Clinical Regression and Remission of Primary Refractory Angiocentric Lymphoma Following Autologous Tumour Peptide Antigen-charged Dendritic Cells After High-dose Chemotherapy and Autologous Stem Cell Rescue

We report on the case of a 34-year old man with a previously refractory high-grade non-Hodgkin's Lymphoma which regressed following dendritic cell based immunotherapy after high-dose chemotherapy. Antigen presenting cells known as dendritic cells were cultured from harvested autologous peripheral blood progenitor cells. The dendritic cells were then exposed to unfractionated tumour peptides derived from a skin biopsy section inflitrated with lymphoma. These charged dendritic cells infused into the patient together with autologous T-lymphocytes after high-dose chemotherapy with peripheral blood stem cell rescue. Although the lymphoma relapsed after the high-dose chemotherapy it regressed again following the dendritic cell infusion. The patient's T-lymphocytes demonstrated in vitro reactivity to tumour peptides whereas the lymphocytes of controls did not. We propose that the lymphoma regression occurred because of a T cell mediated response against the tumour induced by the charged dendritic cells.

Pilot study: effects of G-CSF on neutrophil ex-vivo function post bone marrow transplantation

The effects of human recombinant granulocyte colony stimulating factor (G-CSF) on neutrophil recovery have been studied in patients undergoing bone marrow transplantation for haematological disease. Nine patients (five autografts and four allografts) were studied while receiving daily doses of G-CSF (range 2-20 micrograms/kg body weight) were compared to eight patients (four autografts and four allografts) who did not receive G-CSF as a control group. In both groups flow cytometry was used to determine neutrophil IgG Fc receptor (FcRII, FcRIII) expression. Phagocytosis and metabolic burst was assessed using IgG opsonized bacteria. The patients' neutrophils were studied prior to conditioning in autografts and donor cells were studied in allografts. Studies were repeated at neutrophil recovery (neutrophil count 1.0 x 10(9)/l) and ten days post recovery. At recovery FcRII expression was slightly increased in all groups, whereas the number of cells expressing FcRIII was reduced. This reduction was significant in the patients receiving rG-CSF at recovery and post recovery compared to the pretreatment levels. The ability to phagocytose bacteria in cells from patients receiving G-CSF was also reduced. The associated metabolic burst was significantly reduced in the autograft group but not the allograft group receiving rG-CSF. The reduced function and reduced expression of FCRIII suggests the presence of immature neutrophils in patients receiving rG-CSF post BMT.

Generation of reactive oxygen species is not involved in idarubicin-induced apoptosis in human leukaemic cells

The anthracycline antibiotic idarubicin (IDA) induces double-stranded DNA breaks, the generation of reactive oxygen species (ROS) and apoptosis in human leukaemic cells. It is unclear whether the generation of ROS is associated with the apoptotic process. Using the T-lymphoblastic leukaemic CEM cell line, we found that IDA-induced DNA breaks were correlated with final cell death. The reduction in mitochondrial membrane potential (Deltapsim) and the generation of ROS occurred simultaneously with IDA-induced activation of caspase-9 and caspase-3. Inhibition of caspases by a pan-caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-fmk) completely blocked IDA-induced reduction of Deltapsim, apoptosis and final cell death. Interestingly, ROS generation was significantly enhanced by Z-VAD-fmk. ROS generation was neither caspase dependent nor part of the apoptotic process. IDA-mediated reduction in Deltapsim is caspase dependent and is not a consequence of the generation of ROS. These results indicate that IDA-induced generation of ROS and apoptosis are separate events. Inhibition of caspases facilitates IDA-mediated generation of ROS.

c-IAP1 blocks TNFalpha-mediated cytotoxicity upstream of caspase-dependent and -independent mitochondrial events in human leukemic cells

Tumor necrosis factor-alpha (TNFalpha) mediates cytochrome c release from mitochondria, loss of mitochondrial membrane potential (DeltaPsim) and apoptosis in sensitive leukemic cells. In the present study, by using the human leukemic U937 cell line, we demonstrate that the cytochrome c release is caspase-8-dependent and can be blocked by an inhibitor of caspase-8, Z-Ile-Glu (OMe)-Thr-Asp(OMe)-fluoromethyl ketone (Z-IETD.fmk), or a pan caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (Z-VAD.fmk). However, TNFalpha-mediated loss of DeltaPsim was not inhibited by caspase inhibitors. The apoptotic process was blocked by either Z-IETD.fmk or Z-VAD.fmk in cells with lower DeltaPsim. U937 cells with stable transfection of the cellular inhibitor of apoptosis protein 1 (c-IAP1) are resistant to TNFalpha-induced activation of caspases, Bid cleavage, cytochrome c release and DeltaPsim collapse. In addition, both c-IAP1 and XIAP were not up-regulated upon prolonged exposure to TNFalpha. In contrast, there was a caspase-dependent cleavage of XIAP, but not c-IAP1, during treatment with TNFalpha for 7 days. These results demonstrate that c-IAP1 blocks TNFalpha signaling at a level controlling both activation of caspase-8 and a signal to cause loss of DeltaPsim. The sensitive U937 cell line failed to acquire resistance and gain a self-protecting advantage against apoptosis, upon induction of c-IAP1 expression.

Bax translocation is crucial for the sensitivity of leukaemic cells to etoposide-induced apoptosis

Bax translocation from cytosol to mitochondria is believed to be a crucial step for triggering cytochrome c release from mitochondria. However, it is unclear whether Bax translocation is associated with Bax induction by DNA damaging agents. The induction of Bax in response to DNA damaging agents has been considered to be linked with p53. In this study, we used the p53 negative human chronic myeloid leukaemia K562 cell line. Bax up-regulation occurred at the whole cell level after DNA damage induced by etoposide. However, after incubation with etoposide, Bax failed to translocate to mitochondria and as a result, the apoptotic process was blocked. A Bax stable transfectant, the K/Bax cell line, expressed more Bax protein in the cytosol, mitochondria and nuclei. This Bax overexpression induced cytochrome c release, a reduction of cytochrome c oxidase activity and mitochondrial membrane potential (Delta(Psi)m). However, Bax-induced apoptosis was blocked downstream of mitochondria in K562 cells. The increased levels of mitochondrial Bax sensitized cells to etoposide-induced activation of caspases-2, -3 and -9 and apoptosis. However, after transient transfection with the Apaf-1 gene, K/Bax cells were sensitized to etoposide-induced caspase activation and apoptosis to a larger extent compared with Bax or Apaf-1 transfection alone. We therefore conclude that two mechanisms contribute to the resistance of K562 cells to etoposide-induced apoptosis; firstly failure of Bax targeting to mitochondria and, secondly, deficiency of Apaf-1. Uncoupling of Bax translocation from Bax induction can occur in response to etoposide-induced DNA damage.

Quantitative determination of apoptosis on leukemia cells by infrared spectroscopy

Quantitation of apoptotic cell death in vivo has become an important issue for patients with acute leukemia. We describe herein a new analytical method, based on infrared (IR) spectroscopy, to estimate the percentage of apoptotic leukemic cells in two different cell lines (CEM and K562), induced with etoposide (VP-16). As the percentage of apoptosis increases, the protein structure shifts from dominantly beta-sheet to unordered (random coil), the overall lipid content increases and the amount of detectable DNA decreases. These changes can be directly related to the percentage of apoptosis as determined by two standard reference methods: flow cytometry and DNA ladder formation. The correlation between the significant IR spectral changes and the percentage of apoptotic leukemia cells in the two cell lines was optimal up to 24 h following etoposide treatment (r = 0.99 for CEM cells and r = 0.96 for K562 cells). Furthermore, IR spectroscopy is able to detect apoptotic changes in these cells already after 4 h treatment with VP-16, compared to flow cytometry which needs 6 h to observe significant changes. Our study suggests that IR spectroscopy may have potential clinical utility for the early, fast and reagent free assessment of chemotherapeutic efficacy in patients with leukemia.

Apaf-1 protein deficiency confers resistance to cytochrome c-dependent apoptosis in human leukemic cells

The human leukemia cell lines K562, CEM, CEM/VLB(100), human leukemic blasts, and the bladder cancer J82 cell line have different sensitivities to UV light-induced apoptosis. It is reported that resistance to UV light-induced apoptosis occurs at a point in the apoptotic pathway upstream of caspase-3 but downstream of mitochondrial cytochrome c release. It is demonstrated that the block is due to deficiency of Apaf-1, a critical member of the apoptosome. Sensitivity to apoptosis was independent of caspase-9b or XIAP (inhibitors of apoptosis proteins) expression or levels of procaspase-9. Transfection of Apaf-1 conferred sensitivity to apoptosis in resistant cells. Apaf-1 deficiency may constitute a significant mode of resistance to apoptosis in human leukemia.

Malignancy: Myeloma - the Elusive Cure

Myeloma accounts for 1% of all malignancies and is characterised by the malignant expansion of plasma cells. It is essentially incurable with a median survival of 6 months untreated. Typically disseminated at presentation, myeloma requires systemic therapy, in those patients with advanced or progressive disease. Of single agent therapies, oral mephalan remains the gold standard, either alone or in combination with steroids. 40% will respond with an increase in median survival from under 1 year to around 36 months. Combination chemotherapy produces an advantage in remission induction but no clear benefit for either survival or remission duration has been shown over standard melphalan and prednisolone. Significant melphalan dose escalation produces increased response rates and increased complete remission rates, however at the expense of increased toxicity. This has been ameliorated to an extent using stem cell support, however, although autografting may be superior to conventional chemotherapy it is not a curative treatment and modifications such as purging or tandem procedures remain to be fully evaluated. Allogeneic transplantation is only an option in a tiny minority of patients and has a high treatment-related mortality. Interferon alpha may improve the relapse free survival but has little effect on overall survival as the majority of patients will relapse. Experimental approaches, such as P-gp inhibition or thalidomide, are appropriate in this poor prognosis group. In many patients palliative care remains the only therapeutic option and close attention should be therefore paid to the prevention and treatment of renal failure, anaemia, infection, hypercalcaemia and bone disease.

Liposomal daunorubicin (DaunoXome) in combination with cyclophosphamide, vincristine and prednisolone (COP-X) as salvage therapy in poor-prognosis non-Hodgkins lymphoma

We treated 33 patients with a variant of the standard 3 weekly CHOP regime, replacing doxorubicin with liposomal daunorubicin (DaunoXome, NeXstar Pharmaceuticals) 120 mg/m2 (COP-X). Eighteen subjects had relapsed/refractory aggressive NHL and 15 had indolent NHL/CLL. Median number of courses received was 4 (1-8). Thirty-two patients were evaluable for efficacy and 26 (81%) responded. 88% of patients with aggressive NHL responded; three (18%) patients achieved complete remission (CR), 12 (70%) achieved partial remission (PR), 1 (6%) patient had stable disease (SD) and 1 (6%) patient progressed through treatment. Median duration of response for patients with aggressive NHL was 3 months. The response rate in indolent NHL/CLL was 73%. Four (27%) patients achieved CR, 7 (46%) PR and 4 (27%) SD. At two years post treatment, 55% of the patients with indolent NHL/CLL remain progression-free, although 4 patients have proceeded to consolidation therapy. Twenty-seven out of 28 (96%) patients developed neutropenia of short duration following one or more of their treatments. Twenty-three patients developed an infection at some stage during therapy (all associated with neutropenia) and required hospitalisation. There were two toxic deaths (infection) both of which occurred in patients who were neutropenic before starting COP-X. Platelet toxicity was mild in patients with normal platelet counts at the commencement of therapy. Alopecia and mucositis were mild. No clinical evidence of myocardial failure was observed. We conclude that the substitution of DaunoXome for doxorubicin in the CHOP regimen to form COP-X provides excellent efficacy against non-Hodgkin's lymphoma. Response durations were short but comparable to those reported with other regimens. COP-X was well tolerated with some suggestion of reduced non-haematological toxicity. The regimen should be considered as an alternative to CHOP with potentially less non-haematological toxicity, particularly cardiac; further studies are required to evaluate the regimen in this context.

TRAIL-Induced Apoptosis in Type I Leukemic Cells Is Not Enhanced by Overexpression of Bax

We have previously shown that Bax translocation was crucial in TNFalpha or etoposide-induced apoptosis. Overexpression of Bax sensitized chronic myeloid leukemic K562 cells to etoposide-induced apoptosis. Treatment with TNF-related apoptosis-inducing ligand (TRAIL) induces a loss of mitochondrial membrane potential (DeltaPsim), cytochrome c release from mitochondria, activation of caspases-8, -9, and -3, and cleavage of Bid in the K562 cell line. Bax failed to sensitize K562 cells to TRAIL-induced apoptosis. TRAIL did not induce Bax expression and/or translocation from cytosol to mitochondria in the K562 cell line. However, 100 microM Z-VAD.fmk, a pan caspase inhibitor, completely blocked TRAIL-initiated mitochondrial alterations and cleavages of caspases and Bid. We propose that TRAIL-induced apoptosis in K562 cells is via Type I apoptotic signal pathway. Bax translocation is not essential for TRAIL-induced cytochrome c release and DeltaPsim collapse in the Type I cells.

8-Cl-adenosine mediated cytotoxicity and sensitization of T-lymphoblastic leukemia cells to TNFalpha-induced apoptosis is via inactivation of NF-kappaB

These data show that 8-Cl-cAMP is cytotoxic to the lymphoblastic leukemia cell line CEM and its vinblastine selected multidrug resistant derivative, CEM/VLB100 although PKA was not involved in these effects. The cytotoxic effects of 8-Cl-cAMP was abrogated by cotreatment with either ADA or IBMX which indicated a degradation form of 8-Cl-cAMP was needed for this cytotoxicity. CEM and CEM/VLB100 cells displayed a notable sensitivity to 8-Cl-adenosine-induced growth inhibition and apoptosis. 8-Cl-adenosine increased the cytosolic levels of IkappaBalpha which prevented NF-kappaB nuclear translocation. 8-Cl-adenosine also prevented TNFalpha-induced IkB decay and NF-kappaB activation in CEM and CEM/VLB100 cells.

Apaf-1XL is an inactive isoform compared with Apaf-1L

Apaf-1 plays a crucial role in the cytochrome c/dATP-dependent activation of caspase-9 and -3. We found that the human myeloid leukemic K562 cells were more resistant to cytochrome c-induced activation of caspase-9 and -3 in a cell-free system compared with the human T-lymphoblastic subclone CEM/VLB(100) cells. Apaf-1 cDNA sequencing revealed an additional insert of 11 aa between the CARD and CED-4 (ATPase) domains in K562 cells, which was identical to the sequence of Apaf-1XL. Immunoprecipitation of Apaf-1 with caspase-9 after a cell-free reaction demonstrated that Apaf-1XL in the K562 cell line showed a lower binding ability to caspase-9 compared with Apaf-1L protein. The resistance of K562 cells to cytochrome c-dependent apoptosis may be partly due to this Apaf-1XL form. These results suggest that the additional insert between CARD and CED-4 domains might affect Apaf-1 recruitment of caspase-9 during apoptosis.

Autologous transplantation with Philadelphia-negative progenitor cells for patients with chronic myeloid leukaemia (CML) failing to attain a cytogenetic response to alpha interferon

Between October 1993 and March 1999, 29 patients with CML who were ineligible for allogeneic BMT underwent PBSC harvest using idarubicin, cytarabine and G-CSF. In 9/29 (31%) patients all collected stem cells were Ph-negative, and 15/29 patients' (52%) collections were substantially (>95%) Ph-negative. The proportion of patients from whom Ph-negative stem cells were obtained was similar between patients who had, or had not, received prior alphaIFN. Fifteen patients in chronic phase (median age 45) proceeded to PBSCT following busulphan 16 mg/m2 and cyclophosphamide 120 mg/m2. Nine of the 13 patients who had failed to respond to prior alphaIFN proceeded to stem cell transplantation as soon as was feasible and six of the newly diagnosed patients were transplanted after failing to achieve a cytogenetic response after a minimum of 12 months on alphaIFN following progenitor cell harvest. The median number of days to neutrophils >0.5 and platelet >50 was 18 (range 13-69) and 28 (range 13-234), respectively. There was no procedure-related mortality. At median follow-up of 2.3 years post autograft 10 of 15 patients remain alive and in chronic phase. Overall survival for all 27 patients at 5 years after initial diagnosis is 70% and median survival from diagnosis 7.3 years. Survival for alphaIFN non-responders who were transplanted is 74% at 5 years from diagnosis and 75% at 3 years from transplant. Cytogenetic analysis performed 3 months post transplant demonstrated one patient with a complete cytogenetic response, seven with a partial response and three with no response. Six patients remain partially Ph-negative, with one major CR. Survival for all patients in the protocol is favourable compared with conventional therapy and is particularly encouraging following PBSCT for alphaIFN non-responsive patients. Patients not responding to alphaIFN can be induced into Ph-negativity with PBSCT but this may not always be sustainable. There seems to be no obvious disadvantage in harvesting stem cells after prior exposure to alphaIFN, providing an adequate alphaIFN-free rest period is used.

Upregulation of lipocortin 1 inhibits tumour necrosis factor-induced apoptosis in human leukaemic cells: a possible mechanism of resistance to immune surveillance

The signal transduction pathway through which tumour necrosis factor (TNF) induces apoptosis in leukaemic cells may involve activation of cytosolic phospholipase A(2) (cPLA(2)). The steroids dexamethasone (Dex) and 1,25(OH)(2) D(3) both render U937 leukaemic cells resistant to TNF-induced apoptosis. In this study, we found that Dex inhibited both spontaneous and TNF-induced activation of cPLA(2). Dex had no direct effect on cellular cPLA(2) levels, but facilitated cPLA(2) degradation upon subsequent stimulation of cells with TNF. In addition, Dex increased synthesis of the endogenous cPLA(2) inhibitor lipocortin 1 (LC1). An antisense oligonucleotide to LC1 could completely abrogate Dex-induced resistance to the cytotoxic action of TNF. Constitutive LC1 levels were relatively higher in myeloid leukaemic blasts showing resistance to TNF than TNF-sensitive myeloid leukaemic cell lines. Our data suggest that Dex confers the resistance of U937 cells to TNF-induced apoptosis by upregulating intracellular levels of LC1 and by facilitating a negative-feedback loop, which is activated upon stimulation with TNF. High constitutive levels of LC1 in leukaemic blasts may protect them against immune-mediated killing.

Successful therapy of transplant-associated veno-occlusive disease with a combination of tissue plasminogen activator and defibrotide

A 36-year-old man underwent matched unrelated donor bone marrow transplantation for chronic myeloid leukaemia. He developed severe hepatic veno-occlusive disease as an early post-transplant complication. Tissue plasminogen activator was initially felt to be contraindicated since the patient had concomitant pericarditis. Defibrotide was therefore commenced as treatment for veno-occlusive disease. The pericarditis improved but the veno-occlusive disease continued to worsen (peak bilirubin 353 micromol/l). Tissue plasminogen activator followed by a heparin infusion was therefore administered. However, he proceeded to develop haemorrhagic cardiac tamponade that required drainage. Thrombolysis was therefore discontinued and treatment with defibrotide resumed after an interval of 48 h. The veno-occlusive disease gradually resolved and defibrotide was discontinued once the bilirubin had plateaued. He was discharged home on day +52 post-transplant.

Low-dose continuous chemotherapy (LBCMVD-56) for refractory and relapsing lymphoma

BACKGROUND

Although lymphoid malignancies are generally chemosensitive, relapse is common. The use of high-dose therapy can make subsequent cytotoxic therapy intolerable. There is a need to develop regimens with low acute toxicity which are suitable for use in patients post-high dose therapy and following the failure of standard protocols.

PATIENTS AND METHODS

Twenty-six patients with lymphomas, fifteen of whom had received high-dose therapy, were treated with a novel regimen consisting of low-dose lomustine, chlorambucil, daily subcutaneous bleomycin, vincristine and methotrexate with dexamethasone on an eight-week cycle (LBCMVD-56). A median of three cycles was given.

RESULTS

The overall response rate at 12 weeks was 67% (21% complete remission (CR)) with a median overall survival of 13 months. A symptomatic response was seen in 72%. Previous high-dose therapy did not compromise the response rate. Toxicity was acceptable with grade 3-4 haematological toxicity seen in 27% of cycles, gastrointestinal toxicity seen in 11% and pulmonary toxicity seen in 8%. Thirty-one percent of patients required hospitalisation at some point during this treatment most commonly for neutropenic sepsis.

CONCLUSIONS

LBCMVD-56 is an inexpensive, outpatient-based regimen with low acute toxicity and a high response rate in this heavily pre-treated group of patients.

CCNU (lomustine), idarubicin and dexamethasone (CIDEX): an effective oral regimen for the treatment of refractory or relapsed myeloma

We report the results of a non-randomized pilot study of an oral regimen comprising CCNU (lomustine; 25 or 50 mg/m2 on day 1), idarubicin (4-demethoxydaunorubicin) (10 mg/m2 on days 1-3) and dexamethasone (10 mg b.d. on days 1-4) in patients with relapsed or refractory myeloma. Treatment was given every 28 d for a maximum of six courses. Sixty patients were entered of whom 57 were evaluable. Overall response rate (partial or minor response) was 49% with 30% of patients achieving a partial response (50% tumour reduction). Response rates were higher in patients with untested relapse than in those with refractory disease (overall response rates 56% vs. 31%). The major toxicity was neutropenia and the regimen was otherwise well tolerated. The median survival from entry of all patients was 15 months, with 30% of patients alive at 2 years. This regimen represents a useful addition to available treatment options.

Cytokine modulated cell-membrane bound tumour necrosis factor expression is associated with enhanced monocyte-mediated killing of human leukaemic targets

Cytokines such as interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) activate monocytes both in vitro and in vivo. We therefore studied whether the anti-leukaemic activity of monocytes could be augmented by IL-3 alone or in combination with GM-CSF. Using normal human monocytes stimulated with IL-3, GM-CSF, LPS or combinations of growth factor and LPS, we studied their cytotoxic activity against leukaemic cell-lines and primary AML blasts. IL-3 like GM-CSF, augmented the expression and secretion of TNF but did not prime for further expression and secretion of TNF in response to LPS. Neither GM-CSF or IL-3 increased the expression or secretion of TNF receptor p55 (TNF-Rp55), although both agents increased expression of TNF receptor p75 (TNF-Rp75). Monocyte-mediated cytotoxicity (MMC) against K562 and U937 cell-lines was increased by both GM-CSF and IL-3 stimulation, and both cytokines primed monocytes for increased killing of K562 and KG-1 cell-lines as well as primary AML blasts in response to LPS. The mechanism of action of MMC was largely confirmed to be via surface-bound TNF, although other TNF-independent mechanisms must have been involved.

Mechanisms of resistance to apoptosis in human AML blasts: the role of differentiation-induced perturbations of cell-cycle checkpoints

Alterations in the response of leukaemic cells to apoptosis-inducing stimuli may account for resistance to chemotherapy and treatment failure, either by disruption of the apoptotic pathway itself or by altered DNA repair; quiescent cells and those with disrupted cell-cycle checkpoints may also display decreased apoptosis. Quiescence can be induced by the differentiation of myeloid cells, and this led us to investigate whether the modulation of drug-induced apoptosis associated with differentiation might be a model for quiescence-associated resistance generally. We have demonstrated that resistance to idarubicin-induced apoptosis increased with greater duration of incubation of HL60 and U937 cells with ATRA and 1,25(OH)2 D3 and that this protective effect correlated with the degree of G0/G1 accumulation. In addition, the cytoprotective effects held for other classes of cytotoxic drugs with different mechanisms of action to idarubicin. Prolonged exposure to idarubicin or vinblastine was associated with diminution of the protective effect and re-entry of cells into cycle. The full cytoprotective effect was restored by resupplementation with ATRA or 1,25(OH)2 D3 during exposure to idarubicin, with concomitant persistence of G0/G1 accumulation. Differentiating agents prevented the accumulation of leukaemic cells at the G2/M checkpoint in response to low concentrations of idarubicin. Understanding how differentiating agents modulate these cell-cycle checkpoints, and how quiescent cells evade apoptosis, may allow the development of therapeutic strategies to limit such apoptosis-inhibiting effects and maximise cell kill from chemotherapy.

Monocyte-macrophage system as targets for immunomodulation by intravenous immunoglobulin

Pooled human intravenous immunoglobulin (IVIg) has been used successfully to treat or ameliorate the clinical manifestations of humoral immune deficiencies, haematological disorders, HIV infection and many other diseases states. However, the mechanism of action of IVIg remains unclear. Several mechanisms of action of IVIg have been proposed. These include Fcy receptor blockade, accelerated clearance of endogenous pathogenic auto-antibodies, inhibition of components of the complement cascade, neutralization of super-antigens and bacterial toxins as well as anti-cytokine and anti-idiotype effects. A major contributor to host immunity and immune surveillance against infection, tissue or cell damage and malignancy is the monocyte/macrophage system. Monocyte-directed inflammation is a desirable consequence of microbiological or malignant challenge. However, monocyte hyperactivity may contribute to certain pathological conditions. These include the systemic inflammatory response syndrome (SIRS), septic shock, other dysregulated inflammatory disorders and auto-immunity. Novel therapies that can suppress the hyperactive state or correct monocyte/macrophage dysfunction without compromising normal host cell-mediated immunity are desirable. In this review, we discuss the immunomodulatory effects of IVIg focussing particularly upon the monocyte/macrophage system in pertinent disease states.

Constitutive levels of cAMP-dependent protein kinase activity determine sensitivity of human multidrug-resistant leukaemic cell lines to growth inhibition and apoptosis by forskolin and tumour necrosis factor alpha

The cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) signal pathway regulates cell proliferation, differentiation and cell death. It may also regulate the multidrug resistance (MDR) phenotype in leukaemic cells. These data showed that MDR1+ K/Dau600 cells exhibited a higher basal level of PKA activity than MDR- parental cells. The significance of this on tumour necrosis factor alpha (TNFalpha)-induced apoptosis and cytostasis was investigated further. In comparison with MDR1- parental cells, K/Dau600 cells had a higher expression of PKA regulatory subunit RIalpha and nuclear catalytic subunit PKAcalpha. They were also more susceptible to inhibition of proliferation and induction of apoptosis by TNFalpha and/or forskolin, but this could be attenuated by H89. An increase in cAMP was associated with the apoptosis in the K/Dau600 cell line. Forskolin inactivated NF-kappaB in K/Dau600 cells but not in K562 cl. 6 cells, whereas TNF activated NF-kappaB in K562 cl.6 cells but not in K/Dau600 cells. 8-Cl-cAMP exhibited similar inhibitory effects on the proliferation of all of the cell lines used via its metabolite 8-Cl-adenosine, which indicates that these effects were independent of residual PKA or cAMP. Therefore, the differential sensitivity to apoptosis and/or growth inhibition could be mediated via cAMP, partly through PKA via NF-kappaB and partly by PKA-independent pathways.

Pgp-positive leukaemic cells have increased mtDNA but no increased rate of proliferation

Cells of solid tumours tend to rely on glycolysis for energy. On the other hand, increased glycolysis in solid tumour cells expressing the multidrug resistance protein MDR-1 has been associated with increased malignancy in tumours. We have previously shown that cells of the MDR-1-positive CEM/VLB100 leukaemic cell line have increased mitochondrial electron transport chain (mtETC) activity compared with parental CEM cells. In the present study we used infrared (IR) spectroscopy to demonstrate that the mitochondrial DNA (mtDNA) content in the CEM/VLB100 cell line was significantly increased compared to that in the parental CEM cells. The increase in mtDNA was not accompanied by an increase in mitochondrial protein as both lipid and protein levels were decreased in CEM/VLB100 mitochondria. The ATP content was similar in these two cell lines. However, the ATP-dependent membrane efflux pump function in CEM/VLB100 cells was significantly reduced when mitochondrial ATP synthesis was inhibited by oligomycin, a specific inhibitor of mitochondrial F0F1-ATPase. Proliferation of CEM/VLB100 cells was significantly decreased compared to parental CEM cells, and was independent of p53 expression. Thus, we conclude that: (1) IR spectroscopy is a potential powerful technique for detecting mtDNA, protein and lipid contents simultaneously; (2) leukaemic cells mainly rely on mtDNA for energy; (3) increased expression of an ATP-dependent membrane efflux pump such as Pgp may up-regulate ATP generation and mtDNA content. These metabolic perturbations may exist merely to serve the efflux pump and do not result in an increase in leukaemic cell proliferation. In addition, the associated reduction in mitochondrial lipid and protein may contribute to sensitize the cells to cytochrome c release.

Cost effectiveness of amphotericin B plus G-CSF compared with amphotericin B monotherapy. Treatment of presumed deep-seated fungal infection in neutropenic patients in the UK

OBJECTIVE

To assess the economic impact of adding granulocyte colony-stimulating factor (G-CSF) to amphotericin B to treat a presumed deep-seated fungal infection in neutropenic patients. This study was conducted from the perspective of the National Health Service (NHS) hospital sector.

DESIGN

We used our previously reported trial as the clinical basis for the analysis (see Participants and interventions). These data were combined with resource utilisation data, enabling us to construct a decision tree model of the treatment paths attributable to managing patients in each arm of the trial. The model was used to calculate the cost effectiveness of using amphotericin B plus G-CSF compared to amphotericin B monotherapy in neutropenic patients with a presumed deep-seated fungal infection.

SETTING

An adult leukaemia/bone marrow transplant (BMT) unit in a large UK teaching hospital.

PARTICIPANTS

Patients with a neutrophil count of < 0.5 x 10(9)/L and having a presumed deep-seated fungal infection after either chemotherapy or stem cell/bone marrow transplantation for haematological malignancy.

INTERVENTIONS

29 patients received intravenous amphotericin B (1 mg/kg daily) plus subcutaneous G-CSF (3 to 5 micrograms/kg daily) and 30 patients received intravenous amphotericin B (1 mg/kg daily) monotherapy. The clinical trial showed that 62% of patients responded to antifungal treatment with amphotericin B plus G-CSF compared to 33% of patients who responded to amphotericin B monotherapy (p = 0.027). Nonresponders went on to receive a lipid formulation of amphotericin B.

MAIN OUTCOME MEASURE AND RESULTS

The mean cost per patient treated with amphotericin B plus G-CSF was 11,247 Pounds and the corresponding cost for amphotericin B monotherapy was 14,317 Pounds (1996/1997 values)--a cost reduction of 3070 Pounds per patient. Sensitivity analyses demonstrated that the addition of G-CSF to conventional amphotericin B in the treatment of a presumed deep-seated fungal infection offers not only clinical benefits, but cost benefits which are robust to changes in clinical and economic parameters.

CONCLUSION

From a UK hospital perspective, amphotericin B plus G-CSF is cost effective compared with amphotericin B monotherapy in managing a presumed deep-seated fungal infection in neutropenic patients. This result should provide strong arguments to clinicians and policy-makers for the adoption of this treatment strategy in such patients.

Epic as an effective, low toxicity salvage therapy for patients with poor risk lymphoma prior to beam high dose chemotherapy and peripheral blood progenitor cell transplantation

We treated 33 patients with relapsed or refractory non-Hodgkin's lymphoma (NHL) or Hodgkin's disease (HD) with a combination of etoposide, prednisolone, ifosfamide and carboplatin (EPIC). After a median of two courses (range 1-5) complete response was achieved in 7 (22%) patients and partial response in 12 (37%) patients, an overall response rate of 59%. The regimen was well tolerated with myelosuppression being the most common toxicity. There were no toxic deaths. 25 (78%) patients were able to proceed to high dose therapy (BEAM) with peripheral blood progenitor cell transplantation either immediately post EPIC or following further salvage therapy. Most patients mobilised peripheral blood progenitor cells well and 24 out of 25 patients subsequently undergoing autologous transplantation had rapid regeneration of counts. EPIC is an effective salvage therapy in the majority of patients with relapsed or refractory lymphoma and does not appear to be toxic to stem cells. Although severe, myelosuppression is of short duration and the generally low toxicity enables patients to proceed to successful peripheral blood stem cell harvest and transplantation.

Effects of PARP inhibition on drug and Fas-induced apoptosis in leukaemic cells

Poly (ADP-ribose) polymerase (PARP) is activated following binding to DNA strand breaks and is cleaved in cells undergoing apoptosis. Work predominantly in murine systems has suggested that inhibitors of PARP might potentiate the effects of chemotherapeutic agents and be used as adjuncts to cancer therapy. Therefore, we studied the role of PARP in drug-induced apoptosis in HL-60, myeloid leukaemia cells and found that pre-treatment with 3-aminobenzamide (3AB) or 6(5H)-phenanthridinone, inhibitors of PARP, resulted in resistance to, rather than potentiation of apoptotic death induced by DNA-damaging agents, idarubicin, etoposide and fludarabine, as determined by flow cytometry, following propidium iodide staining. 3AB treated CEM/VLB100, mdr-expressing human lymphoblastic leukaemia cells were also found to be more resistant to idarubicin compared to cells treated with idarubicin alone, however, apoptosis was not reduced in parental CCRF-CEM cells under the same conditions. Similar results were obtained using agents with primary modes of action which do not involve DNA damage, vinblastine and a fas-ligating antibody (CH11). The precise role of PARP has yet to be defined but might involve effects on cell cycle progression. We conclude that PARP activation appears to be involved in apoptosis in certain leukaemic cell lines and that these effects are independent of lineage or p-glycoprotein. Constitutive failure to activate PARP might be responsible for conferring resistance to apoptosis.

Inhibition of FAS/FAS-ligand does not block chemotherapy-induced apoptosis in drug sensitive and resistant cells

It has been suggested that one means by which chemotherapeutic agents exert their effect on leukaemic cells, is via autocrine induction of fas-ligand which then binds to fas (CD95), activates the caspase pathway and results ultimately in apoptotic death. In order to test this hypothesis, we have treated leukaemic cell lines with various chemotherapeutic agents (idarubicin, etoposide, fludarabine and 2-CdA) with and without pre-treatment with fas (ZB4) and fas-ligand (NOK-1) blocking monoclonal antibodies. Cell cycle analysis and quantitation of apoptosis were performed by flow cytometry following propidium iodide staining. HL-60 cells were found to be sensitive to the induction of apoptosis with all drugs tested but were highly resistant to treatment with a fas-ligating antibody (CH11). Apoptosis was neither inhibited in parental CEM cells nor their mdr-expressing drug resistant counterpart, CEM/VLB100 by pre-treatment with either ZB4 or NOK1. In addition, CEM/VLB100 were slightly more sensitive to treatment with CH11 (100 ng/ml) than parental CEM cells (% age apoptosis = 30.35 and 23.675, p = 0.024) and at least as sensitive to recombinant fas-ligand (50 ng/ml) (% age apoptosis = 26.6 and 20.2, p = NS). We conclude that it is unlikely that fas/fas-ligand interactions play a significant role in the induction of apoptosis by these chemotherapeutic agents in the leukaemic cell lines tested.

The potential for monocyte-mediated immunotherapy during infection and malignancy--Part II: in vivo activation by exogenous cytokines and clinical applications

The monocyte system exhibits a range of immunological mechanisms that may be harnessed for therapeutic effect against infection and malignancy. The advent of novel therapies aimed at treating infection and malignancy is complemented by a resurgence of clinical interest in immunotherapeutic programmes to treat diseases by modification or direct augmentation of host immunity. Cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and IFN-gamma modulate the function of monocytes and have been used to experimentally probe the immunotherapeutic potential of monocytes against micro-organisms and malignancy. However, monocytes rarely act alone but communicate with other leukocytes involved in cell-mediated immunity. In particular monocytes cooperate with the T-helper (Th1 and Th2) sub-populations of peripheral lymphocytes. Moreover, sub-populations of monocytes, as identified by the co-expression of membrane-associated CD14 and CD16, have been shown to exist. At the preclinical level, this provides a unique opportunity to explore the effect of immunotherapeutic strategies on the function of monocyte sub-populations against infectious or malignant challenge and may allow immunotherapeutic strategies to be targeted towards specific monocyte sub-populations. Preclinical and clinical studies in human subjects suggest that GM-CSF and other cytokines such as IFN-gamma are the most promising biological response modifiers for augmenting monocyte-mediated immunity. In this review, the immunotherapeutic potential of the monocyte system will be discussed in the context of combating microbial and malignant disease.

The potential for monocyte-mediated immunotherapy during infection and malignancy. Part I: apoptosis induction and cytotoxic mechanisms

The mononuclear phagocyte system consists of peripheral blood monocytes and tissue macrophages that collectively play a major role in host immunity. Far from existing solely as phagocytic scavengers of cell debris and foreign matter, monocytes are highly active and responsive to inflammatory and immunological signals that activate their microbicidal and tumoricidal functions. Cytokines that are secreted as an integral component of the innate immune response such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and -IFN may directly activate the functions of the monocyte system. A key mediator of the effector functions of monocytes is tumour necrosis factor (TNF) which transduces its signals upon binding to specific transmembrane receptors. TNF is highly cytotoxic to micro-organisms and susceptible malignant cells and in most cases delivers its cytotoxic signal to tumour cells by highly regulated mechanisms of programmed cell death or apoptosis. We believe that the numerous functions of the monocyte system may be harnessed for therapeutic gain both in the context of microbiological infection and malignant disease. In this review, the mechanisms by which secreted and monocyte cell-membrane-associated TNF induce apoptosis will be discussed. In addition, the cell-associated and secretory immunological mechanisms employed by monocytes in host defence will be discussed in the context of the their ability to combat infection and neoplasia.

Monocyte dysfunction in patients with multiple myeloma and lymphoplasmacytic disorders is related to serum paraprotein levels

We have investigated monocyte function in 30 patients with lymphoplasmacytic disorders and in 21 age and sex matched normal controls. Marked abnormalities of all facets of monocyte function were demonstrated in six patients with multiple myeloma (MM) and a single patient with Waldenström's macroglobulinaemia (WM) plus significant paraproteinaemia. Serious infection occurred in three of these patients. An inverse relationship between the level of the serum paraprotein and impairment of monocyte phagocytosis plus killing of Candida albicans was observed. Crossover studies suggested that these abnormal findings were constitutive and not reversed by removal of the serum paraprotein. The data suggest that monocyte function is constitutively abnormal in patients with MM and can be further, but reversibly, inhibited by high paraprotein levels. Further research is required to confirm these findings, ascertain whether monocyte function can be normalized using chemotherapy or growth factors, and if so, whether their tumouricidal functions could be harnessed in the treatment of this currently incurable condition.

Subcellular distribution and redistribution of Bcl-2 family proteins in human leukemia cells undergoing apoptosis

It has been suggested that the ratio of Bcl-2 family proapoptotic proteins to antiapoptotic proteins determines the sensitivity of leukemic cells to apoptosis. However, it is believed that Bcl-2 family proteins exert their function on apoptosis only when they target to the mitochondrial outer membrane. The vinblastine-resistant T-lymphoblastic leukemic cell line CEM/VLB100 has increased sensitivity to tumor necrosis factor-alpha (TNF-alpha)-induced cytochrome c release, mitochondrial respiratory inhibition, and consequently apoptosis, compared with parental CEM cells. However, there was no difference between the two cell lines in the expression of Bcl-2 family proteins Bcl-2, Bcl-XL, Bcl-XS, Bad, and Bax at the whole cell level, as analyzed by Western blotting. Bcl-2 mainly located to mitochondria and light membrane as a membrane-bound protein, whereas Bcl-XL was located in both mitochondria and cytosol. Similar levels of both Bcl-2 and Bcl-XL were present in the resting mitochondria of the two cell lines. Although the proapoptotic proteins Bcl-XS, Bad, and Bax were mainly located in the cytosol, CEM/VLB100 mitochondria expressed higher levels of these proapoptotic proteins. Subcellular redistribution of the Bcl-2 family proteins was detected in a cell-free system by both Western blotting and flow cytometry after exposure to TNF-alpha. The levels of Bcl-2 family proteins were not altered at the whole cell level by TNF-alpha. However, after exposure to TNF-alpha, Bax, Bad, and Bcl-XS translocated from the cytosol to the mitochondria of both cell lines. An increase in Bcl-2 levels was observed in CEM mitochondria, which showed resistance to TNF-alpha-induced cytochrome c release. By contrast, decreased mitochondrial Bcl-2 was observed in CEM/VLB100 cells, which released cytochrome c from the mitochondria and underwent apoptosis as detected by fluorescence microscopy. We conclude that mitochondrial levels of Bcl-2 family proteins may determine the sensitivity of leukemic cells to apoptosis and that, furthermore, these levels may change rapidly after exposure of cells to toxic stimuli.

Liposomal amphotericin (AmBisome) in the prophylaxis of fungal infections in neutropenic patients: a randomised, double-blind, placebo-controlled study

Liposomal amphotericin (AmBisome) 2 mg/kg three times weekly was compared with placebo as prophylaxis against fungal infection in patients undergoing chemotherapy or bone marrow transplantation (BMT) for haematological malignancies. Prophylaxis began on day 1 of chemotherapy and continued until neutrophils regenerated or infection was suspected. Of 161 evaluable patients, 74 received AmBisome and 87 received placebo. Proven fungal infections developed in no patients on AmBisome and in three on placebo (3.4%) (P = NS). Suspected fungal infections requiring intervention with systemic antifungal therapy (usually amphotericin B) occurred in 31 patients on AmBisome (42%) and in 40 on placebo (46%) (P = NS). Suspected deep-seated infections developed in 21 (28.3%) and 31 (35.6%) patients, respectively (P = NS). Time to develop a suspected or proven deep-seated infection showed a trend in favour of AmBisome (P = 0.11). Fifty patients had fungal colonisation (48 with Candida spp, two with Aspergillus spp) of at least one body site during prophylaxis; 15 patients while receiving AmBisome (20%) and 35 while on placebo (40%) (P < 0.01). Time to colonisation was significantly delayed in the group receiving AmBisome (P < 0.05). Treatment-related toxicity was modest and no additional toxicity was observed in patients receiving AmBisome. AmBisome 2 mg/kg three times weekly is safe and reduces fungal colonisation in patients receiving intensive chemotherapy or BMT. However, despite encouraging trends, prophylactic AmBisome did not lead to a significant reduction in fungal infection or in requirement for systemic antifungal therapy.

Monocyte anergy in septic shock is associated with a predilection to apoptosis and is reversed by granulocyte-macrophage colony-stimulating factor ex vivo

The effects of priming monocytes from septic patients with granulocyte-macrophage colony-stimulating factor (GM-CSF) ex vivo were investigated. Monocytes from septic patients had depressed plasma GM-CSF and dysregulated levels of other cytokines compared with normal subjects. Membrane expression of CD71 and HLA-DR were depressed, and monocytes were anergic to lipopolysaccharide (LPS) stimulation in vitro, which was associated with spontaneous and accelerated activation-induced apoptosis by LPS. Priming monocytes with GM-CSF ex vivo augmented membrane cytokine expression, CD71, and HLA-DR. GM-CSF priming augmented cytokine secretion in response to LPS stimulation, restored cytokine secretion in monocytes from septic patients, and reversed their predilection to undergo apoptosis. Thus, monocyte dysfunction in septic shock is associated with depressed plasma levels of GM-CSF and enhanced apoptosis; however, GM-CSF stimulation ex vivo restored normal monocyte function and cytokine secretion by a mechanism that may depend on abrogating apoptosis.

Autologous transplantation in chronic myeloid leukaemia using peripheral blood stem cells

Forty-three patients with chronic myeloid leukaemia in first chronic phase were recruited to study intensive chemotherapy (idarubicin plus cytarabine; IdAC) followed by collection of peripheral blood stem cells (PBSC) in the recovery phase. PBSC autografting was performed on 32 patients. One patient died during mobilization and three died following autograft. All procedural deaths occurred in patients who received IdAc more than a year from diagnosis. Nine further patients died, eight following progression of CML. 72% of transplanted patients showed a major cytogenetic response but most cases have returned to Philadelphia-positive haemopoiesis. 62% of autografted patients remain alive (median survival from diagnosis 52 months). Four of the 11 patients who did not receive a transplant remain in chronic phase.

Adhesion molecules in clinical medicine

Cellular adhesion molecules (CAMs) are critical components in the processes of embryogenesis, tissue repair and organization, lymphocyte function, lymphocyte homing and tumor metastasis, as well as being central to the interactions between hemopoietic progenitors and bone marrow microenvironment, and between leukocytes and platelets with vascular endothelium. Expression of CAMs regulates normal hemopoiesis and migration and function of mature hemopoietic cells. CAMs are an important part of the inflammatory response and may regulate cytokine synthesis. In addition, CAM expression may be critical for tumorigenesis. Monoclonal antibodies to CAMs have been developed for clinical use; initial results suggest that these agents have great potential in the prevention and treatment of inflammation, thrombosis, reperfusion injury, and graft rejection.

Evaluation of the murex hybrid capture cytomegalovirus DNA assay versus plasma PCR and shell vial assay for diagnosis of human cytomegalovirus viremia in immunocompromised patients

We evaluated a cytomegalovirus (CMV) 24-hour shell vial assay (SVA), the Murex Hybrid Capture CMV DNA assay (HCA), and a CMV plasma PCR for the detection of CMV viremia in renal and bone marrow transplant recipients and human immunodeficiency virus-infected patients. CMV viremia was detected by at least one method in 125 of 317 evaluable samples (39.4%) from 78 patients and was detected in 19.8% of samples by SVA, 26.8% by HCA, and 32.2% by plasma PCR. There was moderate to substantial agreement between the results of the different tests (kappa coefficient = 0.415 to 0.631). However, HCA and plasma PCR were significantly more sensitive than SVA (P = 0.001 and P < 0.0001, respectively; McNemar's test), and plasma PCR was more sensitive than HCA (P = 0.031; McNemar's test). HCA and plasma PCR were more consistently positive than SVA during viremic episodes (P = 0.0002 and P < 0.0001, respectively; McNemar's test). The use of HCA or plasma PCR may therefore improve the diagnosis and management of CMV disease in susceptible patient groups.

Adult T-cell leukemia/lymphoma in London: clinical experience of 21 cases

Adult T-cell leukemia/lymphoma (ATLL) is uncommon in the United Kingdom and has so far been restricted to people of Afro-Caribbean extraction. Between 1981 and 1995, 21 cases presented to 2 inner London teaching hospitals where 17% of the population are of Afro-Caribbean origin. Clinical presentations were similar to those of the disease in HTLV-I-endemic areas. Major responses (CR + PR) were obtained in 10/16 assessable patients (63%) treated with combination chemotherapy. However, median survival was only 5.5 months. Disease progression and opportunistic infection were the major causes of treatment failure and death. Three patients (14%) relapsed in the central nervous system (CNS). Our cases confirm the profound immunosuppression in ATLL. The poor prognosis of acute and lymphoma types of ATLL highlight the need for new approaches to treatment such as zidovudine and alpha-interferon, incorporating prophylaxis against CNS disease and opportunistic infections.

Failure to activate cytosolic phospholipase A2 causes TNF resistance in human leukemic cells

Activation of cytosolic phospholipase A2 (cPLA2) by TNF has been shown to be an important component of the signaling pathway leading to cell death. The role of cPLA2 in the cytotoxic action of TNF was investigated in a panel of human leukemic cell lines. TNF could activate cPLA2 only in U937 and HL60 TNF-sensitive leukemic cells, but not in KG1a, CEM, and CEM/VLB100 cells that are relatively resistant to TNF. Pretreatment with 4-bromophenacyl bromide, a cPLA2 inhibitor, rendered U937 and HL60 cell lines resistant to the cytotoxic effect of TNF. Immunoblot and reverse-transcriptase PCR demonstrated that cPLA2 expression was detectable at both transcriptional and translational levels in all leukemic cell lines studied, although CEM and CEM/VLB100 cells expressed cPLA2 mRNA and protein at lower levels. The protein synthesis inhibitor, cycloheximide, increased TNF-induced cPLA2 activity and cytotoxicity in both CEM and CEM/VLB100 cell lines. Low levels of cPLA2 activity in the KG1a cell line could be activated by the cPLA2 activator mellitin, or the calcium ionophore A23187. The data suggest that cPLA2 activity is involved in TNF-induced cytotoxicity in leukemic cells. Resistance to TNF-induced cytotoxicity may involve either protein inhibitors that act upstream of cPLA2 in the TNF-signaling pathway or constitutive defects of cPLA2 itself, possibly involving calcium utilization.

1,25-Dihydroxyvitamin D3 protects human leukemic cells from tumor necrosis factor-induced apoptosis via inactivation of cytosolic phospholipase A2

The mechanism by which tumor necrosis factor (TNF) induces death of cancer cells appears to involve the activation of cytosolic phospholipase A2 (cPLA2). U937 human leukemic cells treated with 1,25-dihydroxyvitamin D3 [1,25(OH)2D3; 10(-8) M] become resistant to TNF, an effect that is independent of cell cycle status and expression of TNF receptors or BCL-2. In this study, TNF produced a dose- and time-dependent enhancement of [3H]arachidonic acid release in U937 cells. The amount of [3H]arachidonic acid release was positively associated with TNF-induced apoptosis. Both immunofluorescence microscopy and Western blotting of cell subcompartments demonstrated translocation of cPLA2 from the cytosol to the cell membrane in response to TNF. In addition, TNF up-regulated expression of cPLA2 mRNA. An antisense oligonucleotide to cPLA2 and the cPLA2 inhibitor 4-bromophenacyl bromide significantly inhibited TNF-induced cytotoxicity. Prior incubation of cells with 1,25(OH)2D3 significantly inhibited (a) TNF-induced [3H]arachidonic acid release and apoptosis, (b) TNF-induced translocation of cPLA2 to the membrane, and (c) the up-regulation of cPLA2 mRNA with TNF. Furthermore, the inhibitory effect of 1,25(OH)2D3 was not reversed by inhibitors of transcription or translation. The data suggest that activation of cPLA2 is involved in TNF-induced apoptosis of leukemic cells. 1,25(OH)2D3 directly inhibits cPLA2 translocation and mRNA up-regulation induced by TNF. Disruption of cPLA2 activation may represent a possible mechanism whereby leukemic cells can become resistant to TNF-mediated killing.

Granulocyte-macrophage colony-stimulating factor induces activation and restores respiratory burst activity in monocytes from septic patients

Monocyte activation in response to recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) was examined in vitro in septic shock patients. These monocytes exhibited a greater respiratory burst activity than monocytes from healthy subjects; the response to secondary stimulation with bacterial stimuli was attenuated. GM-CSF restored the ability of monocytes to respond appropriately to secondary stimulation. Expression of certain integrin adhesion molecules, L-selectin, and Fcgamma receptors was increased on monocytes of septic shock patients; expression of CD11c was reduced. GM-CSF up-regulated integrin expression and decreased L-selectin, FcgammaRII, and FcgammaRIII expression. Septic patients exhibited greater biologic activity of monocyte tissue factor than did healthy subjects. Priming monocytes with GM-CSF accelerated tissue factor activation following stimulation with lipopolysaccharide and bacterial culture supernatant. Certain parameters of monocyte function may be restored by exposure to GM-CSF. This benefit may be offset by an increase in monocyte procoagulant activity.

Early evaluation of liposomal daunorubicin (DaunoXome, Nexstar) in the treatment of relapsed and refractory lymphoma

We have treated 19 patients with relapsed or refractory lymphoma with liposomally encapsulated daunorubicin (DaunoXome) at two dose schedules; 40 mg/m2 repeated every 14 days and 120 mg/m2 repeated every 21 days. Non-haematological toxicity was mild, in particular, no patient treated with the higher dose schedule showed clinical deterioration in cardiac function. At the lower dose (10 patients) no objective responses were seen but at the higher dose (9 patients) one complete response and two partial responses were achieved. Liposomal daunorubicin at 120 mg/m2 appears to have some activity against refractory lymphoma and we suggest that further studies with this agent are required.

Modulation of idarubicin-induced apoptosis in human acute myeloid leukemia blasts by all-trans retinoic acid, 1,25(OH)2 vitamin D3, and granulocyte-macrophage colony-stimulating factor

The relationship between differentiation of human myeloid cells and apoptosis remains unclear. Recent studies have shown that terminal differentiation need not necessarily lead to the apoptotic demise of myeloid cells, while other studies have shown that induction of differentiation is associated with increased resistance to apoptosis-inducing agents, such as chemotherapy and gamma-irradiation. Such results are pertinent to the treatment of acute myeloid leukemia (AML) and myelodysplastic syndrome, where differentiating agents and hemopoietic growth factors are being combined with chemotherapy to enhance response and limit toxicity. To elucidate the factors governing apoptosis in human AML blasts, we have studied the cytotoxic effect of idarubicin on HL60, U937 and KG1 cells, after incubation with all-trans retinoic acid (ATRA), 1, 25(OH)2 D3, and granulocyte-macrophage colony-stimulating factor (GM-CSF ). We show that prior incubation of human myeloid leukemic cells with ATRA or 1,25(OH)2 D3 induced resistance to idarubicin-induced apoptosis, which was modulated by coincubation with GM-CSF. The altered chemosensitivity of cells depended on the degree of G0/G1 cell-cycle arrest induced by incubation with ATRA, 1, 25(OH)2 D3, and GM-CSF and was independent of differentiation status or Bcl-2 oncoprotein expression. These findings suggest that cell-cycle arrest in human leukemic cells can be induced by exogenous agents and may promote drug resistance. Determining the mechanisms by which cell-cycle arrest is induced may permit understanding of the processes by which the cells escape cytotoxic drug-mediated apoptosis.

G-CSF after peripheral blood stem cell transplantation in lymphoma patients significantly accelerated neutrophil recovery and shortened time in hospital: results of a randomized BNLI trial

We have undertaken a prospective randomized study in 90 patients with relapsed or resistant lymphomas to assess the value of G-CSF (lenograstim) in the acceleration of myeloid recovery after peripheral blood stem cell transplantation (PBSCT). A common regimen of cyclophosphamide 1.5 g/m2 on day 1 and lenograstim 263 microg s.c. on days 2-10 with two aphereses on days 10 and 11 was used for stem cell mobilization. 77% of patients achieved an adequate PBSC collection in two harvests (> 2 x 10(8) MNC/kg or > 2 x 10(6) CD34+ cells/kg). 65 patients went on to receive high-dose BEAM chemotherapy and engraftment data was available for 62. 34 patients had been randomized to receive lenograstim 263 microg/d s.c. and 28 to no growth factor. The median time to ANC > 0.5 x 10(9)/l was 9 d in the lenograstim arm versus 12.5 d in the no-lenograstim arm (P=0.0001). This was associated with a median duration of time in hospital post PBSCT of 13 d in the lenograstim arm versus 15.5 d in the no-lenograstim arm (P=0.0002). Median days to platelet independence, platelet transfusions, incidence of infection and red cell transfusion were the same in both arms. These data indicate that lenograstim significantly accelerated myeloid recovery after PBSCT and shortened the duration of hospital stay.

Mitochondrial ultracondensation, but not swelling, is involved in TNF alpha-induced apoptosis in human T-lymphoblastic leukaemic cells

Mitochondrial permeability transition (PT) pore opening and mitochondrial swelling have been reported in association with apoptosis. Conformational alterations of mitochondria induced by tumour necrosis factor-alpha (TNF alpha), and the association with TNF alpha-induced apoptosis, were, therefore, studied in the human acute T-lymphoblastic leukaemia (T-ALL) cell line, CCRF-CEM and its vinblastine-resistant CEM/VLB100 cell line by transmission electron microscopy (TEM). The CEM/VLB100 cell line possessed more condensed (C phase) mitochondria in the resting state compared with its parental cell line, consistent with increased activity of the mitochondrial electron transport chain (ETC). Following exposure to TNF alpha, conformational alterations of mitochondria occurred in both apoptotic and non-apoptotic cells. Orthodox (O phase) mitochondria in non-apoptotic cells underwent C-phase, transitional O-phase and slightly swollen (S-phase) conformational changes. TNF alpha-induced mitochondrial swelling was a late event and was found to a far lesser extent than mitochondrial condensation. No swollen mitochondria were observed in apoptotic cells. Ultracondensed (UC phase) mitochondria were observed in cells undergoing both TNF alpha-induced and spontaneous apoptosis and were seen when TNF alpha-induced apoptosis was inhibited by 3-methyladenine (3MA). The structural integrity of UC phase mitochondria persisted through the apoptotic process. We conclude that TNF alpha-induced mitochondrial swelling and apoptosis are separate events. Mitochondrial ultracondensation is associated with the processes signalling apoptosis and is not a result of TNF alpha-induced apoptotic shrinkage.

Monocyte-mediated killing of human leukaemia is enhanced by administration of granulocyte-macrophage colony stimulating factor following chemotherapy

We studied the capacity of recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF) to modulate monocyte anti-leukaemic activity when administered to patients following myelosuppressive chemotherapy. The leukaemic cell lines K562, U937 and KG-1 were used as models of human leukaemia as they exhibit differential sensitivity to cell-mediated or TNF-mediated cytotoxicity. Monocyte tumouricidal activity was augmented by rhGM-CSF or lipopolysaccharide (LPS) alone in vitro against leukaemic blasts, whereas granulocyte-colony stimulating factor (rhG-CSF) was without effect. rhGM-CSF and LPS exhibited an additive effect in stimulating the cytotoxic effect of monocytes against K562 blasts compared with either agent alone (P < 0.001). Both cell-mediated and soluble TNF-mediated killing of leukaemic blasts was augmented by rhGM-CSF administration to patients following chemotherapy. This effect persisted for up to 4 weeks after cessation of GM-CSF therapy. The administration of rhGM-CSF significantly increased the anti-leukaemic activity of monocytes against leukaemic targets that were resistant to secreted TNF, probably via a transmembrane TNF-dependent mechanism. Therapy with rhG-CSF exhibited a minimal effect. We conclude that administration of rhGM-CSF, but not rhG-CSF, augments the tumouricidal properties of the monocyte-macrophage system, particularly during recovery from myelosuppressive chemotherapy. Moreover, the killing mechanism is direct and not mediated by an antibody-dependent cellular cytotoxic (ADCC) mechanism. Killing of TNF-resistant leukaemic cells in particular may be augmented via cell-to-cell contact.

The role of vitamin D derivatives and retinoids in the differentiation of human leukaemia cells

The capabilities of 1alpha, 25-dihydroxyvitamin D3 (1,25(OH)2D3), and two novel vitamin D analogues, EB1089 and KH1060, to induce the differentiation of two established leukaemia cell lines, U937 and HL-60, were assessed alone or in combination with the retinoid compounds, 9-cis retinoic acid (9-cis RA) and all-trans retinoic acid (ATRA). The vitamin D derivatives acted to increase the differentiation of U937 and HL-60 cell cultures in a dose-dependent manner, as determined by nitroblue tetrazolium (NBT) reduction, with EB1089 and KH1060 being more effective than the native hormone. As an additional index of leukaemic cell differentiation, induction of expression of the phenotypic cell surface antigen, CD14, and the beta2-integrins, CD11b and CD18 by the vitamin D and retinoid compounds were monitored using fluorescence activated cell sorting (FACS) analyses. Following 96-hr treatment of U937 and HL-60 cells with 5 x 10(-10) M of the vitamin D derivatives, a striking increase in CD14 antigen expression was apparent, indicating the promotion by these compounds of a monocyte/macrophage lineage of cells. CD11b and CD18 antigen expression were also raised above control levels. In contrast, both retinoid compounds used at the higher concentration of 1 x 10(-8) M were not effective inducers of CD14 antigen expression. However, CD11b and CD18 were both readily increased in U937 and HL-60 cell cultures. Treatment of U937 cell cultures with the vitamin D compounds and the retinoids resulted in cooperative effects on induction of differentiation, with correlation by both NBT reduction and FACS analyses of CD14 antigen expression. The presence of 9-cis RA or ATRA appeared to contribute to the further increase of CD14 in these cells. HL-60 cell cotreatment with these compounds also displayed enhanced cooperative effects in phagocytic function by NBT reduction. However, analysis of CD14 revealed a dramatic diminution in HL-60 cells treated with the combinations of the vitamin D derivatives and the retinoids. Assessment of HL-60 cell morphology treated with these combinations demonstrated the presence of a mixed population of monocytes and granulocytes. CD11b and CD18 antigen expression was also enhanced in both cell lines with cotreatment. The ability of EB1089 and KH1060 to induce leukaemic cell differentiation may provide an additional option for therapeutic use alone or together with other differentiation agents such as 9-cis RA or ATRA.