Development of a novel multiplexed assay for quantification of transforming growth factor-β (TGF-β).

Changes in activity or levels of transforming growth factor-β (TGF-β) are associated with a variety of diseases; however, measurement of TGF-β in biological fluids is highly variable. TGF-β is biologically inert when associated with its latency-associated peptide (LAP). Most available immunoassays require exogenous activation by acid/heat to release TGF-β from the latent complex. We developed a novel electrochemiluminescence-based multiplexed assay on the MesoScale Discovery® platform that eliminates artificial activation, simultaneously measures both active TGF-β1 and LAP1 and includes an internal control for platelet-derived TGF-β contamination in blood specimens. We optimized this assay to evaluate plasma levels as a function of activation type and clinical specimen preparation. We determined that breast cancer patients' plasma have higher levels of circulating latent TGF-β (LTGF-β) as measured by LAP1 than healthy volunteers (p < 0.0001). This assay provides a robust tool for correlative studies of LTGF-β levels with disease, treatment outcomes and toxicity with a broad clinical applicability.