Mediators of Inflammation / 2014 / Article / Tab 2

Review Article

Cytokines as Biomarkers in Rheumatoid Arthritis

Table 2

Description and characteristics of assays measuring cytokines.

Cytokine assay techniqueDescriptionCharacteristics

BioassaysBioassays (commonly used shorthand for biological assays) are typically assays by which the potency or the nature of a substance is estimated by studying its effects on living organisms
They can be conducted to measure the concentration/effects of a cytokine on a living cell
Example: IL-2 bioassay using an IL-2 dependent cell line that will undergo apoptosis in the absence of IL-2 in a dose dependent manner
They require tissue culture facility
Low specificity
Semiquantitative detection
Highly sensitive with detection limit < 1 pg/mL
Narrow analytical range
Time consuming (24–96 h)
Low precision (CV = 20–100%)
Drug interference
Laborious protocol with high staff cost

ELISAQuantitative detection of a molecule (bioactive and inactive) based on its capture by an antibody followed by its detection by another antibody coupled with a detection (commonly named ELISA)
It requires specialised equipment
Less sensitive than bioassays <10 pg/mL
Relatively large sample volume
Wide analytical range
High reagent cost
Excellent precision (CV = 5–10%)
No drug interference
Simple and relative rapid protocol

Solid phase assay (Luminex)Technology based on the detection of dyed microbeads capturing a cytokine with a first antibody and quantifying it with a second antibody coupled with fluorescence and lasers detection
It allows multiplex detection
Small sample volume
Lower sensitivity than ELISA
Large range of analytes
Sensitive to interferences from heterophilic antibodies (i.e., naturally occurring anti-antibodies), anti-cytokine antibodies, and presence of soluble receptors

Other solid phase assays Mosaic ELISA
ELISA like technology allowing multiple detection of cytokines in a 96-well plate format by spotting capture antibodies
Small sample volume
Lower sensitivity than ELISA
Only 8 analytes per test

Molecular techniquesAll techniques allowing mRNA quantification
Earlier detection of cytokines at transcriptional level however may not represent cytokine production and release
They require specialised equipment
Highly specific
Highly sensitive as they can detect changes at the single-cell level
Complete analytical range (from single cytokine to as many as needed)
Excellent precision
No drug interference
Simple and relative rapid protocol
Relatively high cost