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S Spisani

Publications and source records attributed to S Spisani.

At least 73 records · Page 4Linked to original sources
PubMed1994

Neutrophils from patients with myelodysplastic syndromes: relationship between impairment of granular contents, complement receptors, functional activities and disease status.

Myelodysplastic syndromes (MDS) are stem cell disorders of clonal origin in which infections and leukemic transformation are quite frequent. Neutrophils from 28 patients with MDS were analysed by flow cytometry for the expression of the two complement receptors CR1 and CR3, the antigenic reactivity of some granule constituents--myeloperoxidase, lysozyme, elastase, lactoferrin--and functional activities, such as locomotion, respiratory burst and cytotoxicity. The results were correlated with the FAB disease subtypes, grouped as low risk (RA) and high risk patients (RAEB, RAEB-t, CMML) and with 30 healthy subjects. A significant reduction in the percentage of neutrophil CR1, CR3 positivity and chemotaxis induced by endotoxin-activated serum was detected in the high risk group when compared with the low risk group and healthy controls. Furthermore, the high risk group also showed a low amount of myeloperoxidase, elastase, lysozyme and superoxide anion, but both low and high risk groups displayed reduced cellular cytotoxicity in comparison with the control. This work indicates that MDS patients belonging to the more advanced FAB categories frequently show multiple abnormalities in the expression of neutrophil complement receptors, and granular components (> 3), as well as in cell functions, suggesting the possibility of using these phenotypic abnormalities in the monitoring of disease progression.

Chemotaxis, Leukocyte↗
PubMed1994

Modified chemotactic peptides: synthesis and biological activity of HCO-Met-delta ZLeu-delta ZPhe-OMe.

For-Met-delta ZLeu-delta ZPhe-OMe (3) has been synthesized as a new analogue of the prototypical chemotactic agent For-Met-Leu-Phe-OMe (fMLP-OMe). Compound 3 is characterized by presence of two consecutive alpha,beta-didehydro amino acid residues [delta ZLeu = (Z)-alpha,beta-didehydroleucine; delta ZPhe = (Z)-alpha,beta- didehydrophenylalanine] located at the central and C-terminal position, respectively. When tested on human neutrophils the N-formyltripeptide 3, although less active than the parent, is able to induce chemotaxis, superoxide anion production and lysozyme release. The activity of 3 has been compared to that of related fMLP-OMe analogues containing a single delta ZPhe residue located at the C-terminal position.

Amino Acid Sequence↗
PubMed1994

Synthesis and biological activity of D-glucopyranosyl peptide T derivatives.

The solid phase procedure, based on the Fmoc (9-fluorenylmethyloxycarbonyl) chemistry, was used to prepare some peptide T analogues in which D-glucopyranosyl units are beta-O-glycosidically linked to Thr4 and/or Thr5 side chains. All glycopeptides showed significant human monocyte chemotaxis and high resistance to degradation by plasma or brain enzymes.

Amino Acid Sequence↗
PubMed1994

Synthesis and activity of new linear and cyclic peptide T derivatives.

Linear and head to tail cyclic hexapeptide analogs (Xaa-Thr-Thr-Asn-Tyr-Thr, Xaa = D-Asp or D-iso-Asp) of peptide T were prepared and tested for human monocyte chemotaxis. All new compounds showed significant bioactivity. In particular, the conformational restriction introduced into cyclo(-D-iso-Asp-Thr-Thr-Asn-Tyr-Thr-) was very suitable for CD4 receptor binding. The cyclic peptides also proved to be highly resistant to degradation by plasma or brain enzymes.

Amino Acid Sequence↗
PubMed1993

Synthesis and chemotactic activity of the fMLP analog HCO-Hmb-Leu-Phe-OMe.

The new fMLP analog HCO-Hmb-Leu-Phe-OMe (1), containing (S)-2-hydroxy-4-(methylthio)butyric acid (Hmb) in place of L-methionine at the N-terminal position, has been synthesized and fully characterized. The peptide 1 has been designed in order to improve the understanding of the role exerted by the formamido group in the binding interaction with the formylpeptide chemotactic receptors. Chemotaxis, superoxide anion production, and lysozyme release have been measured for both 1 and its deformylated analog Hmb-Leu-Phe-OMe 2. Results indicate that a strong hydrogen bond of the OH....O = C type may complement a weak H-bonding interaction involving the formylic proton as H-bond donor.

Amino Acid Sequence↗
PubMed1993

Fibroblasts increase adhesion to neutrophils after stimulation with phorbol ester and cytokines.

In our research there was spontaneous adhesion between resting fibroblasts and neutrophils in vitro which could be increased by stimulating either the coculture of cells or each cell type separately with various stimulants. Interferon-gamma, interleukin-1, and interleukin-6 significantly increased adhesion; however, the highest adhesive response was obtained when cocultures were treated with phorbol myristate acetate (PMA). As PMA-stimulated fibroblasts show the highest adhesion to resting neutrophils, it was suggested that adhesion was primarily due to an effect on fibroblasts. Without Mg2+ PMA did not stimulate fibroblast adhesion, whereas in the absence of Ca2+ the response was only partially reduced. Spontaneous adhesion was independent of both neutrophil integrins and fibroblast ICAM-1, whereas cytokine-stimulated adhesion was blocked by mAbs against ICAM-1; PMA-stimulated adhesion was not affected by mAbs anti-ICAM-1, but was partially inhibited by mAbs anti-beta 2 integrins. These results suggested the presence of mechanisms able to modulate the adhesive fibroblast-neutrophil interaction in inflammatory and wound healing processes.

Calcium↗
PubMed1993

Structure-activity relationships of cyclic and linear peptide T analogues.

Using the potent cyclic peptide T analog [formula: see text] as parent compound, a series of analogues were synthesized and their potencies in a monocyte chemotaxis assay were compared with those of correspondingly modified linear peptides. Structure-activity relationships observed with cyclic compounds did not always parallel those determined with linear analogues. [formula: see text] showed the highest affinity to CD4 receptor of monocytes of any peptide thus far studied. It also proved to be highly resistant to degradation by plasma or brain enzymes.

Amino Acid Sequence↗
PubMed1992

Modulation of neutrophil functions by activated platelet release factors.

Platelets activated with physiological agonists, such as thrombin, ADP, or collagen, released products able to modulate neutrophil functions. In particular, platelet supernatant contained an inhibitor of superoxide anion generation induced by phorbol ester and a chemotactic factor for human neutrophils. The proteolytic digestion of platelet supernatant completely abrogated chemotactic activity without interfering with the inhibitory effect, indicating the presence of different molecules involved in the modulation of different neutrophil functions. This was further confirmed by the pretreatment of platelets with aromatic benzamidine which abolished chemotactic activity, but did not affect superoxide inhibition of neutrophils. This report provides evidence for interaction of platelets and inflammatory cells, suggesting that platelets are able to induce accumulation of neutrophils and control their respiratory burst, which also has a critical role in tissue damaging in inflammation.

Benzamidines↗
PubMed1992

New chemotactic peptide analogs with high biological activity for human neutrophils.

As a part of a research programme aimed at studying structure activity relationships in the field of chemotactic peptides, modified analogs of the chemoattractant N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) were examined for their capacity to activate several functions of human neutrophils. 4-Aminotetrahydrothiopyran-4carboxylic acid (Thp) and 2-aminoindane-2-carboxylic acid (Ain) were chosen as achiral, conformationally restricted amino acids suitable for mimicking the external Met and Phe residues of FMLP-OMe. The replacement of both produces a high locomotion activity, greater than the parent peptide; in contrast, the two Thp-containing analogs induce neither superoxide production nor lysozyme release. From these results we can hypothesize two different signal transduction systems: one which provides for movement, the other for superoxide generation and granule enzyme release.

Amino Acid Sequence↗
PubMed1991

CD16 and CR3 receptors distinguish between the two mechanisms of tumour cytotoxicity in neutrophils.

Previous studies have suggested that phorbol ester-activated neutrophils kill both antibody non-coated and antibody-coated K562 target cells. In this report the contribution of the receptors Fc gamma III (CD16) and CR3 (CD11b/CD18) in the lytic process was investigated. In neutrophils CD16 and CR3 are up-regulated by the phorbol ester up to 4 and 10 times, respectively. As expected, lysis of non-immunized K562 targets is not affected by the treatment of neutrophils with anti CD16, AB8.28, whereas lysis of immunized targets is decreased by 50%. In addition, the interaction of CD16 and AB8.28 induces calcium mobilization and increases granule secretion. Surprisingly, the simultaneous binding of AB8.28 and anti-CR3 OKM1 to neutrophils completely abolishes the lysis of antibody-coated targets. Unlike CD16, CR3 does not possess a functional role and binding of OKM1 to CR3 does not affect cytotoxicity of immunized K562 targets, but it blocks lysis of non-coated target almost completely, indicating a function as adhesion protein for CR3. These studies demonstrate a distinct role of CD16 and CR3 in mediating antibody-dependent and antibody-independent cellular cytotoxicity, respectively.

Antibodies, Monoclonal↗
PubMed1991

Evaluation of CR1 expression in neutrophils from chronic myeloid leukaemia: relationship between prognosis and cellular activity.

The expression of the complement receptor CR1 has been evaluated using an immunoalkaline phosphatase staining method on peripheral blood neutrophils and granulocyte precursors from 22 patients with chronic myeloid leukaemia (CML) and 15 healthy subjects. The immunocytochemical labelling pattern of CR1 was evaluated semiquantitatively on cell smears using three different anti-CR1 monoclonal antibodies. The scoring method showed that seven patients with CML had a marked reduction in CR1 expression which did not change with in vitro stimulation of neutrophils with phorbol-myristate-acetate (PMA) whereas control cells responded to PMA, increasing the receptor level two-fold. In addition, functional analysis of neutrophils with low CR1 expression from CML patients showed a very low cytolytic activity against K562 tumour target, suggesting a relationship between the cellular content of CR1 and neutrophil tumouricidal activity. The involvement of CR1 in neutrophil-mediated lysis is consistent with complete lack of tumour toxicity following receptor neutralization by anti-CR1 monoclonal antibodies. Interferon therapy improved CR1 expression and the cytolytic response of neutrophils in three out of five CML patients with a moderately low CR1 score. CML patients non-responding to interferon therapy and those with a very low CR1 score, independent of the clinical stage, progressed more rapidly into the advanced clinical stage and blastic crisis.

Complement C3b↗
PubMed1991

Synthesis and properties of chemotactic peptide analogs. II. HCO-Met-Leu-Phe-OMe analogs containing cyclic alpha,alpha-disubstituted amino acids as Met and Phe mimicking residues.

As a part of a research program aimed at studying structure activity relationship in the field of chemotactic peptides, modified analogs of the potent chemoattractant HCO-Met-Leu-Phe-OH (fMLP) of the general formula HCO-Xaa-Leu-Yaa-OMe are examined. 4-Aminotetrahydrothiopyran-4-carboxylic acid (Thp) and 2-aminoindane-2-carboxylic acid (Ain) have been chosen as achiral, conformationally restricted amino acids suitable to mimick the external Met and Phe residues of fMLP-OMe. Studies on a first model, namely [Ain3]fMLP-OMe 1, have already been reported (12). Here the two remaining analogs [Thp1, Ain3] 2 and [Thp1] 3 have been synthesized. The conformation in the crystal of the disubstituted analog 2 has been determined and compared with those adopted by the parent fMLP-OMe and by previously studied models. The backbone conformation of 2 is characterized by helical folding centred at each of the three residues with the central Leu presenting helical handedness opposite to those of the two adjacent achiral residues. This conformation presents strong similarities with that adopted in the crystal by fMLP-OMe and resembles the conformation of fMLP bound to immunoglobulin (Bence-Jones dimer). The conformationally restricted analogs 2 and 3 are more active than the parent in the stimulation of directed mobility of human neutrophils but are practically inactive in the superoxide production. Crystals of 2 are orthorhombic, s.g. P2(1)2(1)2(1), with a = 21.934 (8), b = 10.856 (2), c = 10.380 (2) A. The structure has been refined to R = 0.071 for 2301 independent reflections with I greater than 1.5 sigma.

Amino Acid Sequence↗
PubMed1990

Chemotactic response of human monocytes to pentapeptide analog derived from immunodeficiency virus protein gp 120.

The octapeptide sequence of peptide T is contained within the envelope of HIV and seems to mediate the viral binding to CD4 expressing cells, including monocytes. The biological activity of the alpha-aminobutyric acid pentapeptide derived from the C-terminal sequence of peptide T, in which the polar side chain of threonine in position 4 is substituted by a hydrophilic group, is measured by the monocyte chemotaxis assay. The chemotactic activity of human monocytes is assessed by determining the concentration at which the pentapeptide analog is maximally active and the effectiveness at that concentration, in comparison with peptide T and two shorter homologs, the pentapeptide and tetrapeptide. These experiments suggest that the synthetic analog is a potent chemotactic factor active at picomolar concentrations and that it competes with peptide T for the monocyte binding site.

Chemotaxis, Leukocyte↗
PubMed1990

Dual mechanism in induction of human neutrophil cytotoxicity: activation of protein kinase C and elevation in intracellular calcium.

Human neutrophils can damage the non-immunized K562 cell line when stimulated by phorbol myristate acetate (PMA). The combination of the activation of protein kinase C by phorbol and the increase of free intracellular calcium by ionophore potentiates the lytic reaction. The OKT9-immunized target cells are not able to induce by themselves the lytic response in neutrophils, but by combining the two signals, the antigenic stimulus and PMA, a high level of cytolytic response is attained. The addition of EGTA does not affect neutrophil cytotoxicity against antibody-coated targets, while it markedly reduced the lytic reaction against non-immunized targets; in contrast, the addition of EGTA together with the ionophore ionomycin completely suppresses the lysis of immunized and non-immunized targets. The treatment of neutrophils with the protein kinase C inhibitor H-7 causes a dose-related inhibition of the lytic functions that is greater on unsensitized K562. Thus the interaction of Fc receptors with immunized targets is required for reaching the maximal cytolysis. The enhanced lytic activity that occurs in the presence of immunized targets is mediated by calcium flux, as detected by using the monoclonal antibody AB8.28 which binds to FcIII receptors (FcRIII), thus supporting that both signals are involved.

Antibodies, Monoclonal↗
PubMed1990

Synthesis, metabolic stability and chemotactic activity of peptide T and its analogues.

Acquired immunodeficiency syndrome (AIDS) is initiated by the attachment of the human immunodeficiency virus (HIV) to a surface glycoprotein CD4 present on T4 helper/inducer lymphocytes, monocytes/macrophages and other cells. A simple octapeptide (H-Ala-Ser-Thr-Thr-Thr-Asn-Tyr-Thr-OH, peptide T) seems to inhibit HIV infectivity and to activate human monocyte chemotaxis. In order to study in vitro metabolic stability and structure-activity relationships, peptide T and a number of analogues were prepared and tested on human monocytes by chemotactic assay. Peptide T and the shorter fragments T(3-8)-OH and T(4-8)-OH displayed potent bioactivity (maximal chemotactic activity in the range 10(-11)-10(-10) M). The C-terminal heptapeptide showed a reduction of potency, while further truncations at N-terminus of T(4-8)-OH abolished the biological action. In the octapeptide series, whereas the alpha-amino butyric acid (Abu) substitution for Thr4 was well tolerated, the same "slight" structural change at Thr5 or Thr8 was very detrimental. Finally, [D-Asn6]T(1-8)-OH analogue has low chemotactic activity. All these results indicate that i) the C-terminal pentapeptide is the minimum sequence required for bioactivity, ii) residues 5 to 8 appear to play a crucial biological role, iii) peptide T chemotaxis is mediated, at least in part, through the polar properties of Thr side chains at the critical positions 5 and 8, while the Thr4 does not interfere with biological characteristics of peptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

Neutrophil defect associated with hairy cell leukemia.

We have investigated the motility, superoxide anion production and tumor cell lysis of neutrophils from five patients affected by hairy cell leukemia. Random locomotion and chemotaxis towards denaturated casein and activated serum was normal as well as the superoxide production by opsonized zymosan. In contrast, chemotaxis and superoxide generation induced by FMLP and TPA were markedly reduced. The low responsiveness of neutrophils to TPA was also observed by evaluating cell lysis, against either non-immunized K562 target cells or antibody-coated tumor targets. In hairy cell leukemia neutrophils showed a selective reduced response to TPA and FMLP that, directly or indirectly, activate PKC, suggesting an impairment in the system of signal transduction.

Cell Movement↗