Description and characteristics of assays measuring cytokines.
Cytokine assay technique
Description
Characteristics
Bioassays
Bioassays (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
ELISA
Quantitative 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 techniques
All 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
