Claudia Angiolini

Detection of Eosinophils in Whole Blood Samples by Flow Cytometry

A flow cytometric method to detect and study human eosinophils in whole blood was established. Normal subjects and patients with various types of eosinophilia (hypereosinophilic syndromes, allergic diseases, dermatitis, Hodgkins Disease, parasitosis) were studied. Whole blood samples were treated for 10 minutes at room temperature with a commercially available reagent (FACS Lysing Solution, Becton Dickinson) which acts both as a fixative and as a lysing agent. Eosinophils were identified as a granulocytic subpopulation with higher SSC and FSC properties. This cell population was characterized by evident autofluorescence and hypodiploid DNA features after propidium iodide staining. The purity of the eosinophil population sorted after electronic gating was close to 100%. A very significant correlation between eosinophil counting by our whole blood method and other two assays, namely routine automatic counting by the H*3 Bayer System and eosinophil detection by depolarized SSC, was obtained. The phagocytic properties of eosinophils were also studied by means of a commercially available diagnostic kit, thus demonstrating that our method is also suitable for the study of those granulocytic functions which can be evaluated by flow cytometry.

Inhibitory Effects of Human Neutrophil Functions by the 45-kD Glycoprotein Derived from the Parasitic Nematode Trichinella spiralis

Aim: We evaluated the effect of the 45-kD protein of Trichinella spiralis (gp45), purified by affinity chromatography, on random migration and chemotaxis, the oxidative metabolism of human neutrophils and on the CD11b upregulation induced by formyl-methionyl-leucyl-phenylalanine (f-MLP). Methods: Donor neutrophils incubated with different amounts of gp45 (0.5, 1, 1.5, 2 μg/ml) or buffer and the random migration and chemotaxis, evaluated by means of a special technique of image analysis, and the chemiluminescence response to f-MLP or phorbol myristate acetate (PMA) were analyzed. The effect on CD11b upregulation was assessed incubating cells with the protein, when activating them with f-MLP. Results: The results showed that gp45 inhibited both random and stimulated migrations, and reduced the response to f-MLP and PMA. Furthermore, gp45 significantly reduced the upregulation of the CD11b induced by f-MLP. Conclusion: The results show that gp45 inhibits PMN in different functions, suggesting an anti-inflammatory action.

Actin polymerization in neutrophils from patients affected by myelodysplastic syndromes—A flow cytometric study

In this study F-actin polymerization in neutrophils from 21 patients affected by myelodysplastic syndromes (MDS) was evaluated by means of a flow cytometric assay. Neutrophils were stimulated with formyl-methionyl-leucyl-phenylanaline (fMLP; 10(-8) M final concentration) for 15, 30, 60 and 120 sec, and F-actin content was determined using fluorescein-isothiocyanate phallacidin as a specific probe. Eight normal subjects were studied as controls. We found that F-actin polymerization was defective in ten patients, with very impaired values after 60 and 120 sec of stimulation with fMLP. The remaining 11 patients showed a prevalent neutrophil population with normal F-actin polymerization and neutrophil sub-populations with either defective or undetectable F-actin polymerization. In the first group, patients with very poor prognosis (refractory anemia with excess blasts, refractory anemia with excess blasts in leukemic transformation, trisomy 8, multiple karyotypic abnormalities) were present, although patients with aberrations of karyotype were present in the second group. It is possible that defects in neutrophil F-actin polymerization may be responsible for neutrophil dysfunction, which has frequently been observed in MDS.

Interactions between platelets and neutrophils in essential thrombocythaemia. Effects on neutrophil chemiluminescence and superoxide anion generation

Abstract. Essential thrombocythaemia (ET) is frequently associated with neutrophil and platelet dysfunction, and with increased incidence of vascular complications (thrombosis, haemorrhage). Several interactions between platelets and neutrophils have been reported, and the reciprocal actions between these cells may have an important role both in thromboregulation and in diseases such as those caused by uncontrolled neutrophil activation. In the current paper the authors studied 15 patients affected by ET and 10 normal subjects as controls. Circulating neutrophils and platelets were purified and were re‐combined in constant ratios (50:1, 100:1 and 200:1) and the individual platelet to neutrophil ratio. Super‐oxide anion (O‐2) generation and luminol‐enhanced chemiluminescence (CL) were studied after neutrophil stimulation with fMLP. In normal subjects both O‐2 generation and CL were inhibited by autologous platelets in a dose‐dependent manner. In ET patients, on the contrary, platelet‐dependent inhibition of O‐2 generation did not occur, while a dose‐dependent inhibition of CL was observed. Two groups of ET patients were found: patients with neutrophil O‐2 generation and CL within the normal range, and patients with significantly reduced neutrophil respiratory burst. However, no differences were found between these two groups of patients in terms of platelet effects towards fMLP‐stimulated neutrophils. Therefore, platelets from ET patients were not able to exert the homeostatic control towards neutrophil O‐2 generation shown by platelets from normal subjects, and this phenomenon may have a role in the clinical setting. In fact, O‐2 has been shown to be a very strong direct platelet activator, is able to inactivate nitric oxide (which is a powerful inhibitor of platelet aggregation and adhesion to endothelium), and is directly involved in neutrophil‐mediated tissue damage.

Luminol-enhanced, whole blood chemiluminescence of human neutrophils evaluated by means of an automated, computer-assisted, and high-sensitivity luminescence analyzer

SummaryLuminol-enhanced whole blood chemiluminescence of human neutrophils was studied using opsonized zymosan as a stimulus. Heparinized blood (0.5μl) was used, and the chemiluminescence signals were recorded by a very sensitive, automated, and computer-assisted luminometer (LB 950, Berthold, Wildbad, Germany). The following parameters were provided: integral values over the total measuring time, peak values, the time to reach maximum value, and the time to reach half maximum value. Normal subjects, neutropenic patients, subjects with total or partial myeloperoxidase deficiency, patients with recurrent infections, phagocytic defects, thrombocythemic patients, and those with non-Hodgkins lymphomas undergoing therapy with recombinant human granulocyte colony-stimulating factor were studied. The integral response of chemiluminescence and the time of reach half maximal value were useful indicators of chemiluminescence defects; the assay, was able to detect chemiluminescence responses in neutropenic subjects with neutrophil levels as low as 0.6×109/I; differences between cellular and plasma defects could be identified; the quenching effect of exerted by erythrocytes was negligible.

Neutrophil functions in essential thrombocythemia

Chronic myeloproliferative diseases, such as chronic myeloid leukemia and polycythemia vera, are associated with neutrophil dysfunction. Very little data is available on essential thrombocythemia (ET). In the current study we evaluated 21 patients with ET. All patients were studied at least 16 weeks after any cytostatic therapy and 10 days after any other therapy. Neutrophil functions were investigated as follows: flow cytometric evaluation of whole blood phagocytosis of opsonized FITC-conjugated E. coli; whole blood chemiluminescence after stimulation with opsonized zymosan and evaluation by an automated, computer-assisted luminometer (LB 950, Berthold); and chemiluminescence and superoxide anion generation by purified neutrophils after f-MLP and PMA stimulation. Chemiluminescence and superoxide anion generation after f-MLP stimulation were found to be significantly lower than in normal subjects, whereas values within the normal ranges were registered after PMA stimulation. Phagocytosis-associated chemiluminescence was found to be impaired both by using zymosan opsonized with autologous plasma and zymosan opsonized with normal plasma, despite a normal phagocytic activity. These data show the presence in ET of a complex neutrophil dysfunction that may be related to an impaired signal transduction during both the phagocytic process and f-MLP stimulation.