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Results for “Complement Inactivator Proteins”

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At least 19 recordsLinked to original sources
PubMed1975

Cyanate as an inactivator of complement proteins.

Sodium cyanate added to normal human serum or serum from patients with sickle-cell disease resulted in the functional inactivation of C3, C5, C6, C7, and the C3b inactivator, but not C8 and C9. Final concentrations as low as 0.5 mM in serum caused inactivation of 12 to 64% of the C3 after 8 hr at 37 degrees C. The activity of the inactivated C3, C5, and C3b inactivator was not restored by dialysis. Most of the functional activity of C3 in cyanate-treated sera was destroyed by very small quantities of 14C-labeled cyanate that was bound to the protein. C3 inactivation by cyanate occurred in heated sera (50 degrees C, 30 min) and sera treated with EDTA, probably indicating that one mechanism for inactivation was by a direct carbamylation reaction. Both C3 and C5 showed two anodal-migrating forms in two dimensional antigen-antibody crossed electrophoresis in some sera treated with low concentrations of cyanate. Measurements of circular dichroism of highly purified carbamylated C3 showed no detectable changes in structure even though most of the functional activity was destroyed. Purified, inactive C3 that was carbamylated with 14C-labeled cyanate was capable of binding to EAC142, but the resulting EAC1423 was weakly positive for immune adherence and negative for agglutination with anti-C3 antiserum. Unlabeled, cell-bound C3b on EAC142 was not susceptible to cyanate action as shown by no loss in immune adherence and positive agglutination with anti-C3 antiserum. The C3b inactivator was more susceptible to cyanate than C3 in a short time period, whereas both were inactivated after 8 hr. Since cyanate is currently being evaluated as a treatment for sickle-cell disease, the inactivation of C3 by the drug is an important consideration for such patients who are already deficient in C3 dependent heat-labile opsonins that aid in host defense.

Anemia, Sickle Cell↗
PubMed1975

[Acquired C1-esterase inhibitor deficiencies during lymphoid syndromes].

Very marked abnormalities of the complement system were discovered in two patients suffering from a lymphoid syndrome and an IgM 7S dysglobulinaemia. The abnormalities in the complement system were related to a deficiency in C1-estérase (C1 INH). Several findings suggest that such a deficiency is acquired, in particular the absence of any family history of angio-neurotic oedema and, above all, the detection of a marked fall in levels of the C1 fraction which does not exist in the congenital form of deficiency of the inhibitor. The IgM 7S immunoglobulins found in the serum of both patients are probably responsible for the abnormalities in the complement system observed. Such acquired deficiencies in C1 INH are extremely rare since only a few cases have been reported in the literaute, in particular two cases in patients with lymphosarcoma with a serum IgM 7S.

Aged↗
PubMed1976

C1 and human platelets. III. Role of C1 subcomponents in platelet aggregation induced by aggregated IgG.

Studies have been performed with platelets using C1 haemolytic assays and platelet aggregation induced by anti-C1q, anti-C1s and aggregated IgG in the presence of C1 subcomponents C1q, C1r and C1s. C1q was removed by EDTA or modified by collagenase from human platelets while after the same treatment C1s remained bound to the platelets. EDTA treated platelets were no longer aggregated by aggregated IgG. The addition of C1q restored the reactivity of the platelets to aggregated IgG while the addition of C1r or C1s was without effect. Furthermore, the addition of C1r or C1s to C1q inhibited the action of C1q in platelet aggregation induced by IgG.The possible association between the different C1 subcomponents and human platelets is discussed.

Complement C1↗
PubMed1976

C1 inactivator.

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Amino Acids↗
PubMed1976

Irreversible enzyme inhibitors. Inhibitors of guinea pig complement derived by quaternization of substituted pyridines with benzyl halides.

A series of 83 compounds derived from hydrocarbon-substituted pyridines by quaternization with PhCH2Br usually containing a 2-SO2F or 6-Cl-2-SO2F group was synthesized and evaluated as inhibitors of guinea pig complement and in most cases its C1 component. The most active compounds were 3-(4-phenylphenylbutyl)-N-(6-choro-2-fluorosulfonylbenzyl) pyridinium bromide (43) and 3-(4-phenylphenylbutyl)-N-(2-fluorosulfonylbenzyl) pyridinium bromide (44), each showing 50% inhibition at 7.8 muM. The most effective irreversible inhibitor of the C1 component was N-(6-chloro-2-fluorosulfonylbenzyl)-5,6-benzoquinolinium bromide (87), which showed 50% inhibition at 4 muM.

Animals↗
PubMed1977

Inhibition of the reconstitution of the haemolytic activity of the first component of human complement by a pepsin-derived fragment of subcomponent C1q.

1. A fragment of subcomponent C1q, which contained all the collagen-like features present in the intact molecule, was isolated by pepsin digestion as described by Reid [Biochem. J. (1976) 155, 5-17]. 2. The pepsin-derived fragment of subcomponent C1q did not bind to antibody-coated erythrocytes under conditions where complete binding of sub-component C1q took place. 3. The peptic fragment blocked the reconstitution of C1 haemolytic activity by competing with intact subcomponent C1q in the utilization of a mixture of the other two subcomponents, C1r and C1s. 4. Reduction and alkylation of the interchain disulphide bonds in the pepsin fragment did not markedly affect its inhibitory effect, whereas heating at 56 degrees C for 30min completely abolished the effect. 5. Lathyritic rat skin collagen and CNBr-derived peptides of pig type II collagen showed no ability to mimic the inhibitory effect of the pepsin fragment when tested over the same concentration range as used for the peptic fragment. 6. The peptic fragment was unable to block efficiently the reconstitution of C1 haemolytic activity unless it was added to the mixture of subcomponents C1r and C1s before the attempt to reconstitute C1 haemolytic activity, in solution, or on the surface of antibody-coated erythrocytes. 7. Evidence was obtained that suggested that subcomponent C1q bound the subcomponent C1r-C1s complex more efficiently when the subcomponent C1q was bound to antibody than when it was free in solution.

Binding Sites, Antibody↗
PubMed1976

Occurrence of C1 inactivator and other proteinase inhibitors in euglobulin fractions and their influence on fibrinolytic activity.

Considerable amounts of C1 inactivator and inter-alpha-trypsin inhibitor pecipitate during euglobulin fractionation of human plasma. The amount precipitated depends on the ionic strength and the pH during the fractionation procedure. In contrast, alpha1-anti-trypsin, alpha2-macroglobulinand antithrombin II are present in euglobulin fractions in trace amounts only. The fibrinolytic activity of the euglobulin fractions is inhibited by the endogenous C1 inactivator, particularly as shown by comparison of normal and hereditary angioneurotic edema (HANE) plasma.

Angioedema↗
PubMed1976

Acquired angioedema with lymphoproliferative disorder: association of C1 inhibitor deficiency with cellular abnormality.

A patient with a lymphoproliferative disorder, angioedema, and an acquired deficiency of the inhibitor of the activated first component of complement was studied. The patient's complement profile revealed depletion of the first component of complement, which has not been seen in angioedema of the hereditary type. There was no evidence for C1-depleting activity in the patient's plasma. The majority of the patient's peripheral blood mononuclear cells resembled B cells in their memebrane receptor properties and in that they carried easily detectable immunoglobulin, predominantly IgM. However, these cells were unusual in that they phagocytosed both latex particles and C3-coated erythrocytes. Morphological study of the cells infiltrating the patient's lung revealed immature, atypical, and plasmacytoid lymphocytes and immunoblasts. Both the patient's peripheral blood mononuclear cells and a suspension of cells from the pulmonary infiltrate were capable of depleting the first component of complement and its inhibitor from homologous plasma. Normal ABO-compatible cells did not possess this property. The data suggested that the patient's abnormal lymphoid cells may have interacted with the complement system to produce a biochemical defect and a clinical syndrome closely resembling angioedema of the hereditary type.

Aged↗
PubMed1977

[Study by means of enzymatic and immunochemical determination of Cl esterase inhibitor in 59 patients with hereditary angioneurotic edema].

Serum C1 esterase inhibitor was determined in 138 members of 18 italian families with hereditary angioedema by immunochemical and enzymatic assays. On the basis of quantitative and functional findings, the type A of hereditary angioedema was diagnosed in 44 subjects, and the type B in 15. Some technical devices concerning serum sample handling were identified. The influence of heparin, EDTA, and citrate on C1 esterase inhibitor activity of normal plasma was also investigated.

Adult↗
PubMed1977

[Experimental analysis of the complement-binding activity of gamma-globulin].

It was experimentally demonstrated that the anticomplimentary characteristics of gamma-globulin perparations was associated with disturbances of the colloid condition of the serum system and the absence of any stabilizing action of albumin and other serum proteins. It is also expressed as a result of a high complement-binding activity of protein aggregates. The anticomplementary characteristics of the nonaggregated part of protein in commercial preparations of gamma-globulin could be depressed by the addition of albumin or fresh serum; as to the anticomplementary characteristics of protein aggregates -- it remains unchanged. An intermolecular electrostatic interaction exists between albumin and gamma-globulin; it prevents sorption of the complement on Fc-fragment of IgG, whose destruction leads to the manifestation of the gamma-globulin complement-binding activity.

Blood Proteins↗