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C REACTIVE PROTEIN

BY: M S RAHMAN MODERATOR: DR. VARSHA A SINGH

2IntroductionCRP

An acute phase protein

In response to different inflammatory stimuli

Infection or tissue damage

Produced, mainly in the liver

Extra hepatic - neurons, atherosclerotic plaques, monocytes, and lymphocytes.(The mechanisms regulating synthesis - unknown)

Phylogenetically high- plasma protein

3Acute-phase protein

Plasma concentration- increases (positive ) - decreases (negative)

- least 25 percent - inflammatory disorders.

Positive APP: - CRP,mannose binding protein,

Complement factors,ferritin, Ceruloplasmin, serum

amyloid A etc.

Negative APP:- Albumin, transferrin, retinol-binding protein, antithrombin,

transcortin

4History First acute-phase protein

It was discovered by Tillett and Francis in 1930 in the plasma of patients during the acute phase of pneumococcal infection.

CRP, named for its capacity to precipitate the somatic C-polysaccharide of Streptococcus pneumoniae.

5STRUCTURE OF CRP

An annular (ring-shaped), pentameric protein .

composed of five identical nonglycosylated polypeptide subunits.

Half-life - 19 hours , constant , health and disease.

Molecular weight -25106 Da

6STRUCTURE OF CRP

Belongs to the pentraxin family of calcium dependent ligand-binding plasma proteins

7Production

This is the early and rapid host response to tissue injury.

Local expansion of pathogen number

Direct activation of compliment in tissues

Degranulation of mast cells

8 Release of inflammatory mediators

Systemically active mediators:

(IL-1, IL-6, TNF-α)

Initiate production of CRP in liver

Activation of C/EBP gene at transcription level

Release of CRP in circulation

9Binding of CRP with phosphocholine Receptors

Bacterial cellwall

Apoptotic Cell

Inflammated tissue

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Phagocytosis of bacteria with the production of CRP

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CRP PRODUCTION AND KILLING OF APOPTOTIC CELLS

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CRP PRODUCTION AND KILLING OF

INFLAMMATED TISSUE

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Hepatic synthesis –

Very rapid, single stimulus. Healthy young adult-

Median concentration 3.0 mg/l.

Serum concentrations rise - 6 hr (above 5 mg/l )

-peaks around 48 hours.

CLINICAL APPLICATION

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RANGE OF CRP LEVELS

VIRAL INFECTIONS: <40mg/l

BACTERIAL INFECTIONS: 40-200 mg/l

SEVERE BACTERIAL INFECTIONS/ TRAUMA/ BURNS: >200 mg/l

Following an acute-phase stimulus-

-Increase up to 10000-fold

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Acute Inflammation

ChronicInflammation

Tissue Injury

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A. Acute inflammation:

Bacterial infection

Pneumococcal pneumonia

Acute rheumatic fever

Bacterial endocarditis

Staphylococcal osteomyelitis

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B. Chronic inflammation:

Systemic lupus erythematosis Rheumatic arthritis Reiter’s syndrome, psoriatic

arthriopathy, arthritis following jejuno-ileal bypass

Polyarteritis nodosa, disseminated systemic vasculitis, coetaneous

vasculitis Polymyalgia rheumatica

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Crohn’s disease Ulcerative colitis Dermomyositis Osteoarthritis Neoplastic diseases Smokers Obesity Diabetes

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C. Tissue injury:

Tissue injury and surgery

Acute myocardial ischemia

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CLINICAL USES OF CRP

1. Screening

Infection

Inflammation/ Tissue damage

Obesity/Hypertension- risk of CHD

DM type II

Atherosclerosis.

2.Diagnosis of Meningitis-

Bacterial/ viral

Monitoring of the response to treatment of inflammation and infection.

e.g. : acute pancreatitis

Diagnostic Prognostic

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Lab Diagnosis

Quantitative

Semiquantitative rapid latex Agglutination

ELISAChemiluminescent

ImmunoassayLaser nephlometryBNA nephelometer Quantum dots and immunochromatogr

aphic testImmunoturbidimetr

y

Qualitative

Latex Agglutination

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Latex agglutination test

Principle

CRP antigen + mono specific anti-human CRP

Agglutination

Detect greater then 6µ/ml CRP.

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Semiquantitave Rapid latex slide test

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Quantitative Method

ELISASandwich Assay

(Peroxidase)

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Quantum dots and immunochromatographic test

Rabbit IgG

Human CRP

QD/anti-CRP conjugate

QD-labeled goat-anti-rabbit Ab

Quantum dots (QDs) are introduced as fluorescent probes and immunochromatographic strips to develop quantitative fluorescence point-of-care tests (QF-POCT) to analyze C-reactive protein (CRP) levels

sample pad Test line Control line Absorbent pad

Y CRP Ab2

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Quantum dots and immunochromatographic test

Distance from sample pad

Flu

ore

scen

ce in

ten

sit

y

27Quantitative Method

Use Streptavidin-HRP as enzyme and enhanced ECL system as substrate reagent.

Relative luminosity values (RLU) is scanned by photon counter reader

Chemiluminescent Immunoassay Kits

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Quantitative Method Laser Nephlometry

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Principle

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Light Source: polychromatic tungsten filament lamp

Monochromator : captures light of multiple

wavelength and changes to singlewavelength.

(

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Sample: Ag-Ab Complex

scattered light produced

Photodetector

an electronic signal

converted to a turbidity value.

interaction of the incident light and the sample volume

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Ab complex

Immunoturbidimetry-

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Light Source: polychromatic tungsten filament lamp

Monochromator : captures light of multiple

wavelength and changes to singlewavelength.

(

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Sample: Ag-Ab Complex

Absorbed light produced

Photodetector

an electronic signal

converted to a turbidity value.

interaction of the incident light and the sample volume

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THANK YOU