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Results for “Complement C1 Inactivator Proteins”

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PubMed1979

[Significance of the complement system in acute pancreatitis in rats].

The influence of complement system in acute pancreatitis in the rat was examined. Two different experimental procedures were used to induce pancreatitis: distal choledochal ligature and the Pfeffer model as modified by NEVALAINEN. In both procedures an acute pancreatitis developed and complement depression was noted. These results showed that consumption of complement will occur even in pancreatitis induced by other than immunologic models. In a second series the same experimental procedures were used in rats that had been decomplemented by application of cobra venom factor. It was possible to produce an acute pancreatitis of moderate severity.

Acute Disease↗
PubMed1979

Acquired C1 inhibitor deficiency in a case of lymphosarcoma of the spleen. Reversal of complement abnormalities after splenectomy.

A patient with an extensive lymphosarcoma of the spleen without involvement of other lymphoid organs and hypogammaglobulinaemia showed the characteristic complement profile of an acquired C1-inhibitor deficiency. Both functional and immunochemical studies revealed extremely low levels of the inhibitor of C1-esterase. Correction of the low levels of early acting complement components and of the low C1-inhibitor level followed the splenectomy. In vitro tests showed that lymphosarcoma tissue pieces or cells were able to interact with complement, resulting in a depletion of the haemolytic activity. These findings provide evidence that tumour cells were responsible for the abnormalities of the complement system.

Aged↗
PubMed1975

Protease inhibitors in plasma of patients with chronic urticaria.

The hypothesis that deficiencies of plasma protease inhibitors might play a role in the pathogenesis of chronic urticaria was evaluated. Plasma levels were measured in patients with urticaria and a matched control group for alpha1-antitrypsin, alpha2-macroglobulin, total trypsin-inhibiting capacity, kallikrein-inhibiting capacity, and the complement factors C1 esterase inhibitor, C3, and C4. A total of 92 patients with chronic urticaria or more than three months' duration was studied. Patients with acquired cold urticaria had significantly decreased levels of alpha1-antitrypsin and total antitrypsin activity. In patients with acquired angioneurotic edema, alpha1-antitrypsin levels and antichymotrypsin activities were lowered, with less significant decreases in anti-trypsin and antikallikrein activities. Levels of C1 esterase inhibitor , C3, and C4 were normal in all groups. There was no correlation between the increased sensitivity to intracutaneously administered kallikrein injection and deficiencies of of protease inhibitors.

Adolescent↗
PubMed1980

[The effect of burns on the complement system].

Serum levels of total complement CH 50 and the complement components C1, C1 inactivator, C2, C4, C3c, and C3 activator were measured in 20 patients with burn injuries. The findings were assessed for any possible correlations between the results of serological investigations, severity of burns and clinical aspects of the patients.

Adolescent↗
PubMed1982

[Hereditary complement deficiencies].

Complement deficiencies of all nine C-components have been observed. Hereditary defects of early components of the classical pathway - C1, C4, C2 - are often associated with diseases of the immuncomplex-type especially with systemic lupus erythematosus, dermatomysitis, vasculitis and nephritis. Deficiencies of C3 and C3b inactivator are linked to severe and recurrent bacterial infections. Patients with hereditary defects of the so-called late components, C5-C9, show increased susceptibility to recurrent disseminated infections by neisseria gonorrhoeae and meningitidis. The most frequent of the defects of the complement system is the hereditary deficiency of C1-inactivator which is associated with hereditary angioneurotic edema. In this paper the C-defects and their genetics are described and possible pathomechanisms are discussed.

Complement Activating Enzymes↗
PubMedDate not supplied

[Biochemical data on C1 intrinsic activation (author's transl)].

C1 activation can be triggered by immune complexes and various effectors such as extrinsic proteases, bacterial or viral membranes, polyanions and polysaccharides. The basic mechanism of activation involves a limited proteolytic cleavage of C1r, with the generation of a proteolytic activity. Highly purified proenzymic C1r was obtained in high yield from human plasma by an indirect affinity chromatography step. Activation of isolated C1r in a fluid phase proceeded according to two distinct coexisting mechanisms: 1) an autocatalytic intradimer activation mediated by the pro-site of non-activated C1r; 2) an autocatalytic interdimer proteolysis triggered by nascent activated C1r formed in the course of the first reaction. DFP and C1-inhibitor did not have any effect on the first mechanism but were able to block the second mechanism. C1 activation is discussed in the light of recent results obtained by others from electron microscopy, and a tentative model is proposed.

Antigen-Antibody Complex↗
PubMed1983

Complement activation and impaired capacity to solubilize immune complexes or to prevent their formation in essential mixed cryoglobulinemia.

The complement profile, the immune complex solubilizing capacity (ICSC), the immune complex precipitation inhibition capacity (ICPIC), the presence of cryoprecipitable material, and the presence of immune-aggregate- and non-immune-aggregate mediated C1q-binding activity was assessed in serum samples from 23 patients suffering from essential mixed cryoglobulinemia (EMC). No correlation between the levels of cryoglobulins and the clinical activity of EMC was found. The mean C1q-binding activity in EMC serum samples was abnormally elevated 28 +/- 29% (mean +/- SD). In six out of eight serum samples that contained C1q-binding material, evidence was obtained that such material was of the complexed immunoglobulin G (IgG) type. Among the levels of C1q, C1r, C2, C4, C3, C5, C6, C1-inhibitor, C3d, B, I, H, as well as the total hemolytic activity and the activity of the alternative pathway of the complement, the mean serum concentrations of C1, C2, and C4 and in consequence the mean total hemolytic activity were significantly reduced, whereas the mean levels of C3d were significantly elevated in the EMC serum samples. The capacity of the 23 EMC serum samples to solubilize preformed immune precipitates from bovine serum albumin (BSA) and rabbit anti-BSA antibodies as well as their capacity to prevent the formation of the precipitable form of such complexes was analyzed. Compared to the ICSC and the ICPIC of 30 normal human sera, the ICSC and the ICPIC of EMC serum samples were reduced to 57 +/- 24% and 38 +/- 33%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Generation of the classical pathway C3 convertase (EAC4b2a) by proteolytic enzymes.

The formation of EAC 4b2a is a two step reaction: first, the temperature- and time-independent binding of C2 to EAC4b2a resulting in EAC4b2 , secondly, the enzymatically triggered conversion of EAC4b2 to EAC4b2a . In the classical cascade of complement activation, the generation of C3 convertase activity is triggered by the C1 esterase, C1-s, which is part of C-1. Evidence is presented that the enzymes trypsin, chymotrypsin, plasmin, and pronase are also able to activate EAC4b2 to EAC4b2a . Kinetic studies showed that the formation of C3 convertase by these enzymes was dependent on concentration, temperature, and time. The optimal conditions were found as follows: trypsin, 2 micrograms/ml (final conc.) for 8 min at 23 degrees C; chymotrypsin 165 micrograms/ml for 18 min at 23 degrees C; plasmin 0.8 units/ml for 15 min at 23 degrees C; pronase 1.25 microgram/ml for 15 min at 23 degrees C. Even under optimal (tmax) conditions the number of generated EAC4b2a differed from enzyme to enzyme: trypsin (= 100%), pronase (58.3%), chymotrypsin (47.9%), and plasmin (12.9%). The enzymes were also able to generate C3 convertase activity from C2 which was adsorbed to EAC1i4b , a C1 inactivator treated and therefore hemolytically inactive intermediate ( EAC1i4b2 ). These findings underline the biological importance of C1 esterase replacing enzymes.

Animals↗