Standard Curve
Example of Human C1q standard curve in Assay Diluent A1. Plotted are the background-subtracted data.
This standard curve is provided for demonstration only.
Human C1q OneStep ELISA Kit
Human C1q OneStep ELISA Kit
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Product Details
Product Details
Product Specification
| Antigen | C1q |
| Immunogen | Recombinant Protein |
| Antibody Type | Recombinant mAb |
| Reactivity | Hu |
| Purification | Protein A |
| Stability & Storage | 12 months from date of receipt / reconstitution, 2 to 8°C as supplied. |
Kit
| Precision | Intra-assay: 2.0%； Inter-assay: 2.4% |
| Sample type | Serum; EDTA Plasma, Heparin Plasma, Citrate Plasma; Cell Culture Supernatant |
| Assay type | Sandwich (quantitative) |
| Sensitivity | 21.44 pg/mL |
| Range | 78.1 pg/mL – 5000 pg/mL |
| Recovery | Human Serum: 89% Human EDTA Plasma: 104% Human Heparin plasma: 113% Human Citrate Plasma: 117% Cell Culture Supernatant (1640): 102% |
| Assay time | 60 minutes |
| Species reactivity | Hu |
Background
Human C1q is a subunit of the C1 complex, which serves as the recognition molecule that initiates the classical complement pathway of the immune system. It is a hexameric protein comprising 18 polypeptide chains (six each of A, B, and C chains) that assemble into a bouquet-like structure with six globular heads connected by collagen-like stalks. These globular heads recognize and bind to a diverse array of ligands, including the Fc regions of immunoglobulin G (IgG) and immunoglobulin M (IgM) when they are bound to antigens, as well as pentraxins, apoptotic cells, and pathogen surfaces. Upon ligand binding, C1q undergoes a conformational change that activates the associated serine proteases C1r and C1s, triggering the downstream complement cascade. Beyond its classical role in innate immunity, C1q also functions as a key opsonin, promoting phagocytosis of apoptotic cells and immune complexes, thereby aiding in the clearance of cellular debris and maintenance of tissue homeostasis. Furthermore, C1q is involved in regulating synaptic pruning in the central nervous system and has been implicated in neurodevelopmental disorders. Consequently, C1q deficiency in humans is associated with an increased susceptibility to autoimmune diseases such as systemic lupus erythematosus (SLE), highlighting its critical role in bridging innate and adaptive immunity while preventing autoimmunity.
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ELISA
Spike Recovery
The recovery of Human C1q was evaluated in activated samples spiked with concentrations spanning the entire assay range.
Spike Recovery
Recovery of Human C1q was assessed by spiking a 5000 pg/mL standard into matrix diluted 60,000-fold. Serial dilutions of the spiked sample were prepared, and the percent recovery was calculated for each dilution relative to the expected concentration.
Dilution Linearity
The concentrations of Human C1q were measured and interpolated from the target standard curves and corrected for sample dilution.
The leftmost bar in the graph shows biological samples diluted in Assay Diluent to 0.003% concentration. "undiluted" was defined as 0.003% biological sample. The subsequent bars represent two-fold serial dilutions of this reference.
The mean target concentration was determined to be 71.2 μg/mL in Human Serum.
The mean target concentration was determined to be 112.5 μg/mL in Human EDTA plasma.
The mean target concentration was determined to be 90.4 μg/mL in Human Heparin plasma.
The mean target concentration was determined to be 20.2 μg/mL in Human Citrate plasma.
Serum levels in healthy individuals
Duplicate measurements were performed on serum samples obtained from eight individual healthy donors. Data are reported as dilution factor-corrected interpolated. The resultant mean C1q concentration was 114.6 μg/mL, with a distribution spanning 74.4 to 177.3 μg/mL across the donor cohort.
Intra-Assay Precision (Precision within an assay)
Three samples of known concentration were tested fifteen times on one plate to assess intra-assay precision.
Inter-Assay Precision (Precision between assays).
Three samples of known concentration were tested in separate assays to assess inter-assay precision. Assays were performed with at least three lots of components.
Determination of Minimum Detectable Dose (MDD)
The MDD was determined using three independent lots of assay components. For each lot, 19 replicate measurements of the diluent (zero calibrator) were performed. The mean (AVERAGE) and standard deviation (STDEV) of the 19 replicates were calculated. The MDD for each lot was then calculated according to the following formula:
MDD = 2 × STDEV + AVERAGE
Cross‑reactivity
The heatmap displays O.D.450 ratios for serum samples from multiple species. Color intensity is proportional to the O.D.450 ratio (test species / reference species). Darker colors indicate higher cross‑reactivity.
HOOK Effect Threshold
The upper limit of the HOOK effect was established at 100× the highest calibrator concentration (equivalent to a 2-log10 increase). No HOOK effect was observed below this threshold, confirming that samples within this concentration range yield reliable quantitative results without signal depression.
Protocol Diagram
