Immunology Lab: CRP

CRP

C-reactive protein

CRP subunit structure

5 identical subunits held by non-covalent bonds

CRP synthesis site

Primarily synthesized in the liver

CRP presence in serum

Trace constituent; always present in small amounts

CRP original thought

Antibody to the C-polysaccharide of pneumococci

CRP actions

Opsonization, agglutination, precipitation, complement activation (classical pathway)

CRP binding cells

Neutrophils, monocytes, macrophages

CRP role in immune defense

Defends against microbes during antibody lag period

CRP as a marker

Most widely used marker of acute inflammation

CRP rapid increase timeframe

4-6 hours after infection, surgery, or trauma

CRP peak levels timeframe

24-72 hours after trauma

CRP peak level magnitude

Up to 100-1000 fold increase

Common markers of inflammation

Pain, heat, redness, swelling

Mnemonic for CRP conditions

Very Happy Birthday To All Creative Minds

CRP conditions (V)

Viral infections

CRP conditions (H)

Heart disease and myocardial infarction

CRP conditions (B)

Bacterial infections

CRP conditions (T)

Tuberculosis

CRP conditions (A)

Autoimmune diseases (RA, SLE)

CRP conditions (C)

Collagen diseases (scleroderma)

CRP conditions (M)

Malignant diseases (cancer)

Type of serological technique

Latex agglutination

Is the test qualitative or quantitative?

Primarily qualitative (also semi-quantitative)

Known in the CRP test

Anti-human CRP antibody (IgM)

Unknown in the CRP test

CRP (C-reactive protein)

Latex reagent contents

Latex particles coated with anti-human CRP in buffer

Positive control CRP concentration

≥6 mg/L

Negative control CRP concentration

CRP positive result

Agglutination observed; CRP ≥6 mg/L

CRP negative result

Smooth, homogenous solution; CRP

Cause of false positives

Bacterial contamination, rheumatoid factor, pregnancy, oral contraceptives, intrauterine devices

Cause of false negatives

Weak reactions at 200-400 mg/L; dilution required >400 mg/L

Procedure step 1

Place 1 drop each of negative and positive controls into wells

Procedure step 2

Add 1 drop latex reagent to each well

Procedure step 3

Mix with stir stick, change sticks to prevent contamination

Procedure step 4

Rock slide back and forth for 3 minutes

Procedure step 5

Observe for agglutination

Disposal

Sharps (none); biohazard: well cards, paper towels, stir sticks