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PubMedDate not supplied

In vitro methods for detection of circulating immune complexes.

The possible pathologic consequences of the presence of circulating immune complexes in certain disease states has caused considerable attention to be given to the development of laboratory procedures capable of quantitatively measuring the presence of immune complexes in serum. Many assays are available which utilize differing properties of immune complexes for their detection. Examples of assays which depend on different biologic properties of circulating immune complexes are presented and discussed. Included are the Raji cell assay, Clq binding assay, inhibition of rheumatoid agglutination, and nephelometric assays for determination of circulating immune complexes.

Agglutination Tests↗
PubMed1987

Proteolysis and deglycosylation of human C1 inhibitor. Effect on functional properties.

The effects of proteolysis and deglycosylation on C1 inhibitor (C1Inh) were tested with respect to both its ability to form complexes with C1s and its capacity to block C1 autoactivation. Limited proteolysis of C1Inh by Staphylococcus aureus V8 proteinase, proline-specific endopeptidase or elastase generated a major high-Mr (approximately 86,000) fragment. In contrast with the fragment produced by elastase, which was inactive, the fragments resulting from V8 proteinase and proline-specific endopeptidase treatment retained activity. Deglycosylation with N-glycanase or O-glycanase, or both, had no major effect on the functional activity of C1Inh.

Complement C1 Inactivator Proteins↗
PubMed1988

Hereditary angioedema. Undersuspected, underdiagnosed.

Although hereditary angioedema accounts for only a small fraction of all angioedema, it is relatively common among inherited deficiencies of plasma proteins. The occurrences of upper respiratory obstruction, of attacks following trauma, and of episodes of abdominal pain are clues to the diagnosis, and the absence of a family history is no reassurance against it. Measurement of C4 concentration is a useful screening test: Normal values exclude the diagnosis, while subnormal values mandate measurement of C1 INH by immunoassay or functional assay. The functional assay is required to detect the genetic variant form. The importance of making the diagnosis is threefold. It facilitates prevention of life-threatening complications, such as upper airway obstruction and needless abdominal surgery. It leads to use of short-term prophylactic measures to prevent complications associated with trauma. In patients with disability due to frequent attacks, suppression or elimination of all symptoms can be achieved by chronic treatment with impeded androgens.

Adult↗
PubMed1985

Synthesis of C1 inhibitor (C1-INA) by a human monocyte-like cell line, U937.

Human monocytes are known to synthesize many of the components of complement, including C1-INA. In this report we demonstrate that the human monocyte-like cell line U937 is also capable of synthesizing functional C1-INA. This was shown in several ways, including 1) incorporation of tritiated amino acids into antigenic C1-INA, immunoprecipitation, and detection by fluorography; 2) a sensitive ELISA, which allowed quantitation of antigenic C1-INA in cell lysates, and 3) a C2-dependent hemolytic assay in which the functional activity of U937 C1-INA was assayed. Data from the ELISA indicate that U937 cells contain between 2.1 to 12.8 ng of C1-INA per 1 X 10(6) cells. Furthermore, fluorescence-activated cell sorter analysis revealed that approximately 16% of U937 cells carry C1-INA as a surface bound antigen. Other proteins found to be synthesized by U937 cells include C1r, C8, and possibly alpha-2-macroglobulin. These results suggest that the U937 cell line could be a convenient and valuable model for the study of monocyte C1-INA synthesis and physiology.

Amino Acids↗
PubMed1988

Hereditary angioedema in Czechoslovakia. Clinical, immunological, genetic and therapeutic studies of 16 families.

The analysis of the findings in 16 families with hereditary angioedema detected in Czechoslovakia over the years 1975-1986 is being presented. In 14 families C1-inhibitor deficiency and in two families afunction of C1-inhibitor was established. Of the total number of 175 examined family members C1-inhibitor defect was registered in 66 subjects (60 with deficiency and 6 with afunction), and of these 48 suffered from clinical symptoms of edematous attacks affecting the skin, larynx, intestine and urinary tract, whereas 18 subjects were asymptomatic. Genealogical studies confirmed that the defect is inherited as an autosomal dominant trait. In 16 patients long-term prophylactic treatment with Danol was introduced. The effective minimum dosage was tested individually for each patient.

Angioedema↗
PubMed1989

[A case of hereditary angioneurotic edema provoked by functional insufficiency of C1-inactivator].

The hemolytic activity of complement, the concentration of C1-inactivator, of C1q and C4 components of complement as well as the activity of contact-activated kallikrein and the functional activity of C1-inactivator were studied in the plasma of a female patient with hereditary angioneurotic edema (HAE), of her mother, sister and normal donors. The hemolytic activity of complement, the concentration of C1-inactivator and C1q in the blood plasma of the persons examined turned out unchanged as compared with the same parameters in donors. Meanwhile in the patient with HAE and her mother with symptoms similar to HAE, the concentration of C4 appeared lower than that in the patient's sister not suffering from the disease and in donors. The activity of contact-activated kallikrein in the plasma of the patient's sister and mother exceeded the activity of the enzyme in donors. The least activity of plasma kallikrein was recorded in the proband. The functional activity of C1-inactivator in the proband constituted 50-60% of the activity of that parameter in her sister and donors. The magnitude of the functional activity of C1-inactivator in the patient's mother approximated its magnitude in the proband. Therefore, the development of HAE in the given case was mainly provoked by functional insufficiency of C1-inactivator. The magnitude of the spontaneous TAME-esterase kallikrein-like activity in the blood plasma of the patient with HAE remained within normal.

Adult↗
PubMed1982

Familial angioedema associated with C1 esterase-inhibitor deficiency. A new genetic variant in hereditary angioedema?

In the absence of a positive family history for hereditary angioedema (HAE), both siblings in a family were found to have clinical and laboratory findings similar to those in HAE. Both siblings became symptom free after receiving danazol treatment, accompanied by a subnormal rise in C1 esterase inhibitor and C4 levels. As both siblings and their father share HLA haplotype A2, B7, the influence of other HLA loci on the clinical expression of this disorder should be considered. Although the disorder found in these siblings may be inherited as a recessive disorder, which to our knowledge has never been described before, or may have developed as the result of spontaneous genetic mutation, it is more appropriate to classify these two cases as familial angioedema until proved otherwise.

Adolescent↗
PubMed1987

[Complement activation after the intravascular administration of contrast media: a comparison between ionic and nonionic x-ray contrast media].

The effects of intravascular radiographic contrast media on the complement system were investigated in 46 patients. An ionic (sodium-/meglumine amidotrizoate, n = 22) or a non-ionic (iohexol, n = 24) contrast agent was applied for an i.v. urography. The levels of the complement-compounds C1q, C3, C5 and of the C1 inhibitor were determined at the end of the infusion and 20 minutes later. In both groups we obtained a significant (p less than 0.01) decrease of C3 during infusion for 10 to 15%. 20 minutes later these values were almost normalized again. Infusion of iohexol additionally caused a marked consumption of C5 and C1q (reduction to 85%), while the ionic contrast agent had no significant effect on these components. Both contrast media caused a decrease of the C1-inhibitor levels. Our results demonstrate an activation of the complement system by i.v. application of radiographic contrast media. The decrease of the C1q-level due to infusion of iohexol indicates an additional involvement of the classical activation pathway of the complement cascade.

Complement Activating Enzymes↗
PubMed1981

Clinical presentation and diagnosis of hereditary angio-oedema in five families.

The clinical features of 16 patients with deficiency of C1 esterase inhibitor are described. Severity ranged from no symptoms in 2 young subjects to repeated and severe abdominal pain and angio-oedema. Diagnostic techniques are described and the ease with which the diagnosis can be established is emphasized. A functional assay is required in addition to immunological determination of the protein in order to detect a minority of patients who have ineffective inhibitor. Experience of treatment with tranexamic acid is reviewed and its place in management in relation to androgens is discussed.

Adult↗
PubMedDate not supplied

Prekallikrein activation in the adult respiratory distress syndrome.

Prekallikrein is the zymogen form of plasma kallikrein, a proteolytic enzyme of the contact system of blood coagulation, fibrinolysis and kinin formation. To assess whether prekallikrein was activated in the adult respiratory distress syndrome (ARDS), we examined plasma samples from 12 critically ill patients including five individuals with ARDS. Using the ratio between functional prekallikrein and prekallikrein-kallikrein antigen as an index for prekallikrein activation, we found that prekallikrein was extensively activated in patients with ARDS, while this was significantly less in the case of critically ill patients without ARDS. Following activation of prekallikrein in plasma, kallikrein reacts with its substrates and with protease inhibitors, among which the alpha 2-glycoprotein C1-inhibitor. Thus, we examined whether C1-inhibitor of critically ill individuals was modified in a way suggesting that it had reacted with kallikrein. Such a modification was found in the five patients with ARDS, while it was not detectable in the seven patients without ARDS. This observation further confirmed the activation of prekallikrein in patients with ARDS. We suggest that plasma kallikrein-mediated reactions, which include bradykinin release and neutrophil activation, may contribute to the pathogenesis of ARDS.

Adolescent↗
PubMed1991

Substrate properties of C1 inhibitor Ma (alanine 434----glutamic acid). Genetic and structural evidence suggesting that the P12-region contains critical determinants of serine protease inhibitor/substrate status.

The serine protease inhibitor (serpin) C1 inhibitor inactivates enzymes involved in the regulation of vascular permeability. A patient from the Ma family with the genetic disorder hereditary angioedema inherited a dysfunctional C1 inhibitor allele. Relative to normal plasma, the patients's plasma contained an additional C1 inhibitor immunoreactive band, which comigrated with normal C1 inhibitor cleaved by plasma kallikrein, C1s, or factor XIIa. C1 inhibitor Ma did not react with a monoclonal antibody to a neoepitope that is present in complexed and cleaved normal C1 inhibitor, suggesting conformational differences between cleaved normal C1- inhibitor and cleaved C1 inhibitor Ma. Molecular cloning and sequencing of exon 8 of the C1 inhibitor Ma allele revealed a single C to A mutation, changing alanine 434 to glutamic acid. Ala 434 of C1 inhibitor aligns with the P12 residue of the prototypical serpin alpha 1-antitrypsin. The P12 amino acid of all inhibitory serpins is alanine, and it is present in a highly conserved region on the amino-terminal side of the serpin-reactive center loop. Whereas normal C1 inhibitor expressed by transfected COS-1 cells formed complexes with and was cleaved by kallikrein, fXIIa, and C1s, COS-1-expressed Ala434---Glu C1 inhibitor was cleaved by these enzymes but did not form complexes with them. These results, together with evidence from other studies, suggest that serpin protease inhibitor activity is the result of protein conformational change that occurs when the P12 region of a serpin moves from a surface location, on the reactive site loop of the native molecule, to an internal location within sheet A of the complexed inhibitor.

Amino Acid Sequence↗
PubMed1979

Hereditary angio-oedema: treatment with danazol. Report of a case.

An 8-year-old boy with hereditary angio-oedema was treated with danazol under close endocrinological supervision. The boy's C1 esterase inhibitor (C1inh) and C4 levels increased rapidly to near normal values under a daily dose of 400 mg and were maintained at about 50% of the normal by maintenance doses of 200 mg danazol every other day. Throughout the entire treatment period (11 months) the boy has been maintained free from attacks of angio-oedema. No hormonal imbalance was detected in the follow-up period. Our results indicate that danazol should be suitable for the treatment of HAE not only in adults but also in prepubescent children.

Angioedema↗
PubMed1985

[Effect of Expafusion (HES 40/0.5) on the corpuscular elements of blood and inhibitors of blood coagulation].

The present study reports on an investigation of 32 normal subjects who were given intravenously 500 ml of hydroxyethyl starch (HES) over 30 min. In 16 normal subjects, 500 ml of blood had been previously withdrawn over 20 min. Tolerance proved to be good. Side effects such as hyperergic reactions, influence on circulatory or cardiac function were not observed. Changes in corpuscular elements of blood did not exceed the dilution effect and mostly returned to the initial value 60 min after termination of HES infusion. The change in thrombocyte function, immunoglobulins and the inhibitors alpha 1-antitrypsin, alpha 2-macroglobulin, as well as C1-inactivator and C3-activator only slightly, but not more pronounced than it could have been expected by the dilution effect. A favorable effect could be recorded in erythrocyte filtration according to Schmidt-Schoenbein. Here, we found an improved flow property which exceeded the hemodilution effect and lasted over the 4-hour test period. In addition, thrombocyte aggregation during ADP administration in the Born chamber did not show any change which suggests that a clinically relevant effect on thrombocyte function and thus the danger of hemorrhage during HES administration can be excluded.

Adolescent↗