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PubMed1985

Reduced opsonisation of protein A containing Staphylococcus aureus in sera with cryoglobulins from patients with active systemic lupus erythematosus.

Among a total of 41 patients with systemic lupus erythematosus (SLE) 11 of 14 patients with active disease had reduced capacity (p less than 0.05) to opsonify Staphylococcus aureus in undiluted sera, as compared with nine of 27 patients with inactive disease (p less than 0.02). The opsonic reduction in the active patients increased with the number of active organ systems (p less than 0.002). No correlation was found between reduced opsonisation and corticosteroid treatment, or serum concentrations of complement components (C) of the classical pathway, or bacteria-associated activated C3. When the cryoglobulin fraction of immune complexes (IC) was removed, normal opsonic capacity was restored, and the opsonic reduction could be transferred with the cryoglobulins to pooled serum. Increased IC values, as measured by C1q binding assay, were found in conjunction with reduced opsonic capacity (p less than 0.04). Since opsonisation in SLE sera of a protein A deficient strain of S. aureus was normal, reduced S. aureus phagocytosis in SLE sera may be explained by IC binding to staphylococcal protein A.

Adolescent↗
PubMed1980

Hereditary angioneurotic edema: immunochemical 'activity' without clinical expression.

An 11-year-old white female with focal glomerulonephritis was found to have an absence of functional C1 esterase inhibitor. C1 esterase inhibitor measured by immunochemical means, however, was only slightly reduced. After an initial time period marked by variable hypocomplementemia, presumably due to immune complex formation associated with the nephritis, immunochemical signs of active and severe hereditary angioneurotic edema (HANE) developed. These have been unremitting for 3 1/2 years. Clinical signs of HANE, however, have never developed. Thus, during this time, there have been no clinical abnormalities despite the fact that free C1 esterase activity has been persistently present in this patient's serum and serum levels of functional C1 esterase inhibitor, C2 and C4 have been continuously less than 2% of normal. It appears, therefore, that this patient has an unusual form of HANE mainifested solely by the complement alterations seen during symptomatic attacks but without clinical expression of that serologic activity.

Angioedema↗
PubMed1988

Role of EAC1q4 in C1a transfer reaction (C1aTR) and further information on the nature of the EAC1q4 site.

The complement intermediates EAC1, EAC4, and EAC1q4 were prepared with guinea pig, porcine, as well as human complement. EAC4 and EAC1q4 were made from EC4 and EAC14 respectively. The C1a transfer reaction (C1aTR), the second step of Borsos' C1a fixation and transfer test, was carried out with various combinations of these intermediates. It was found that the EAC1q4, instead of the EAC4, was the C1a acceptor, and the C1rs subcomponents rather than the whole C1 molecule should have to transfer in the C1aTR. The EAC41 derived from EC4 generated no EAC1q4 in EDTA medium as the EAC14 did. This presented evidence for the joining of C4 to A in the EAC1q4 site.

Animals↗
PubMed1990

Regulation of the hepatic synthesis of C1 inhibitor by the hepatocyte stimulating factors interleukin 6 and interferon gamma.

C1 inhibitor (C1INH), the major plasma inhibitor of activated C1, kallikrein, and activated Hageman factor, may be an important factor in limiting inflammatory injury mediated by the complement and contact systems. C1INH is thought to be synthesized primarily in the liver; however, the regulators of hepatic C1 inhibitor synthesis are completely unknown. In this report, we analyze the regulation of C1INH synthesis by hepatocyte stimulating factors in human hepatoma cell lines and primary hepatocytes. Interleukin-6 and interferon gamma increase C1INH production in both hepatoma cells and hepatocytes. These cytokines stimulate de novo synthesis of functional C1INH, acting at a pretranslational level as assessed by Northern blotting. The stimulatory effects of interleukin-6 and interferon gamma on C1INH synthesis are separate and are differentially modulated by interleukin-1. These results establish that hepatic C1INH synthesis is regulated by hepatocyte stimulating factors and reveal novel interactions between these factors.

Acute-Phase Proteins↗
PubMed1991

Amino acid residues 1101-1105 of the isotypic region of human C4B is important to the covalent binding activity of complement component C4.

The C4A and C4B isotypes of human C4 show certain functional differences that stem from their relative preference for transacylation to amino (-NH2) vs hydroxyl (-OH) nucleophiles, respectively, on complement-activating surfaces. Comparison of amino acid sequences of the alpha-chain fragment of C4, C4d, has shown C4A- and C4B-specific sequences at residues 1101-1106 are the only consistent structural difference between isotype, i.e., Pro, Cys, Pro, Val, Leu, Asp in C4A and Leu, Ser, Pro, Val Ile, His in C4B. These residues may be responsible either in part or entirely for properties associated with isotype. To examine the functional role of residues 1101-1106 in C4B-mediated hemolysis, whole serum or immunopurified human C4 with allotypes, A3B1, A3, B2B1, or B1 were preincubated in the presence or absence of an antipeptide mAb (BII-1) specific for amino acid residues 1101-1105 of C4B. Sensitized sheep E and C4-deficient guinea pig serum was then added and lysis measured by absorbance at 415 nm. Our results show lysis of antibody-sensitized sheep E is inhibited by antibody and C4B2B1, C4B1, or C4A3B1 but not antibody and C4A3. The interference of hemolysis by BII-1 could not be explained by inhibition of activation of C4B or inhibition of C3 or C5 convertase activity. Furthermore, results from uptake experiments show that BII-1 interferes with the covalent binding activity of C4B, indicating residues 1101-1105 play a role in the covalent binding reaction of C4B to the target E-antibody complex.

Amino Acid Sequence↗
PubMed1990

[A simplified method for the assessment of C1 esterase inhibitor function].

From the result that the activated form of C1-s(C1-s) prolonged the kinetics of hemolysis via complement, this assay was applied to assess C1 esterase inhibitor (C1INH) function. In the kinetic assay, the complement hemolytic activity was evaluated by the time which required to cause 50% reduction of the initial turbidity of sensitized sheep erythrocytes, and was expressed as T1/2. (1) T1/2 of pooled normal human sera (p-NHS) showed dose-dependent prolongation by the addition of various amounts of C1-s. (2) Preincubation of various amounts of functionally pure C1INH with the constant amounts of C1-s inhibited dose-dependently the prolongation of T1/2 by C1-s. (3) The C1INH activity of NHS was 840 +/- 80 units/ml (n = 6) and that of the C1INH deficient serum was 80 units/ml, which were calculated from the standard curve established by the addition of various amounts of purified C1INH. This test requiring only C1-s and sensitized sheep erythrocytes is simple technically and high in sensitivity, and seems to be useful for the routine assay for C1INH function of human sera.

Animals↗
PubMed1977

An investigation of the complement system in patients with periodic disease (results from 29 cases).

The complement system was investigated in 29 patients suffering from authentic periodic disease. A statistically significant increase in C4, also in total complement and C3 could be demonstrated. It is possible that the increase in C4 was due to the macrophages which are always present in the infiltrates of periodic disease. This biological observation is of clear practical importance for the diagnosis of the condition both before and after colchicine therapy.

Complement C1 Inactivator Proteins↗
PubMed1978

Inhibition of the classical and alternative pathways by amino acids and their derivatives.

Effects of various aminoacids and their derivatives on the classical pathway and alternative pathway of the complement were studied. Leupeptin, acetyl-leucyl-leucyl-arginal, inhibited CH50 and Cl-esterase, but did not inhibit the alternative pathway. When aminoacids of carbon chains of the order of seven were used, arginine and lysine had stronger effects than trans-aminomethyl cyclohexane carboxylic acid (t-AMCHA), cis-aminomethyl cyclohexane carboxylic acid (cis-AMCHA) and epsilon aminocaproic acid (EACA). SH-compounds, cysteine, homocysteine and glutathione, had the strongest inhibitory effects among these aminoacids on both classical and alternative pathways. When effects on Cl esterase were compared, arginine, lysine, t-AMCHA, cis-AMCHA and EACA had weak inhibition while SH-compounds showed strong inhibition. Poly-L-lysine, which had extremely strong inhibition of CH50, had no inhibition of Cl esterase. The inhibitory effects of antifibrinolytic agents, EACA and t-AMCHA, were weak but when effects on early parts of the classical pathway, C(1,4,2)H50 were tested, some inhibitory activities were recognized. Thus inhibitory effects of these agents were due to their activities on the early parts of the classical pathway.

Amino Acids↗
PubMedDate not supplied

[Hereditary angioedema by defict of C1 esterase. Our experience in 8 cases].

Eight cases of hereditary angioedema, all of them with low values of C1-sterase inhibitor are analyzed. In 7 cases the C3 and C4 components of the complement were assessed; the results showed marked descent of C4. The 8 patients came from 4 different families; only 2 of them were males. Six patients presented digestive disorders, reporting colic pain, nausea and vomiting. In 1 of them the abdominal picture was the only evidence of the disease. In 5 patients the angioedema episodes occurred following traumatisms and in 3 because of emotional states. The duration of the attacks varied from several hours to six days. There was a familial history in all cases. Three of the patients had repeated episodes of pharyngolaryngeal angioedema, two of them requiring emergency tracheotomy because of suffocating crisis. Six patients were treated with Epsilon aminocaproic acid (16 to 20 gr daily) or with tranexamic acid (1 to 3 gr. daily). In 4 cases the results were excellent with either of these antifibrinolytic drugs. No side effects were observed in the tranexamic acid therapy whilst they were frequent in the treatment with Epsilon aminocaproic acid.

Adolescent↗
PubMed1985

[Current diagnostic possibilities in hereditary angioedema and acquired angioedema].

Amidolytic assays for the determination of C1 esterase inhibitor have been proposed some years ago; however, the substrates employed lacked sensitivity. The recent development of a C1 esterase-sensitive substrate (N-alpha-methoxycarbonyl-l-lysyl(epsilon-CBO)-glycyl-arginyl-4-nit roanilide) provides a method that can be routinely used. Any interferences with other plasma proteases could not be observed. Normal range was ascertained to be 1.48 +/- 0.23 kU/l; within-run precision revealed C.V.'s of 1.74% (for the normal range) and 7.3% (for the pathological range). This method can be considered most suitable for functional determination of C1 esterase inhibitor and is superior to the determination of antikallikrein activity. To point out to the diagnostic relevance of a functional C1 esterase inhibitor assay some examples are illustrated.

Angioedema↗
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↗
PubMed1984

The role of immune complexes in the activation of the first component of human complement.

Immune complex-induced C1 activation and fluid phase C1 autoactivation have been compared in order to elucidate the immune complex role in the C1 activation process. Kinetic analyses revealed that immune complex-bound C1 activates seven times faster than fluid phase C1 spontaneously activates. The rate of spontaneous C1 activation increased after decreasing the solution ionic strength. In fact at one-half physiologic ionic strength (i.e., 0.08 M), the kinetics of spontaneous C1 activation were indistinguishable from the kinetics of activation of immune complex-bound C1 at physiologic ionic strength. The enhanced fluid phase C1 activation at low ionic strength resulted neither from C1 nor C1q aggregation, nor from selective effects on the C1r2S2 subunit; however, at the reduced ionic strength, the C1 association constant (defined for C1q + C1r2S2 in equilibrium C1qr2S2) did increase to 2.3 X 10(8) M-1, which is equal to that for C1 bound to an immune complex at physiologic ionic strength. Therefore, C1 can spontaneously activate in the fluid phase as rapidly as C1 on an immune complex when the strength of interaction between C1q and C1r2S2 is the same in both systems. In conclusion, under physiologic conditions, C1q and C1r2S2 are two weakly interacting proteins. Immune complexes provide a site for the assembly of a stable C1 complex, in which C1q and C1r2S2 remain associated long enough for C1q to activate C1r2S2. Thus, immune complexes enhance the intrinsic C1 autoactivation process by strengthening the association of C1q with C1r2S2.

Antigen-Antibody Complex↗