Human Complement 4,C4 ELISA Kit

Code CSB-E08705h
Size 96T,5×96T,10×96T
Trial Size 24T ELISA kits trial application
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Product Details


The Human Complement 4 (C4) ELISA kit is specifically designed and validated to quantitatively detect the levels of C4 in the serum, plasma, or tissue homogenates. It is not intended for diagnostic use and only used for scientific research in humans. The kit has undergone rigorous quality control in multiple parameters, including sensitivity, specificity, precision, linearity, recovery, and inter-batch difference. Refer to the product instructions for more details.

This assay is based on the Sandwich-ELISA mechanism (the C4 in the sample is sandwiched between the pre-coated C4 antibody and HRP-labeled C4 antibody) and enzyme-substrate chromogenic reaction. The color intensity is positively related to the amount of C4 bound in the initial step. The levels of C4 in the samples can be determined by referring to the O.D. (optical density) of the samples to the standard curve.

C4 in humans is a protein involved in the intricate complement system that protects the body from infections, dead cells, and foreign material. It exerts multiple critical functions in immunity, tolerance, and autoimmunity with the other numerous components. Furthermore, C4 plays a crucial role in connecting the recognition pathways of the overall system instigated by antibody-antigen (Ab-Ag) complexes to the other effector proteins of the innate immune response.

Target Name Complement 4,C4
Alternative Names Acidic C4 ELISA Kit; Acidic complement C4 ELISA Kit; Basic C4 ELISA Kit; Basic complement C4 ELISA Kit; C3 and PZP-like alpha-2-macroglobulin domain-containing protein 2 ELISA Kit; C3 and PZP-like alpha-2-macroglobulin domain-containing protein 3 ELISA Kit; C4; Chido form ELISA Kit; C4; Rodgers from ELISA Kit; C4A anaphylatoxin ELISA Kit; C4A ELISA Kit; C4A2 ELISA Kit; C4A3 ELISA Kit; C4A4 ELISA Kit; C4A6 ELISA Kit; C4AD ELISA Kit; C4B ELISA Kit; C4B_2 ELISA Kit; C4B1 ELISA Kit; C4B12 ELISA Kit; C4B2 ELISA Kit; C4B3 ELISA Kit; C4BD ELISA Kit; C4F ELISA Kit; C4S ELISA Kit; CH ELISA Kit; Chido form of C4 ELISA Kit; CO4 ELISA Kit; CO4A_HUMAN ELISA Kit; Complement C4 A ELISA Kit; Complement C4 B ELISA Kit; Complement C4 gamma chain ELISA Kit; complement C4-A ELISA Kit; complement C4-B ELISA Kit; complement C4-B-like ELISA Kit; complement C4B1a ELISA Kit; Complement component 4A (Rodgers blood group) ELISA Kit; Complement component 4A ELISA Kit; complement component 4B (Chido blood group) ELISA Kit; complement component 4B (Chido blood group); copy 2 ELISA Kit; Complement component 4B (Childo blood group) ELISA Kit; Complement component 4B ELISA Kit; Complement component 4F ELISA Kit; Complement component 4S ELISA Kit; CPAMD2 ELISA Kit; CPAMD3 ELISA Kit; RG ELISA Kit; Rodgers form of C4 ELISA Kit
Abbreviation C4
Uniprot No. P0C0L4
Species Homo sapiens (Human)
Sample Types serum, plasma, tissue homogenates
Detection Range 0.41 ng/mL-300 ng/mL
Sensitivity 0.41 ng/mL
Assay Time 1-5h
Sample Volume 50-100ul
Detection Wavelength 450 nm
Research Area Others
Assay Principle quantitative
Measurement Sandwich
Intra-assay Precision (Precision within an assay): CV%<8%      
Three samples of known concentration were tested twenty times on one plate to assess.  
Inter-assay Precision (Precision between assays): CV%<10%      
Three samples of known concentration were tested in twenty assays to assess.    
To assess the linearity of the assay, samples were spiked with high concentrations of human C4 in various matrices and diluted with the Sample Diluent to produce samples with values within the dynamic range of the assay.
  Sample Serum(n=4)  
1:1000 Average % 96  
Range % 93-99  
1:2000 Average % 100  
Range % 97-103  
1:4000 Average % 89  
Range % 86-92  
1:8000 Average % 100  
Range % 97-104  
The recovery of human C4 spiked to levels throughout the range of the assay in various matrices was evaluated. Samples were diluted prior to assay as directed in the Sample Preparation section.
Sample Type Average % Recovery Range  
Serum (n=5) 86 83-90  
EDTA plasma (n=4) 95 91-99  
Typical Data
These standard curves are provided for demonstration only. A standard curve should be generated for each set of samples assayed.
ng/ml OD1 OD2 Average Corrected  
300 2.873 2.897 2.885 2.786  
100 1.916 1.968 1.942 1.843  
33.3 1.281 1.299 1.290 1.191  
11.1 0.878 0.898 0.888 0.789  
3.7 0.495 0.472 0.484 0.385  
1.23 0.195 0.212 0.204 0.105  
0.41 0.187 0.192 0.190 0.091  
0 0.101 0.097 0.099    
Materials provided
  • A micro ELISA plate ---The 96-well plate has been pre-coated with an anti-human C4 antibody.
  • Two vials lyophilized standard ---Dilute a bottle of the standard at dilution series, read the OD values, and then draw a standard curve.
  • One vial HRP-conjugated C4 antibody (100 x concentrate) (120 μl/bottle) ---Bind to the C4 in the samples or standards and react with the substrate to make the solution chromogenic.
  • One HRP-conjugate Diluent(20 ml/bottle) ---Dilute the HRP-conjugated C4 antibody
  • Two vials Sample Diluent (20 ml/bottle) ---Dilute the sample solution.
  • One vial Wash Buffer (25x concentrate) (20ml/bottle) ---Wash away unbound or free substances.
  • One vial TMB Substrate (10 ml/bottle) ---Act as the chromogenic agent. TMB interacts with HRP, eliciting the solution turns blue.
  • One vial Stop Solution (7ml/bottle) ---Stop the color reaction. The solution color immediately turns from blue to yellow.
  • Four Adhesive Strips (For 96 wells) ---Cover the microplate when incubation.
  • An instruction manual
Materials not provided
  • A microplate reader capable of measuring absorbance at 450 nm, with the correction wavelength set at 600 nm or 630 nm.
  • An incubator can provide stable incubation conditions up to 37°C±5°C.
  • Centrifuge
  • Vortex
  • Squirt bottle, manifold dispenser, or automated microplate washer
  • Absorbent paper for blotting the microtiter plate
  • 50-300ul multi-channel micropipette
  • Pipette tips
  • Single-channel micropipette with different ranges
  • 100ml and 500ml graduated cylinders
  • Deionized or distilled water
  • Timer
  • Test tubes for dilution
and FAQs
Storage Store at 2-8°C. Please refer to protocol.
Lead Time 3-5 working days

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Target Data

Function Non-enzymatic component of C3 and C5 convertases and thus essential for the propagation of the classical complement pathway. Covalently binds to immunoglobulins and immune complexes and enhances the solubilization of immune aggregates and the clearance of IC through CR1 on erythrocytes. C4A isotype is responsible for effective binding to form amide bonds with immune aggregates or protein antigens, while C4B isotype catalyzes the transacylation of the thioester carbonyl group to form ester bonds with carbohydrate antigens.; FUNCTION
Gene References into Functions
  1. The purpose of this study was to evaluate C4A and C4B in patients with congenital adrenal hyperplasia in relation to CYP21A2 genotype and psychiatric and autoimmune comorbidity. We determined the copy numbers of C4A and C4B in 145 patients with CAH .No association was found between C4 copy number and autoimmune disease. PMID: 30465166
  2. Low C4 in systemic lupus erythematosus patients is due to consumption rather than deficient synthesis related to lower C4A & B gene copy numbers. PMID: 30041577
  3. Report strong association of systemic lupus erythematosus in individuals with low copy numbers of C4 and in particular in patients with complete deficiency of C4A. PMID: 29050534
  4. An increase in serum C4, as wall as a decrease in C3, was an important outcome determinant for patients with immunoglobulin A nephropathy. PMID: 28697742
  5. for the first time, a complete overview of C4 in SLE from genetic variation to binding capacity using a novel test. As this test detects crossing over of Rodgers and Chido antigens, it will allow for more accurate measurement of C4 in future studies. PMID: 29080553
  6. The study re-evaluates low-resolution crystal structures of C4 via interactive molecular-dynamics flexible fitting. In terms of biology, the results provide a better structural framework for understanding the pivotal function of the C4 protein within the complement system. PMID: 27599733
  7. An elevated number of C4 genes was observed in Alzheimer's disease (AD) patients as compared with healthy controls. The presence of high C4A and C4B copy numbers in AD patients could explain the increased C4 protein expression observed in AD patients, thus highlighting a possible role for C4A and C4B copy number variations in the risk of developing AD. PMID: 27758680
  8. This study shows that the C4c/C4 ratio seems to be a better diagnostic measure than total antigenic C4 alone. Our findings underline that screening with total antigenic C4 implies a risk of overlooking C1-INH-HAE patients. PMID: 28412283
  9. In comparison with C4-intact patients, C4-deficient patients had a different clinical/serologic lupus-like phenotype and lacked the lupus interferon signature. PMID: 27274010
  10. C4 copy number variations and deficiency of C4A both play an important role in the risk and manifestations of systemic lupus erythematosus in East Asian and European populations PMID: 26814708
  11. Complement C4A deficiency appears to be an important factor for the genetic risk and pathogenesis of juvenile dermatomyositis, particularly in patients with a DR3-positive background. PMID: 26493816
  12. Coronary atherosclerosis is distinguished by serum C4 complement up-regulation and ceruloplasmin down-regulation. PMID: 28091899
  13. find strong statistical significance for association of increased copy number of C4A (OR 0.81 (0.73; 0.89);P = 4.4 x 10(-5)), with the effect most pronounced in individuals over 78 years (OR 0.67 (0.55; 0.81)) and females PMID: 27090374
  14. Copy Number Variation Scan Identifies Complement Component C4 as Novel Susceptibility Gene for Crohn's Disease. PMID: 26595553
  15. genetic polymorphism is associated with acute graft versus host disease in unrelated hematopoietic stem cell transplantation PMID: 26602146
  16. important role of complement C4a in inhibiting the HBV DNA secretion in chronic hepatitis b PMID: 26119402
  17. C4A and C4B gene copy numbers are stronger risk factors for juvenile-onset than for adult-onset systemic lupus erythematosus. PMID: 26800705
  18. Complement C4A deficiency (gene copy number <=1) was identified as a risk factor in a case-control study of juvenile dermatomyositis, particularly when subjects concurrently carried the HLA-DRB1*0301 allele. PMID: 26493816
  19. Increased age, rs2857009 single nucleotide polymorphism of complement component C4 and hepatitis C virus genotype were associated with disease progression. PMID: 25573496
  20. Low C4 was associated with non-Hodgkin's lymphoma in primary Sjogren's syndrome. PMID: 26359802
  21. Schizophrenia risk from complex variation of complement component 4 PMID: 26814963
  22. C4 levels were significantly lower in Factor XII-hereditary angioedema than in idiopathic non-histaminergic acquired angioedema. PMID: 25744496
  23. our study indicates that Finnish NTM patients had significantly more often C4 deficiencies than the healthy control subjects. PMID: 24638111
  24. Complement components C3a and C4a, but not C5a, display antimicrobial activity against P. aeruginosa, E. coli, B. subtilis, and C. albicans. PMID: 17132627
  25. C4 is a novel cellular substrate of the HCV NS3/4A protease. PMID: 24349192
  26. Low C4 gene copy numbers are associated with superior graft survival in patients transplanted with a deceased donor kidney. PMID: 23715124
  27. serum C4a desArg is a potential biomarker for the severity of histological findings in patients with IgA nephropathy. PMID: 23708385
  28. Our findings indicate that a high copy number of C4A confers risk for Behcet disease by modulating the expression of C4A and enhancing IL-6 production. PMID: 23918728
  29. Studies indicate that initiation of lectin compleme pathway leads to activation of the serine proteases MASP-1 and MASP-2 resulting in deposition of C4 on the activator and assembly of the C3 convertase. PMID: 23911397
  30. C4d might be a biomarker for evaluating the risk for IUGR and disease control in patients with systemic lupus erythematosus and pregnancy-induced hypertension. PMID: 23530559
  31. Studies indicate beta-defensins (DEFB4, DEFB103, DEFB104), chemokine ligand 3 like 1 (CCL3L1), Fc gamma receptor 3B (FCGR3B), and complement component C4 (C4) for copy number variation in disease association. PMID: 22837109
  32. Complement 4a plasma protein was identified as increased in Alzheimer's disease PMID: 22052466
  33. Deletion variants of C4 were found to be associated with SLE in Korean women, but did not reach statistical significance. PMID: 23335107
  34. study concludes that the association of C4 gene copy with systemic lupus erythematosus(SLE)was replicated in Chinese Han population, which highlighted the importance of C4 in SLE pathogenesis of diverse populations PMID: 21904924
  35. The precise order and size of all C4 genes were determined in RCCX, a multiallelic copy number variation locus. PMID: 22785613
  36. C4A deficiency is one of the minor defects of the innate immunity that may predispose children and young adults to recurrent respiratory infections. PMID: 22406254
  37. congenital adrenal hyperplasia patients have increased C4 copy number variation, with mutation-specific associations that may be protective for autoimmune disease PMID: 22886582
  38. C4A appears to associate with the protection of residual beta-cell function in new-onset type 1 diabetes. PMID: 22151770
  39. analysis of gene copy number of complement C4A, C4B and C4A silencing mutation by real-time quantitative polymerase chain reaction PMID: 22737222
  40. analysis of the structural basis for activation of the complement system by component C4 cleavage PMID: 22949645
  41. Complement C4a gene expression is regulated both by obesity and by the region between visceral and subcutaneous adipose tissue. PMID: 22616691
  42. Past, present, and future perspectives of C4d as a biomarker, focusing on its use in solid organ transplantation and discussing its possible new roles in autoimmunity and pregnancy. Review. PMID: 22297669
  43. We showed no evidence for a role of hs-CRP, C3 and C4 in the association between BMI and asthma symptoms in overweight children. PMID: 21801245
  44. Although complete homozygous deficiency of complement C4 is one of the strongest genetic risk factors for SLE, partial C4 deficiency states do not independently predispose to the disease. PMID: 22387014
  45. Individuals with 4, 2, and 2 copies of C4, C4A and C4B genes, especially those with A2B2 polymorphism may associate with the development of Graves' disease PMID: 21943165
  46. Data show that in the UK cohort, total C4 GCN ranged from 2 to 6, with copy numbers from 0 to 4 observed for both C4A and C4B, while in the Spanish cohort, C4A GCN from 0 to 6 and C4B GCN from 0 to 5. PMID: 21857912
  47. The study shows the complement component C4A in the plasmas of sePE women is lower than the severe, late-onset PE women, and the Apolipoprotein A-I level is higher in sePE women than slPE women. PMID: 21677994
  48. C4 mRNA levels of the two isoforms (C4A and C4B) were significantly reduced in hepatocytes transfected with RNA from HCV genotype 1a or 2a. PMID: 21345967
  49. The reduction in olfactory function in these hereditary angioedema cases seems to correlate with complement C4 and CH50 levels. PMID: 20649895
  50. not demonstrate that C4 gene copy number associates with transplant outcome PMID: 21164027

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Involvement in disease Complement component 4A deficiency (C4AD); Systemic lupus erythematosus (SLE)
Subcellular Location Secreted, Cell junction, synapse, Cell projection, axon, Cell projection, dendrite
Tissue Specificity Complement component C4 is expressed at highest levels in the liver, at moderate levels in the adrenal cortex, adrenal medulla, thyroid gland,and the kidney, and at lowest levels in the heart, ovary, small intestine, thymus, pancreas and spleen. The extra
Database Links

HGNC: 1323

OMIM: 120790

KEGG: hsa:720

STRING: 9606.ENSP00000396688

UniGene: Hs.534847

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