Essential role for the p55 tumor necrosis factor receptor in regulating hematopoiesis at a stem cell level

Hematopoietic stem cell (HSC) self-renewal is a complicated process, and its regulatory mechanisms are poorly understood. Previous studies have identified tumor necrosis factor (TNF)-alpha as a pleiotropic cytokine, which, among other actions, prevents various hematopoietic progenitor cells from proliferating and differentiating in vitro. However, its role in regulating long-term repopulating HSCs in vivo has not been investigated. In this study, mice deficient for the p55 or the p75 subunit of the TNF receptor were analyzed in a variety of hematopoietic progenitor and stem cell assays. In older p55(-/-) mice (>6 mo), we identified significant differences in their hematopoietic system compared with age-matched p75(-/-) or wild-type counterparts. Increased marrow cellularity and increased numbers of myeloid and erythroid colony-forming progenitor cells (CFCs), paralleled by elevated peripheral blood cell counts, were found in p55-deficient mice. In contrast to the increased myeloid compartment, pre-B CFCs were deficient in older p55(-/-) mice. In addition, a fourfold decrease in the number of HSCs could be demonstrated in a competitive repopulating assay. Secondary transplantations of marrow cells from primary recipients of p55(-/-) marrow revealed impaired self-renewal ability of p55-deficient HSCs. These data show that, in vivo, signaling through the p55 subunit of the TNF receptor is essential for regulating hematopoiesis at the stem cell level.

Dendritic cell immunotherapy for cancer: application to low-grade lymphoma and multiple myeloma

The confirmation that most cancers express one or more molecular changes, which may act as tumour-associated antigens (TAA), combined with the knowledge that T lymphocytes recognize even single amino acid differences in MHC presented peptides has stimulated renewed clinical interest in immunotherapeutic strategies. Dendritic cells (DC) are now recognized as specialist antigen-presenting cells, which initiate, direct and regulate immune responses. Recent data suggest that DC are not recruited into, or activated by, cancers and that other abnormalities in DC function are associated with malignancy, including multiple myeloma. This provides a rationale for designing immunotherapeutic strategies, which exploit DC as nature's adjuvant either in vivo or in vitro. Low-grade lymphoma and multiple myeloma are slowly progressive malignancies, which generally express a unique immunoglobulin idiotype as a potential TAA. Data from animal models and clinical studies suggest that DC-based immunotherapy strategies, applied when the patient has minimal residual disease, may improve the long-term prognosis in these diseases.

Differential roles of IL-1 and TNF-alpha on graft-versus-host disease and graft versus leukemia

We demonstrate an increase in graft-versus-host disease (GVHD) after experimental bone marrow transplant (BMT) when cyclophosphamide (Cy) is added to an otherwise well-tolerated dose (900 cGy) of total body irradiation (TBI). Donor T cell expansion on day +13 was increased after conditioning with Cy/TBI compared with Cy or TBI alone, although cytotoxic T lymphocyte (CTL) function was not altered. Histological analysis of the gastrointestinal tract demonstrated synergistic damage by Cy/TBI and allogeneic donor cells, which permitted increased translocation of LPS into the systemic circulation. TNF-alpha and IL-1 production in response to LPS was increased in BMT recipients after Cy/TBI conditioning. Neutralization of IL-1 significantly reduced serum LPS levels and GVHD mortality, but it did not affect donor CTL activity. By contrast, neutralization of TNF-alpha did not prevent GVHD mortality but did impair CTL activity after BMT. When P815 leukemia cells were added to the bone marrow inoculum, allogeneic BMT recipients given the TNF-alpha inhibitor relapsed at a significantly faster rate than those given the IL-1 inhibitor. To confirm that the role of TNF-alpha in graft versus leukemia (GVL) was due to effects on donor T cells, cohorts of animals were transplanted with T cells from either wild-type mice or p55 TNF-alpha receptor-deficient mice. Recipients of TNF-alpha p55 receptor-deficient T cells demonstrated a significant impairment in donor CTL activity after BMT and an increased rate of leukemic relapse compared with recipients of wild-type T cells. These data highlight the importance of conditioning in GVHD pathophysiology, and demonstrate that TNF-alpha is critical to GVL mediated by donor T cells, whereas IL-1 is not.

IL-11 separates graft-versus-leukemia effects from graft-versus-host disease after bone marrow transplantation

We recently showed that IL-11 prevents lethal graft-versus-host disease (GVHD) in a murine bone marrow transplantation (BMT) model of GVHD directed against MHC and minor antigens. In this study, we have investigated whether IL-11 can maintain a graft-versus-leukemia (GVL) effect. Lethally irradiated B6D2F1 mice were transplanted with either T cell-depleted (TCD) bone marrow (BM) alone or with BM and splenic T cells from allogeneic B6 donors. Animals also received host-type P815 mastocytoma cells at the time of BMT. Recipients were injected subcutaneously with recombinant human IL-11 or control diluent twice daily, from 2 days before BMT to 7 days after BMT. TCD recipients all died from leukemia by day 23. All control- and IL-11-treated allogeneic animals effectively rejected their leukemia, but IL-11 also reduced GVHD-related mortality. Examination of the cellular mechanisms of GVL and GVHD in this system showed that IL-11 selectively inhibited CD4-mediated GVHD, while retaining both CD4- and CD8-mediated GVL. In addition, IL-11 treatment did not affect cytolytic effector functions of T cells after BMT either in vivo or in vitro. Studies with perforin-deficient donor T cells demonstrated that the GVL effect was perforin dependent. These data demonstrated that IL-11 can significantly reduce CD4-dependent GVHD without impairing cytolytic function or subsequent GVL activity of CD8(+) T cells. Brief treatment with IL-11 shortly after BMT may therefore represent a novel strategy for separating GVHD and GVL.

Keratinocyte growth factor separates graft-versus-leukemia effects from graft-versus-host disease

The major obstacles to successful outcome after allogeneic bone marrow transplantation (BMT) for leukemia remain graft-versus-host disease (GVHD) and leukemic relapse. Improved survival after BMT therefore requires more effective GVHD prophylaxis that does not impair graft-versus-leukemia (GVL) effects. We studied the administration of human recombinant keratinocyte growth factor (KGF) in a well- characterized murine BMT model for its effects on GVHD. KGF administration from day -3 to +7 significantly reduced GVHD mortality and the severity of GVHD in the gastrointestinal (GI) tract, reducing serum lipopolysaccharide (LPS) and tumor necrosis factor (TNF)alpha levels, but preserving donor T-cell responses (cytotoxic T lymphocyte [CTL] activity, proliferation, and interleukin [IL]-2 production) to host antigens. When mice received lethal doses of P815 leukemia cells at the time of BMT, KGF treatment significantly decreased acute GVHD compared with control-treated allogeneic mice and resulted in a significantly improved leukemia-free survival (42% v 4%, P <.001). KGF administration thus offers a novel approach to the separation of GVL effects from GVHD.

Pretransplant chemotherapy reduces inflammatory cytokine production and acute graft-versus-host disease after allogeneic bone marrow transplantation

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) is known to be a critical effector molecule in the pathogenesis of graft-versus-host disease (GVHD), and elevated levels during bone marrow transplantation (BMT) conditioning are associated with more severe GVHD. Many patients receive chemotherapy prior to BMT, but its effect on subsequent toxicities is controversial.

METHODS

We studied the effect of prior chemotherapy on GVHD severity and inflammatory cytokine generation in a well-established murine model of allogeneic BMT (B6-->B6D2F1).

RESULTS

Three weeks after a single dose of cyclophosphamide, bone marrow and splenic cellularity was reduced by 50% and the production of TNF-alpha to LPS stimulation by macrophages was also markedly impaired (both before and after total body irradiation). Allogeneic BMT recipients previously treated with cyclophosphamide had significantly less GVHD and improved survival relative to recipients previously pretreated with diluent only. This survival advantage was associated with reduced systemic levels of both TNF-alpha and interleukin-1beta 7 days after BMT. This reduction occurred despite equivalent serum levels of lipopolysaccharide, consistent with the reductions in TNF-alpha and interleukin-1beta production by host macrophages after cyclophosphamide pretreatment.

CONCLUSIONS

These data support the notion that patients entering BMT conditioning without prior cytotoxic treatment (e.g., patients with chronic myeloid leukemia) may be at increased risk of posttransplant complications associated with excessive inflammatory cytokine production.

Granulocyte colony-stimulating factor-mobilized allogeneic stem cell transplantation maintains graft-versus-leukemia effects through a perforin-dependent pathway while preventing graft-versus-host disease

Minimization of graft-versus-host disease (GVHD) with preservation of the graft-versus-leukemia (GVL) effect is a crucial step to improve the overall survival of allogeneic bone marrow transplantation (BMT) for patients with hematological malignancies. We and other investigators have shown that granulocyte colony-stimulating factor (G-CSF)-mobilized allogeneic peripheral stem cell transplantation (PBSCT) reduces the severity of acute GVHD in murine models. In this study, we investigated whether G-CSF-mobilized PBSC maintain their GVL effect in a murine allogeneic transplant model (B6 --> B6D2F1). B6 mice (H-2(b)) were injected subcutaneously with human G-CSF (100 micrograms/kg/d) for 6 days and their splenocytes were harvested on day 7 as a source of PBSC. G-CSF mobilization dramatically improved transplant survival compared with nonmobilized controls (95% v 0%, P <.001). Systemic levels of lipopolysaccharide and tumor necrosis factor-alpha were markedly reduced in recipients of allogeneic G-CSF-mobilized donors, but cytolytic T lymphocyte (CTL) activity against host tumor target cells p815 was retained in those recipients. When leukemia was induced in recipients by coinjection of p815 tumor cells (H-2(d)) at the time of transplantation, all surviving recipients of G-CSF-mobilized B6 donors were leukemia-free at day 70 after transplant, whereas all mice who received T-cell-depleted (TCD) splenocytes from G-CSF-mobilized B6 donors died of leukemia. When splenocytes from G-CSF-mobilized perforin-deficient (pfp-/-) mice were used for transplantation, 90% of recipients died of leukemia, demonstrating that perforin is a crucial pathway mediating GVL effects after G-CSF-mobilized PBSCT. These data illustrate that G-CSF-mobilized allogeneic PBSCT separate GVL from GVHD by preserving perforin-dependent donor CTL activity while reducing systemic inflammation.

High affinity binding of [3H]epibatidine to rat brain membranes

Several compounds, such as epibatidine, A-85380, and their analogs, have been identified recently as nAChR ligands whose affinities lie in the low picomolar range. Accurate measurement of such high affinities is fraught with certain technical difficulties, which may account for the inconsistency of previously reported affinities of epibatidine, ranging from 4 to 60 pM. Here, we demonstrate that (+/-)-[3H]epibatidine (1-500 pM) binds to a single population of sites in rat brain with KD of 8 +/- 2 pM. This affinity was confirmed in both kinetic experiments and competition assays with (+/-)-[3H]epibatidine and (-)-[3H]cytisine, which were performed under experimental conditions developed specifically for ligands with subnanomolar affinities. Variations from these conditions decreased the observed affinities.

Congenital dyserythropoiesis with intererythroblastic chromatin bridges and ultrastructurally-normal erythroblast heterochromatin: a new disorder

Two non-anaemic subjects, a father and daughter, with a new form of congenital dyserythropoiesis are reported. The features of their disorder are: (1) an abnormal blood film with basophilic stippling of red cells and oval macrocytes, (2) various dysplastic changes in the erythroblasts, including internuclear chromatin bridges, (3) ultrastructurally-normal erythroblast heterochromatin, (4) normal serum thymidine kinase activity, and (5) a probable autosomal dominant inheritance. The last three features distinguish this disorder from CDA type I.

Tumor necrosis factor- alpha production to lipopolysaccharide stimulation by donor cells predicts the severity of experimental acute graft-versus-host disease

Donor T cell responses to host alloantigen are known predictors for graft-versus-host disease (GVHD); however, the effect of donor responsiveness to an inflammatory stimulus such as lipopolysaccharide (LPS) on GVHD severity has not been investigated. To examine this, we used mouse strains that differ in their sensitivity to LPS as donors in an experimental bone marrow transplant (BMT) system. Lethally irradiated (C3FeB6)F1 hosts received BMT from either LPS-sensitive (LPS-s) C3Heb/Fej, or LPS-resistant (LPS-r) C3H/ Hej donors. Mice receiving LPS-r BMT developed significantly less GVHD as measured by mortality and clinical score compared with recipients of LPS-s BMT, a finding that was associated with significant decreases in intestinal histopathology and serum LPS and TNF-alpha levels. When donor T cell responses to host antigens were measured, no differences in proliferation, serum IFN-gamma levels, splenic T cell expansion, or CTL activity were observed after LPS-r or LPS-s BMT. Systemic neutralization of TNF-alpha from day -2 to +6 resulted in decreased intestinal pathology, and serum LPS levels and increased survival after BMT compared with control mice receiving Ig. We conclude that donor resistance to endotoxin reduces the development of acute GVHD by attenuating early intestinal damage mediated by TNFalpha. These data suggest that the responsiveness of donor accessory cells to LPS may be an important risk factor for acute GVHD severity independent of T cell responses to host antigens.

Interleukin-11 promotes T cell polarization and prevents acute graft-versus-host disease after allogeneic bone marrow transplantation

Administration of IL-11 prevented lethal graft-versus-host disease (GVHD) in a murine bone marrow transplant (BMT) model (B6 --> B6D2F1) across MHC and minor H antigen barriers (survival at day 50: 90 vs 20%, P < 0.001). Surpisingly, IL-11 administration polarized the donor T cell cytokine responses to host antigen after BMT with a 50% reduction in IFNgamma and IL-2 secretion and a 10-fold increase in IL-4. This polarization of T cell responses was associated with reduced IFNgamma serum levels and decreased IL-12 production in mixed lymphocyte cultures (MLC). In addition, IL-11 prevented small bowel damage and reduced serum endotoxin levels by 80%. Treatment with IL-11 also reduced TNFalpha serum levels and suppressed TNFalpha secretion by macrophages to LPS stimulation in vitro. IL-11 thus decreased GVHD morbidity and mortality by three mechanisms: (a) polarization of donor T cells; (b) protection of the small bowel; and (c) suppression of inflammatory cytokines such as TNFalpha. We conclude that brief treatment with IL-11 may represent a novel strategy to prevent T cell-mediated inflammatory processes such as GVHD.

The role of cytokines in acute graft-versus-host disease

Graft-versus-host disease (GVHD) remains the principal complication limiting the wider application of allogeneic bone marrow transplantation (BMT). Advances in basic immunology during the last decade have demonstrated how interactions between immunologically competent cells are governed by cytokines, and much recent research has focused on the roles of these mediators in the pathogenesis of acute GVHD. This article reviews current evidence that dysregulated cytokine production can be considered a cascade of sequential monocyte and T-cell activation that is responsible for many of the manifestations of acute GVHD. We suggest that cytokine dysregulation can be conceptualized in three phases. Phase 1 is initiated by the conditioning of the host, which induces inflammatory processes in recipient tissues. Donor T-cell activation by host alloantigens and subsequent cytokine secretion in phase 2 is facilitated by the consequences of phase 1. The T-cell-derived cytokines of phase 2 activate distal inflammatory mediators, which, in synergy with T- and NK-cell-mediated cytotoxicity, produce the systemic morbidity of GVHD-associated immunosuppression in phase 3. Data from both experimental and clinical studies involving cytokines and their blockade in the prevention or treatment of GVHD are reviewed.

Total body irradiation and acute graft-versus-host disease: the role of gastrointestinal damage and inflammatory cytokines

The influence of bone marrow transplantation (BMT) conditioning regimens on the incidence and severity of graft-versus-host disease (GVHD) has been suggested in clinical BMT. Using murine BMT models, we show here an increase in GVHD severity in several donor-recipient strain combinations after intensification of the conditioning regimen by increasing the total body irradiation (TBI) dose from 900 cGy to 1,300 cGy. Increased GVHD was mediated by systemic increases in tumor necrosis factor alpha (TNF alpha). Histologic analysis of gastrointestinal tracts showed synergistic damage by increased TBI and allogeneic donor cells that permitted increased translocation of lipopolysacharide (LPS) into the systemic circulation. In vitro, LPS triggered excess TNF alpha from macrophages primed by the GVH reaction. In addition, macrophages isolated within 4 hours of conditioning were primed in proportion to the TBI dose itself to secrete TNF alpha. Thus, the higher TBI dose increased macrophage priming and increased gut damage after allogeneic BMT, causing higher systemic levels of inflammatory cytokines and subsequent severe GVHD. These data highlight the importance of conditioning in GVHD pathophysiology and suggest that interventions to prevent LPS stimulation of primed macrophages may limit the severity of GVHD after intensive conditioning for allogeneic BMT.

The use of low dose Orgaran in heparin-induced thrombocytopenia associated with in vitro platelet aggregation at higher Orgaran concentrations

We report a case of heparin-induced thrombocytopenia with in vitro antibody cross-reactivity by platelet aggregometry to both low molecular weight heparin and the heparinoid Org 10172 (Orgaran). The in vitro reactivity with Orgaran was only present at the upper limit of concentrations that would normally be used therapeutically. Low dose Orgaran therapy was initiated, allowing successful renal replacement therapy without invoking further thrombocytopenia or thrombosis. Interestingly, in vitro platelet aggregometry following treatment did not reveal increasing sensitivity to Orgaran. This case indicates that negative in vitro platelet aggregometry at defined lower concentrations of Orgaran may predict in vivo safety at the same levels despite positive platelet aggregometry reactions at higher concentrations of Orgaran.

Acquired heparin-like anticoagulants: a second case in metastatic breast carcinoma and literature review

We report the second case of an acquired heparin-like anticoagulant in a patient with disseminated breast carcinoma. All but one of the small numbers of other cases have also been associated with an underlying malignancy. We comment on the distinction between an immunoglobulin and proteoglycan causing the antithrombin effect and suggest points of interest for consideration in any future cases together with a review of treatment options.

High dose therapy and autologous bone marrow versus blood cell rescue. South Island Bone Marrow Transplant Unit

AIMS

To compare haematological recovery and supportive care requirements for patients receiving high dose therapy (HDT) supported by rescue with either autologous cytokine mobilised blood cells (BC) or autologous bone marrow (BM). To identify stem cell harvest criteria predictive of rapid haematological recovery after rescue with BC.

METHODS

Single arm, open study in four groups of 69 consecutive patients undergoing HDT in a single institution from 1986-95. Group 1 contained patients with solid tumours or myeloma rescued with BC alone (n = 14); group 2 patients with solid tumours rescued with BM (n = 31); group 3 patients with acute leukaemia rescued with BM (n = 21); and group 4 patients with solid tumours rescued with both BC and BM (n = 3).

RESULTS

Haemopoietic recovery was most rapid for group 1 where, in comparison with the BM group transplanted for similar disease (group 2), highly significant reductions were observed for median days to 1) neutrophil s >/= 0.5 x 10(9)L (12 v 22; p 0.0001); 2) neutrophils >/= 1.0 x 10(9)/L (14 v 27 ; p = 0.0001); platelets >/= 20 x 10(9) /L (11 v 20; p = 0.0005); and 4) platelets >/= 50 x 10(9)/L (15 v 27; p = 0.001). Similar significant reductions for the BC group over group 2 were also observed for median, (1) inpatient days (22 v 30; p = 0.0001); (2) red cell transfusions (2 v 5; p = 0.01) ; (3) platelet transfusions (2 v 6; p = 0.0001); (4) days of fever (2 v 8; p = 0.001); and (5) days on IV antibiotics (8 v 14; p = 0.02). Group 3 patients yielded data either similar to or less advantageous to that in group 2 and group 4 patients yielded data intermediate between groups 1 and 2. Data from BC harvests suggested that yields of CD34+ cells of > 2.0 x 10(6)/kg and/or of colony forming units-granulocyte-macrophage (CFU-GM) of > 6.0 x 10(4)/kg were predictive of rapid haemopoietic recovery.

CONCLUSION

For haemopoietic rescue following single HDT for solid tumours BC has considerable advantages over BM.

Donor leukocyte infusions in the treatment of chronic myeloid leukemia in relapse post bone marrow transplantation

A 25-yr-old Caucasian man presented in 1988 with Philadelphia chromosome (Ph) negative, bcr-abl rearranged, chronic phase chronic myeloid leukemia (CML). He was treated with human leukocyte antigen matched sibling allogeneic bone marrow transplantation but relapsed 5 yrs later. At this time he was given donor leukocyte infusions from the original bone marrow donor, seeking an immune anti-leukemic effect. This treatment induced graft versus host disease and severe bone marrow aplasia, requiring immunosuppression and repeat donor marrow infusion (without prior conditioning). Graft versus host disease was controlled and full donor hematopoiesis was restored, resulting in complete eradication of the leukemic clone at a molecular level. The patient remains in complete clinical and molecular remission and off all immunosuppression 24 mths later. This emphasizes a potentially powerful graft versus leukemia effect in CML.

RADIOAUTOGRAPHS SHOWING THE DISTRIBUTION OF SULPHUR IN WHEAT

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AN INSTALLATION OF LARGE SAND-CULTURE BEDS SURMOUNTED BY INDIVIDUAL AIR-CONDITIONED GREENHOUSES

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THE CONTINUOUS MEASUREMENT OF PHOTOSYNTHESIS, RESPIRATION, AND TRANSPIRATION OF ALFALFA AND WHEAT GROWING UNDER FIELD CONDITIONS

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