Treatment strategy and results in children treated on three Dutch Childhood Oncology Group acute myeloid leukemia trials.

This report describes the long-term follow-up data of three consecutive Dutch Childhood Oncology Group acute myeloid leukemia (AML) protocols. A total of 303 children were diagnosed with AML, of whom 209 were eligible for this report. The first study was the AML-82 protocol. Results were inferior (5-year probability of overall survival (pOS) 31%) to other available regimes. Study AML-87 was based on the BFM-87 protocol, with prophylactic cranial irradiation in high-risk patients only, and without maintenance therapy. This led to a higher cumulative incidence of relapse than that reported by the Berlin-Frankfurt-Münster (BFM), but survival was similar (5-year pOS 47%), suggesting successful retrieval at relapse. The subsequent study AML-92/94 consisted of a modified BFM-93 protocol, that is, without maintenance therapy and prophylactic cranial irradiation. However, all patients were to be transplanted (auto- or allogeneic), although compliance was poor. Antileukemic efficacy was offset by an increase in the cumulative incidence of nonrelapse mortality, especially in remission patients, and survival did not improve (5-year pOS 44%). Our results demonstrate that outcome in childhood AML is still unsatisfactory, and that further intensification of therapy carries the risk of enhanced toxicity. Our patients are currently included in the MRC AML studies, based on the results of their AML 10 trial.

BFM-oriented treatment for children with acute lymphoblastic leukemia without cranial irradiation and treatment reduction for standard risk patients: results of DCLSG protocol ALL-8 (1991-1996).

Modern treatment strategies, consisting of intensive chemotherapy and cranial irradiation, have remarkably improved the prognosis for children with acute lymphoblastic leukemia. However, patients with a potential for cure are at risk of severe acute and late adverse effects of treatment. Furthermore, in 25-30% of patients treatment still fails. The objectives of the DCLSG study ALL 8 were to decrease the toxicity and to increase the effectivity of BFM-oriented treatment. Decrease of toxicity was aimed at by confirmation of the results of the previous DCLSG study ALL-7, showing that the majority (94%) of children with ALL can successfully be treated with BFM-oriented therapy without cranial irradiation, and by reduction of treatment for standard risk (SRG) patients. To increase the cure rate in medium risk (MRG) patients the efficacy of high doses of intravenous 6-mercaptopurine (HD-6MP) during protocol M and in SRG patients the efficacy of high doses of L-asparaginase (HD-L-ASP) during maintenance treatment was studied in randomized studies. Patient stratification and treatment were identical to protocol ALL-BFM90, with the following differences: no prophylactic cranial irradiation, SRG patients received only phase 1 of protocol I. Four hundred and sixty-seven patients entered the protocol: 170 SRG, 241 MRG and 56 HRG patients. The 5 years event-free survival rate for all patients was 73% (s.e. 2%); for SRG, MRG and HRG patients 85% (s.e. 3%), 73% (s.e. 3%) and 39% (s.e. 7%), respectively. In patients >1 year of age at diagnosis unfavorable prognostic factors were male sex, >25% blasts in the bone marrow at day 15 and initial white blood cell count (WBC) >50 x 10(9)/l. The cumulative risk of CNS relapse rate was 5% (s.e. 1%) at 5 years. These results confirm that the omission of cranial irradiation in BFM-oriented treatment does not jeopardize the overall good treatment results, nor does early reduction of chemotherapy in SRG patients. No benefit was observed from treatment intensification with HD-L-ASP in SRG patients, nor from HD-6MP in MRG patients.

The effect of two different dosages of intravenous immunoglobulin on the incidence of recurrent infections in patients with primary hypogammaglobulinemia. A randomized, double-blind, multicenter crossover trial.

BACKGROUND: In patients with hypogammaglobulinemia, substitution with immunoglobulin is the treatment of choice to reduce both frequency and severity of bacterial infections. Even with treatment, however, infections still occur in these patients. OBJECTIVE: To determine whether doubling the standard dose of intravenous immunoglobulin would affect the incidence and duration of infections. DESIGN: Multicenter, double-blind, randomized, crossover study. SETTING: 15 outpatient clinics in the Netherlands. PATIENTS: 43 patients with primary hypogammaglobulinemia, 41 of whom completed the protocol. INTERVENTION: Patients received standard-dose immunoglobulin therapy for 9 months, followed by a 3-month washout period, and high-dose intravenous immunoglobulin therapy for 9 months, or vice versa. MEASUREMENTS: The primary outcome measures were total number and duration of infections. Other measures were periods of fever, hospital admissions, use of antibiotics, absence from school or work, and trough levels of serum immunoglobulin. Side effects from the study medication were also recorded. RESULTS: Compared with the standard dose of intravenous immunoglobulin (adults, 300 mg/kg of body weight every 4 weeks; children, 400 mg/kg every 4 weeks), high-dose therapy (adults, 600 mg/kg every 4 weeks; children, 800 mg/kg every 4 weeks) significantly reduced the number (3.5 vs. 2.5 per patient; P = 0.004) and duration (median, 33 days vs. 21 days; P = 0.015) of infections. Trough levels of IgG increased significantly during high-dose therapy. The incidence and type of side effects did not differ significantly for the two dosages. CONCLUSION: In patients with hypogammaglobulinemia, doubling the standard dose of intravenous immunoglobulin significantly reduced the number and duration of infections.

Point mutations in the promoter region of the CYBB gene leading to mild chronic granulomatous disease.

Chronic granulomatous disease (CGD) is a clinical syndrome of recurrent bacterial and fungal infections caused by a rare disorder of phagocytic cells. In CGD, the phagocytes are unable to generate oxygen radicals after stimulation of these cells, due to a defect in the NADPH oxidase system. This NADPH oxidase is a multicomponent enzyme of at least four subunits, of which the beta-subunit of cytochrome b558, gp91-phox, is encoded by an X-linked gene (called CYBB). We report here five patients from two families; in each family we found a different mutation in the promoter region of CYBB. Both mutations prevented the expression of gp91-phox in the patients' neutrophils and thus caused inability of these cells to generate oxygen radicals. However, the mutations left the gp91-phox expression and the function of the NADPH oxidase in the patients' eosinophils intact. The relatively mild course of the CGD in these patients can probably be attributed to the fact that the eosinophils have retained their oxidative capacity. Furthermore, our results indicate that neutrophils and eosinophils differ in their regulation of gp91-phox expression.

Intracellular reactions in single human granulocytes upon phorbol myristate acetate activation using confocal Raman microspectroscopy.

We have obtained new evidence for the occurrence of intracellular NADPH-oxidase activity in neutrophilic and eosinophilic granulocytes upon stimulation with phorbol myristate acetate (PMA). PMA activation leads to a partial translocation of cytochrome b(558) from the membranes of the specific granules to the plasma membrane. It was suggested that NADPH-oxidase activity only takes place in the plasma membrane, leading to an extracellular release of oxygen metabolites because cellular self-destruction can be avoided in this way. The effects of PMA activation were indirectly studied in recent experiments employing scavengers of extracellular superoxide anion and hydrogen peroxide, and support for intracellular NADPH-oxidase activity was obtained. In this paper we use Raman microspectroscopy as a direct method to study intracellular molecular reactions that result from cellular triggering by PMA. The molecular specificity of this microscopic method enables us to show that intracellular reduction of both myeloperoxidase (MPO) and cytochrome b(558) occurs in neutrophilic granulocytes. Control measurements with cytochrome b(558)-deficient neutrophilic granulocytes did not show a reduction of intracellular MPO. This is direct support for the occurrence of intracellular NADPH-oxidase activity in organelles that must be in close contact with the azurophilic granules that contain MPO. Furthermore, a comparison was made with chemical reactions occurring in eosinophilic granulocytes after activation with PMA. Moreover, in these cells an intracellular reduction of eosinophil peroxidase was observed.

A missense mutation in the heavy subunit of gamma-glutamylcysteine synthetase gene causes hemolytic anemia.

gamma-Glutamylcysteine synthetase (GCS) catalyzes the initial and rate-limiting step in the biosynthesis of glutathione. gamma-GCS consists of a heavy and a light subunit encoded by separate genes. Hereditary deficiency of GCS has been reported in 6 patients with hemolytic anemia and low erythrocyte levels of glutathione and gamma-glutamylcysteine. In addition, 2 patients also had generalized aminoaciduria and developed neurologic symptoms. We have examined a Dutch kindred with 1 suspected case of GCS deficiency. The proband was a 68-year-old woman with a history of transient jaundice and compensated hemolytic anemia. One of her grandchildren was also GCS deficient; he was 11 years old and had a history of neonatal jaundice. The enzyme defect was confirmed and GCS activity was found to be less than 2% of normal in the erythrocytes of both patients. The complementary DNA (cDNA) for the heavy subunit of GCS was sequenced in these patients and in several members of the family. The proband and her GCS- deficient grandson were identified as homozygous for a 473C-->T substitution, changing codon 158 from CCC for proline into CTC for leucine. Several family members with half-normal GCS activity in their erythrocytes were heterozygous for the mutation.

Four novel mutations in the gene encoding gp91-phox of human NADPH oxidase: consequences for oxidase assembly.

The superoxide-forming nicotinamide adenine dinucleotide phosphate reduced (NADPH) oxidase of human phagocytes comprises membrane-bound and cytosolic proteins, which, upon cell activation, assemble on the plasma membrane to form the active enzyme. Patients with chronic granulomatous disease (CGD) are defective in one of the phagocyte oxidase (phox) components, p47-phox or p67-phox, which reside in the cytosol of resting phagocytes, or gp91-phox or p22-phox, which constitute the membrane-bound cytochrome b(558). In four X-linked CGD patients we have identified novel missense mutations in CYBB, the gene encoding gp91-phox. These mutations were associated with normal amounts of nonfunctional cytochrome b(558) in the patients' neutrophils. In phorbol-myristate-stimulated neutrophils and in a cell-free translocation assay with neutrophil membranes and cytosol, the association of p47-phox and p67-phox with the membrane fraction of the cells with Cys369-->Arg, Gly408-->Glu, and Glu568--> Lys substitutions was strongly disturbed. Only a Thr341-->Lys substitution, residing in a region of gp91-phox involved in flavin adenine dinucleotide (FAD) binding, supported a normal translocation. Thus, the introduction or reversal of charge at residues 369, 408, and 568 in gp91-phox destroys the correct binding of p47-phox and p67-phox to cytochrome b(558). Based on mutagenesis studies of structurally related flavin-dependent oxidoreductases, we propose that the Thr341-->Lys substitution results in impaired hydride transfer from NADPH to FAD. Because we found no electron transfer in solubilized neutrophil plasma membranes from any of the four patients, we conclude that all four amino acid replacements are critical for electron transfer. Apparently, an intimate relation exists between domains of gp91-phox involved in electron transfer and in p47/p67-phox binding. (Blood. 2000;95:666-673)

Molecular basis and enzymatic properties of glucose 6-phosphate dehydrogenase volendam, leading to chronic nonspherocytic anemia, granulocyte dysfunction, and increased susceptibility to infections.

We have investigated the blood cells from a woman with a low degree of chronic nonspherocytic hemolytic anemia and frequent bacterial infections accompanied by icterus and anemia. The activity of glucose 6-phosphate dehydrogenase (G6PD) in her red blood cells (RBCs) was below detection level, and in her leukocytes less than 3% of normal. In cultured skin fibroblasts, G6PD activity was approximately 15% of normal, with 4- to 5-fold increased Michaelis constant (Km) for NADP and for glucose 6-phosphate. Activated neutrophils showed a decreased respiratory burst. Family studies showed normal G6PD activity in the RBCs from all family members, including both parents and the 2 daughters of the patient. Sequencing of polymerase chain reaction (PCR)-amplified genomic DNA showed a novel, heterozygous 514C-->T mutation, predicting a Pro172-->Ser replacement. Analysis of G6PD RNA from the patient's leukocytes and fibroblasts showed only transcripts with the 514C-->T mutation. This was explained by the pattern of X-chromosome inactivation, studied by means of the human androgen receptor (HUMARA) assay, which proved to be skewed in the patient, her mother, and one of the patient's daughters. Thus, the patient has inherited a de novo mutation in G6PD from her father and an X-chromosome inactivation determinant from her mother, causing exclusive expression of the mutated G6PD allele. Purified mutant protein from an Escherichia coli expression system showed strongly decreased specific activity, increased Km for NADP and for glucose 6-phosphate, and increased heat lability, which indicates that the defective phenotype is due to 2 synergistic molecular dysfunctions: decreased catalytic efficiency and protein instability.

Intensive treatment of children with acute lymphoblastic leukemia according to ALL-BFM-86 without cranial radiotherapy: results of Dutch Childhood Leukemia Study Group Protocol ALL-7 (1988-1991).

In The Netherlands from July 1988 to October 1991, children (0 to 16 years of age) with de novo acute lymphoblastic leukemia (ALL) were treated according to protocol ALL-7 of the Dutch Childhood Leukemia Study Group (DCLSG). In this protocol, chemotherapy and treatment stratification were identical to the ALL-BFM-86 protocol (Reiter et al, Blood 84:3122, 1994), but cranial irradiation was restricted to patients with initial central nervous system (CNS) involvement. Patients were stratified into 3 risk groups, based on leukemia cell mass and response to initial treatment: standard-risk group (SRG), risk group (RG), and experimental group (EG). As in ALL-BFM-86, a randomized study on late intensification (protocol S) was performed in RG patients, and during the study (since October 1990), early reinduction treatment (protocol II) was introduced for SRG patients. Treatment duration for all patients was 18 months. Two hundred eighteen children entered the study: 74 SRG, 127 RG, and 17 EG patients. The overall complete remission (CR) rate was 98%. The 5-year event-free survival (EFS) for all DCLSG ALL-7 patients was 65. 3% (standard error [SE] 3.2%), which was significantly different from the 73% (SE 1%) 5-year EFS achieved in the ALL-BFM-86 study (P =.02, Z-test). However, restricting the analysis to SRG patients receiving protocol II with a total duration of treatment of 18 months, the 5-year EFS rates were 64.6% (SE 4.0%) and 67% (SE 4%), respectively, and no significant difference could be established (P =.67, Z-test). The 5-year EFS rates for SRG, RG, and EG patients were 63.5% (SE 5.6%), 66.6% (SE 4.2%), and 63.3% (SE 12.0%), respectively. SRG patients receiving protocol II fared better than patients not receiving protocol II (5-year EFS 76.7% [SE 7.7] and 54. 5% [SE 7.5], respectively). No difference in 5-year EFS was observed in RG patients randomized to receive or not to receive late intensification with protocol S. The overall CNS relapse rate at 5 years was 5.5%. The incidence rate at 5 years was 11.4% in SRG patients not receiving protocol II, whereas no CNS relapses occurred in SRG patients receiving protocol II. Six children died in first complete remission and 2 children developed a second malignancy (thyroid carcinoma and acute nonlymphoblastic leukemia). Systemic high-dose methotrexate (MTX) and intrathecal chemotherapy is a safe and effective method of CNS prophylaxis in the context of BFM-oriented treatment for all children with ALL, regardless of the risk group (with the possible exception of T-ALL patients with high white blood cell counts). The results of the DCLSG ALL-7 study confirm those of the ALL-BFM-86 study showing that early reinduction with protocol II is essential in the treatment of SRG patients and that late intensification with protocol S does not improve the prognosis for RG patients.

Clinical and laboratory work-up of patients with neutrophil shortage or dysfunction.

Neutrophils have a crucial function in the defense against bacteria and fungi. Indeed, during chronic, severe neutropenia and in case of severe neutrophil dysfunctions, the patients may suffer recurrent and sometimes life-threatening infections. This article describes the clinical symptoms, the theory behind the antimicrobial systems of neutrophils, the methods to diagnose the various aberrations, and the possibilities for treating these patients. A few of the most common causes of neutropenia and neutrophil dysfunctions are described in detail, including recent genetic information regarding the cause of these diseases.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) ameliorates chemotherapy-induced neutropenia in children with solid tumors.

Neutropenia is one of the risk factors for severe therapy-related morbidity in childhood malignancies. We have studied the potential of GM-CSF to shorten the neutropenic period after normal-dose chemotherapy in children who were treated for solid tumors. Patients with osteosarcomas, with Ewing sarcomas, or with rhabdomyosarcomas received 10 daily subcutaneous doses GM-CSF (Leucomax, 5 micrograms/kg) after a course of normal-dose chemotherapy in an open-label study. Because these patients were treated with different combinations of chemotherapeutic agents, they were randomized before each pair of identical courses of chemotherapy to receive GM-CSF after the first or after the second course. Fourteen such combinations could be evaluated in eight patients. The results show that GM-CSF significantly reduced the mean duration of the chemotherapy-induced neutropenia (mean reduction +/- SEM in days: 2.2 +/- 0.6, P = .003). There was no significant difference between the mean number of days with fever in either group. GM-CSF was well tolerated by all patients. We conclude that GM-CSF reduced the mean neutropenic period in children with solid tumors who were treated with standard-dose chemotherapy.

Leukocyte adhesion deficiency type 1 (LAD-1)/variant. A novel immunodeficiency syndrome characterized by dysfunctional beta2 integrins.

Leukocyte adhesion deficiency (LAD) is characterized by the inability of leukocytes, in particular neutrophilic granulocytes, to emigrate from the bloodstream towards sites of inflammation. Infectious foci are nonpurulent and may eventually become necrotic because of abnormal wound healing. LAD-1 is characterized by the absence of the beta2 integrins (CD11/CD18) on leukocytes. When expression is completely absent, patients often die within the first year. However, low levels of beta2 expression may result in a milder clinical picture of recurrent infection, which offers a better prognosis. In this paper, we describe the in vivo and in vitro findings on a patient with clinical features of a mild LAD-1 disorder, i.e., suffering from bacterial infections without apparent pus formation in the presence of a striking granulocytosis, showing no delayed-type hypersensitivity reaction upon skin testing, no specific antibody generation, but normal in vitro T cell proliferation responses after immunization. Expression levels of CD11/CD18 proteins were completely normal, but leukocyte activation did not result in CD11/ CD18 activation and high-avidity ligand-binding. In vitro chemotaxis and endothelial transmigration of the neutrophils as well as leukocyte aggregation responses were almost absent. On the other hand, beta1 and beta3 integrin-mediated adhesion functions were completely normal. During follow-up, a bleeding tendency related to decreased beta3 activation became clinically apparent, different from previously described cellular adhesion molecule variants. Therefore, this is the first well-documented case of a clinical combined immunodeficiency syndrome that results from nonfunctional CD11/CD18 molecules, and thus designated LAD-1/ variant.

Chronic bullous disease of childhood and a paecilomyces lung infection in chronic granulomatous disease.

A 12 year old boy suffering from p67-phox deficient chronic granulomatous disease presented with a bullous skin disease and a lung infection with paecilomyces species. The histopathology of a bullous lesion showed subepidermal blister formation and microabcesses containing eosinophils in the dermal papillae. By direct immunofluorescence, linear staining of IgA at the dermal-epidermal junction was detected which confirmed the clinical diagnosis of chronic bullous disease of childhood (linear IgA dermatosis).

Academic pediatrics in the Emma Children's Hospital, Academic Medical Center in Amsterdam (The Netherlands).

In 1988 the Emma Children's Hospital and the department of pediatrics of the Academic Medical Center in Amsterdam (The Netherlands) merged. With the integration of the Emma Children's Hospital and the academic pediatric department, an academic children's hospital (ECH/ AMC) was established with all pediatric subspecialties including oncology, pediatric hematology/ hemostasis, and immunology. The research is organized in special research institutes. Oncology patients are referred from all over The Netherlands (and consist of one third of the total Dutch pediatric oncology patients) and from many other countries. Considerable effort is given to the care of patients with hemophilia and congenital clotting disorders. One of the special fields in immunology is the care for children infected with human immunodeficiency virus (HIV). The Emma Children's Hospital AMC participates in national and international programs for human immunodeficiency virus and AIDS research and immunological diseases, especially chronic granulomatous disease, in which an internationally appreciated know-how has been built up.

IgG glycation and function during continuous ambulatory peritoneal dialysis.

IgG in dialysate may have an important role in anti-infection mechanisms during continuous ambulatory peritoneal dialysis (CAPD). As Fc fragment oligosaccharidic chains are crucial for IgG effector functions, we have tested the hypothesis that IgG glycation might occur during CAPD and modify IgG properties. Purified normal IgG was incubated with glucose solutions of different concentrations and pH. Separation of glycated IgG was performed by affinity chromatography. Complement activation (C3c deposition) and phagocytosis by polymorphonuclear leucocytes (PMN) were studied in vitro using Staphylococcus aureus Wood (STAW) as antigen. In addition, we compared the percentages of glycated IgG in IgG purified from sera and dialysates of 12 CAPD patients. The percentage of glycated IgG after in vitro incubation of normal IgG with glucose solutions was directly proportional to glucose concentrations, incubation time and pH. Glycated IgG anti-STAW induced a higher C3c deposition than non-glycated IgG anti-STAW (C3c/IgG (mean +/- SD) 0.96 +/- 0.06 vs 0.79 +/- 0.08; P = 0.027). PMN phagocytosis was not affected by IgG glycation. The percentages of glycated IgG in dialysates of CAPD patients were greater than those in corresponding sera (5.38 +/- 2.36% vs 4.56 +/- 2.47%; P = 0.006). It is concluded that IgG glycation may take place in the peritoneal cavity during CAPD and lead to enhanced complement activation. This could explain the high degree of complement activation previously described in dialysate of CAPD patients and might theoretically result in a reduction of complement factors available in dialysate for adequate anti-infection mechanisms.

Effect of interferon-gamma, in vitro and in vivo, on mRNA levels of phagocyte oxidase components.

During the international placebo-controlled trial on the efficacy of interferon-gamma (IFN-gamma) in chronic granulomatous disease (CGD), 19 patients entered the study via our Institute. One patient stopped treatment shortly thereafter. RNA was purified from the mononuclear cells of the remaining 18 CGD patients before and during this placebo-controlled trial. The mRNA levels for the NADPH oxidase components were subsequently analyzed. Compared with the placebo-treated CGD patients, the mRNA levels for p47-phox were significantly increased in the IFN-gamma-treated CGD patients (P < 0.002). No significant changes were observed in the mRNA levels of the other oxidase components. These findings are in agreement with observations in vitro and indicate that IFN-gamma is active on the NADPH oxidase in vivo as well. However, it remains questionable whether these effects in vivo can explain the observed reduction of infections in these patients.

The use of rhG-CSF in chronic autoimmune neutropenia: reversal of autoimmune phenomena, a case history.

An 8-year-old boy had been suffering from chronic autoimmune neutropenia for more than 5 years. The neutropenia proved to be resistant to high-dose steroids and intravenous (either low-or high-dose) immunoglobulin (Ig) therapy. The chronic autoimmune thrombocytopenia and recurrent phases of autoimmune haemolytic anaemia did, however, respond to high-dose prednisone. Other signs of immune dysregulation in this patient consisted of insulin-dependent diabetes mellitus type I (IDDM) and an acquired hypogammaglobulinaemia, most compatible with common variable immunodeficiency (CVI). Prior to rhG-CSF therapy the child had suffered for more than 2 years from recurrent life-threatening bacterial infections. Anti-neutrophil autoantibodies had pan-Fc gamma RIII (CD116, NA1/NA2) specificity. The neutropenia as well as the antineutrophil autoantibodies disappeared when subcutaneous rhG-CSF therapy was started. Upon tapering rhG-CSF, anti-Fc gamma RIII antibodies reappeared together with an absolute neutropenia. Renewed administration resulted again in the normalization of symptoms. Soluble Fc gamma RIII (sFc gamma RIII) antigen levels in plasma increased dramatically during rhG-CSF treatment. These high levels of sFc gamma RIII together with increased numbers as well as decreased apoptotic reactions of neutrophils apparently result in adsorption of the autoantibodies in vivo, contributing to the normalization of autoimmune-mediated neutropenia upon rhG-CSF treatment. Long-term administration of rhG-CSF represents as alternative in the treatment of autoimmune neutropenia.

A single dose of granulocyte-macrophage colony-stimulating factor induces systemic interleukin-8 release and neutrophil activation in healthy volunteers.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) are frequently used in the clinical management of neutropenia. These cytokines not only enhance the proliferation of myeloid precursor cells but also influence the function of mature leukocytes. In a previous study, we found that the in vivo effects of G-CSF on neutrophils differed from those in vitro. In the present study, we investigated the effects of a single dose of recombinant GM-CSF (7.5 microg/kg, subcutaneously) on neutrophils, eosinophils, and monocytes in healthy volunteers. We analyzed leukocyte kinetics, phenotypical changes, neutrophil degranulation, and systemic cytokine production. After GM-CSF injection, phenotypical changes included upregulation of CD11b on all three cell types and a decreased expression of L-selectin and Fc(gamma)RIII on neutrophils. Neutrophil degranulation was evident from the increased plasma concentrations of lactoferrin and elastase. GM-CSF induced the release of interleukin-8 (IL-8), but not of IL-6 or tumor necrosis factor alpha. In comparison to the results from our previous study with G-CSF in healthy volunteers, GM-CSF induced a stronger activation of mature neutrophils but had a much less pronounced effect on the production and maturation of neutrophil precursors. These data may help to guide the choice between the two cytokines in different clinical situations.

Limitations on the use of dihydrorhodamine 123 for flow cytometric analysis of the neutrophil respiratory burst.

Intracellular oxidation of dihydrorhodamine 123 (DHR) to the fluorescent compound rhodamine 123 (Rho123) was used to detect the production of oxygen metabolites in activated neutrophils. Total leukocyte preparations can be used in this assay, which is a great advantage when priming of the respiratory burst is studied. We have defined the conditions that should be taken into account when priming is studied with this assay. We found that neither the extent nor the kinetics of DHR oxidation match those of NADPH oxidase activity. In addition, DHR oxidation is influenced by the absolute and relative number of neutrophils in the leukocyte suspension, by the DHR concentration and by myeloperoxidase availability. The results presented in this study emphasize the need for carefully designed experiments when DHR is used to study the respiratory burst in neutrophils.