Table 4: Ratio of cytokine concentrations measured from samples spiked with cytokine and then PEG-precipitated and samples which were PEG-precipitated and then spiked with cytokine. Mean ± SD given.

AnalyteRatio spiked sample precipitated : sample matrix precipitated, then spiked mean ± SD

IL-1β0.94 ± 0.15
IL-41.01 ± 0.14
IL-60.95 ± 0.16