-stimulatory blockade. Th1 cytokine responses to the superantigen staphylococcal enterotoxin B are preserved in all donors. Furthermore, proliferative responses to CMV viral lysate are retained after effective allospecific co-stimulatory blockade in the majority of donors in whom CMV-specific Th1 cytokine+ CD4+ T cells could be detected in untreated PBMCs cultured in parallel. These data demonstrate that HLA-mismatched alloantigen-specific co-stimulatory blockade effectively reduces proliferative responses to alloantigens whilst retaining pathogen-specific CD4+ cells. Moreover, the capacity to secrete cytokines of these pathogen-specific T cells supports the hypothesis that they will be functional when adoptively transferred. An ongoing multicentre proof-of concept dose escalation study is underway in which this strategy is utilized to generate HLA mismatched donor T cells which are administered after haploidentical AHSCT to augment immune recovery without GvHD. Furthermore, the application of highly sensitive assays to quantify pathogen-specific immunity in donor T cells after alloantigen-specific co-stimulatory blockade may allow donor and recipient-specific T cell dosing strategies to be applied to minimize treatment-associated toxicity.