Background: Chronic inflammation is etiologically related to several cancers. We evaluated the performance [ability to detect concentrations above the assay's lower limit of detection, coefficients of variation (CV), and intraclass correlation coefficients (ICC)] of 116 inflammation, immune, and metabolic markers across two Luminex bead-based commercial kits and three specimen types.
Methods: From 100 cancer-free participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Trial, serum, heparin plasma, and EDTA plasma samples were utilized. We measured levels of 67 and 97 markers using Bio-Rad and Millipore kits, respectively. Reproducibility was assessed using 40 blinded duplicates (20 within-batches and 20 across-batches) for each specimen type.
Results: A majority of markers were detectable in more than 25% of individuals on all specimen types/kits. Of the 67 Bio-Rad markers, 51, 52, and 47 markers in serum, heparin plasma, and EDTA plasma, respectively, had across-batch CVs of less than 20%. Likewise, of 97 Millipore markers, 75, 69, and 78 markers in serum, heparin plasma, and EDTA plasma, respectively, had across-batch CVs of less than 20%. When results were combined across specimen types, 45 Bio-Rad and 71 Millipore markers had acceptable performance (>25% detectability on all three specimen types and across-batch CVs <20% on at least two of three specimen types). Median concentrations and ICCs differed to a small extent across specimen types and to a large extent between Bio-Rad and Millipore.
Conclusions: Inflammation and immune markers can be measured reliably in serum and plasma samples using multiplexed Luminex-based methods.
Impact: Multiplexed assays can be utilized for epidemiologic investigations into the role of inflammation in cancer etiology.