Name
C1q, Human, ELISA kit
Catalog nr
HK356
(lot number and expiry date are indicated on the label)
Short description
C1q forms together with C1r and C1s the C1 macromolecule, the first component of the classical complement pathway. The formation of an antibody–antigen complex (immune complex) is the principal way of activating the classical pathway of the complement system. C1q triggers the activation process when it docks onto antibodies within these immune complexes. In this way, C1q acts to bridge the...
Size
2 x 96 det.
Application
Manual
Description
C1q forms together with C1r and C1s the C1 macromolecule, the first component of the classical complement pathway. The formation of an antibody–antigen complex (immune complex) is the principal way of activating the classical pathway of the complement system. C1q triggers the activation process when it docks onto antibodies within these immune complexes. In this way, C1q acts to bridge the innate and adaptive immune systems. Interaction of immune complexes with C1q induces a conformational change within the C1 complex, which results in activation of the classical pathway. C1q functions as recognition unit by binding to the heavy chain of IgG or IgM (Fc gamma and Fc micro) provided that the immunoglobulins are bound to their antigen. Furthermore, C1q can bind to apoptotic blebs, where it activates the classical complement pathway and mediates phagocytosis. As such, C1q promotes the clearance of apoptotic cells and subsequent exposure of auto-antigens, thereby preventing stimulation of the immune system. C1q is predominantly produced by macrophages but also by follicular dendritic cells, interdigitating cells and cells of the monocyte-macrophage lineage. C1q deficiency has a profound effect on host defense and clearance of immune complexes. Inherited C1q deficiency is also associated with the development of systemic lupus erythematosus (SLE). In the case of C1q deficiency, SLE is found in 90% of reported cases. C1q plays a role in the prevention of autoimmunity by facilitating the physiological clearance and processing of apoptotic debris. Absence of C1q may cause autoimmunity by impairment of the clearance of apoptotic cells.
Anti-C1q autoantibodies deposit in glomeruli together with C1q but induce overt renal disease only in the context of glomerular immune complex disease. This provides an explanation why anti-C1q antibodies are especially pathogenic in patients with SLE.
Low C1q levels are associated with proliferative glomerulonephritis (WHO class III and IV). Furthermore, C1q concentrations decrease prior to clinical manifestations of flares of the disease. Low C1q levels have also been shown to predict the histopathological outcome of lupus nephritis. A single nucleotide polymorphism in the C1QA gene results in decreased C1q serum levels and has been linked to photosensitive Lupus-specific skin disease, subacute cutaneous lupus erythematosus (SCLE).
Cross Reactivity
| Cross reactant | Reactivity (Yes/No) |
| Mouse C1q | Strong |
| Rat C1q | Strong |
Species
Human
Features
- Working time of 3½ hours.
- Minimum concentration which can be measured is 7.8 ng/ml.
- Measurable concentration range of 7.8 – 500 ng/ml.
- Working volume of 100 µl
Typical standard curve
Principle
The human C1q ELISA is a ready-to-use solid-phase enzyme-linked immunosorbent assay based on the sandwich principle with a working time of 3½ hours.
The efficient format of 2 plates with twelve disposable 8-well strips allows free choice of batch size for the assay.
Samples and standards are incubated in microtiter wells coated with antibodies recognizing human C1q.
Biotinylated tracer antibody will bind to captured human C1q.
Streptavidin-peroxidase conjugate will bind to the biotinylated tracer antibody.
Streptavidin-peroxidase conjugate will react with the substrate, tetramethylbenzidine (TMB).
The enzyme reaction is stopped by the addition of oxalic acid.
The absorbance at 450 nm is measured with a spectrophotometer. A standard curve is obtained by plotting the absorbance (linear) versus the corresponding concentrations of the human C1q standards (log).
The human C1q concentration of samples, which are run concurrently with the standards, can be determined from the standard curve.
The efficient format of 2 plates with twelve disposable 8-well strips allows free choice of batch size for the assay.
Samples and standards are incubated in microtiter wells coated with antibodies recognizing human C1q.
Biotinylated tracer antibody will bind to captured human C1q.
Streptavidin-peroxidase conjugate will bind to the biotinylated tracer antibody.
Streptavidin-peroxidase conjugate will react with the substrate, tetramethylbenzidine (TMB).
The enzyme reaction is stopped by the addition of oxalic acid.
The absorbance at 450 nm is measured with a spectrophotometer. A standard curve is obtained by plotting the absorbance (linear) versus the corresponding concentrations of the human C1q standards (log).
The human C1q concentration of samples, which are run concurrently with the standards, can be determined from the standard curve.
Use
The human C1q ELISA kit is to be used for the in vitro quantitative determination of human C1q and Ig containing circulating immune complexes (CIC) in serum, plasma and bronchoalveolar lavage fluid (BALF) samples. This kit is intended for laboratory research use only and is not for use in diagnostic or therapeutic procedures.
Storage and stability
- Upon receipt, store individual components at 2 - 8°C. Do not freeze.
- Do not use components beyond the expiration date printed on the kit label.
- The standard, tracer and streptavidin-peroxidase are stable in lyophilized form until the expiration date indicated on the kit label, if stored at 2 - 8°C.
- The exact concentration of the standard is indicated on the label of the vial and the certificate of quality control.
- Once reconstituted the standard is stable for 12 hours, if stored at 2 - 8°C. For longer stability we recommend to store aliquots at –20°C. Stored at –20°C the standard will be stable for 1 month.
- Once reconstituted, tracer and streptavidin-peroxidase are stable for 1 month if stored at 2 - 8°C.
- Upon receipt, foil pouch around the plate should be vacuum-sealed and unpunctured. Any irregularities to aforementioned conditions may influence plate performance in the assay.
- Return unused strips immediately to the foil pouch containing the desiccant pack and reseal along the entire edge of the zip-seal. Quality guaranteed until expiration date if stored at 2 - 8°C.
Also available
Scientific info
C1q deficiency is linked to autoimmune disorders
Human C1q ELISA: a reliable measurement
C1q: first step in classical complement activation
- C1q is an integral part of the first component of complement (C1)
- Formation of an antibody-antigen complex (immunocomplex) activates the classical pathway of the complement system.
- C1q triggers the activation process by docking onto antibodies within these immunocomplexes
- C1q bridges the innate and adaptive immune systems
- Necrosis and apoptosis results in exposure of endogenous danger patterns, which can be directly recognized by C1q, thus activating the classical pathway
- Activated C1 cleaves complement proteins C2 and C4, resulting in the formation of C4bC2a, also called C3 convertase
C1q and diseases
- Deficieny of C1q is directly linked to Systemic Lupus Erythematosus (SLE) and glomerulonephritis due to homozygous congenital deletions
- Deficiency of C1q is associated with a higher risk of pyogenic infections
- Decrease in C1q serum levels results in reduced uptake of apoptotic cells
- The decrease of phagocytosis results in increased autoimmunity resulting in more circulating auto-antibodies
Matrix influences in human C1q ELISA
- Different matrices were evaluated in the human C1q ELISA
- Serum as well as plasma has to be diluted 200x to obtain reliable measurement (Fig 1)
- C1q in bronchoalveolar lavages (BAL) can be detected accurately when BAL is diluted at least 2x (Fig 2)
- No influence of anticoagulant was detected
Validation of human C1q ELISA
- C1q-depleted serum was spiked with purified C1q
- Recovery of spiked C1q was within the limits of 80-120%
- No C1q was detected in C1q-depleted serum
Reference standard
- Purified C1q derived from Complement Technology Inc was used to validate our standard calculation (Fig 3)
- Perfect match between external C1q source and Hycult Biotech C1q (R2= 0.9997)
Specifications of human C1q ELISA (Cat.# HK356)
- Working time of 3.5 hours
- 100 µl sample/well
- Detection limit of 15.6 ng/ml
- Concentration range 15.6 – 1000 ng/ml
- Useful for serum, plasma and BAL
- Detection of unbound C1q as well as C1q-immunocomplexes (CIC)
- Cross-reactive with mouse and rat C1q
MSDS
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