IL-6 promotes CD4+ T-cell and B-cell activation during Plasmodium infection.

Humoral immunity develops in the spleen during blood-stage Plasmodium infection. This elicits parasite-specific IgM and IgG, which control parasites and protect against malaria. Studies in mice have elucidated cells and molecules driving humoral immunity to Plasmodium, including CD4+ T cells, B cells, interleukin (IL)-21 and ICOS. IL-6, a cytokine readily detected in Plasmodium-infected mice and humans, is recognized in other systems as a driver of humoral immunity. Here, we examined the effect of infection-induced IL-6 on humoral immunity to Plasmodium. Using P. chabaudi chabaudi AS (PcAS) infection of wild-type and IL-6-/- mice, we found that IL-6 helped to control parasites during primary infection. IL-6 promoted early production of parasite-specific IgM but not IgG. Notably, splenic CD138+ plasmablast development was more dependent on IL-6 than germinal centre (GC) B-cell differentiation. IL-6 also promoted ICOS expression by CD4+ T cells, as well as their localization close to splenic B cells, but was not required for early Tfh-cell development. Finally, IL-6 promoted parasite control, IgM and IgG production, GC B-cell development and ICOS expression by Tfh cells in a second model, Py17XNL infection. IL-6 promotes CD4+ T-cell activation and B-cell responses during blood-stage Plasmodium infection, which encourages parasite-specific antibody production.

CD3bright signals on γδ T cells identify IL-17A-producing Vγ6Vδ1+ T cells.

Interleukin-17A (IL-17A) is a pro-inflammatory cytokine that has an important role at mucosal sites in a wide range of immune responses including infection, allergy and auto-immunity. γδ T cells are recognized as IL-17 producers, but based on the level of CD3 expression, we now define the remarkable ability of a CD3(bright) γδ T-cell subset with an effector memory phenotype to rapidly produce IL-17A, but not interferon-γ. CD3(bright) γδ T cells uniformly express the canonical germline encoded Vγ6/Vδ1(+) T-cell receptor. They are widely distributed with a preferential representation in the lungs and skin are negatively impacted in the absence of retinoic acid receptor-related orphan receptor gammat expression or endogenous flora. This population responded rapidly to various stimuli in a mechanism involving IL-23 and NOD-like receptor family, pyrin domain containing 3 (NLRP3)-inflammasome-dependent IL-1ß. Finally, we demonstrated that IL-17-producing CD3(bright) γδ T cells responded promptly and strongly to pneumococcal infection and during skin inflammation. Here, we propose a new way to specifically analyze IL-17-producing Vγ6/Vδ1(+) T cells based on the level of CD3 signals. Using this gating strategy, our data reinforce the crucial role of this γδ T-cell subset in respiratory and skin disorders.

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.

Successful immunotherapy of HCMV disease using virus-specific T cells expanded from an allogeneic stem cell transplant recipient.

Opportunistic infection remains the principal cause of mortality in allogeneic stem cell transplant recipients with active extensive chronic graft-versus-host disease. Human cytomegalovirus (HCMV) represents an important cause of disease in this setting and the toxicity of protracted and recurrent antiviral treatment together with eventual drug resistance represents a significant limitation to therapy. Although the expansion and adoptive transfer of HCMV-specific T cells from the healthy original donor can be an effective strategy to control viral replication, this is not possible when donors are seronegative or are subsequently inaccessible. Here we demonstrate for the first time, the successful expansion of HCMV-specific T cells from a seropositive transplant recipient of a seronegative graft with active HCMV disease and the long-term reconstitution of protective antiviral immunity following their adoptive transfer back into the patient.

Impact of cytokine gene polymorphisms on graft-vs-host disease.

Allogeneic hematopoietic stem cell transplantation (SCT) remains the only available curative therapy for hematological malignancy. It does, however, result in significant morbidity and mortality, predominantly as a consequence of infections, leukemic relapse and graft-vs-host disease (GVHD). While differences in human leukocyte antigen (HLA) molecules between donor and host make a crucial contribution to the alloreactivity driving the donor-antihost response, the cytokine milieu consisting of molecules that both promote and regulate the alloresponse after transplantation is also critical. As such, genetic studies correlating donor and/or host cytokine polymorphisms with disease outcomes have provided useful insight into disease pathogenesis, often confirming effects that have been dissected in animal models of the disease. It is now clear that the polymorphic expression of key cytokines (particularly tumor necrosis factor and interleukin 10) has a demonstrable effect on disease outcome and overall transplant-related mortality. Consideration of the role of genetic polymorphisms in GVHD severity and procedural mortality associated with SCT will lead to improvements in patient outcome such that the addition of non-HLA genetic typing of potential donors will allow optimization of donor selection for a given recipient. This review provides a discussion of the current state of the literature regarding polymorphic expression of the key GVHD cytokines and their capacity to predict clinical disease outcome.

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.

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.

LPS antagonism reduces graft-versus-host disease and preserves graft-versus-leukemia activity after experimental bone marrow transplantation.

Acute graft-versus-host disease (GVHD) and leukemic relapse remain the two major obstacles to successful outcomes after allogeneic bone marrow transplantation (BMT). Recent studies have demonstrated that the loss of gastrointestinal tract integrity, and specifically the translocation of LPS into the systemic circulation, is critical to the induction of cytokine dysregulation that contributes to GVHD. Using a mouse BMT model, we studied the effects of direct LPS antagonism on GVHD severity and graft-versus-leukemia (GVL) activity. Administration of B975, a synthetic lipid-A analogue from day 0 to day +6, reduced serum TNF-alpha levels, decreased intestinal histopathology, and resulted in significantly improved survival and a reduction in clinical GVHD, compared with control-treated animals. Importantly, B975 had no effect on donor T cell responses to host antigens in vivo or in vitro. When mice received lethal doses of P815 tumor cells at the time of BMT, administration of B975 did not impair GVL activity and resulted in significantly improved leukemia-free survival. These findings reveal a critical role for LPS in the early inflammatory events contributing to GVHD and suggest that a new class of pharmacologic agents, LPS antagonists, may help to prevent GVHD while preserving T cell responses to host antigens and GVL activity.

Combination antithymocyte globulin and soluble TNFalpha inhibitor (etanercept) +/- mycophenolate mofetil for treatment of steroid refractory acute graft-versus-host disease.

Antitumor necrosis factor-alpha antibodies are increasingly being used for the treatment of steroid-refractory acute graft-versus-host disease (GVHD) complicating allogeneic stem cell transplantation. We retrospectively reviewed the outcomes of 16 patients with refractory acute predominantly visceral GVHD treated with combination antithymocyte globulin (ATG), tacrolimus and etanercept +/- mycophenolate mofetil (MMF) at our institution. Overall response rate (CR+PR) was 81%, with median survival post commencing salvage immunosuppression 224 days (range 20-1216 days). In total, eight patients (50%) died, including from progressive GVHD in two cases (13%), infection in five (31%) and relapse of underlying malignancy in one (6%). In comparison to our previous experience of ATG+tacrolimus as treatment for refractory visceral GVHD, both response rate and overall survival were improved with addition of etanercept, with no apparent increase in infectious complications. As such, use of etanercept in combination with ATG +/- MMF for treatment of steroid refractory acute GVHD appears to be associated with high response rates, significant survival and no unexpected toxicity. Further study of this immunosuppression combination in a larger cohort of patients in this setting is indicated.

Tumor cell vaccine elicits potent antitumor immunity after allogeneic T-cell-depleted bone marrow transplantation.

Allogeneic bone marrow transplantation (BMT) is currently restricted to hematological malignancies because of a lack of antitumor activity against solid cancers. We have tested a novel treatment strategy to stimulate specific antitumor activity against a solid tumor after BMT by vaccination with irradiated tumor cells engineered to secrete granulocyte-macrophage colony-stimulating factor (GM-CSF). Using the B16 melanoma model, we found that vaccination elicited potent antitumor activity in recipients of syngeneic BMT in a time-dependent fashion, and that immune reconstitution was critical for the development of antitumor activity. Vaccination did not stimulate antitumor immunity after allogeneic BMT because of the post-BMT immunodeficiency associated with graft-versus-host disease (GVHD). Remarkably, vaccination was effective in stimulating potent and long-lasting antitumor activity in recipients of T-cell-depleted (TCD) allogeneic bone marrow. Recipients of TCD bone marrow who showed significant immune reconstitution by 6 weeks after BMT developed B16-specific T-cell-cytotoxic, proliferative, and cytokine responses as a function of vaccination. T cells derived from donor stem cells were, therefore, able to recognize tumor antigens, although they remained tolerant to host histocompatibility antigens. These results demonstrate that GM-CSF-based tumor cell vaccines after allogeneic TCD BMT can stimulate potent antitumor effects without the induction of GVHD, and this strategy has important implications for the treatment of patients with solid malignancies.

G-CSF modulates cytokine profile of dendritic cells and decreases acute graft-versus-host disease through effects on the donor rather than the recipient.

Allogeneic peripheral blood stem cell transplantation (PBSCT) is increasingly used instead of bone marrow transplantation, particularly in HLA identical sibling pairs. Despite the presence of significantly increased numbers of T cells in the PBSC graft, acute graft-versus-host disease (GVHD) is not increased. We have investigated whether granulocyte-colony stimulating factor (G-CSF) administration to PBSCT recipients, both with and without donor G-CSF pretreatment, further modulates acute GVHD in a murine model of PBSCT. Recipients of G-CSF mobilized splenocytes showed a significantly improved survival (P<0.001) and a reduction in GVHD score and serum LPS levels compared with control recipients. G-CSF treatment of donors, rather than recipients, had the most significant effect on reducing levels of tumor necrosis factor (TNFalpha) 7 days after transplantation. As a potential mechanism of the reduction in TNFalpha, we demonstrate G-CSF decreased dendritic cells TNFalpha, and interleukin-12 production to lipopolysaccharide. In conclusion, G-CSF modulates GVHD predominantly by its effects on donor cells, reducing the production of TNFalpha. G-CSF treatment of bone marrow transplantation recipients, without pretreatment of the donor, does not have an impact on acute 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.

Tumor necrosis factor-alpha neutralization reduces lung injury after experimental allogeneic bone marrow transplantation.

BACKGROUND: Idiopathic pneumonia syndrome (IPS) is a frequent and potentially fatal complication of bone marrow transplantation (BMT). We have previously shown that experimental IPS is associated with increased levels of lipopolysaccaride (LPS) and tumor necrosis factor-alpha (TNFalpha) in the bronchoalveolar lavage (BAL) fluid, and that administration of LPS to animals with extensive graft versus host exacerbated underlying lung injury (Blood 1996; 88: 3230). METHODS: Lethally irradiated CBA mice received BMT from allogeneic (B10.BR) or syngeneic (CBA) donors. The role of TNFalpha in the exacerbation of pulmonary toxicity caused by LPS injection and in the evolution of IPS after allogeneic BMT was examined by neutralizing TNFalpha after BMT using a soluble binding protein (rhTNFR:Fc). RESULTS: Five weeks after BMT, administration of rhTNFR:Fc dramatically reduced mortality and prevented the exacerbation of lung injury caused by LPS administration. This protective effect was associated with preservation of pulmonary function and with marked reductions of cells, neutrophils, and LPS in the BAL fluid of treated animals. TNFalpha neutralization from week 4 to 6 after allogeneic BMT effectively halted the progression of systemic GVHD and significantly reduced, but did not prevent lung injury that developed during the treatment period. CONCLUSIONS: We conclude that TNFalpha is central to early LPS induced toxicity in this model and is a significant, but not the exclusive contributor to the development of IPS after allogeneic BMT.

Assessment of cardiotoxicity during haemopoietic stem cell transplantation with plasma brain natriuretic peptide.

Cardiac failure is a known complication of haemopoietic stem cell transplantation (HSCT) and is often difficult to diagnose as patients may have multiple medical problems. Since brain natriuretic peptide (BNP) is largely a hormone of cardiac ventricular origin and is released early in the course of ventricular dysfunction, we have examined the value of serial plasma BNP levels for detecting cardiac failure in patients undergoing cytotoxic conditioning for HSCT. Fifteen patients undergoing HSCT were evaluated (10 undergoing autologous HSCT; five undergoing allogeneic HSCT). BNP was measured by radioimmunoassay prior to therapy and weekly for 5 weeks. Seven patients had a significant rise in BNP level (above a previously established threshold of 43 pmol/l associated with cardiac failure), occurring 1-4 weeks post commencement of conditioning. In three of these patients, cardiac failure was subsequently diagnosed clinically 3, 9 and 23 days after a BNP level of 43 pmol/l had been detected. These three patients had the highest peak BNP levels for the group and in each case elevation in BNP level occurred for a period exceeding 1 week. Although numbers were relatively small, a BNP >43 pmol/l was significantly associated with the inclusion of high-dose cyclophosphamide in the preparative regimen (P = 0.02). BNP levels showed no relationship to febrile episodes. In conclusion, these results show that plasma BNP may be used as a marker for early detection of cardiac dysfunction in patients undergoing HSCT, particularly if levels are increased for periods exceeding 1 week. Measurement of BNP during HSCT may be helpful in patients at risk of cardiac failure, in complex clinical situations and in monitoring the cardiotoxicity of preparative regimens.

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.

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.

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.

Immunotherapy following relapse of acute leukaemia after T-cell-replete allogeneic peripheral blood progenitor cell transplantation: importance of new onset chronic graft-versus-host disease.

INTRODUCTION: To further define the relative impact of immunotherapy and subsequent development of graft-versus-host disease (GVHD) on survival in patients with relapsed acute leukaemia postallogeneic hematopoietic stem cell transplant (SCT), we performed a single-centre retrospective analysis of 32 actively treated patients between 2003 and 2011. METHODS: A total of 13 patients were identified who were treated actively with cessation of immunosuppression ± Fludarabine, Cytarabine, G-CSF (FLAG) induction, but no donor leucocyte infusion (DLI) (non-DLI group) and 19 patients received the same step-wise therapy plus G-CSF mobilized DLI (G-DLI group). RESULTS: Groups were not statistically different with regards to baseline characteristics; however, the G-DLI group contained more sibling donors as opposed to unrelated donors than the non-DLI group. With a median follow-up of 47 months, the median overall survival (OS) of the non-DLI and G-DLI groups was not statistically different (8 months vs. 9 months, respectively, P = 0.5). Survival at 3 years was <10% in both groups. Univariate analysis identified response to FLAG, and new onset chronic GVHD as the only factors associated with improved OS. CONCLUSION: Second donor stem cell infusions are unwarranted in the treatment of relapse after allogeneic SCT and therapeutic strategies should focus on cytoreduction followed by immune modulation with the aim of invoking chronic GVHD.