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PubMed1984

The catabolism of C1(-)-inhibitor and the pathogenesis of hereditary angio-edema.

A sufficient explanation for the observations that HAE is a dominantly transmitted disease and that the hemizygotes have levels of the normal protein of only in the region of 15%-20% of normal can be given by proposing that a substantial proportion of the catabolism of C1(-)-esterase inhibitor involves the prior formation of a complex with one of the enzymes with which the inhibitor reacts. This part of the catabolism will be largely independent of inhibitor concentration, i.e. of zero order, and for this reason occurs similarly in normals and in hemizygotes. Estimates of the extent of this zero order metabolism can be obtained from turnover data with normal and dysfunctional C1(-)-inhibitor and the results are consistent with the observed levels. In the form of the disease associated with the dysfunction protein the dysfunctional protein makes up more than 85% of the total protein found for the same reason. The extent of the enzyme inhibitor complex dependent catabolism (RO) can be determined in vivo by simultaneous turnovers of dysfunctional and normal inhibitor and gives a measure of the extent of activation of this group of enzymes. The value of this technique in clinical practice is described elsewhere.

Angioedema↗

PubMed1981

Clinical and biochemical effects of stanozolol therapy for hereditary angioedema.

Stanozolol, an inexpensive anabolic steroid with a 30:1 anabolic:androgenic ratio, was administered to 12 male and 15 female patients with biochemically proven hereditary angioedema over a 2-yr period to obtain a systematic assessment of the relationship between drug dosage and clinical response, incidence of side effects, and amelioration of complement abnormalities. All 27 patients attained the minimal effective dose, ranging from 0.5 to 2 mg daily, which controlled the frequency and intensity of symptoms with minimal side effects. At daily maintenance doses of 2, 1, and 0.5 mg the frequencies of attacks per weeks of therapy were 1/14.6, 1/7.2, and 1/8.2 wk, respectively. Side effects with maintenance therapy included menstrual abnormalities and virilization in four females and elevation of serum creatinine phosphokinase (CPK) in five males. In six patients on maintenance doses of stanozolol, serum levels of testosterone, free thyroxin (T4), and thyroxin binding globulin (TBG) (four males), and of estradiol, progesterone, T4, and TBG (two females) were normal. Slightly low serum levels of progesterone and TBG were found in two females who had normal menstrual cycles. Statistically significant elevations above pretherapy levels of serum inhibitor to the activated first component of complement function and C4 protein and function occurred when patients were on maintenance therapy, but these measurements remained below the lower limit of normal range. Higher doses of stanozolol (4 mg/day), which caused greater immunochemical responses, were unnecessary for control of clinical disease and were unjustified for chronic therapy because of more frequent side effects.

Adolescent↗

PubMed2003

Diagnosis and management of hereditary angioedema: an American approach.

Hereditary angioedema (HAE) is an autosomal dominant disease characterized by recurrent episodes of angioedema, and caused by a deficiency of the plasma protein C1 inhibitor. HAE attacks carry a substantial risk of morbidity or even mortality, making it imperative that the correct diagnosis be established and an appropriate management plan be in place. This report reviews the current diagnostic and therapeutic approaches available in the United States. Areas in which the diagnostic or therapeutic tools are deficient are discussed, and the prospects for improved therapeutic modalities highlighted.

Acute Disease↗

PubMed1995

Reduction in transmission of hepatitis C after the introduction of a heat-treatment step in the production of C1-inhibitor concentrate.

BACKGROUND: The transmission of viral infections via protein concentrates made from a large pool of plasma depends on the selection of donors, fractionation process, and virucidal methods. To date, no data are available on the infectivity risk of plasma concentrates of the inhibitor of the first component of complement (C1-INH). STUDY DESIGN AND METHODS: The prevalence of blood-borne viral infections and levels of transaminases were evaluated in patients treated with a large-pool plasma concentrate of the inhibitor of C1-INH before and after the introduction of virucidal methods. The study included 85 patients with hereditary angioedema and 4 with acquired angioedema. The patients were divided into three groups: 1) 48 untreated patients; 2) 22 patients treated with non-virus-inactivated C1-INH concentrates; and 3) 19 patients treated with virus-inactivated concentrates. Serum samples obtained at various times after the infusion of concentrate were assayed for alanine amino-transferase and tested for hepatitis B surface antigen and antibodies to hepatitis C virus (anti-HCV) and human immunodeficiency virus (anti-HIV); anti-HCV-negative subjects exposed to the concentrate were also tested for HCV RNA. RESULTS: Prevalences of HCV infection and elevated alanine aminotransferase are significantly lower in patients treated with virus-inactivated concentrates than in those exposed to non-virus-inactivated concentrates. No patients were anti-HIV positive. CONCLUSION: This study suggests that C1-INH concentrates transmitted HCV, but that the virucidal methods adopted are effective in reducing the infectivity.

Adolescent↗

PubMed1988

Plaque-lift testing of expression vector lambda gt11 with gold-labeled immunoglobulins.

Colloidal gold particles were coated with affinity-purified antibodies against the human plasma protein, C1 inhibitor, and used to probe for fusion proteins of C1 inhibitor with beta-galactosidase encoded by recombinant bacteriophage lambda gt11 DNA. Plaque-lift tests were done with recombinant proteins immobilized on nitrocellulose applying anti-C1 inhibitor gold particles followed by the silver enhancement treatment. This procedure resulted in a sensitive and specific staining of the recombinant proteins and allowed the selective detection of relevant clones in a complex cDNA expression library. Under optimized conditions, plaque-lift testing was completed within 2.5 h after removal of nitrocellulose filters from the plate. Hence, the immunogold detection method provides an alternative to conventional enzyme- or radionuclide-based screening procedures for cDNA expression libraries.

Animals↗

PubMed1993

Differential diagnosis of human ascites: inhibitors of the contact system and total proteins.

To assess their accuracies as markers for malignancy, we assayed alpha 2-macroglobulin, C1-inhibitor, alpha 1-protease inhibitor, and total proteins in ascites and plasma from patients with gastrointestinal cancer (n = 15) and non-malignant liver disease (n = 13), using functional and immunologic assays. For all inhibitors and total proteins determined in ascites, the values in the cancer group were significantly higher than the corresponding values in the group with non-malignant liver disease. The diagnostic accuracy for differentiating malignancy-related from non-malignant ascites was 93% for a alpha 1-protease inhibitor value > or = 50% of the pool plasma value and 90% for alpha 2-macroglobulin > or = 16%, C1-inhibitor > or = 40% (all functional assays), and total proteins > or = 20 g/l (biuret). In conclusion, functional assays for alpha 2-macroglobulin, C1-inhibitor, and alpha 1-protease inhibitor and determination of total proteins in ascites appeared to be very informative tests for the differential diagnosis of ascites. The test for alpha 1-protease inhibitor gave higher specificity (92% versus 77%) and likelihood ratio for a positive test (12 versus 4) compared with the other tests.

Adult↗

PubMed1984

[Hereditary angioneurotic edema: a molecular disease caused by a defect in the O-glycosylation of C1 esterase inhibitor (C1-INH)].

A quantitative and qualitative study of neutral and aminosaccharides in C 1-esterase inhibitor (C 1-INH), protein of the complement system, was performed. We observe a mixed glycosylation of the molecule with an N-glycosylated: O-glycosylated chain ratio of 1: 4. The loss of the inhibitory activity of the molecule in hereditary angioedema (O ANH) is associated with an O-glycosylation deficiency which differs according to the two molecular variants: C 1-INH (1 A) and C 1-INH (II) previously described.

Angioedema↗

PubMedDate not supplied

Activation systems in contrast idiosyncrasy.

Both animal and human data suggest the possibility that the C1 esterase inhibitor may play an important controlling role in contrast media systemic reactions. This critical controlling protein has a major inhibitory effect on C1, kallikrein, activated factor XII of the intrinsic coagulation system, and on plasmin. In addition, it probably has other inhibitory effects not so well documented. Any circumstance that contributes to a continuing activation of the complement, coagulation, kinin, or fibrinolytic systems may result in partial consumption of the inhibitor and predispose the individual to adverse reactions to contrast challenge.

Anaphylaxis↗

PubMed1998

General anaesthetic for a pilonidal sinus excision in a patient with hereditary angio-oedema.

Hereditary angio-oedema is an autosomal dominant condition resulting in a deficiency of C1 esterase inhibitor protein in serum. The condition is characterized by oedematous attacks in the skin, mucous membranes and gastrointestinal tract triggered by mental and physical stress. We present the rare case of a young girl with known hereditary angio-oedema and spina bifida occulta being admitted for an elective pilonidal sinus excision. This case presented different challenges for the anaesthetists and surgeons.

Adolescent↗

PubMed1995

Complement C1 inhibitor is produced by brain tissue and is cleaved in Alzheimer disease.

C1 inhibitor was identified in human brain tissue by Western blotting and by immunohistochemistry using multiple antibodies to the native protein. The presence of C1 inhibitor mRNA was identified by reverse transcriptase-polymerase chain reaction analysis of brain mRNA extracts. The mRNA was also detected in cultured postmortem human microglia and in the IMR-32 human neuroblastoma cell line. Immunohistochemically, the native protein was detected in residual serum of capillaries and pyramidal neurons of both control and Alzheimer disease cases, as well as in occasional senile plaques of Alzheimer tissue. The reacted protein was detected on dystrophic neurites and neuropil threads in Alzheimer tissue by 4C3 monoclonal antibody, which recognizes a neoepitope following suicide inhibition. These data indicate that C1 inhibitor, a regulatory molecule controlling multiple inflammatory proteolytic cascades, is produced in normal brain. In Alzheimer disease, C1 inhibitor undergoes a prominent reaction in abnormal neuronal processes, such as dystrophic neurites and neuropil threads.

Alzheimer Disease↗

PubMed1992

Hereditary angioedema complicated with chronic renal failure: report of sibling cases.

Hereditary angioedema (HAE) is known as a deficiency state of C1 inhibitor (C1 INH), an important protease inhibitor protein involved in the complement system. As with other components of the classical pathway of the complement system, a state of its deficiency often causes clinical immunoregulatory disorders. A 45-yr-old brother and a 63-yr-old sister with HAE both developed chronic renal failure, probably due to chronic glomerulonephritis, and required regular hemodialysis. This is, to our knowledge, the first report of sibling cases of HAE associated with chronic renal failure.

Angioedema↗

PubMed2001

C1 inhibitor deficiency: hereditary and acquired forms.

C1 inhibitor deficiency can be hereditary or acquired. The hereditary disorder has two types, each of which is inherited as a dominant disorder, with genetic mechanisms leading either to low levels of normal C1 INH and little or no mutant problem as a result of mRNA or protein synthetic defects or degradative mechanisms (Type I) or with point mutations and synthesis of a functionless protein product with transinhibition of the normal allele (Type II). The acquired disorder with low C1q is due to C1 INH consumption associated with lymphoma or connective tissue disease (Type I) and/or autoimmune mechanisms (Type II). The swelling of all types is due to absence of inhibition of the plasma kinin forming cascade with liberation of bradykinin while complement activation, a critical marker of the disorder, is not responsible for the swelling. Treatment employs androgenic compounds, antifibrinolytic agents, or replacement therapy.

Angioedema↗

PubMed1998

Hepatic veno-occlusive disease with severe capillary leakage after peripheral stem cell transplantation: treatment with recombinant plasminogen activator and C1-esterase inhibitor concentrate.

Severe veno-occlusive disease (VOD), characterised by elevated serum bilirubin levels, is a known complication in the first 3 weeks after peripheral blood stem cell transplantation (PBSCT). Severe VOD is associated with capillary leakage and multiple organ dysfunction and leads to high mortality. We report a 17-year-old male, who developed VOD with capillary leakage (CL) after allogeneic PBSCT. The patient presented with a maximum serum bilirubin of 25.4 mg/dl, weight gain (10% of baseline weight), generalized edema, cardiovascular insufficiency, complement activation, jaundice and a decreased AT and protein C functional activity. After VOD and CL were diagnosed the patient was treated with recombinant human plasminogen activator (rt-PA) and C1 esterase-inhibitor concentrate (C1-INH-C). The clinical symptoms resolved and the patient's status stabilized. The patient was in an adequate clinical state 5 months after transplantation. We noted that the combined therapy with rt-PA and C1-INH-C in this high-risk situation led to a resolution of VOD with CL.

Adolescent↗

PubMed1985

Elevated plasmin-alpha 2-antiplasmin complex levels in hereditary angioedema: evidence for the in vivo efficiency of the intrinsic fibrinolytic system.

The contact activation and fibrinolytic systems were assessed in 5 patients with hereditary angioedema (HAE). Reductions in F XII levels and increase in kallikrein-like activity in some patients indicated activation of the contact (intrinsic) system of coagulation. A great increase in plasmin-alpha 2-antiplasmin complex in all subjects indicated that in this disease, there is a constantly ongoing fibrinolysis. Since C1-inhibitor, the deficient protein in HAE, is a poor inhibitor of the well-known extrinsic (tissue-type) plasminogen activator, but the major inhibitor of the contact activation system and a related in vitro phenomenon termed intrinsic fibrinolysis, our data show that this fibrinolytic system is also sometimes operating efficiently in vivo. Furthermore, the known clinical data on HAE are compatible with a role of intrinsic fibrinolysis in the pathophysiology of this disease.

Angioedema↗

PubMed1981

A C1-inhibitor-complex assay (INCA): a method to detect C1 activation in vitro and in vivo.

A radioimmunoassay (the C1-inhibitor-complex assay, INCA) is described for the detection of complexes that are composed of at least C1s and C1-inhibitor. This INCA is based on demonstrating that C1s and C1-inhibitor (C1-In) are linked: after an incubation with anti-C1s-Sepharose, bound C1sC1-In complexes are detected by 125I-anti-C1-In. C1sC1-In complexes were prepared by the addition of a slight excess of C1s to normal human serum (NHS). As little as 2 ng C1-In bound to C1s was detected. Additional free C1s in serum hardly influenced the detection of C1sC1-In complexes. Complexes presumably composed of C1rC1s(C1-In)2 were generated by the addition of aggregated IgG to NHS. This generation was inhibited by lowering the temperature to 0 degrees C, and by EDTA, and depended on the concentration of aggregated IgG. These complexes had a sedimentation value of approximately 9S. Complexes of C1s and C1-In were also generated in NHS by the addition of DNP-albumin and protein A, but not by zymosan. The INCA was applied to blood samples from normal donors and patients. Sixteen out of 19 samples from patients with acute glomerulonephritis contained increased amounts of C1rC1s(C1-In)2 complexes as compared with the amounts in blood samples from normal donors. The INCA provides a useful tool to assess the activation of C1 in the presence of C1-In, both in vitro and in vivo.

Complement Activation↗

PubMed1989

Synthesis and expression of C1 inhibitor by human umbilical vein endothelial cells.

The biologic activity of C1 esterase, activated forms of factor XII and kallikrein at sites of vascular inflammation may be regulated by C1 inhibitor (C1 INH) elaborated by endothelial cells. Therefore, we investigated whether human umbilical vein endothelial cells (HUVEC) in culture produce C1 INH. Passaged HUVEC contain 1.6 +/- 0.8 micrograms of C1 INH/10(8) cells (mean +/- S.D.; n = 7) which was immunochemically similar to plasma C1 INH measured by a competitive enzyme-linked immunosorbent assay. Methylamine-treated lysates of HUVEC contained a functional inhibitor of purified kallikrein (2.7 +/- 0.8 micrograms activity/10(8) cells, mean +/- S.D.; n = 4). The HUVEC-derived kallikrein inhibitory activity was mostly C1 INH because it was reversed by chemically treating the lysate with chloroform and was neutralized by anti-C1 INH antibody. A lysate of HUVEC derived from an umbilical cord from a patient with Type I hereditary angioedema contained less than 30% of the normal levels of C1 INH antigen and activity. Immunohistochemical staining of HUVEC demonstrated a diffuse pattern of staining for C1 INH. HUVEC C1 INH was also expressed on the endothelial cell surface as detected by binding of anti-C1 INH antibody to intact monolayers and was elaborated progressively into the overlying media over the first 24 h in culture. HUVEC incubated with [35S] methionine secreted a metabolically labeled protein having a molecular mass of 92 kDa immunoisolated using polyclonal or monoclonal antibodies to human C1 INH. A mRNA transcript encoding for C1 INH was detected by slot blot hybridization. Incubation of HUVEC with gamma-interferon stimulated the expression of the 2.1 kilobase mRNA for C1 INH and increased the level of C1 INH produced by these cells. Production and expression of C1 INH by endothelial cells may help modulate the complement system and the contact system of plasma proteolysis on the vascular surface in vivo.

Blotting, Northern↗

PubMed1987

Altered C1 inhibitor genes in type I hereditary angioedema.

Hereditary angioedema is an inherited disease transmitted as an autosomal dominant trait and characterized by deficient activity of C1 inhibitor, a glycoprotein that limits intravascular activation of complement. The unavailability of markers for the C1 inhibitor locus has so far precluded access to the genetic bases of the disorder. Using a recombinant-DNA probe for the C1 inhibitor gene, we identified a cluster of four distinctive DNA restriction sites in a multigeneration family. The strict cosegregation of these markers with a low C1 inhibitor level supports the conclusion that a defective structural gene is responsible for the disease. The occurrence of distinct DNA markers in patients from unrelated kinships indicates that, like forms of the condition displaying dysfunctional C1 inhibitor variants, those characterized by protein deficiency are also genetically heterogeneous. Although multiple restriction-site changes in the C1 inhibitor gene are carried by certain patients, DNA markers for this locus are strikingly infrequent among normal persons. These findings indicate that the gene alterations responsible for hereditary angioedema arise more often from DNA rearrangements than from nucleotide substitutions. Such variations in the structure of the C1 inhibitor gene may provide the basis for early and direct identification of persons at risk.

Angioedema↗

PubMed1979

Response of variant hereditary angioedema phenotypes to danazol therapy. Genetic implications.

Hereditary angioedema (HAE), an auto-somal dominant disorder characterized by attacks of episodic edema is associated with decreased functional levels of the C1 esterase inhibitor. Approximately 85% of patients have lowered antigen levels of a normal inhibitor protein. 15% of patients have normal or elevated antigenic levels of functionless protein. We have examined the response to danazol therapy of patients with the variant HAE phenotypes possessing the abnormal protein in an effort to determine if these patients possess a normal structural C1 inhibitor allele. Four patients with a variant HAE phenotype were treated successfully with danazol. In two patients, distinguished by the presence of a functionless, albumin-bound, C1 inhibitor (phenotype 2), phenotypic analysis of the danazol response by bidirectional immunoelectrophoresis revealed the appearance of the normal C1 inhibitor gene product during danazol therapy. This relatively cathodal C1 inhibitor peak appears in conjunction with the development of nearly normal functional activity. All of the functional C1 inhibitory activity which appeared in the phenotype 2 treatment serum was associated with the electrophoretically normal inhibitor. This normal protein could be separated from the functionless inhibitor protein by immunoadsorption and molecular sieve chromatography. Danazol therapy of the two patients with an electrophoretically normal, functionless C1 inhibitor (phenotype 3) also resulted in a clinical remission associated with development of a significant increment in functional serum C1 inhibitory activity and C1 inhibitor protein. These findings demonstrate that these two HAE phenotypic variants are heterozygous for the normal serum C1 inhibitor, a finding which was not apparent before phenotypic analysis of this serum during danazol therapy. These data provide strong evidence for a basic similarity between the common form of HAE and its phenotypic variants. They also suggest that a structural gene lesion may result in the abnormalities of serum C1 inhibitor function and disease expression in all three of these HAE phenotypes.

Angioedema↗