Carlo Sacchetti

In vitro Effects of Synthetic Chemotactic Peptides on Neutrophil Function

The effects of the three synthetic chemotactic N-formyl-L-methionyl peptides, namely f-met-phe, f-met-val and f-met-ala, on neutrophil chemotaxis, adhesiveness, oxidative metabolism, phagocytosis and killing were evaluated in vitro. The three peptides displayed different stimulating properties, with relative activity f-met-phe greater than f-met-val greater than f-met-alal for all functions tested. Experiments performed with chemotactically deactivated neutrophils showed that deactivation does not interfere with neutrophil functions other than chemotaxis and does not prevent further stimulation by the same chemo-attractant. The results demonstrate that the interaction of a single chemotactic agent with neutrophil membrane can trigger different cellular responses, dependent in their type and intensity on the concentrations of the chemotactic factor and on the functional state of the cell.

Buckley's syndrome

An infant girl with chronic eczema, recurrent infections, elevated IgE and impaired neutrophil chemotaxis appeared to belong to the group of patients described by Buckley, Wray & Belmaker (1972). An hereditary influence is suggested by a similar defect found in the patients mother. Levamisole improved the in vitro defect and the clinical picture.

Ox Erythrocyte Cytotoxicity by Phorbol Myristate Acetate-Activated Human Neutrophils

Human neutrophils activated by phorbol myristatc acelatc were cytoioxic lo ox erythrocyles. as determined by the 51Cr release method. Maximal cytolysis was obtained with a phorbol myristute acetate concentration of 5 ng/ml and with an etTcctor to target cell ratio of 1:4. An inlact neutrophil metabolic burst and production of oxygen‐dcrived‐frec radicals were essential lor the cytotnxic event, since neulrophils from patients with chronic granulo‐malous disease failed to exhibit any ox erythrocyte lysis. The target cell destruction was completely prevented by catalase, was unaffected by supcroxidc dismutase. and was reduced approximately to one‐third by azide and cyanide. These data suggest that, under our experimental conditions, the ox erythrocyte killing by phorbol myristatc acetate‐activated neutrophils mainly depends on myelopcroxidasc and hydrogen peroxide.

Reversal by cimetidine of histamine-induced inhibition of true chemotaxis in neutrophil polymorphonuclears

SummaryThe effects of histamine and cimetidine on neutrophil locomotion were studied in vitro in experimental conditions able to dissociate random from truly directional motility. Histamine 10−4 mol/l inhibited the true chemotactic response. Cimetidine was able to reverse the histamine-induced inhibition of true chemotaxis.Since histamine-induced inhibition of neutrophil chemotaxis may play a role in allergic patients with repeated infections, and since cimetidine has been shown to enhance cell-mediated immunity in vivo, often impaired in such cases, the use of cimetidine is suggested for the prevention of recurrences in these patients.

Lazy leukocyte syndrome

ZusammenfassungBei einer 35jährigen Patientin bestanden seit Jahren Neutropenie und Infektanfälligkeit. Die Diagnose eines „Lazy Leukocyte“Syndroms ergab sich aus folgenden Befunden: gestörte Neutrophilen-Chemotaxis; eingeschränkte ungerichtete Motilität und In-vivo-Migration; verminderte Granulozyten-Freisetzung aus dem Knochenmark bei EtiocholanolonReiz trotz normaler Knochenmarks-Zellularität. Klinische Befunde und pathophysiologische Aspekte der bisher mitgeteilten 5 Fälle dieses Syndroms werden besprochen.SummaryA-35-year-old woman with a long-lasting history of neutropenia and recurrent infections was found to have defective neutrophil chemotaxis, random motility, and in vivo migration. Although the bone marrow granulocyte reserve was normal, the patient failed to release an appropriate amount of granulocytes after injection of etiocholanolone. These features are characteristic of the so-called „Lazy leukocyte syndrome“. The clinical presentation of the five cases of this syndrome so far reported and its pathophysiological aspects are discussed.

In vitro function of chronic myelocytic leukemia granulocytes. Effects of irradiation and storage.

Granulocyte function was studied in 9 patients with untreated, Ph1-positive chronic myelocytic leukemia (CML). The nitroblue tetrazolium reduction by stimulated granulocytes was impaired in all patients; 4 patients also had diminished phagocytosis and 2 others defective Chemotaxis. In spite of this variety of polymorphonuclear (PMN) functional impairments, there is little evidence of increased susceptibility to infections in CML patients. This suggests that CML-PMN leucocytes (PMNs) may be successfully used for transfusion into neutropenic recipients, as previously reported. To evaluate the effects of irradiation and liquid storage on CML-PMNs, 5 of our patients were subjected to leukapheresis by continuous-flow centrifugation in the Aminco Celltrifuge, and granulocyte functional capacities were also evaluated on the cell-rich plasma immediately after collection and after short-term storage at 4°C with or without irradiation (1500 rads). As evaluated by in vitro studies, granulocytes maintained, even after irradiation, functional activities similar to those found immediately after collection up to 24 h of storage at 4°C and presented a moderate loss of function after 48 h. Chemotaxis appeared to be the most sensitive detector for cellular damage of stored leucocytes, irradiated and non-irradiated, so that it might be used for assessment of leucocyte function before transfusion.

Effects of N-(2-mercaptopropionyl) glycine on neutrophil locomotion.

The effects of the sulphydryl group donor N-(2-mercaptopropionyl) glycine on neutrophil locomotion were evaluated in vitro. The drug, when used at a concentration of 10(-3) M was found to stimulate the random migration and chemotaxis of normal neutrophils as a result of an enhanced rate of locomotion. The true chemotactic response was unaffected. N-(2-mercaptopropionyl) glycine appeared to exert its effect on the whole moving cell population.

Stimulation of granulocyte adhesiveness by the chemotactic peptide N-formyl-L-methionyl-L-phenylalanine

SummaryThe in vitro effects of the peptide N-formyl-L-methionyl-L-phenylalanine on granulocyte adhesiveness and chemotaxis were investigated. N-formyl-L-methionyl-L-phenylalanine, when used at concentration chemotactically effective, increased significantly granulocyte adhesiveness. When granulocyte adhesiveness was inhibited by colchicine, the inhibition could not be reversed by subsequent treatment with N-formyl-L-methionyl-L-phenylalanine. These results suggest that microtubular system is involved in the stimulation of granulocyte adhesiveness by N-formyl-L-methionyl-L-phenylalanine.

Influence of the spleen on the blood distribution of the leukocytes producing colony-stimulating activity (CSA) in man

SummaryThe colony-stimulating activity (CSA) produced by the blood leukocytes has been studied before and after epinephrine administration in ten normal, 15 splenomegalic, and seven splenectomized subjects through a double layer agar culture system.A significant increase of mean values of the CSA per milliliter produced by blood monocytes has been observed after epinephrine administration in the groups of normal and of splenomegalic subjects. In the group of splenectomized subjects the baseline mean value of CSA per milliliter of blood was higher than those observed in the other groups, but it did not show any increase after epinephrine infusion.The CSA produced by 106 blood leukocytes was similar in all three groups of subjects, and it was not similarly modified by epinephrine administration.Our results seem to indicate that the leukocytes producing CSA are distributed within two rapidly exchangeable blood compartments, the spleen representing an important section of the marginal compartment of blood monocytes.