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PubMed1987

Complement and anaphylatoxin responses to cross-clamping of the aorta. Studies during general anaesthesia with or without extradural blockade.

Complement activation and anaphylatoxin formation were studied in 28 patients undergoing aortic reconstructive surgery under general anaesthesia. In 12 of the patients an extradural catheter was placed in the L1-2 space and 2% mepivacaine was injected until blockade reached the T4 level. The remaining 16 patients were operated upon under general anaesthesia alone. Complement activation was not obvious until aortic cross-clamping. The release of anaphylatoxin was less pronounced during cross-clamping in the extradural group.

Aged↗
PubMed1987

C5a and thromboxane generation associated with pulmonary vaso- and broncho-constriction during protamine reversal of heparin.

The authors conducted a study in humans to determine the mediators associated with acute pulmonary vaso- and broncho-constriction occurring episodically with protamine reversal of heparin anticoagulation. Of 48 adult patients investigated prospectively after termination of cardiopulmonary bypass, two presented a sudden increase of airway pressure, acute pulmonary hypertension, and systemic hypotension 1-3 min after right atrial protamine injection. In these two subjects, plasma levels of C5a increased from 0.7 and 2.2 to 9.8 and 9.9 ng/ml, respectively, and thromboxane B2 increased from 0.26 and 0.34 to 7.5 and 16.2 ng/ml 1 minute after drug injection. A third subject not identified prospectively had an identical reaction and mediator profile (C5a, 10.2 ng/ml; TxB2, 18.6 ng/ml at 1 min). The plasma levels of these mediators were unchanged in the remaining patients (C5a, 0.7 +/- 1.1 [x +/- S.D.] to 0.6 +/- 0.9 ng/ml; TxB2, 0.16 +/- 0.12 to 0.15 +/- 0.07 ng/ml). Plasma histamine was not involved in this type of reaction, but increased from 0.7-10.4 ng/ml in a fourth patient who became hypotensive without acute pulmonary hypertension, bronchoconstriction, or elevation of C5a or TxB2. The authors' data indicate that the generation of high plasma levels of C5a anaphylatoxins and thromboxane is associated with pulmonary vaso- and broncho-constriction induced by protamine reversal of heparin in humans.

Adult↗
PubMedDate not supplied

In vitro activation of human complement by polyacrilonitrile dialyzer membrane assayed by complement binding to bystander red cells.

Quantitation of complement activation by polyacrilonitrile (PAN) dialyzer membrane is complicated by the high adsorptive capacity of the membrane for fluid phase anaphylotoxins. Assays for these anaphylotoxins, therefore, underestimate the degree of complement activation produced by this membrane. Alternative methods of measuring in vitro complement activation by the PAN and Cuprophan membranes were explored by incubating normal human erythrocytes with the membranes in the presence of serum. This led to deposition of C3d on these "innocent bystander" red cells, and provided an independent parameter for measuring complement activation. The PAN membrane caused significantly more C3d deposition on red cells, and thus more complement activation than Cuprophan. The possible significance of complement activation by PAN membrane, in consideration of its property of binding the resultant anaphylotoxins, is discussed.

Acrylic Resins↗
PubMed1987

Psoriasis and leukocyte chemotaxis.

Transepidermal migration of leukocytes, with resultant formation of microscopic or macroscopic sterile subcorneal pustules is a phenomenon characteristically noted in psoriasis and related sterile pustular dermatoses. It is natural to assume the presence of potent neutrophil chemotactic substances in the subcorneal portion of the lesional epidermis, because this location is the target of the in vivo leukocyte chemotaxis. In fact, crude psoriasis scale extracts show remarkably high neutrophil chemotactic and activating properties as compared with those of other non-psoriatic inflammatory dermatoses. We isolated a psoriatic leukotactic factor (PLF) having a molecular mass of around 12 kD, distinct from those common to other inflammatory changes involving the skin or those released by bacteria. Further analysis of PLF identified C5 cleavage fragments, together with other chemotactic peptides, such as those derived from monocytes. Likewise, potent low-molecular-mass chemotactic factors, including cell membrane lipid derived chemotactic factor, e.g. leukotriene B4, are also increased in psoriatic lesions, as in other nonpsoriatic inflammatory dermatoses. However, their activity to stimulate the generation of oxygen radicals in neutrophils was found to be much weaker than that of PLF. The peripheral blood leukocytes from active psoriatic patients show enhanced function in chemotaxis, phagocytosis, active oxygen production, and enzyme release; patients' sera contain substances such as anaphylatoxins that activate leukocyte function. Further research is required for clearer understanding of the series of events resulting in the leukocyte chemotaxis, as well as for the elucidation of the background immunoregulatory mechanisms.

Cell Movement↗
PubMed1987

Is contact activation of the coagulation system involved in the genesis of the first-use syndrome?

A number of mechanisms have been thought to be involved in the pathogenesis of the first-use syndrome. These include IgE antibody-mediated response to ethylene oxide-related antigens, membrane activation of the alternative complement pathway, activation of tissue mast cells and basophils by materials released from the dialyzer into the circulation, and transfer of bacterial products through high flux dialyzer. However, the possible role of the activation of blood coagulation system and platelets during dialysis has not been considered. The present communication reviews the theoretical basis for a possible connection between dialysis-induced activation of platelets and coagulation system with the first-use syndrome. Although the available data concerning the activation of intrinsic coagulation pathway during dialysis are conflicting, there is no controversy as to the occurrence of platelet activation. It is suggested that biochemical events triggered by activation of these systems may in part contribute to the genesis of first-use syndrome.

Anaphylaxis↗
PubMed1990

Measurement of the chemotactic complement fragment C5a in rheumatoid synovial fluids by radioimmunoassay: role of C5a in the acute inflammatory phase.

Evidence suggests that complement is activated in rheumatoid joints. A sensitive radioimmunoassay for the activation fragment of C5, C5a, which is a potent chemoattractant for neutrophils, was therefore developed. A mean C5a concentration in 22 rheumatoid joint fluids of about 2.5 x 10(-9) mol/l was found. This concentration of C5a is sufficient to induce two of the characteristic features of the acute inflammatory phases of rheumatoid arthritis: neutrophil accumulation and microvascular plasma protein leakage. In animal models it has been shown that C5a is a potent inducer of inflammatory oedema by a neutrophil dependent mechanism. A striking feature of the acute inflammatory phases of rheumatoid arthritis is the appearance of high numbers of neutrophils in the synovial fluid. It is suggested that C5a might have a role in mediating neutrophil accumulation and, as a consequence, may be important in acute joint swelling and pain.

Adult↗
PubMed1987

Biocompatibility of artificial organs: an overview.

Papers that are presented in this symposium on biocompatibility of foreign surfaces used in artificial organs are commented upon and set in an overall context of the biocompatibility of foreign surfaces to blood. A working formulation of the events comprising lack of biocompatibility of hemodialysis membranes to the complement system is given as a possible model to which other foreign surfaces may be compared.

Animals↗
PubMed1990

A modification of cellulose that facilitates the control of complement activation.

Complement activation by Cuprophan hemodialysis membranes has been linked to a variety of pathological sequelae (neutropenia and various cardiopulmonary manifestations) seen in the clinical setting. The modification of reactive surface hydroxyl groups on regenerated cellulose with various dicarboxylic-acid anhydrides has been found to significantly limit the complement-activating potential of these materials. Of the anhydrides tested, maleic anhydride appears to display the most dramatic and consistent diminution of complement activation compared to unmodified cellulose (0-10% of control values for C3b deposition and C3a/C5a production). Current evidence suggests that this maleated derivative facilitates the factor-H control of C3 and C5 convertase activity and thus may help limit complement activation by normal regulatory mechanisms. In addition, this modification may help limit the production of other inflammatory mediators that may result in diminished levels of cellular activation.

Biocompatible Materials↗
PubMed1992

Anticoagulation-dependent inhibition of in vitro complement activation by anti-apo-B sepharose 4B CL.

During LDL apheresis, various combinations of heparin and citrate are used for anticoagulation. With an in vitro batch system we examined whether heparin/citrate combinations can be optimized in terms of complement activation inhibition without the loss of anticoagulant potency. Plasma anticoagulated by using six clinically applicable regimens was incubated with anti-apo-B antibody-coupled Sepharose 4B CL, and the anaphylatoxin content of the supernatant was investigated. A significant dose-dependent reduction of complement activation was achieved by anticoagulating whole blood with 10 U/ml heparin (p < 0.05) if compared with serum whereas citrate inhibited more effectively the generation of C5a (desarg) even at a low concentration (ACD-B 1:20) (p < 0.01). The lowest anaphylatoxin level was generated when heparin (10 U/ml) plus citrate (ACD-B 1:10) were applied, although such an approach may be of limited clinical interest. The empirically chosen heparin plus citrate ratio (2 U/ml, 1:20, respectively) provides for an optimal and almost ideal inhibition of complement activation and contributes considerably to the good tolerability of the immunoadsorbent.

Apolipoproteins B↗
PubMed1988

The significance of complement activation in the pathogenesis of hypersensitivity pneumonitis: sequential changes of complement components and chemotactic activities in bronchoalveolar lavage fluids.

Hypersensitivity pneumonitis (HP) is believed to be induced by immunological mechanisms, the details of which remain to be clarified. While a role for cellular immunity is accepted in the pathogenesis of HP, several clinical observations also suggest a role for immune-complex-mediated lung injury. We have previously demonstrated the presence of chemotactic factors for polymorphonuclear cells (PMNs) in bronchoalveolar lavage (BAL) fluids of acutely ill patients with the summer type of HP found in Japan. The present study correlated chemotactic factors for PMNs with the level of C5a des Arg in BAL fluids obtained from patients with summer type HP. Furthermore, this study demonstrated that PMNs were increased in BAL fluids obtained after 2 days of avoidance of exposure to the presumptive causative agent. The percentage of PMNs in the BAL increased in proportion to the activity of the chemotactic factors. Finally, leukotriene B4 was not detected in concentrated BAL or supernatant fluids of cultured macrophages. These results suggest that complement activation in the respiratory tract may occur as the early event in the pathogenesis of HP.

Alveolitis, Extrinsic Allergic↗
PubMed1987

The properties of human C5a anaphylatoxin. The significance of C5a formation during hemodialysis.

Human C5a anaphylatoxin is a potent bioactive molecule that possesses both spasmogenic and leukocyte-related properties. As such, it normally serves as a local mediator of the acute inflammatory response. Additionally, C5a, through its actions of mononuclear phagocytes, may act to bridge the gap in the acute-chronic inflammatory continuum. While these properties are critical to normal host defense mechanisms, it is now apparent that this anaphylatoxin and/or its des-Arg74 derivative, may exert significant systemic effects that are manifest as cardiopulmonary abnormalities and intravascular activation of granulocytes. Knowledge of these properties is critically important for understanding the clinical sequelae exhibited by patients undergoing extracorporeal circulation since we now know that both hemodialysis and cardiopulmonary bypass [28-30] procedures promote intravascular complement activation and C5a formation. Viewed in this context, it seems reasonable to postulate that many of the immediate and delayed responses to extracorporeal circulation might be mediated by C5a formed in the extracorporeal circuit (table IV). For example, it is now recognized that a few particularly susceptible patients display adverse reactions during the initial phases of hemodialysis. The symptoms of this so-called 'first-use syndrome' may range from severe urticaria and angioedema to life-threatening bronchospasm, hypotension, and cardiopulmonary collapse. Some investigators have presented data which suggest that complement-derived products may be causative of these symptoms in some patients [31]. While this hypothesis remains to be confirmed, present evidence clearly demonstrates that C5a alone may produce many of the observed phenomena. In addition to the acute effects produced by C5a, both our own basic studies and the clinical investigations presented by others at this conference suggest that the long-term effects of repeated C5a exposure in the dialyzed patient may be considerable. Thus, there has been a great deal of interest in the role of complement-derived mediators as initiators of leukocyte degranulation and toxic oxygen radical production and an exploration of the significance of these events in the eventual development of chronic pulmonary fibrosis in the dialyzed patient. Similarly, the effects of repeated exposure to IL-1 that has been postulated to occur as a result of C5a triggering of monocytes during dialysis is currently an active area of investigation.(ABSTRACT TRUNCATED AT 400 WORDS)

Anaphylatoxins↗
PubMed1991

Suppression of vascular injury at the Arthus reaction site by a complement inhibitor, 5,5',5''-(1,3,6-naphthalene-triyl-tris[sulfonylimino])-tris (1,3-benzene disulfonic acid) hexasodium salt.

A novel polyanionic complement inhibitor 5,5,5''-(1,3,6-naphthalene-triyl-tris[sulfonylimino])-tris(1 ,3-benzene- disulfonic acid) hexasodium salt (compound IIb) was tested for its ability to suppress vascular injury at the site of the Arthus reaction (AR). In control animals in which AR was evoked without drug treatment, venules at AR sites ranged from normal (arbitrarily defined as stage I) to destroyed (stage V). Between these two ends of the spectrum were venules with an accumulation of cells and deposits of electron dense material (stage II), accumulations of cells and deposits and small endothelial gappings (stage III), and accumulations of cells and depositions which had spread into perivascular tissue and small gappings (stage IV). In animals treated with compound IIb, the AR stopped at stage III or IV depending on the dose, it never reached stage V. In other words compound IIb treatment resulted in protection of endothelium, basal lamina and other structures from the destruction which is characteristically observed in the AR. The effect of high doses of compound IIb was similar to that described before for suramin.

Animals↗
PubMed1987

Relationships of serum opsonins and complement in human experimental gingivitis.

This study assessed the phagocytosis of polymorphonuclear neutrophils and the opsonic capacity of serum in experimental human gingivitis. Relationships were sought among these two measurements, clinical indices of gingivitis and complement-related opsonins. Measurements of chemiluminescence provided an index of phagocytosis and of opsonic capacity. Test group Plaque Index scores were higher than the control group on Days 7, 14, and 21, while the Gingival Index of the test group was elevated only on Day 21. Phagocytosis of test subjects' PMNs and opsonic capacity of their sera were no different from that of the controls'. Levels of C3 in both nonactivated and activated sera of the test group were significantly lower than that of the control group only on Day 14. In the test group, differences of per cent C3 conversion occurred between Days 14 and 21, and Plaque Index scores were inversely correlated with the order of per cent C3 data on these same days. Our results also indicate that complement contributes significantly to the serum opsonic capacity. The levels of developing plaque and subsequent gingival inflammation are apparently related to the degree of complement activation.

Adult↗