Detectability of cytokine and chemokine using ELISA, following sample-inactivation using Triton X-100 or heat.

Clinical samples are routinely inactivated before molecular assays to prevent pathogen transmission. Antibody-based assays are sensitive to changes in analyte conformation, but the impact of inactivation on the analyte detectability has been overlooked. This study assessed the effects of commonly used inactivation-methods, Triton X-100 (0.5%) and heat (60 °C, 1 h), on cytokine/chemokine detection in plasma, lung aspirates, and nasopharyngeal samples. Heat significantly reduced analyte detectability in plasma (IL-12p40, IL-15, IL-16, VEGF, IL-7, TNF-β) by 33-99% (p ≤ 0.02), while Triton X-100 minimally affected analytes in plasma and nasopharyngeal samples (11-37%, p ≤ 0.04) and had no significant impact on lung aspirates. Structural analysis revealed that cytokines affected by heat had more hydrophobic residues and higher instability-indices. As the protein-detectability was affected differently in different sample types, the sample environment could also influence protein stability. This underscores the importance of selecting the most suitable inactivation methods for clinical samples to ensure accurate cytokine/chemokine analysis in both clinical and research settings.