PubMed Health⌕ Search

Biomedical subjects

F Patrone

Publications and source records attributed to F Patrone.

At least 19 recordsLinked to original sources
PubMed1992

Influence of ST 789 on human neutrophil function in vitro.

We report the results of our in vitro experiments on the effects of an L-Arg terminal synthetic hypoxanthine derivative (ST 789) on human neutrophil function. To verify the hypothesis that the reported immunomodulatory effects of ST 789 in vivo are accounted for, at least in part, by effects on phagocytic cells, we experimented in parallel also with methisoprinol, a well known stimulator of neutrophil chemotaxis, structurally related to ST 789. Our results demonstrate that ST 789 is able to improve the true chemotactic response of human neutrophils without interfering with other phagocytic functions, following a pattern largely shared by methisoprinol. Accordingly, ST 789 may be able, when used in vivo, to prime neutrophils for timely and efficient migration to inflammatory sites, and it could be considered for therapeutic use in patients with impaired inflammatory response or severe infections.

Adjuvants, Immunologic↗
PubMed1991

Tumor cell lysis by activated human neutrophils: analysis of neutrophil-delivered oxidative attack and role of leukocyte function-associated antigen 1.

The lysis of tumor cells, and other nucleated mammalian cells, by neutrophilic polymorphonuclear leukocytes (PMNs) triggered by phorbol myristate acetate (PMA) represents a widely used model system to dissect the PMN cytolytic armamentarium, potentially responsible for the cell damage at tissue sites of PMN activation. Although oxidants are generally considered to be instrumental in the target lysis by PMNs, the mediators actually involved remain a matter of controversy. Moreover, other factors potentially crucial to the lysis have not been clearly identified. In order to reexamine the determinants of the cytolytic process, we studied the events underlying the PMA-triggered PMN-delivered attack against two different targets, selected on the basis of preliminary experiments (B lymphoblastoid Daudi cells and erythroleukemic K 562 cells). The results suggest that the lysis is promoted by hypochlorous acid (HOCl) or a compound with characteristics very similar to HOCl itself. No evidence was obtained for the intervention or contribution of hydrogen peroxide (H2O2), hydroxyl (OH.) radicals, and the major HOCl-derived chloramines. PMNs appeared to use 35% of the generated H2O2 to produce HOCl, while the remainder appears to be consumed by PMNs themselves and target cells as well. Moreover, PMNs and target cells coaggregated at an early step of the cytolytic reaction, through a process efficiently prevented by a monoclonal antibody (MoAb J-90) directed against leukocyte function-associated antigen-1 (LFA-1). The inhibition of the PMN-target aggregation by the MoAb J-90 resulted in the impairment of the lysis, despite a normal generation of HOCl. Thus, the data demonstrate that the PMA-triggered lysis of tumor target cells by PMNs requires at least two events, occurring simultaneously: the LFA-1-mediated effector-target adherence and the PMN production of HOCl. The intervention of the LFA-1-mediated PMN-target adherence in the PMA-triggered lysis is likely to allow PMNs to focus HOCl on the target cell surface and suggests that the process requires a sort of molecule to molecule recognition at the effector-target surface level.

Antibodies, Monoclonal↗
PubMed1991

Suppression of lymphokine-activated killer (LAK) cell function by neutrophil polymorphonuclear leukocytes.

Peripheral blood neutrophil polymorphonuclear leukocytes (PMN) from healthy donors were found to inhibit the cytolytic efficiency of interleukin 2 (IL-2)-activated lymphocytes (LAK cells) in a dose-dependent manner. The inhibitory activity of PMN was not merely due to PMN acting as cold alternative targets, PMN ingestion of the label released by target cells or cell overcrowding in test wells. Heat-treated (50 degrees C, 30 min) lysates from PMN maintained their ability to inhibit LAK cell cytotoxicity, whereas PMN supernatants were completely ineffective. Oxidant scavengers (catalase, superoxide, dismutase) did not affect the PMN-mediated inhibition of LAK cell function. The results suggest that PMN contain heat-stable factor(s) able to suppress LAK cytotoxicity and potentially capable of limiting the therapeutic efficacy of IL-2 and/or LAK cells.

Catalase↗
PubMed1990

Cytoprotection against neutrophil derived hypochlorous acid: a potential mechanism for the therapeutic action of 5-aminosalicylic acid in ulcerative colitis.

The aim of the present study was to investigate the effects of 5-aminosalicyclic acid (5-ASA) on the cell injury mediated by activated neutrophils. We used a system constituted of neutrophils, triggered with phorbol myristate acetate, and 51Cr-labelled Daudi cells as targets. The results show that 5-ASA is capable of efficiently preventing neutrophil-mediated lysis. 5-ASA was up to 10-fold more effective than taurine, which acts as an hypochlorous acid scavenger. Moreover, 5-ASA was found to compete with taurine for the neutrophil derived hypochlorous acid. The results are consistent with the conclusion that 5-ASA is capable of limiting the neutrophil mediated cell damage by scavenging the generated hypochlorous acid. This may represent a potential mechanism for the therapeutic action of 5-ASA in ulcerative colitis.

Aminosalicylic Acids↗
PubMed1990

Inactivation of neutrophil-derived hypochlorous acid by nimesulide: a potential mechanism for the tissue protection during inflammation.

The anti-inflammatory drug nimesulide was found to effectively reduce the availability of hypochlorous acid, the most potent chlorinated oxidant generated by the myeloperoxidase system of activated neutrophils. Such an effect was observed at concentrations achievable in vivo after the oral administration of the drug. Higher concentrations of nimesulide were also found to limit both the oxygen consumption and the superoxide anion/hydrogen peroxide production by neutrophils. Taken together, the results suggest that nimesulide is endowed with a high potential to efficiently control the harmful effects of oxidants produced by neutrophils at inflammatory tissue sites.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1989

Platelets as scavengers of neutrophil-derived oxidants: a possible defence mechanism at sites of vascular injury.

Platelets (PLTs) were found to inhibit the chemiluminescence (CL) response of neutrophils (neutrophilic polymorphonuclear leukocytes, PMNs) activated with phorbol myristate acetate. The inhibition of the PMN CL response could be efficiently prevented by pulsing PLTs with carmustine (BCNU) to block their glutathione cycle. In ancillary experiments, the CL response of PMNs was inhibited by catalase (H2O2-scavenger), -azide (myeloperoxidase-MPO-inhibitor), taurine (hypochlorous acid-HOCl-scavenger) and chloride ion omission. These data suggest that the PMN CL response requires the HOCl production by the following pathway: H2O2 + Cl--MPO----H+ HOCl + H2O. Therefore, the BCNU-preventable PLT-induced inhibition of CL may reflect the consumption of PMN-derived H2O2 by the PLT glutathione cycle with a consequent impairment of the HOCl production. Consistent with such a possibility, PLTs lowered the H2O2 and HOCl recovery from PMNs via a BCNU-inhibitable process. Based on these results, we suggest that PLTs have the capacity of limiting the oxidant production by PMNs. This PLT capacity may represent a natural device for the protection of vascular structures from PMN-mediated oxidative stresses.

Blood Platelets↗
PubMed1989

Platelets as inhibitory cells in neutrophil-mediated cytolysis.

Neutrophilic polymorphonuclear leukocytes (PMNs), triggered by opsonized zymosan (OPZ), lysed chicken red blood cells as measured by a chromium 51 release method. The lysis was prevented by scavengers of hypochlorous acid. When platelets were added to the cytolytic system, a dose-dependent inhibition of the lysis was observed. Moreover, platelets lowered the HOCl recovery from OPZ-triggered PMNs. A positive linear relationship was found between the extent of the lysis mediated by and the amount of HOCl recovered from PMNs. Finally, both the inhibition of the lysis and the reduction of the HOCl recovery induced by platelets were prevented by pulsing platelets with carmustine (BCNU) to block their glutathione cycle. These results suggest that platelets act by consuming via their glutathione cycle significant amounts of PMN-derived hydrogen peroxide, with a consequent impairment of the PMN HOCl production and, in turn, lytic efficiency. Consistent with such a conclusion, platelets were found to consume PMN-derived H2O2 via a BCNU-inhibitable process. Further, the platelet inhibitory activity could be abolished by the addition of an appropriate extra-flux of enzymatically generated H2O2. No evidence for a platelet-induced inhibition of OPZ-PMN interaction, PMN myeloperoxidase release, and H2O2 production was obtained. The present study provides direct evidence for a platelet-dependent mechanism capable of controlling the PMN production of highly reactive oxidants and, in turn, the PMN cytolytic activity.

Acute-Phase Reaction↗
PubMed1989

Effector-target co-aggregation as a crucial step in the neutrophil-mediated tumour cell lysis.

The Daudi cell lysis by human neutrophils, incubated with phorbol myristate acetate (PMA), was inhibited by amino acids (taurine, methionine), consistent with the involvement of hypoclorous acid (HOCl) in the lytic process. Also, the lysis was inhibited by a monoclonal antibody (mAb J-90) directed against the leukocyte function-associated antigen-1 (LFA-1). The inhibition of the target cell lysis by mAb J-90 is not due to a HOCl-scavenging mechanism, as suggested by the use of control mAb Dako M-1 (anti CD-15). As detected by the microscopic examination of samples from test tubes and measured by monitoring the light transmission from the cell suspensions, neutrophils and Daudi cells were found to co-aggregate during the lytic reaction. Co-aggregation was efficiently inhibited by the mAb J-90. The results suggest that tumour cell lysis by PMA-triggered human neutrophils involves at least two events: production of HOCl and LFA-1-mediated effector-target adhesion.

Antibodies, Monoclonal↗
PubMed1989

Defective antibody-dependent tumour cell lysis by neutrophils from cancer patients.

Neutrophil antibody-dependent cellular cytotoxicity (ADCC) against Raji target cells was studied in 32 patients with lung or gastro-intestinal carcinoma and 25 healthy controls. Seventeen of the patients (53%) had defective ADCC. Moreover, neutrophils obtained from patients with defective ADCC were found to bind IgG-coated target cells normally. Thus, the defect responsible for the impaired lysis appears to be distal to the Fc receptor (FcR)-mediated target cell binding by neutrophils.

Adult↗
PubMed1988

Monocyte-derived macrophages as helper cells in monocyte-mediated cytolysis.

Human peripheral blood monocytes (M), incubated with opsonized zymosan particles (OPZ), lysed human erythrocyte (RBC) targets, as detected by a 51Cr release method. Conversely, cells derived in vitro from M (monocyte-derived macrophages, MDM) were ineffective. When added to the M-RBC system, MDM enhanced the lysis. The lysis by M and M plus MDM was prevented by catalase, azide and amino acids (alanine, taurine), consistent with the requirement for hypochlorous acid (HOCl). Moreover, MDM per se incapable of generating HOCl augmented the HOCl recovery from the M-RBC system. The results provide evidence for a previously unrecognized form of interaction between two distinct populations of mononuclear phagocytes.

Amino Acids↗
PubMed1988

Neutrophil-induced depletion of adenosine triphosphate in target cells: evidence for a hypochlorous acid-mediated process.

Human neutrophils, incubated with phorbol myristate acetate (PMA), caused a rapid and substantial adenosine triphosphate (ATP) depletion in lymphoblastoid Daudi cells without producing lysis. Catalase (which destroys hydrogen peroxide), taurine and methionine (which scavenge hypochlorous acid), and chloride omission from the medium prevented the ATP fall. An ATP depletion comparable to that induced by neutrophils was observed by replacing neutrophils with an appropriate myeloperoxidase-H2O2-Cl- enzymatic system. Together, these data suggest that the neutrophil ATP depleting activity involves the myeloperoxidase-catalyzed transformation of H2O2 into HOCl. Moreover, the free H2O2 remaining in the neutrophil extracellular environment is ineffective. In fact, a comparable amount of enzymatically generated H2O2 did not cause Daudi cell ATP loss. A direct role for H2O2 in the neutrophil-induced Daudi cell ATP depletion was observed only under artificial conditions, that is, in the presence of the heme enzyme inhibitor azide, which prevented the HOCl production but dramatically augmented the extracellular H2O2 level. Similar levels of ATP depletion in Daudi cells were induced by amounts of reagent HOCl comparable to those generated by neutrophils. As the generated HOCl can rapidly react with a variety of neutrophil-derived nitrogenous compounds (primarily ammonia and taurine) to yield chloramines, these chlorinated oxidants might contribute to the neutrophil-mediated ATP depletion. Nevertheless, the main and well-characterized chloramines (ammonia-derived monochloramine, NH2Cl, and taurine monochloramine, TauNHCl) were devoid of ATP-depleting capacity. Thus, the results suggest that the neutrophil-induced ATP depletion in Daudi cells is HOCl-dependent, is not mediated by NH2Cl or TauNHCl, and could be promoted either by HOCl directly or by an unknown derivative oxidant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1988

Cytolysis mediated by phagocytosing neutrophils. Influence of the presence of an alternative target cell population.

When added to the hypochlorous acid (HOCl)-dependent cytolytic system constituted of opsonized zymosan (OPZ)-triggered neutrophils and chicken erythrocyte (CRBC) targets, human erythrocytes (HRBCs) inhibited the lysis. The replacement of HRBCs with cells pretreated with amino-triazole (AT) to inactivate catalase prevented the HRBC inhibitory effect almost completely. HRBCs, pretreated with carmustine (BCNU) to inhibit glutathione cycle activity, behaved as untreated cells. Thus, HRBCs appear to protect CRBCs via an AT-inhibitable, i.e. catalase-dependent, process. When measured under conditions similar to those used for the lytic assay, both the hydrogen peroxide (H2O2) and the HOCl recovery from the neutrophil-CRBC system was reduced by HRBCs and restored by pulsing HRBCs with AT but not BCNU. The results suggest that HRBC catalase rescues CRBCs from neutrophil-delivered attack by "stealing" H2O2 from the neutrophil HOCl-generating myeloperoxidase (MPO)-H2O2 system.

Animals↗
PubMed1987

Augmentation of neutrophil-mediated erythrocyte lysis by cells derived in vitro from human monocytes.

Neutrophilic polymorphonuclear leukocytes (PMNs) were incubated with opsonized zymosan and lysed human erythrocytes (RBCs) as measured by a 51Cr release method. Conversely, myeloperoxidase (MPO)-negative hydrogen peroxide (H2O2)-generating cells, derived in vitro from human monocytes (monocyte-derived cells (MDCs), were ineffective per se but capable of augmenting the lysis by PMNs. The lysis by PMNs and PMNs plus MDCs was inhibited by catalase, azide, taurine, and alanine, consistent with the requirement for hypochlorous acid (HOCl). As detected under conditions similar to those used for lytic assays, MDCs failed to produce HOCl but augmented the HOCl recovery from the PMN-RBC system. Moreover, when the extent of the lysis was plotted as a function of the HOCl recovery, a positive linear relationship was found. Although the actual size of the H2O2 extracellular pool could not be measured because of the inexistence of a reliable assay to probe our cytolytic model without perturbing the equilibrium of the system, the results presented suggest that MDCs enhance the PMN-mediated lysis by improving the HOCl production, presumably by supplying extra amounts of H2O2 to be handled by PMN MPO. In fact, the events mediated by MDCs could be reproduced by using an appropriate H2O2-generating enzymatic system (glucose-glucose oxidase). The present study provides direct evidence for the possibility of cooperation between MPO-positive and MPO-negative phagocytes in exerting functions (HOCl production and, in turn, cytolysis) possibly relevant to the outcome of inflammatory processes.

Cells, Cultured↗
PubMed1987

Relationship between antibody-dependent tumour cell lysis and primary granule exocytosis by human neutrophils.

Neutrophil-mediated antibody-dependent cellular cytotoxicity (ADCC) against Raji target cells and neutrophil degranulation during the ADCC process were evaluated in the presence and in the absence of different agents able to interfere with the neutrophil release of granule components (anion channel blockers, colchicine, isoproterenol, dimethylxanthine, cAMP). When used at concentrations incapable of preventing the target cell recognition by neutrophils, the majority of these agents inhibited both the ADCC and the release of myeloperoxidase (MPO, primary granule marker) and lysozyme (LZM, primary and secondary granule marker). The inhibition of the ADCC correlated strictly with the inhibition of the MPO release. Thus, the results are consistent with the hypothesis that neutrophil primary granules play a major role in the cytolytic process.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1987

Erythrocyte lysis by monocytes: investigations on the mechanism and role of the target cell hydrogen peroxide catabolizing pathways.

The erythrocyte (RBC) lysis by human monocytes incubated with opsonized zymosan particles (OPZ), was inhibited by catalase, chloride-free medium, azide and hypochlorous acid (HOCl) scavengers (taurine, alanine). These findings suggest the requirement for the HOCl-generating myeloperoxidase-hydrogen peroxide-chloride system (MPO-H2O2-Cl- system). The HOCl-dependent lysis was increased by inhibiting RBC catalase with aminotriazole (AT). Conversely, the inhibition of RBC glutathione cycle with 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) had no detectable effect. Moreover, the recovery of H2O2 and HOCl from OPZ-triggered monocytes was reduced by the presence of RBCs through a process almost completely preventable by pulsing RBCs with AT but not with BCNU. Thus, it appears that RBC targets protect themselves by consuming, primarily via catalase, significant amounts of monocyte-derived H2O2 with a consequent impairment of the HOCl generation. The results suggest a potential role of target cells in modulating the cytolysin production by monocytes.

Erythrocytes↗
PubMed1987

Antibody-dependent tumour cytolysis by human neutrophils: effect of synthetic serine esterase inhibitors and substrates.

The requirement for serine esterase activity in antibody-dependent cellular cytotoxicity (ADCC) in human neutrophils against Raji target cells has been investigated. The lysis was prevented when the serine esterase inhibitors TPCK and TLCK (chloromethyl-ketone derivatives of tosylamino acids) were introduced into the system. Moreover, neutrophils pretreated with TPCK or TLCK and washed were inhibited as well, via a process unaffected by the presence of adequate amounts of enzymatic substrates. This suggests that the inhibition mediated by TPCK and TLCK is independent of serine esterase blockade, therefore implying the inactivation of some other step crucial to the lysis. The addition of synthetic chymotrypsin substrates (tyrosine and phenylalanine esters) impaired the Raji cell lysis in a dose-related manner without altering the constitution of neutrophil-target conjugates. Trypsin ester substrates were ineffective. These results are in agreement with the involvement of a serine esterase activity with chymotrypsin-like specificity, which should participate in the lysis at a post-binding step. We conclude that neutrophil-mediated ADCC, as developed in our model system, needs the intervention of a serine esterase or esterases, like other systems of cell-mediated cytotoxicity.

Antibody-Dependent Cell Cytotoxicity↗