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.

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.

Interaction of vitamin D derivatives and granulocyte-macrophage colony-stimulating factor in leukaemic cell differentiation.

The ability of the physiologically active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and two novel vitamin D analogues, EB1089 and KH1060 to induce the differentiation of the U937 and HL-60 leukaemic cell lines was evaluated, alone or in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF). Studies revealed that following 96 h treatment, the vitamin D derivatives inhibited the proliferation, and induced the differentiation of U937 and HL-60 cells in a dose-dependent manner, as determined by cell counts and nitroblue tetrazolium (NBT) reduction assays, respectively. EB1089 and KH1060 were found to be more effective than 1,25(OH)2D3 in exhibiting their antiproliferative and differentiative effects. In contrast, induction of leukaemic cell differentiation with 1 ng/ml GM-CSF after 96 h was less effective when compared with the vitamin D derivatives used individually. Fluorescence activated cell scanning (FACS) analyses indicated that the vitamin D derivatives readily induced the expression of the monocyte-associated cell surface antigen, CD14, and also the beta2-integrins, CD11b and CD18 in both cell lines after 48 h and 96 h treatment. The ability of EB1089 and KH1060 to induce these antigens was achieved with greater efficacy relative to the native hormone. When U937 and HL-60 cell cultures were cotreated for 48 h with the vitamin D compounds and GM-CSF and analysed by FACS, enhanced effects on CD14 and CD11b induction were observed compared to those of the compounds alone. These co-operative effects may occur as a consequence of molecular events which involve the transcription by vitamin D receptors (VDR) of genes required for the responsiveness of immature cells to factors such as GM-CSF, and place these and other related vitamin D analogues as potential therapeutic agents in the treatment of leukaemia.

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.

Analysis of the platelet-type thrombin receptor in 20 cases of large granular lymphocyte proliferations.

The platelet-type thrombin receptor was expressed by large granular lymphocytes (LGLs) in a variety of proliferative diseases. Twenty patients with LGL proliferative disease were examined, including five T cell clones and a variety of polyclonal proliferations, some secondary to rheumatoid arthritis and Felty's syndrome; 17/20 showed high number of CD3+, CD8+, and CD57+ lymphocytes and 9/20 also had high numbers of CD16+ or CD 56+ positive lymphocytes. The thrombin receptor was present on more than 20% of the LGLs in 13/20 patients. The clonal T cell expansions showed the highest receptor expression with greater than 75% cells positive. Regression analysis of all 20 cases showed striking and highly statistically significant positive Spearman rank correlation between the proportion of thrombin receptor and CD57-positive LGLs (r = 0.56, P = 0.009). A negative correlation with CD56 was also found (r = -0.46, P= 0.043). Dual antibody flow cytometry showed the receptor was more often co-expressed with CD57 (64%) than with CD16 (19%) or CD56 (11%). The expression of the platelet-type thrombin receptor by LGLs of this phenotype raises the possibility of a functional role for thrombin in the pathogenesis of LGL proliferative diseases.

Sezary cell-like leukemia: a distinct type of mature T cell malignancy.

We describe the clinical, ultrastructural, and immunophenotypical characteristics of four cases of an unusual type of T cell leukemia. Clinical features included high WBC, ranging from 26-148 x 10(9)/liter, bone marrow infiltration, splenomegaly, and lymphadenopathy. Skin involvement was not documented at presentation, but it was seen as a terminal event in one patient with a pattern of dermal lymphocytic infiltration different from that usually seen in Sezary syndrome. By ultrastructural analysis, the circulating lymphoid cells were indistinguishable from small Sezary cells in two cases, resembled large Sezary cells in one case, and consisted of a mixture of small Sezary cells and prolymphocytes in the remaining case. The cells from all cases had a mature T cell phenotype, TdT-, CD1a-, CD2+/-, CD3+, CD5+. In addition, the cells were either CD8+, CD4- or CD8+, CD4+ or CD4-, CD8-; and, in only one case, the findings were similar to those of Sezary syndrome cells: CD4+, CD8-, CD7-, BE-2+. In the latter case, serological and immunological assays were positive for HTLV-I while these were negative in two other patients investigated. The features of these patients suggest that Sezary cell leukemia is a distinct clinico-pathological entity although the alternative diagnosis of adult T cell leukemia/lymphoma could not be excluded in the HTLV-I+ case. Sezary cell leukemia appears to be resistant to current chemotherapy regimens and is associated with an aggressive clinical course and short survival.

The ex vivo function and expression of function-associated antigens of peripheral blood neutrophils and monocytes.

The availability of recombinant human granulocyte and granulocyte-macrophage colony-stimulating factors (rhG-CSF and rhGM-CSF) has prompted many studies of the analysis of antigen expression and function of monocytes and neutrophils from patients receiving these factors as therapeutic agents. Preparatory procedures for leukocytes are known to alter antigen expression and so function. We therefore investigated the use of a novel procedure in which live leukocytes are analyzed by flow cytometry without isolation from blood. The expression levels of CD11b, CD13, CD14, CD16, and CD18 antigens and L-selectin (TQ1 and Leu-8 epitopes) on neutrophils and monocytes from 15 normal individuals were determined and compared with a previously used method in which the leukocytes were fixed and the erythrocytes lysed before analysis. Significant differences for the apparent expression of CD11b, CD18, and L-selectin were observed between the two methods. The reasons for this were investigated. Since the new method allowed analysis of live cells, we also investigated whether modulation of antigen expression could be determined following receptor agonist interaction. This was found to be easily achievable, and we advocate using the new procedure where possible for the ex vivo analysis of function and function-associated antigens on monocytes and neutrophils.

Induction of surface tumor necrosis factor (TNF) expression and possible facilitation of surface TNF release from human monocytic cells by granulocyte-macrophage colony-stimulating factor or gamma interferon in combination with 1,25-dihydroxyvitamin D3.

1,25-dihydroxyvitamin D3 (1,25(OH)2D3), gamma interferon (IFN-gamma) and granulocyte-macrophage colony-stimulating factor (GM-CSF) can regulate monocyte maturation and activation. Using the human monocytoid cell line U937, we have shown that these agents increase surface tumor necrosis factor (TNF) expression without directly affecting TNF release. GM-CSF and IFN-gamma combined with 1,25(OH)2D3 increased cellular TNF secretion to levels not seen with these agents alone. Ability to express and secrete TNF in part depended on degree of monocytic maturation. The combination of 1,25(OH)2D3 and GM-CSF, however, facilitated lipopolysaccharide (LPS)-mediated release of surface TNF from U937 cells, an effect that was temporally independent of maximal maturation. 1,25(OH)2D3 plus IFN-gamma was less effective than 1,25(OH)2D3 plus GM-CSF at facilitating TNF secretion. We postulate that 1,25(OH)2D3 and GM-CSF are required together to prime a specific mechanism, probably a protease, which cleaves TNF from the surface of monocytic cells. This protease, once primed, can be activated by a secondary stimulus such as LPS.

Clinical use of intravenous immunoglobulin in blood disorders.

The protective effect of passively administered immunoglobulin has been known for many years. Although its accepted use over the last 40 years has been in the prevention and treatment of infection its widest and, arguably, most important application has been in the prevention of Rhesus haemolytic disease of the newborn. However, the development over the last decade of a number of safe and effective immunoglobulin preparations for intravenous use has allowed its more widespread utilisation in clinically appropriate settings. It is now widely accepted that intravenous immunoglobulin (IVIgG) is indicated, on a repeat basis, as treatment of choice as replacement therapy for patients with primary antibody deficiency. It may also be effective, in the non-immune deficient patient, in the management of certain bacterial as well as viral infections. This is particularly the case in the pre-term neonate but may have an application in the infected intensive care patient. The benefit in these patient groups has led to a re-evaluation of the use of immunoglobulin replacement therapy in the severe secondary antibody deficiency states associated with such haematological conditions as multiple myeloma and chronic lymphocytic leukaemia. These are currently the subject of randomised, controlled studies. The observation that the use of IV IgG may be associated with effects other than passive transfer of antibody were first made by Imbach in Switzerland. While treating children with immunodeficiency he noticed that two with a coincident immune thrombocytopenia had a rapid platelet increment in close association with the immunoglobulin infusion. He subsequently confirmed that this was a rapid and predictable form of therapy in childhood idiopathic thrombocytopenic purpura (ITP) and that in some children it appeared to affect the natural history of the disease. Since these initial observations the response has been confirmed in both children and adults and extended to other immune-based haematological disorders.

The significance of aminopeptidases and haematopoietic cell differentiation.

Aminopeptidases are a group of enzymes found on the cell surface and in the cytoplasmic compartments of many peripheral blood cell types and their progenitors. Their functional roles include the hydrolysis of several biologically active peptides and growth factors and some have proved to be of diagnostic and prognostic value in leukaemia. These enzymes may also be found in serum as a consequence of non-haematopoietic related diseases and so have been used as indicators of liver damage. Haematopoietic cells in the bone marrow go through a process of growth and differentiation before being released into the peripheral circulation where they fulfill many functional roles. The enzyme activities of some aminopeptidases have been shown to modulate the growth of these cells. In addition, the activities of these enzymes themselves can be regulated by haematopoietic growth factors. However, the mechanisms that regulate their expression and activity are not fully understood. In this report the current literature has been reviewed for evidence of expression, regulation and clinical significance.

The role of apoptosis (programmed cell death) in haemopoiesis and the immune system.

Apoptosis, or programmed cell death, is a series of controlled sequential events resulting in the demise of cells without invoking an inflammatory response. It is a naturally occurring process which maintains a cellular balance during both animal development and in the mature adult. Although first described 20 years ago, there is now renewed interest in this phenomenon, particularly in the light of our greater understanding of cellular signalling pathways and their genetic control. This is especially pertinent to haemopoiesis and the overall maintenance of a functional immune system. This review broadly covers the biochemical events of apoptosis and the recognition of apoptotic cells by phagocytes. Reference is made to the selective development of T- and B-cells and to the control of inflammation. Molecular events in apoptosis are also discussed with special reference to aberrant bcl-2 gene expression in follicular B-cell lymphoma and the role of other death genes in the control of apoptosis.

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.

Comparative expression of major histocompatibility complex (MHC) antigens on CD5+ and CD5- B cells in patients with chronic lymphocytic leukaemia (CLL)

The aim of this study was to investigate the expression of major histocompatibility complex (MHC) antigens on CD5+ and CD5- B cells of 13 patients with chronic lymphocytic leukaemia (CLL). This was carried out using a series of monoclonal antibodies (MAbs) against polymorphic and monomorphic class I and class II antigens, as well as to the transferrin receptor and assessed by flow cytometry and direct and indirect immunofluorescence. The expression of these molecules was assessed as mean fluorescent intensity (MFI). The results showed that cells from all 13 individuals expressed monomorphic class I antigens. The number of cases expressing polymorphic HLA-Bw6, -Bw4, -B7, -B27 and -A2 class I antigens on CD5- B cells was 11 (85%), 6(46%), 2(15%), 1(8%), 3 (23%), respectively, which was consistent with the expected population frequency distributions of these antigens. For each of the class I antigens on CD5+ and CD5- B cells, the ratio of the MFI was greater than 1 in 12 of 13 cases. For the transferrin receptor (CD71), this ratio was also almost always greater than 1. These results indicate that, unlike solid tumours where the loss or abnormal expression of class I and II antigens is a frequent event, the expression of class I antigens in CLL patients seems to be normal. This indicates that the loss of these antigens cannot provide the leukaemic cells with a selective advantage to escape immunological detection.

Serum osteocalcin in the management of myeloma.

We have measured serum osteocalcin, a vitamin K-dependent glycoprotein synthesised by osteoblasts in 62 patients, 49 with myeloma, 26 at presentation and 23 previously treated, 7 with Waldenstrom's macroglobulinaemia (WM), and 6 with monoclonal gammopathy of uncertain significance (MGUS). Osteocalcin levels were normal in WM and MGUS. High values were found in 5/26 (19%) patients with myeloma at presentation. There was no relationship between serum osteocalcin and stage of disease. Osteocalcin was normal in all patients in plateau phase, falling to low levels in relapsed patients who failed to respond to further treatment. Serum osteocalcin may be a useful indicator of bone metabolism in myeloma.

Prospective randomised study of double hemi-body irradiation with and without subsequent maintenance recombinant alpha 2b interferon on survival in patients with relapsed multiple myeloma.

Immediately before first hemi-body irradiation, 59 patients with relapsed multiple myeloma were randomised to receive or not to receive subsequent alpha-2b interferon maintenance. 13 patients (22%) [8 of 31 (26%) controls, 5 of 28 (18%) in the interferon arm] received single hemi-body irradiation alone due to progressive disease and/or persistent cytopoenias following the initial procedure. Mean time between upper and lower hemi-body irradiation was 69 days (range 35-294). Of 23 patients randomised to receive interferon and completing double hemi-body irradiation, 15 (65%) achieved peripheral blood counts adequate to allow interferon administration as per study criteria commencing at a mean 116 days (61-241) from time of study entry. The mean period of interferon therapy, starting at a mean 65 days (26-160) post second hemi-body irradiation, is 16.4 months (2-33.5). There was no significant difference in median survival durations (10 months) from time of initial radiotherapy between control and interferon patients.

Effects of cell purification methods on CD11b and L-selectin expression as well as the adherence and activation of leucocytes.

This study investigated the effects of commonly used procedures for the isolation of leucocytes from human blood in comparison with cells in whole blood on the surface expression of CD11b and L-selectin (adhesion molecules which are known to be increased and decreased respectively by cell activation). Washing of granulocytes or monocytes with Hanks' buffered salt solution after separation by either dextran sedimentation or density gradient centrifugation, increased surface expression of CD11b (p < 0.05). The number of monocytes bearing CD11b was enhanced (p < 0.05) by dextran sedimentation and two layer density gradient centrifugation (Histopaque). The increase in CD11b expression on granulocytes was associated with enhanced binding of the cells to endothelial monolayers that were either untreated (r = 0.902; p < 0.001) or treated with tumour necrosis factor alpha (TNF-alpha) (r = 0.68; p = 0.004). The expression of L-selectin was reduced on granulocytes that had been isolated by dextran sedimentation followed by hypotonic lysis of contaminating erythrocytes. All isolates of granulocytes demonstrated a loss of L-selectin following activation with fMLP though this effect was less marked with cells subjected to erythrocyte lysis. The various separation methods had little effect on expression or distribution of CD11b or L-selectin on lymphocytes. We conclude that isolation of lymphocytes by density gradient centrifugation and of granulocytes and monocytes by dextran-sedimentation and centrifugation using Histopaque gradients, but avoiding washing and the use of hypotonic erythrocyte lysis, are appropriate techniques for studying the expression and function of adhesion molecules.

Expression of functional antigens on neutrophils. Effects of preparation.

We have studied how different conditions of cell labelling and isolation affect the expression of five functional antigens on neutrophils from healthy subjects. Fluorescein isothiocyanate conjugated (FITC) antisera specific for the C3bi receptor CR3 (CD11b), aminopeptidase N (CD13), the LPS:LPS binding protein receptor (CD14) and the receptors for human IgG (Fc gamma RII CDw32 and Fc gamma RIII CD16) were incubated with (i) unfixed whole blood at 4 degrees C and at room temperature (RT, approximately 20 degrees C), and the leukocytes prepared for analysis using the Coulter Q-Prep system, (ii) leukocytes which had obtained following the removal of erythrocytes from whole blood by dextran sedimentation and which had been washed or left unwashed at RT, and (iii) leukocytes which had been prepared from whole blood that had been formaldehyde fixed immediately following venesection. The amount of fluorescence associated with the cells was determined by flow cytometry. The expression of CD14 was low under all conditions. However the expression of CD11b, CD16 and CDw32 was significantly higher (p less than 0.05) on neutrophils obtained by dextran sedimentation (n = 4) than on cells which had been fixed with formaldehyde ex vivo; the increase in expression was even greater if the cells had been washed. In contrast, the expression of CD13 on formaldehyde fixed cells was higher than on cells which had been labelled at 4 degrees C or at room temperature and was similar to or slightly lower than that on cells obtained by dextran sedimentation. Increasing the time between 10 and 60 min for which the whole blood was incubated with antisera at RT or at 4 degrees C, resulted in progressive increases in the expression of CD11b and CD13. When neutrophils which had been obtained by dextran sedimentation were incubated with unlabelled antibodies to CD16 or CDw32 and FITC labelled antibodies to CD11b there was a marked increase in the expression of CD11b. Altogether these findings indicate that the analysis of functional molecules on neutrophils (which may be rapidly up-regulated during activation) should be performed under clearly defined and controlled conditions. Dual fluorescence studies may, in some circumstances, produce misleading results.

How should CD34+ cells be analysed? A study of three classes of antibody and five leucocyte preparation procedures.

For patients undergoing stem cell transplantation after intensive marrow ablative therapy it is important to enumerate the CD34+ stem cells in peripheral blood so that the harvest can be timed in order to maximize the number of cells collected by leucophoresis for subsequent haematopoietic reconstitution. The use of rapid flow cytometric techniques for the determination CD34+ leucocyte numbers has been advocated, although there is no consensus as to the best method. In this study, we have examined the effects of preparation procedures for flow cytometry on the binding of four CD34 antibodies (Immu-133, QBEND-10, HPCA2 and BIRMA-K3) to the three classes of epitopes on leucocytes. Whole blood, bone marrow and leucophoresis samples were analysed either directly after labelling with a vital nuclear dye (LDS-751) and fluorochrome-conjugated antibodies or after additional erythrocyte lysis and leucocyte fixation using four commercially available reagents (Q-Prep, OptiLyse B, OptiLyse C and FACS Lysing Solution). By comparison with the results obtained from viable leucocytes in unmanipulated samples, it was found that the binding of all four antibodies could be affected by lysis and fixation procedures and that the binding of the class I antibody Immu-133 was most markedly decreased. We conclude that CD34+ cells are best analysed using a whole blood procedure in which nucleated cells are identified by their side light scatter and the fluorescence associated with a vital nuclear dye (in this instance LDS-751) and the CD34+ cells are detected with fluorescein isothiocyanate- or phycoerythrin-conjugated antibodies.

Idarubicin for remission induction of acute myeloid leukemia: United Kingdom multicenter experience.

Ninety-eight adult patients with acute myeloid leukemia were given variable remission induction/consolidation regimens containing idarubicin. Sixty-nine (70%) were new cases (median age, 56 years) and 29 (30%) were in relapse (n = 24) or had primary refractory disease (n = 5) (median age, 46 years). Complete remission (CR) rates were 57% (39 of 69 patients) of the newly diagnosed patients, with no difference for those below or above 55 years of age (56% v 59%) or for patients exhibiting white blood cell counts of less or more than 50 x 10(9)/L (52% v 69%; P = .8). Of the 39 patients who achieved CR, 26 (67%, 38% of the total number of patients) remain in CR with a median follow-up of 3 months (range, 0 to 61 months). Forty-two percent of the relapsed cases (10 of 24 patients) and 60% of the primary refractory disease cases (three of five patients) achieved CR. Of these 13 responders, six are alive (three continuing in CR and three relapsed) with a median follow-up of 3 months (range, 1 to 20 months), and seven have died with a median survival of 7 months (range, 0 to 12 months). Of the 52 patients who have achieved CR, 84% did so with one course of treatment and 16% with two courses. The presence of normal cytogenetic analysis or favorable chromosomal aberrations significantly improved overall CR rates. The patients in this study had significantly more unfavorable cytogenetic abnormalities than the historic controls. Reported toxicity was hepatic in 13%, cardiac in 9%, and renal in 7% of all cases. These data suggest a comparable efficacy of idarubicin to other anthracyclines in remission induction of acute myeloid leukemia, with a promising role in relapsed/refractory disease.

Intravenous ciprofloxacin as empirical treatment of febrile neutropenic patients.

A randomized study of treatment with ciprofloxacin combined with benzylpenicillin (CB) versus a standard regimen of netilmicin combined with piperacillin (NP) as first-line empiric therapy was conducted in febrile neutropenic patients. Ninety-six patients were evaluable for determination of efficacy: 50 patients received CB and 46 patients received NP. There was no significant difference between the two groups in terms of age or primary diagnosis. Overall clinical response rate at the end of therapy was 66 percent for CB and 65 percent for NP. Microbiologic assessment revealed more pathogens eradicated by CB (64 percent) and fewer persisting (4 percent) than in the NP group (52 percent eradicated, 13 percent persisting). Only 10 percent of patients in the CB group had treatment-related adverse reactions as opposed to 28 percent of the NP-treated patients; these were predominantly renal impairment and were likely to have been due to the aminoglycoside. Staphylococcus epidermidis was the most commonly isolated pathogen, accounting for 38 percent of all isolates and 30 percent of all patients in whom treatment failed. Although streptococci accounted for 18 percent of the isolated pathogens, no treatment failures or superinfections were due to these organisms. This indicates an advantage of combining ciprofloxacin with benzylpenicillin. We conclude that the CB regimen is as effective as the NP treatment and is associated with fewer side effects.