| 1. |
- Bergseth, Grethe, et al.
(författare)
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An international serum standard for application in assays to detect human complement activation products
- 2013
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 56:3 SI, s. 232-239
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Forskningsöversikt (refereegranskat)abstract
- The importance of the complement system in clinical medicine has become evident during the last decades and complement therapeutics has now reached the clinic. Thus, there is an increased interest in and need for assays to evaluate complement activity and dysfunction. Pathologically increased complement activation can indirectly be evaluated by quantification of complement components, but in order to exactly measure such activation, assays for quantification of products formed during activation are required. Progress in this field is hampered by lack of standardization. Therefore, members of the International Complement Standardization Committee, a joint initiative of the International Complement Society and the International Union of Immunological Societies (IUIS), prepared a defined standard for application in assays for complement activation products. We here report on the production and properties of this International Complement Standard #2 (ICS#2). ICS#2 was made from a pool of sera from healthy blood donors (ICS#1) that was activated with a combination of heat-aggregated IgG and zymosan, and subsequently stabilized by adding EDTA and nafamostat mesylate. The protocol was optimized to make the standard applicable in the following activation product assays: C1rs-C1-inhibitor complexes, C4a, C4bc, C4d, Bb, C3bBbP, C3a, C3bc, C3dg, C5a and the soluble terminal C5b-9 complement complex (SC5b-9, TCC). ICS#2 was defined as containing 1000 complement activation units (CAU)/mL for all activation products measured. All activation products were stable after 10 times thawing and freezing and most of the activation products were stable during storage at 4 degrees C for up to 21 days. ICS#2 was produced large-scale and is considered a valuable tool for standardization, calibration and reference control for complement activation assays, providing the necessary prerequisite for quality assessments between complement laboratories.
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| 2. |
- Mollnes, Tom Eirik, et al.
(författare)
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Complement analysis in the 21st century
- 2007
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 44:16, s. 3838-3849
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Tidskriftsartikel (refereegranskat)abstract
- Complement analysis in the clinic is usually associated with the quantification of C3 and C4, measurement of C1-inhibitor and screening for complement activity. These analyses have been available in routine diagnostic laboratories for decades. In recent years, however, the field of complement analysis has expanded considerably, with the introduction of novel assays to detect complement activation products, and spreading still further towards genetic analysis to reveal the basis of complement deficiencies and identify mutations and polymorphisms associated with defined diseases such as atypical haemolytic uraemic syndrome and age related macular degeneration. Here we review the current status of complement analysis, including assays for the quantification of complement activity and complement activation products, together with genetic methods for the detection of deficiencies, mutations and polymorphisms. This is an area where significant developments have been made recently, paralleling the research advances into the role of complement in human disease. It is clear, however, that there is a need for consensus and standardisation of analytical methods. This will be a major challenge for the complement society in the future.
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| 3. |
- Prohaszka, Zoltan, et al.
(författare)
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Complement analysis 2016 : Clinical indications, laboratory diagnostics and quality control
- 2016
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Ingår i: Immunobiology. - : Elsevier BV. - 0171-2985 .- 1878-3279. ; 211:11, s. 1247-1258
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, complement analysis of body fluids and biopsies, going far beyond C3 and C4, has significantly enhanced our understanding of the disease process. Such expanded complement analysis allows for a more precise differential diagnosis and for critical monitoring of complement-targeted therapy. These changes are a result of the growing understanding of the involvement of complement in a diverse set of disorders. To appreciate the importance of proper complement analysis, it is important to understand the role it plays in disease. Historically, it was the absence of complement as manifested in severe infection that was noted. Since then complement has been connected to a variety of inflammatory disorders, such as autoimmune diseases and hereditary angioedema. While the role of complement in the rejection of renal grafts has been known longer, the significant impact of complement. In certain nephropathies has now led to the reclassification of some rare kidney diseases and an increased role for complement analysis in diagnosis. Even more unexpected is that complement has also been implicated in neural, ophtalmological and dermatological disorders. With this level of involvement in some varied and impactful health issues proper complement testing is clearly important; however, analysis of the complement system varies widely among laboratories. Except for a few proteins, such as C3 and C4, there are neither well-characterized standard preparations nor calibrated assays available. This is especially true for the inter-laboratory variation of tests which assess classical, alternative, or lectin pathway function. In addition, there is a need for the standardization of the measurement of complement activation products that are so critical in determining whether clinically relevant complement activation has occurred in vivo. Finally, autoantibodies to complement proteins (e.g. anti-C1q), C3 and C4 convertases (C3 and C4 nephritic factor) or to regulatory proteins (e.g. anti-Clinhibitor, anti-factor H) are important in defining autoimmune processes and diseases based on complement dysregulation. To improve the quality of complement laboratory analysis a standardization commmittee of the International Complement Society (ICS) and the International Union of Immunological Societies (IUIS) was formed to provide guidelines for modern complement analysis and standards for the development of international testing programs.
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| 4. |
- Shahini, Negar, et al.
(författare)
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Increased Complement Factor B and Bb Levels Are Associated with Mortality in Patients with Severe Aortic Stenosis
- 2019
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Ingår i: Journal of Immunology. - : American Association of Immuologists. - 0022-1767 .- 1550-6606. ; 203:7, s. 1973-1980
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Tidskriftsartikel (refereegranskat)abstract
- Inflammation is involved in initiation and progression of aortic stenosis (AS). However, the role of the complement system, a crucial component of innate immunity in AS, is unclear. We hypothesized that circulating levels of complement factor B (FB), an important component of the alternative pathway, are upregulated and could predict outcome in patients with severe symptomatic AS. Therefore, plasma levels of FB, Bb, and terminal complement complex were analyzed in three cohorts of patients with severe symptomatic AS and mild-to-moderate or severe asymptomatic AS (population 1, n = 123; population 2, n = 436; population 3, n = 61) and in healthy controls by enzyme immunoassays. Compared with controls, symptomatic AS patients had significantly elevated levels of FB (2.9- and 2.8-fold increase in population 1 and 2, respectively). FB levels in symptomatic and asymptomatic AS patients were comparable (population 2 and 3), and in asymptomatic patients FB correlated inversely with valve area. FB levels in population 1 and 2 correlated with terminal complement complex levels and measures of systemic inflammation (i.e., CRP), cardiac function (i.e., NT-proBNP), and cardiac necrosis (i.e., Troponin T). High FB levels were significantly associated with mortality also after adjusting for clinical and biochemical covariates (hazard ratio 1.37; p = 0.028, population 2). Plasma levels of the Bb fragment showed a similar pattern in relation to mortality. We concluded that elevated levels of FB and Bb are associated with adverse outcome in patients with symptomatic AS. Increased levels of FB in asymptomatic patients suggest the involvement of FB from the early phase of the disease.
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| 5. |
- Zhao, Fei, et al.
(författare)
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C3-Glomerulopathy Autoantibodies Mediate Distinct Effects on Complement C3-and C5-Convertases
- 2019
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Ingår i: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 10, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- C3 glomerulopathy (C3G) is a severe kidney disease, which is caused by defective regulation of the alternative complement pathway. Disease pathogenesis is heterogeneous and is caused by both autoimmune and genetic factors. Here we characterized IgG autoantibodies derived from 33 patients with autoimmune C3 glomerulopathy. Serum antibodies from all 33 patients as well as purified IgGs bound to the in vitro assembled C3-convertase. Noteworthy, two groups of antibodies were identified: group 1 with strong (12 patients) and group 2 with weak binding C3-convertase autoantibodies (22 patients). C3Nef, as evaluated in a standard C3Nef assay, was identified in serum from 19 patients, which included patients from group 1 as well as group 2. The C3-convertase binding profile was independent of C3Nef. Group 1 antibodies, but not the group 2 antibodies stabilized the C3-convertase, and protected the enzyme from dissociation by Factor H. Also, only group 1 antibodies induced C3a release. However, both group 1 and group 2 autoantibodies bound to the C5-convertase and induced C5a generation, which was inhibited by monoclonal anti-C5 antibody Eculizumab in vitro. In summary, group 1 antibodies are composed of C3Nef and C5Nef antibodies and likely over-activate the complement system, as seen in hemolytic assays. Group 2 antibodies show predominantly C5Nef like activities and stabilize the C5 but not the C3-convertase. Altogether, these different profiles not only reveal a heterogeneity of the autoimmune forms of C3G (MPGN), they also show that in diagnosis of C3G not all autoimmune forms are identified and thus more vigorous autoantibody testing should be performed.
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