Simultaneous quantification of proinflammatory cytokines in human plasma using the LabMAP assay.

There is an emerging trend in the pharmaceutical industry to evaluate a variety of surrogate biomarkers in Phase I/II clinical studies with the intention of determining potential activity of drugs early in clinical development. A number of cytokines expressed in pathological conditions are currently being considered as potential surrogates of disease and/or drug activity. The quantitative measurement of such analytes (biomarkers) in biological fluids has traditionally been performed by bioassays, enzyme-linked immunosorbent assay (ELISA), ribonuclease protection assay (RPA) and polymerase chain reaction (PCR). Typically, these methods have been limited to the measurement of a single analyte, require large sample volume and are time and cost involved. The LabMAP (Luminex) system has been previously used to quantify cytokines in tissue culture supernatants and in animal serum. In the present study, the LabMAP technology was used for quantifying for the first time, pro-inflammatory cytokines such as, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1beta), IL-6 and IL-8 levels in lipopolysaccharide (LPS)-stimulated human plasma samples. Both single-cytokine and two-cytokine (biplexed) panel formats were evaluated and the performance in the two formats was compared. A detailed validation procedure for these determinations is described along with a side-by-side comparison with ELISA results. Our results indicate that the LabMAP system can be used to measure cytokine levels in LPS-stimulated human plasma samples and that the levels obtained by this technique are comparable with ELISA results. It is therefore feasible to use this optimized technology to detect and quantify cytokines and other potential biomarkers in a complex milieu such as human plasma in support of clinical studies.