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Biomedical subjects

C E Hack

Publications and source records attributed to C E Hack.

At least 199 records · Page 11Linked to original sources
PubMed1996

Inactivation of factor Xia in vivo: studies in chimpanzees and in humans.

C1-inhibitor (C1Inh), antithrombin III (ATIII), alpha 1-antitrypsin (a1AT), and alpha 2-antiplasmin (a2AP) are known inhibitors of factor XIa (FXIa). However, their precise contribution to FXIa inactivation in vivo is not known. We investigated FXIa inactivation in chimpanzees and assessed the contribution of these inhibitors to FXIa inactivation in patients with presumed FXI activation. Chimpanzees were infused with FXIa and the various FXIa-FXIa inhibitor complexes formed were measured. Most of FXIa was complexed to C1Inh (68%), followed by a2AP (13%), a1AT (10%), and ATIII (9%). Analysis of the plasma elimination kinetics revealed a half-life time of clearance (t1/2) for the FXIa-FXIa inhibitor complexes of 95 to 104 min, except for FXIa-a1AT, which had a t1/2 of 349 min. Due to this long t1/2, FXIa-a1AT complexes were predicted to show the highest levels in plasma samples from patients with activation of FXI. This was indeed shown in patients with disseminated intravascular coagulation, recent myocardial infarction or unstable angina pectoris. We conclude from this study that in vivo C1Inh is the predominant inhibitor of FXIa, but that FXIa-a1AT complexes due to their relatively long t 1/2 may be the best parameter to assess FXI activation in clinical samples.

Angina, Unstable↗
PubMed1996

Interleukin-6 stimulates coagulation, not fibrinolysis, in humans.

The role of IL-6 as a mediator of haemostatic changes during severe inflammation is controversial. To assess the effect of IL-6 on haemostasis we conducted a controlled cross-over study in eight patients with metastatic renal cell cancer. In all subjects coagulation and fibrinolysis were monitored during and after a 4-h infusion of either 150 micrograms recombinant human (rh) IL-6, or during infusion of saline (control study). Mean maximum IL-6 concentrations were 1418.0 +/- 755.8 pg/ml. Compared to the control study, rhIL-6 induced activation of coagulation as reflected by a 190 +/- 55% increase in the plasma levels of thrombin-antithrombin III complexes (p < 0.001) and by a 24 +/- 11% increase in the plasma levels of in the prothrombin activation fragment F1 + 2 (p < 0.001). In contrast, fibrinolysis was not affected. We conclude that in severe inflammation IL-6 may contribute to the activation of coagulation, whereas other factors mediate changes in fibrinolysis.

Blood Coagulation↗
PubMed1996

Age-related differences in outcome and severity of DIC in children with septic shock and purpura.

We studied the influence of age on mortality and severity of clotting abnormalities in 79 children (median age: 3.1 years) with meningococcal sepsis. Parameters of coagulation and fibrinolysis and plasma levels of cytokines were prospectively measured on admission. The mortality rate was 27%. The age of survivors was significantly different from that of non-survivors (p = 0.013). With the exception of FVII, vWF and t-PA, parameters of coagulation and fibrinolysis, as well as plasma cytokine levels were related to outcome. Patients were divided in two groups: younger and older than median age. The mortality in children < or = 3.1 years was 40% versus 13% in children > 3.1 years (p = 0.006). In contrast to cytokine levels, which were not different between the two age groups, fibrinogen, prothrombin, factors V, VII, VIII, vWF, protein C, antithrombin, FDP, and the ratio PA1-1/t-PA were related to age, indicating a more severe coagulopathy in children < or = 3.1 years despite a similar degree of inflammatory response. A relative deficiency of coagulation factors due to an immature state of the clotting system, as well as an inadequate fibrinolytic response, both related to age may have caused this more severe coagulative response in younger children, and may have contributed to the higher mortality rate.

Adolescent↗
PubMed1995

Monoclonal antibody F1 binds to the kringle domain of factor XII and induces enhanced susceptibility for cleavage by kallikrein.

In a previous study we have shown that monoclonal antibody F1 (MoAb F1), directed against an epitope on the heavy chain of factor XII distinct from the binding site for anionic surfaces, is able to activate factor XII in plasma (Nuijens JH, et al: J Biol Chem 264; 12941, 1989). Here, we studied in detail the mechanism underlying the activation of factor XII by MoAb F1 using purified proteins. Formation of factor XIIa was assessed by measuring its amidolytic activity towards the chromogenic substrate H-D-Pro-Phe-Arg-pNA (S-2302) in the presence of soybean trypsin inhibitor and by assessing cleavage on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Upon incubation with MoAb F1 alone, factor XII was auto-activated in a time-dependent fashion, activation being maximal after 30 hours. Factor XII incubated in the absence of MoAb F1 was hardly activated by kallikrein, whereas in the presence of MoAb F1, but not in that of a control MoAb, the rate of factor XII activation by kallikrein was promoted at least 60-fold. Maximal activation of factor XII with kallikrein in the presence of MoAb F1 was reached within 1 hour. This effect of kallikrein on the cleavage of factor XII bound to MoAb F1 was specific because the fibrinolytic enzymes plasmin, urokinase, and tissue-type plasminogen activator could not substitute for kallikrein. Also, trypsin could easily activate factor XII, but in contrast to kallikrein, this activation was independent of MoAb F1. SDS-PAGE analysis showed that the appearance of amidolytic activity correlated well with cleavage of factor XII. MoAb F1-induced activation of factor XII in this purified system was not dependent on the presence of high-molecular-weight kininogen (HK), in contrast to the activation of the contact system in plasma by MoAb F1. Experiments with deletion mutants revealed that the epitopic region for MoAb F1 on factor XII is located on the kringle domain. Thus, this study shows that binding of ligands to the kringle domain, which does not contribute to the proposed binding site for negatively charged surfaces, may induce activation of factor XII. Therefore, these findings point to the existence of multiple mechanisms of activation of factor XII.

Amino Acid Sequence↗
PubMed1995

Plasma levels of the chemokines monocyte chemotactic proteins-1 and -2 are elevated in human sepsis.

Because of their effects on monocytes, monocyte chemotactic proteins-1 and -2 (MCP-1 and MCP-2) may participate in the pathophysiology of sepsis. We measured circulating MCP-1 and MCP-2 levels in 42 septic patients having positive local or blood cultures. MCP-1 and MCP-2 levels were elevated in 24 (57%) and 25 (59%) of 42 septic patients, respectively, compared with healthy volunteers. Both patients with gram-positive and gram-negative infections had elevated MCP-1 plasma levels (P = .0001) and P < .0001), respectively; Mann-Whitney-U test), whereas patients with gram-positive infection, but not those with gram-negative infection, had increased MCP-2 plasma levels (P= .0182). No relative differences in MCP-1 and MCP-2 plasma levels were observed between several subgroups of patients (sepsis v septic shock; survivors v nonsurvivors), although levels of MCP-1 were the highest in patients with the more severe forms of sepsis, ie, those with shock or a lethal outcome. Serial observations showed that MCP-1 and MCP-2 plasma levels remained elevated for at least 48 hours. MCP-1 correlated weakly with interleukin-8 and MCP-2, the correlations for which were most pronounced in patients with septic shock. MCP-2 correlated with interleukin-8, and surprisingly, with the complement activation product C3a; these correlations further improved when analyzing patients with septic shock or when applying gram-positive infections. Thus, our results not only show increased MCP-1 and MCP-2 levels in patients with sepsis, but also suggest that the synthesis and release of MCP-1 and MCP-2 in sepsis are differently regulated in part.

Chemokine CCL2↗
PubMed1995

Contribution of interleukin-1 to activation of coagulation and fibrinolysis, neutrophil degranulation, and the release of secretory-type phospholipase A2 in sepsis: studies in nonhuman primates after interleukin-1 alpha administration and during lethal bacteremia.

Although studies with interleukin-1 receptor antagonist (IL-1ra) in animal models have shown that IL-1 contributes to mortality in sepsis, the mechanisms whereby IL-1 mediates lethal effects are not well established. A possible mechanism is that IL-1 enhances the activation and release of other inflammatory mediator systems such as coagulation, fibrinolysis, neutrophils, and secretory-type phospholipase A2 (sPLA2). We investigated this possibility by assessing the effect of intravenously injected recombinant human IL-1 alpha (rhIL-1 alpha) on these plasma parameters in baboons. In addition, we examined the course of these inflammatory parameters in baboons after a challenge with a lethal dose of Escherichia coli and while receiving a 24-hour constant infusion of IL-1ra or placebo. Intravenous administration of IL-1 alpha (10 micrograms/kg) induced the formation of thrombin, as evidenced by the appearance of thrombin-antithrombin III (TAT) complexes into the circulation (peak levels, 188 +/- 92 ng/mL at 2 hours), as well as the activation of fibrinolysis, assessed by circulating plasmin-alpha 2-antiplasmin complexes (PAP complexes; peak levels, 0.4% +/- 0.03% of fully activated plasma at 1 hour), the release of tissue-type plasminogen activator (t-PA; peak levels, 6 +/- 2 ng/mL at 2 hours), and its inhibitor, plasminogen activator inhibitor (PAI; peak levels, 724 +/- 246 ng/mL at 4 hours). Il-1 alpha administration also induced the release of sPLA2 (maximal levels, 336 +/- 185 ng/mL at 8 hours), but not degranulation of neutrophils. In the septic baboons, a significant reduction of the formation of thrombin (peak TAT levels decreased from 582 +/- 78 ng/mL to 219 +/- 106 ng/mL; P < .005), the release of t-PA (peak levels decreased from 37 +/- 11 ng/mL to 17 +/- 2 ng/mL; P < .001), and its inhibitor, PAI (peak levels decreased from 2,639 +/- 974 ng/mL to 1,110 +/- 153 ng/mL; P <.001), was observed in the group receiving IL-1ra compared to that receiving placebo. The release of neutrophilic elastase was also significantly attenuated in IL-1a-treated animals (peak levels, 1,024 +/- 393 and 655 +/- 104 ng/mL in control and treatment groups, respectively; P < .05). The difference between sPLA2 levels in both groups, although higher in the controls (maximal levels, 3,140 +/- 1,435 ng/mL in control v 2,217 +/- 1,375 ng/mL in IL-1ra-treated group), was not significant. Thus, IL-1 contributes to activation of various other mediator systems in severe sepsis in nonhuman primates. We propose that these effects may explain the lethal actions of IL-1 in this sepsis model and suggest a similar role for IL-1 in severe human sepsis.

Animals↗
PubMed1995

Inactivation of factor XIa in human plasma assessed by measuring factor XIa-protease inhibitor complexes: major role for C1-inhibitor.

From experiments with purified proteins, it has been concluded that factor XIa (FXIa) is inhibited in plasma mainly by alpha 1-antitrypsin (a1AT), followed by antithrombin III (ATIII), C1-inhibitor (C1Inh), and alpha 2-antiplasmin (a2AP). However, the validity of this concept has never been studied in plasma. We established the relative contribution of different inhibitors to the inactivation of FXIa in human plasma, using enzyme-linked immunosorbent assays (ELISAs) for the quantification of complexes of FXIa with a1AT, C1Inh, a2AP, and ATIII. We found that 47% of FXIa added to plasma formed complexes with C1Inh, 24.5% with a2AP, 23.5% with a1AT, and 5% with ATIII. The distribution of FXIa between these inhibitors in plasma was independent of whether FXIa was added to plasma, or was activated endogenously by kaolin, celite, or glass. However, in the presence of heparin (1 or 50 U/mL), C1Inh appeared to be the major inhibitor of FXIa, followed by ATIII. Furthermore, at lower temperatures, less FXIa-C1Inh and FXIa-a1AT complexes but more FXIa-a2AP complexes were formed. These data demonstrate that the contribution of the different inhibitors to inactivation of FXIa in plasma may vary, but C1Inh is the principal inhibitor under most conditions.

Antithrombin III↗
PubMed1995

Interleukin-1 blockade attenuates mediator release and dysregulation of the hemostatic mechanism during human sepsis.

OBJECTIVE: To define the influence of interleukin-1 activity on coagulation and fibrinolytic system activation and the release of proinflammatory mediators in the early human response to severe infection. STUDY DESIGN: All patients with severe sepsis syndrome who were enrolled from two surgical centers that were participating in a randomized, double-blind, placebo controlled, multicenter, multinational trial of recombinant human interleukin-1 receptor antagonist in the treatment of sepsis syndrome. POPULATION: Twenty-six patients with sepsis syndrome received an intravenous loading dose of recombinant human interleukin-1 receptor antagonist (100 mg) or placebo followed by a continuous 72-hour infusion of recombinant human interleukin-1 receptor antagonist (1.0 [n = 9] or 2.0 [n = 8] mg/kg per hour) or placebo (n = 9). OUTCOME MEASURE: Responses up to 72 hours after initiation of treatment. RESULTS: Plasma levels of the anaphylatoxin C3a and thrombin-antithrombin III complexes were reduced in the high-dose recombinant human interleukin-1 receptor antagonist treatment group after 72 hours (P < .05). Similarly, parameters of fibrinolysis, tissue-type plasminogen activator, and plasminogen activator inhibitor type 1 but not plasmin-alpha 2-antiplasmin complexes, were also significantly reduced (P < .05) after 72 hours of treatment with a high dose of recombinant human interleukin-1 receptor antagonist. Neutrophil elastase-alpha 1-antitrypsin complexes and phospholipase A2 levels were also significantly reduced in the high-dose recombinant human interleukin-1 receptor antagonist treatment group after 72 hours. CONCLUSIONS: The results confirm that activation of the coagulation and fibrinolytic systems and release of soluble inflammatory mediators are consistently observed in patients with severe sepsis syndrome. Interleukin-1 activity contributes to activation of these processes as documented by the reduction in surrogate activation markers during recombinant human interleukin-1 receptor antagonist treatment.

Adult↗
PubMed1995

Interleukin 8-related neutrophil elastase and the severity of the adult respiratory distress syndrome.

The interaction between activated neutrophils and pulmonary endothelium is thought to contribute to the pathogenesis of the adult respiratory distress syndrome (ARDS), but its relation to ARDS severity, which may support a pathogenetic role, is unclear. Therefore, circulating inflammatory mediators, including the neutrophil chemoattractant and activator interleukin 8 (IL-8), the acute phase cytokine IL-6, and the neutrophil product elastase complexed to alpha 1-antitrypsin (alpha 1-AT), were measured prospectively, together with gas exchange, ventilatory and radiographic variables, in 13 mechanically ventilated patients with ARDS, mostly owing to sepsis, at admission into the intensive care unit. Measurements were repeated in the eight improving patients at the time that positive end-expiratory pressure could be reduced to 0 cm H2O. From the gas exchange, ventilatory and radiographic abnormalities, a lung injury score (LIS) was calculated. For pooled data, the LIS and the arterial PO2/inspiratory O2 fraction, the oxygenation ratio, correlated with plasma levels of IL-8 (rs = 0.60, P < 0.01 and rs = -0.65, P < 0.005, respectively), with levels of IL-6 (rs = 0.60, P < 0.01, and rs = -0.68, P < 0.005, respectively), and the oxygenation ratio related to elastase-alpha 1-AT (rs = -0.70, P < 0.005). Levels of IL-8 and IL-6 interrelated (rs = 0.61, P < 0.01) and related to the elastase complexes (rs = 0.45, P < 0.05). Hence, our data support a role of cytokine-induced activation of neutrophils in the clinical severity of ARDS.

Adult↗
PubMed1995

Toxicity of OKT3 increases with dosage: a controlled study in renal transplant recipients.

In the present study we prospectively compared side effects occurring in 12 patients after the first administration of low-dose OKT3 (0.5 mg twice daily) induction therapy with those in 10 patients who were treated with a conventional dose of OKT3 (5 mg daily) for acute rejection. We also investigated cytokine release and activation of complement and neutrophils as all of these are held responsible for OKT3-induced side effects. Low-dose OKT3 resulted in a significantly decreased side effects score compared to that after a conventional dose of OKT3 (1.8 vs 5.1, p = 0.0006). Following the first administration of low-dose OKT3, TNF peak levels were significantly lower than after a conventional dose of OKT3. In contrast to our data on conventional dose OKT3 treatment, the first administration of low-dose OKT3 did not induce complement activation as reflected by C3a and C4b/c levels in plasma. Finally, the increase in neutrophil degranulation products lactoferrin and elastase-varies; is directly proportional to 1-antitrypsin was much less following 0.5 mg OKT3 than following 5 mg. We conclude that OKT3-induced toxicity is dose-dependent and is mediated not only by cytokine release but also by activation of complement and neutrophils.

Dose-Response Relationship, Drug↗
PubMed1995

Therapy with interleukin-2 induces the systemic release of phospholipase-A2.

Therapy with interleukin-2 (IL-2) induces remissions in some forms of cancer. This treatment however, is accompanied by side-effects which, in part, may be mediated by the formation of eicosanoids and platelet-activating factor. We investigated the systemic release of phospholipase A2 (PLA2), a rate-limiting enzyme in the formation of these lipid mediators, in patients receiving IL-2. In a pilot study of 4 patients we observed an increase in PLA2 activity in serial plasma samples obtained during the first day after a bolus infusion of IL-2, which increase closely correlated with that of antigen levels of secretory phospholipase A2 (sPLA2) as measured by enzyme-linked immunosorbent assay (r = 0.92; P < 0.001). In 20 patients, receiving 12 x 10(6)-18 x 10(6) IU IL-2/m2, we then investigated the course of antigenic levels of sPLA2 in relation to those of the cytokines tumour necrosis factor alpha (TNF) and interleukin-6 (IL-6) (both cytokines may induce sPLA2 in vivo). From 4 h on, sPLA2 levels significantly increased, reaching a peak 24 h after the IL-2 infusion. Subsequent IL-2 infusions even induced a further increase of sPLA2. This increase of sPLA2 was presumably not due to a direct effect of IL-2 on, for example, hepatocytes, since this cytokine, in contrast to IL-1, IL-6, TNF and interferon gamma, was not able to induce the synthesis of sPLA2 by Hep G2 cells in vitro. Consistent with this, plasma levels of TNF and IL-6 in the patients rose, reaching peak levels before a zenith of sPLA2 occurred, i.e. at 2 h and 4 h after the start of the IL-2 infusion respectively. sPLA2 levels significantly correlated with the development of the side-effects increase in body weight (r = 0.49; P < 0.0001) and decrease in mean arterial blood pressure (r = 0.40; P < 0.0001). Moreover, maximum sPLA2 levels induced by IL-2 were higher in patients who had progressive disease after therapy than in patients who had stable disease or a partial response.

Humans↗
PubMed1995

Time course of cytokine levels in sepsis.

In severe sepsis, a network of proinflammatory cytokines (TNF, IL-1 beta, IL-6, IL-8) is activated and blood levels of these cytokines are elevated, albeit inconsistently and with large individual variations. In addition, elevated blood levels of anti-inflammatory cytokines (IL-10), as well as of soluble cytokine receptors (sTNF-RI and II, IL-1ra), have been found. They seem to have a regulatory function in the host response. Levels of TNF and IL-6 are usually highest at the time of admission, whereas the time course of IL-1 beta levels (when detectable) can vary considerably. Limited data on IL-8 levels suggest that they may remain elevated for longer periods. Elevated levels of sTNFR and IL-1ra may also persist for a prolonged period of time. The pathogenetic significance of these observations is still unclear, but persistingly high levels of proinflammatory cytokines may be associated with organ failure and mortality.

Humans↗
PubMed1995

Expression of granzyme A and B proteins by cytotoxic lymphocytes involved in acute renal allograft rejection.

Granzymes A and B are serine-proteinases stored in the granules of activated cytotoxic T-lymphocytes and natural killer (NK) cells. Expression of granzymes in tissues can be used as an activation marker for cytotoxic cells. Using mAbs specific for human granzyme A or B in immunohistochemical staining techniques we investigated expression of granzyme A and B by lymphocytes infiltrating acutely rejected renal allografts. Twelve core needle biopsies were taken from ten different patients during an episode of acute rejection. Eleven biopsies contained high numbers of granzyme A and B positive lymphocytes infiltrating tubular epithelium, and vascular and glomerular structures. In one patient infiltrating lymphocytes did not express granzyme A and only low amounts of granzyme B. No correlation was found between the number of granzyme positive cells and the severity of the rejection as classified by conventional histological criteria. In one tissue specimen from a patient with a renal allograft without signs of rejection, the number of granzyme positive cells was much lower compared to that of the transplant group. In spite of the presence of a marked inflammatory infiltrate, no granzyme positive cells were detected in renal biopsies from patients with various inflammatory, not transplant-related, renal diseases. Phenotypic analysis showed that granzymes A and B were expressed by CD56+ NK cells and CD3+ cells, representing cytotoxic T-lymphocytes. Thus, this study demonstrates that granzyme A and B protein-expressing lymphocytes infiltrate the kidney allografts during an acute cellular rejection but not in several other inflammatory renal diseases.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1995

Plasminogen activator and plasminogen activator inhibitor I release during experimental endotoxaemia in chimpanzees: effect of interventions in the cytokine and coagulation cascades.

1. Disseminated intravascular coagulation frequently accompanies Gram-negative sepsis and may contribute to widespread deposition of microthrombi. Besides the endotoxin-induced activation of coagulation, an important role for the fibrinolytic system has been postulated. The precise mechanisms underlying these fibrinolytic changes during endotoxaemia are not known but have been suggested to be mediated directly by cytokines or secondary to thrombin generation. 2. In the present study we have delineated in detail the fibrinolytic response to a bolus injection of endotoxin in non-human primates and analysed the contribution of cytokines and thrombin generation to the endotoxin-induced release of tissue-type plasminogen activator and plasminogen activator inhibitor 1. Chimpanzees received a bolus injection of endotoxin alone or in combination with blocking monoclonal antibodies directed against tumour necrosis factor or interleukin 6 or in combination with pentoxifylline. Furthermore, to assess the effect of coagulation activation on the activation of fibrinolysis, another group of chimpanzees received endotoxin in combination with either anti-tissue factor antibodies or recombinant hirudin. 3. Infusion of endotoxin induced a rapid increase in plasminogen activator activity and tissue-type plasminogen activator antigen levels and subsequent plasmin generation, reaching peak levels 2h after endotoxin administration. Plasminogen activator inhibitor 1 levels remained constant for the first 2 h, after which time a steep increase was observed. Plasminogen activator activity and plasmin generation decreased simultaneously with the rise in plasminogen activator inhibitor 1 levels. Fibrinolytic activity remained suppressed during the remainder of the study owing to sustained increased levels of plasminogen activator inhibitor 1. The administration of pentoxifylline strongly attenuated the release of tissue-type plasminogen activator and plasminogen activator inhibitor 1, whereas the antitumour necrosis factor antibodies blocked the fibrinolytic response entirely. In contrast, interleukin 6-neutralizing antibodies did not affect the fibrinolytic response. Although endotoxin-induced generation of thrombin was completely prevented by the administration of tissue factor-neutralizing antibodies or by hirudin, no effect on the fibrinolytic response was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Monocyte chemotactic protein 1 is released during lethal and sublethal bacteremia in baboons.

The chemokine monocyte chemotactic protein 1 (MCP-1) is a cytokine with chemotactic activity specific for mononuclear phagocytes. To investigate the possible involvement of MCP-1 in the pathogenesis of sepsis, its course was studied in baboons challenged intravenously with a sublethal or lethal dose of Escherichia coli. Levels of MCP-1 started to increase in both groups of animals 2 h after injection of E. coli, reaching peak levels 4 and 6 h after a sublethal (186 +/- 21 ng/mL) or a lethal (213 +/- 24 ng/mL) dose, respectively. Levels of MCP-1 correlated significantly with plasma levels of another chemokine, interleukin-8 (IL-8; r = .826. P < .001), suggesting that common stimuli mediate the release of both cytokines in this model.

Animals↗
PubMed1995

Effect of postponed treatment with an anti-tumour necrosis factor (TNF) F(ab')2 fragment on endotoxin-induced cytokine and neutrophil responses in chimpanzees.

TNF is considered to be an intermediate factor in endotoxin-induced release of other cytokines and endotoxin-induced neutrophil degranulation. Little is known about the effect of postponed treatment with anti-TNF in primate endotoxin models. To assess the effect of delayed treatment with anti-TNF in endotoxaemia, six healthy adult chimpanzees were intravenously injected with Escherichia coli endotoxin (4 ng/kg). In three of these animals the administration of endotoxin was followed after 30 min by a bolus i.v. injection of the anti-TNF F(ab')2 fragment MAK 195F (0.1 mg/kg). Post-treatment with MAK 195F completely prevented the appearance of TNF activity in serum elicited by endotoxin, and markedly reduced the rises in the serum concentrations of IL-6 and IL-8. In addition, the endotoxin-induced increases in the type I and type II soluble TNF receptors were also profoundly inhibited by MAK 195F, suggesting that TNF is involved in the release of its own soluble receptors in endotoxaemia. Neutrophilic leucocytosis was not affected by MAK 195F. In contrast, MAK 195F did significantly abrogate neutrophil degranulation, as measured by the plasma concentrations of lactoferrin. These results indicate that treatment with anti-TNF 30 min after the administration of endotoxin is still effective in attenuating the induction of the cytokine network and of neutrophil degranulation.

Animals↗