CRP ELISA Kit | BioSupply UK

CRP ELISA KIT

INTENDED USE

This Human CRP ELISA Kit is to be used for the in vitro quantitative determination of human c reactive protein (CRP) concentrations in serum and plasma. This CRP ELISA Kit is intended FOR LABORATORY RESEARCH USE only and not for use in diagnostic or therapeutic procedures.

INTRODUCTION

C-Reactive Protein (CRP) is an acute phase protein, originally identified and named for its ability to precipitate the C-polysaccharide of pneumococcus in the presence of calcium. It is the prototypic acute phase reactant whose presence in plasma or serum serves as a useful laboratory indicator of systemic inflammatory disease. Normally, CRP in human biological fluids is present in trace amounts (0.07-8.00 mg/L, median 0.6 mg/L). Stimulated by certain cytokines (IL-1α, IL-1β, TNF-α and β, and indirectly by IL-6), its sythesis by hepatocytes enhanced dramatically. Thus during the acute phase response RP’s serum concentration can increase up to 1000-fold within a few hours.

Human CRP is a kind of nonimmunoglobulin serum substance, a heat labile β-globulin. It is classified in a superfamily of proteins termed pentaxins or pentraxins: cyclic, non-glycosylated structures composed of five apparently identical globular non-covalently linked subunits aggregated symmetrically. Each subunit is 23.05 kD (206 amino acids), with a total molecular weight of 117.5 kDa, and consists of 14 anti-parallel β-strands rranged in two β-sheets.

Among acute phase proteins, CRP is a fast-reacting, sensitive and the most easily measured one. It has a rapid response time, short half life and large incremental change and its catabolism is not affected by the type of inflammation. Moreover, its normalization can monitor the cure process from the disease, hence it has the largest data base of isease-released change. CRP can be used as an early and pre-clinical marker of inflammation. Especially in situations where microbiological diagnosis is difficult or too slow in the clinical context, CRP measurements can be used to infer the presence of bacterial infection. Following acute tissue damage or during the course of infectious and non-infectious diseases, hepatic synthesis of CRP dramatically increases its plasma concentration from 0.58 (range 0.06-8.0) mg/L to 100-500 mg/L within 24-48 hours. Typically, mild elevations of CRP (10-40 mg/L)are seen in a variety of inflammatory conditions such as viral infections, rheumatoid arthritis, Crohn’s disease, post-transplant rejections, infant septic coxitis (arthritis of the hip joint), and neoplasia, whereas more marked rises (CRP 40->500 mg/L) are usual seen in acute and severe bacterial infections such as acute, severe pancreatitis and appenditis, bacterial or purulent meningitis, aspirition pneumonia, sequela-prone osteomyelitis, osteoarthritis, giant cell arthritis, septicaemia, systemic vasculitis, acute sinusitis, acute otitis media, infected urinary tract obstruction, extensive trauma, fractures, burns, infectious post-operative complications and acute myocardial infarction. Combined with IL-6, CRP seems to be a valuable parameter in the early iagnosis of neonatal infections.

Serum amyloid A (SAA) is another major acute phase protein whose response is highly correlated with that of CRP (r=0.75-0.88, P=0.0001). Both CRP and SAA respond sensitively to several stimuli with elevated serum levels including surgical trauma, acute infection and allograft rejection, and show almost similar kinetics in many diseases processes. But they differ in certain responses, e.g., the reactivity and sensitivity of SAA is higher than CRP in viral infection, patients on steroid therapy, chronic allograft rejection. So the combined use of CRP and SAA may distinguish viral from bacterial infection, and may distinguish allograft rejection from infection. Meanwhile, CRP proved more useful than SAA to predict cardiovascular events and monitor process of diseases and the effects of some treatments.

PRINCIPLE OF THE ASSAY

CRP ELISA Kit

CRP ELISA Kit is to be used for the in vitro quantitative determination of human c reactive protein (CRP) concentrations in serum and plasma. This CRP ELISA Kit is intended FOR LABORATORY RESEARCH USE only and not for use in diagnostic or therapeutic procedures. This CRP ELISA Kit applies a technique called a quantitative sandwich immunoassay.

The microtiter plate provided in this kit has been pre-coated with a monoclonal antibody specific for CRP. Standards or samples are then added to the appropriate microtiter plate wells and incubated. CRP if present, will bind and become immobilized by the antibody pre-coated on the wells. The microtiter plate wells are thoroughly washed to remove unbound CRP and other components of sample. In order to quantitate the amount of CRP present in the sample, a standardized preparation of horseradish peroxidase (HRP)-conjugated antibody specific for CRP is added to each well to "sandwich" the CRP immobilized during the second incubation. The wells are thoroughly washed to remove all unbound HRP-conjugated antibodies and a TMB (3,3'5,5' tetramethyl-benzidine) substrate solution is added to each well. The enzyme (HRP) and substrate are allowed to react over a short incubation period. Only those wells that contain CRP and enzyme-conjugated antibody will exhibit a change in colour. The enzyme-substrate reaction is terminated by the addition of a sulphuric acid solution and the colour change is measured spectrophotometrically at a wavelength of 450 nm ± 2 nm.

In order to measure the concentration of CRP in the samples, this kit standard (ready-to use) is assayed at the same time as the samples (diluted if necessary with Sample Diluent). This allows the operator to produce a standard curve of Optical Density (O.D.) versus CRP concentration (μg/mL). The concentration of CRP in the samples is then determined by comparing the O.D. of the samples to the standard curve.