It has been shown that
the amount of cytokine produced by cells correlates with the
expression of cytokine-specific mRNA; reverse-transcription
(RT) polymerase chain reactions (PCR) have therefore also been
widely used. Although RT-PCRs are fast, sensitive and simple
methods to detect the expression levels of cytokine genes, the
results do not always agree with those of bioassays and ELISA,
and do not allow exact determination of cytokine concentrations.
Other assays have therefore been explored.