Effects of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor on respiratory burst activity of neutrophils in patients with myelodysplastic syndromes

Risk of infection in elderly patients with AML and MDS treated with hypomethylating agents

The aim of this small volume is to raise awareness among Italian hematologists using hypomethylating drugs about risk - and even more important about “risk management” - and the treatment of the infectious events that may arise during therapy with these drugs. Since we wanted this review to be an extremely practical tool, we have included the most recent clinical case studies, the indications provided by the guidelines and expert opinions. Infectious complications are among the most common adverse events that can arise during treatment with hypomethylating drugs. For this reason, a large portion of the chapters of this small volume has been dedicated to a detailed description (on the basis of an attentive review of the literature) of what the hematologist can expect to encounter in terms of risk of infection, in patients treated with azacitidine or decitabine, and to the preventive investigations to carry out and the active prophylaxis measures recommended before commencing treatment with these drugs. What led us to write this book was the conviction that the critical sharing of the studies published in literature and of our personal experiences could contribute to prompting reflection on how we operate and that this, in turn, would lead to the best possible management of these treatments, both in patients with myelodysplasia and in patients with acute myeloid leukemia, preventing - and efficiently managing - infectious events - during therapy. We should not be misled by the fact that the treatments are prevalently administered on an outpatient basis; these patients due to their disease and, in particular, to their age, are extremely frail, and infectious and hemorrhagic complications are the main causes of their admissions to hospital. But expert knowledge and management of the risks of infection can guarantee better management of their needs on an outpatient basis, with undeniable advantages for the clinic but, first and foremost, for the patients. (www.actabiomedica.it)

Maitake mushroom extract in myelodysplastic syndromes (MDS): a phase II study

Background

Myelodysplastic syndromes (MDS) are characterized by ineffective erythropoiesis with dysplastic bone marrow leading to peripheral cytopenia, risk of infection, and progression to acute myelogenous leukemia. Maitake mushroom beta-glucan, a dietary supplement, stimulates hematopoietic progenitor cell differentiation, granulocyte colony-stimulating factor production, and recovery of peripheral blood leukocytes after bone marrow injury. This phase II trial examined the effects of Maitake on innate immune function in MDS.

Methods

Myelodysplastic syndromes patients with International Prognostic Scoring System Low- and Intermediate-1-risk disease received oral Maitake extract at 3 mg/kg twice daily for 12 weeks. Primary endpoints included neutrophil count and function tested as endogenous or stimulated neutrophil production of reactive oxygen species (ROS) by flow cytometry compared with age-matched healthy controls (HC). ROS activators were Escherichiacoli, phorbol ester, and the bacterial peptide N-formylmethionyl-leucyl-phenylalanine (fMLP). Complete blood counts, chemistry panels, iron studies, and monocyte function were evaluated.

Results

Of 21 patients enrolled, 18 completed the study and were evaluable. Maitake increased endogenous (basal) neutrophil (p = 0.005) and monocyte function (p = 0.021). Pre-treatment monocyte response to E. coli was reduced in MDS patients compared with HC (p = 0.002) and increased (p = 0.0004) after treatment. fMLP-stimulated ROS production response also increased (p = 0.03). Asymptomatic eosinophilia occurred in 4 patients (p = 0.014). Other changes in albumin, hemoglobin, and total protein were not clinically relevant.

Conclusions

Maitake was well tolerated. Enhanced in vitro neutrophil and monocyte function following treatment demonstrate that Maitake has beneficial immunomodulatory potential in MDS. Further study is warranted.

Acute Functional Enhancement of Circulatory Neutrophils After Intratracheal Instillation with Diesel Exhaust Particles in Rats

We have previously demonstrated that intratracheal instillation (IT) with diesel exhaust particles (DEP) exacerbates myocardial ischemia/reperfusion-induced arrhythmia in rats. Since activated neutrophils play a pivotal role in ischemia/reperfusion arrhythmia, in the present study we investigated the effects of DEP on peripheral neutrophil count and on the oxyradical production (ORP) of neutrophils in rats. We also determined the production of cytokines for better understanding of the relationship between pulmonary inflammation and neutrophil function. Instillation with 5 mg DEP elevated circulatory neutrophil counts (CNC) at 12 and 24 h post-instillation to levels approximately 2.1- and 2.3-fold those in the vehicle-treated animals, respectively. On the other hand, 1-mg DEP caused an approximately 0.4-fold increase in CNC at 6 h. 12-O-Tetradecanoylphorbol 13-acetate-induced ORP in the isolated neutrophil was enhanced at 12 and 24 h after instillation with 5 mg DEP. Cytokine-induced neutrophil chemoattractant-1 (CINC-1), tumor necrosis factor-alpha (TNFalpha) and macrophage inflammatory protein-2 (MIP-2) levels were increased in the bronchoalveolar lavage fluid (BALF) collected from animals that received 5 mg DEP. In serum, a marked elevation of CINC-1 and a slight elevation of MIP-2 were also observed, while TNFalpha was not detected. Granulocyte-macrophage colony-stimulating factor (GM-CSF) was detected in neither BALF nor serum for 24 h after the instillation. These results suggest that IT instillation of DEP enhances systemic oxidative stress by increasing neutrophil count and ORP in the acute period.

Reduced activation of protein kinase B, Rac, and F-actin polymerization contributes to an impairment of stromal cell–derived factor-1–induced migration of CD34+ cells from patients with myelodysplasia

Patients with myelodysplasia (MDS) show a differentiation defect in the multipotent stem-cell compartment. An important factor in stem-cell differentiation is their proper localization within the bone marrow microenvironment, which is regulated by stromal cell–derived factor (SDF-1). We now show that SDF-1–induced migration of CD34+ progenitor cells from MDS patients is severely impaired. In addition, these cells show a reduced capacity to polymerize F-actin in response to SDF-1. We demonstrate a major role for Rac and phosphatidylinositol 3-kinase (PI3K) and a minor role for the extracellular signal-regulated kinase (ERK)1/2 signaling pathway in SDF-1–induced migration of normal CD34+ cells. Furthermore, SDF-1–stimulated activation of Rac and the PI3K target protein kinase B is impaired in CD34+ cells from MDS patients. Lentiviral transduction of MDS CD34+ cells with constitutive active Rac1V12 results in a partial restoration of F-actin polymerization in response to SDF-1. In addition, expression of constitutive active Rac increases the motility of MDS CD34+ cells in the absence of SDF-1, although the directional migration of cells toward this chemoattractant is not affected. Taken together, our results show a reduced migration of MDS CD34+ cells toward SDF-1, as a result of impaired activation of the PI3K and Rac pathways and a decreased F-actin polymerization.

Constitutive activation of SHP2 protein tyrosine phosphatase inhibits ICSBP-induced transcription of the gene encoding gp91PHOX during myeloid differentiation

The IFN consensus sequence-binding protein (ICSBP; also referred to as IFN regulatory factor 8) is a transcription factor which is expressed in myeloid and B cells. In previous studies, we found that ICSBP activated transcription of the gene encoding gp91(PHOX) (the CYBB gene), a rate-limiting component of the phagocyte respiratory burst oxidase expressed exclusively after the promyelocyte stage of myelopoiesis. Previously, we found that CYBB transcription was dependent on phosphorylation of specific ICSBP tyrosine residues. Since ICSBP is tyrosine-phosphorylated during myelopoiesis, this provided a mechanism of differentiation stage-specific CYBB transcription. In the current studies, we found that ICSBP was a substrate for Src homology-containing tyrosine phosphatase 2 (SHP2-PTP) in immature myeloid cells but not during myelopoiesis. Therefore, SHP2-PTP inhibited CYBB transcription and respiratory burst activity in myeloid progenitor cells by dephosphorylating ICSBP. In contrast, we found that ICSBP was a substrate for a leukemia-associated, constitutively active mutant form of SHP2, described previously, throughout differentiation. Consistent with this, constitutive SHP2 activation blocked ICSBP-induced CYBB transcription and respiratory burst activity in differentiating myeloid cells. ICSBP-deficiency and constitutive SHP2 activation have been described in human myelodysplastic syndromes. As these two abnormalities may coexist, our results identified a potential molecular mechanism for impaired phagocyte function in this malignant myeloid disease.

The reduced GM-CSF priming of ROS production in granulocytes from patients with myelodysplasia is associated with an impaired lipid raft formation

Patients with myelodysplasia (MDS) show an impaired reactive oxygen species (ROS) production in response to fMLP stimulation of GM-CSF-primed neutrophils. In this study, we investigated the involvement of lipid rafts in this process and showed that treatment of neutrophils with the lipid raft-disrupting agent methyl-beta-cyclodextrin abrogates fMLP-induced ROS production and activation of ERK1/2 and protein kinase B/Akt, two signal transduction pathways involved in ROS production in unprimed and GM-CSF-primed neutrophils. We subsequently showed that there was a decreased presence of Lyn, gp91(phox), and p22(phox) in lipid raft fractions from neutrophils of MDS. Furthermore, the plasma membrane expression of the lipid raft marker GM1, which increases upon stimulation of GM-CSF-primed cells with fMLP, was reduced significantly in MDS patients. By electron microscopy, we showed that the fMLP-induced increase in GM1 expression in GM-CSF-primed cells was a result of de novo synthesis, which was less efficient in MDS neutrophils. Taken together, these data indicate an involvement of lipid rafts in activation of signal transduction pathways leading to ROS production and show that in MDS neutrophils, an impaired lipid raft formation in GM-CSF-primed cells results in an impaired ROS production.

Impaired interleukin-8- and GROα-induced phosphorylation of extracellular signal-regulated kinase result in decreased migration of neutrophils from patients with myelodysplasia

Patients with myelodysplasia suffer from recurrent bacterial infections as a result of differentiation defects of the myeloid lineage and a disturbed functioning of neutrophilic granulocytes. Important physiological activators of neutrophils are the cytokines interleukin-8/CXC chemokine ligand 8 (IL-8/CXCL8), which activates CXC chemokine receptor 1 and 2 (CXCR1 and CXCR2), and growth-related oncogene (GROalpha)/CXCL1, which stimulates only CXCR2. In this study, we show that migration toward IL-8/GROalpha gradients is decreased in myelodysplastic syndrome (MDS) neutrophils compared with healthy donors. We investigated the signal transduction pathways involved in IL-8/GROalpha-induced migration and showed that specific inhibitors for extracellular signal-regulated kinase (ERK)1/2 and phosphatidylinositol-3 kinase (PI-3K) abrogated neutrophil migration toward IL-8/GROalpha. In accordance with these results, we subsequently showed that IL-8/GROalpha-stimulated activation of ERK1/2 was substantially diminished in MDS neutrophils. Activation of the PI-3K downstream target protein kinase B/Akt was disturbed in MDS neutrophils when cells were activated with IL-8 but normal upon GROalpha stimulation. IL-8 stimulation resulted in higher migratory behavior and ERK1/2 activation than GROalpha stimulation, suggesting a greater importance of CXCR1. We then investigated IL-8-induced activation of the small GTPase Rac implicated in ERK1/2-dependent migration and found that it was less efficient in neutrophils from MDS patients compared with healthy donors. In contrast, IL-8 triggered a normal activation of the GTPases Ras and Ral, indicating that the observed defects were not a result of a general disturbance in CXCR1/2 signaling. In conclusion, our results demonstrate a disturbed CXCR1- and CXCR2-induced neutrophil chemotaxis in MDS patients, which might be the consequence of decreased Rac-ERK1/2 and PI-3K activation within these cells.

Disturbed granulocyte macrophage-colony stimulating factor priming of phosphatidylinositol 3,4,5-trisphosphate accumulation and Rac activation in fMLP-stimulated neutrophils from patients with myelodysplasia

The production of reactive oxygen species (ROS) by human neutrophils is imperative for their bactericidal activity. Proinflammatory agents such as granulocyte macrophage-colony stimulating factor (GM-CSF) can prime ROS production in response to chemoattractants such as N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP). In neutrophils from patients suffering from Myelodysplastic syndromes (MDS), a clonal, hematological disorder characterized by recurrent bacterial infections, this GM-CSF priming is severely impaired. In this study, we set out to further delineate the defects in neutrophils from MDS patients. We examined the effect of GM-CSF priming on fMLP-triggered activation of Rac, a small GTPase implicated in neutrophil ROS production. In contrast to healthy neutrophils, activation of Rac in response to fMLP was not enhanced by GM-CSF pretreatment in MDS neutrophils. Furthermore, activation of Rac was attenuated by pretreatment of neutrophils with the phosphatidylinositol 3-kinase (PI-3K) inhibitor LY294002. Unlike healthy neutrophils, fMLP-induced accumulation of the PI-3K lipid product PI(3,4,5)trisphosphate was not increased by GM-CSF pretreatment in MDS neutrophils. The disturbed Rac and PI-3K activation observed in MDS neutrophils did not appear to reflect a general GM-CSF or fMLP receptor-signaling defect, as fMLP-triggered Ras activation could be primed by GM-CSF in MDS and healthy neutrophils. Moreover, fMLP-induced activation of the GTPase Ral was also normal in neutrophils from MDS patients. Taken together, our data suggest that in neutrophils from MDS patients, a defect in priming of the PI-3K-Rac signaling pathway, located at the level of PI-3K, results in a decreased GM-CSF priming of ROS production.

Reduced expression of flavocytochrome b558, a component of the NADPH oxidase complex, in neutrophils from patients with myelodysplasia

OBJECTIVE

Patients with myelodysplasia (MDS) show a disturbed production of ROS in response to N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP) in granulocyte-macrophage colony-stimulating factor (GM-CSF)-primed neutrophils. Because generation of ROS is mediated by the NADPH oxidase complex, a component of which is flavocytochrome b558, we investigated whether the expression of flavocytochrome b558 in neutrophils from MDS patients is affected.

MATERIAL AND METHODS

Neutrophils were stimulated with fMLP and GM-CSF, and plasma membrane expression of flavocytochrome b558 and specific granule markers were assessed by fluorescence-activated cell sorting analysis. Protein levels of the flavocytochrome b558 subunits gp91phox and p22phox in whole neutrophil lysates were detected by Western blotting.

RESULTS

Stimulation of neutrophils with GM-CSF and fMLP increased the flavocytochrome b558 plasma membrane expression. The fMLP-induced translocation of flavocytochrome b558 was reduced in neutrophils from MDS patients (140%+/-9% vs 180%+/-13%, p<0.05). Analysis of cell surface expression of markers of flavocytochrome b558 containing granules (CD35 and CD66b) indicated that exocytosis of these granules in response to fMLP stimulation was not affected in MDS patients. Western blot analysis demonstrated a decreased protein expression level of the flavocytochrome b558 subunits gp91phox and p22phox in neutrophils from MDS patients.

CONCLUSION

Our results indicate both a lower basal protein level and a disturbed fMLP-induced increase in plasma membrane expression of flavocytochrome b558 in neutrophils from MDS patients, which together might play a role in decreased ROS production.

Decreased phosphorylation of protein kinase B and extracellular signal-regulated kinase in neutrophils from patients with myelodysplasia

Neutrophils from patients with myelodysplastic syndrome (MDS) show a disturbed differentiation pattern and are generally dysfunctional. To study these defects in more detail, we investigated reactive-oxygen species (ROS) production and F-actin polymerization in neutrophils from MDS patients and healthy controls and the involvement of N-formyl-L-methionyl-L-lucyl-L-phenylaline (fMLP) and granulocyte macrophage-colony-stimulating factor (GM-CSF)-stimulated signal transduction pathways. Following fMLP stimulation, similar levels of respiratory burst, F-actin polymerization, and activation of the small GTPase Rac2 were demonstrated in MDS and normal neutrophils. However, GM-CSF and G-CSF priming of ROS production were significantly decreased in MDS patients. We subsequently investigated the signal transduction pathways involved in ROS generation and demonstrated that fMLP-stimulated ROS production was inhibited by the phosphatidylinositol 3 kinase (PI3K) inhibitor LY294002, but not by the MAPK/ERK kinase (MEK) inhibitor U0126. In contrast, ROS production induced by fMLP stimulation of GM-CSF-primed cells was inhibited by LY294002 and U0126. This coincides with enhanced protein kinase B (PKB/Akt) phosphorylation that was PI3K dependent and enhanced extracellular signal-regulated protein kinase 1 and 2 (ERK1/2) phosphorylation that was PI3K independent. We demonstrated higher protein levels of the PI3K subunit p110 in neutrophils from MDS patients and found that though the fMLP-induced phosphorylation of PKB/Akt and ERK1/2 could also be enhanced by pretreatment with GM-CSF in these patients, the degree and kinetics of PKB/Akt and ERK1/2 phosphorylation were significantly disturbed. These defects were observed despite a normal GM-CSF-induced signal transducer and activator of transcription 5 (STAT5) phosphorylation. Our results indicate that the reduced priming of neutrophil ROS production in MDS patients might be caused by a disturbed convergence of the fMLP and GM-CSF signaling routes.

Cytokine priming of the granulocyte respiratory burst in myelodysplastic syndromes

Increased susceptibility to infections in patients with myelodysplastic syndromes (MDS) is thought to be due to neutropenia as well as functional abnormalities of neutrophils. In the present study we examined the effect of two different stimulants (fMLP, PMA) and three cytokines (alphaTNF, G-CSF and GM-CSF), both singly and in combination on granulocyte (RB) in 25 MDS patients compared to seven healthy controls. Single fMLP and PMA-stimulation showed similar results for both groups. Preincubation with cytokines enhanced fMLP-stimulated RB in most MDS patients and controls, but in patients to a significantly lesser extent when compared to the control group (p < or = 0,05). Combinations of alphaTNF + GM-CSF and alphaTNF + G-CSF were highly synergistic in priming fMLP-stimulated burst in both groups. But again, as with the single cytokine priming this effect was markedly reduced in MDS patients compared to controls (p < or = 0,05). A specific priming defect for one of the cytokines or a cytokine combination could not be demonstrated. Serum alphaTNF levels were measured in 18 and neutrophil alkaline phosphatase (NAP) index in 23 patients. Results did not correlate with variations of the RB in MDS patients. We conclude that reduced alphaTNF, GM-CSF and G-CSF priming of granulocyte RB is a frequent finding in MDS and may contribute to the enhanced susceptibility to bacterial infections.

Granulocyte colony-stimulating factor administration modulates the surface expression of effector cell molecules on human monocytes

Granulocyte colony-stimulating factor (G-CSF) has been shown to stimulate human neutrophil functions, both in vitro and in vivo. We examined the effects of G-CSF administration on the surface expression of effector cell molecules on human neutrophils and monocytes. G-CSF (50 micrograms/m2/d) was administered subcutaneously to five healthy volunteers once a day for 7 d. Venous blood was obtained immediately before and after the completion of G-CSF administration and 1 week after the last G-CSF administration. The surface expression of complement receptors (CR), Fc receptors for IgG(FcR) and cellular adhesion molecules on human neutrophils and monocytes were determined by indirect immunofluorescence using flow cytometry and monoclonal antibodies. The expression of CR1, CR3, FcRI and FcRII on neutrophils increased significantly after G-CSF administration and then decreased after the last G-CSF administration. The expression of human leucocyte adhesion molecule-1 (LAM-1) on neutrophils reflected the above expression. On the other hand, the administration of G-CSF increased the expression of CR1, CR3, FcRI and FcRIII on monocytes. The expression of CR1, CR3 and FcRI on monocytes then decreased after the last G-CSF administration, whereas the expression of FcRIII remained at an increased level. These findings indicate that G-CSF administration modulates the expression of effector cell molecules on circulating monocytes as well as on neutrophils, resulting in enhanced defence against selected infections or in potentiation of the tumouricidal capacity of phagocytes in cancer patients.

Serum cytokines, interleukin-2 receptor, and soluble intercellular adhesion molecule-1 in oral disorders

Serum levels of soluble intercellular adhesion molecule-1, soluble interleukin-2 receptor, and cytokines such as interleukin-3, interleukin-4, interleukin-6, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor were examined in patients with oral disorders with 20 healthy persons used as control subjects. Patients studied included 30 with squamous cell carcinoma, 26 with oral lichen planus, 20 with recurrent aphthous ulcer, 19 with acute odontogenic bacterial infection, 16 with pseudomembranous candidiasis, and 16 with herpetic gingivostomatitis. Compared with levels in control subjects, detectable serum levels of interleukin-3 (> or = 10 pg/ml) existed more frequently in pseudomembranous candidiasis (13/16), acute odontogenic bacterial infection (14/19), and squamous cell carcinoma (24/30) and of granulocyte-macrophage colony-stimulating factor (> or = 4 pg/ml) more frequently in recurrent aphthous ulcer (15/20) and squamous cell carcinoma (21/30). These cytokine levels were increased with T stage of squamous cell carcinoma. About 20 pg/ml of interleukin-4 was detected in serum from one third to one fourth of patients with oral lichen planus, recurrent aphthous ulcer, and squamous cell carcinoma. Tumor necrosis factor-alpha was hardly detected in most patients except those with oral lichen planus and squamous cell carcinoma in which about one third of the patients had more than 40 pg/ml of tumor necrosis factor-alpha in serum. More than 10 pg/ml of interleukin-6 was frequently detected in all disorders, especially recurrent aphthous ulcer (18/20), pseudomembranous candidiasis (12/16), and acute odontogenic bacterial infection (17/19).(ABSTRACT TRUNCATED AT 250 WORDS)

Filgrastim. A review of its pharmacological properties and therapeutic efficacy in neutropenia

Filgrastim, a recombinant human granulocyte colony-stimulating factor (G-CSF), has identical biological activity to that of endogenous human G-CSF, but differs in that it contains an N-terminal methionine residue and is not glycosylated. It principally stimulates activation, proliferation and differentiation of neutrophil progenitor cells and has been evaluated in the treatment of patients with various neutropenic conditions, both iatrogenic and disease-related. Two comparative studies have demonstrated that prophylactic administration of filgrastim 230 micrograms/m2/day significantly reduces the incidence, duration and severity of neutropenia in patients with previously untreated small-cell lung cancer receiving standard-dose chemotherapy with CDE (cyclophosphamide, doxorubicin plus etoposide). Concomitant with the amelioration of neutropenia, the incidence of febrile neutropenia was significantly reduced by 50% and there were 35 and 50% decreases in hospitalisation rates and intravenous antibiotic requirements. Since not all patients receiving standard-dose chemotherapy are at risk of infectious complications, prophylactic filgrastim use may be reserved for those patients who have developed febrile neutropenia during a previous cycle of the same regimen. This strategy may prove less costly, although potential savings must be weighed against a greater risk of patient morbidity and reduced quality of life. When combined with standard intravenous antibiotic therapy, filgrastim further decreases morbidity in patients with established febrile neutropenia and may have a positive impact on overall treatment costs by shortening the length of hospitalisation. Attention is focused on the use of haematopoietic growth factors to support dose-intensification of chemotherapy with a view to improving treatment outcomes in patients with chemo-responsive tumours. Filgrastim, used alone, permits modest increases in dose-intensity and/or dose-escalation of some standard-dose chemotherapy regimens. Moreover, the drug has proven useful as an adjunct to myeloablative chemotherapy followed by stem cell rescue with autologous bone marrow transplantation and/or peripheral blood progenitor cells. However, the impact of these dose-intensification approaches on survival remains to be determined in well-controlled clinical studies. Filgrastim is effective in increasing the neutrophil count and decreasing morbidity in patients with severe chronic neutropenia, including Kostmann's syndrome, and in idiopathic and cyclic neutropenia. In addition, filgrastim has accelerated neutrophil recovery in patients with idiosyncratic drug-induced agranulocytosis. Available data indicate that filgrastim is generally well tolerated. The most frequent adverse reaction is mild to moderate medullary bone pain, reported by approximately 20% of patients, although this can generally be controlled using simple analgesics without the need to discontinue treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunological findings in patients with myelodysplastic syndrome

Activation of monocytes and granulocytes in vitro by cytokines, in vivo administration of cytokines, as well as in vivo cytokine production due to infectious and inflammatory diseases causes changes of the surface expression density of certain membrane molecules. In recent studies we attempted to determine the feasibility of using flow cytometric immunophenotyping as a tool to develop a sensitive parameter for detecting infections at an early stage of disease when clinical parameters are still negative. Since infections are an important factor determining the clinical course of myelodysplastic syndromes (MDS), early detection of infection might be beneficial for these immunocompromised patients. We indeed found activation-associated immunophenotypic changes of cell surface antigens on monocytes and granulocytes of clinically infection free MDS patients suggesting enhanced immune activity in these patients, most likely due to latent or beginning infections. In particular, analyses of the expression density of receptors for IgG (Fc gamma Rs), complement receptors, and certain activation-associated surface molecules such as the CD67 and the M5 molecule seem to be of clinical relevance. We will also discuss findings concerning changes of cytokine levels and functional alterations of immunologic parameters in MDS patients.

Complement receptor type 1 (CR1) deficiency on neutrophils in myelodysplastic syndrome

We present a patient with myelodysplastic syndromes (MDS) whose neutrophils exhibited defective expression of complement receptor type 1 (CR1). A 73-year-old man was admitted with an evolution of MDS from RA into RAEBT according to the FAB classification of MDS. The neutrophil alkaline phosphatase (NAP) score was zero. The surface expression of membrane effector molecules on neutrophils was determined by indirect immunofluorescence using flow cytometry and monoclonal antibodies. The expression of CR1 on neutrophils as identified by staining with CD35 was defective in the patient, and the expression of other complement receptors (CR3 and CR4), Fc receptors and adhesion molecules was normal. CR1 deficiency and defective NAP score on neutrophils in the patient might account for impairment of common storage pool, presumably novel intracellular secretory vesicles.