Lumit&[trade] Immunoassays for Simple and Rapid Determination of Cytokine Release from Cell Culture Models

Abstract

Rapid (< 70 min), add-and-read assays for cytokine determination were developed with Lumit™ immunoassay technology. Separate antibodies labeled with complementary SmBiT or LgBiT subunits bind to their shared cytokine target, resulting in proximity-driven reconstitution of NanoBiT luciferase and luminescence signal. Lumit immunoassays for human IL-1β, IL-2, IL-4, IL-6, IL-10, IFN-γ, and TNF-α exhibit LLODs < 10 pg/ml and linearity > 3 logs of analyte in 96-well format. Maximal S/B ratios are greater than 1000, and an assay signal T1/2 of 2 h accommodates batch plate processing. 384-well, assay performance (Z′ > 0.7) on treated human peripheral blood mononuclear cells (hPBMC) indicates the assay format is amenable to screening applications. Assay reagents were added directly to cell wells for multiple culture models. For hPBMC, LPS, R848, or a combination of PMA and ionomycin (CSC) produced dose-and time-dependent release of cytokines with a wide range of responses, all measurable without sample dilution. In a mix of purified CD8+ T cells and target Raji B cells treated with the bispecific T-cell engager Blincyto®, IL-2, IFN-γ, and TNF-α release was observed with an EC50 of ~0.2 ng/ml and max S/B ratios of 82-, 168-, and 31-fold, respectively. For Th2 cells, significant release of IL-4 was observed in response to CSC treatment. An alternative to the no-transfer assay method, split-sample analysis, can be performed to easily determine the levels of multiple cytokines released in the same cell well. The implementation of this novel detection chemistry will enable simple and rapid assay of cytokine release from cells for both low-and high-throughput applications, including quantitative assessments of T cell activation and differentiation.