AffinityImmuno Products

Introduction

IL-36 beta belongs to the interleukin-1 superfamily and, like its paralogs, is predicted to fold into the family’s characteristic 12-stranded beta-trefoil structure; its gene sits within a cluster of nine IL-1-related genes on chromosome 2. Acting through the IL-36 receptor, IL1RL2, paired with the shared accessory chain IL1RAP, IL-36 beta activates NF-kB and MAPK signaling to stimulate production of interleukin-6 and interleukin-8 in synovial fibroblasts, cartilage cells, and adipocytes, and it induces antimicrobial peptides and matrix-degrading enzymes in skin. Through effects on keratinocytes, dendritic cells, and T cells it contributes to epithelial barrier inflammation, and dysregulated IL-36 beta activity has been tied to psoriatic disease, including generalized pustular psoriasis, as well as inflammatory bowel disease and rheumatoid arthritis. Because it is highly related in sequence and function to IL-36 alpha and gamma, antibody pairs with minimal cross-reactivity to those paralogs are needed to measure it specifically.

Like its paralog IL-36alpha, IL-36beta signals through the IL-36 receptor now clinically targeted by spesolimab in generalized pustular psoriasis, and the current page’s own note about needing antibody pairs with minimal cross-reactivity to IL-36alpha/gamma is a genuinely useful piece of technical honesty worth keeping front and center.

Principle of the Assay

This kit uses a sandwich enzyme immunoassay format. Microtiter plate wells are pre-coated with a capture antibody specific to IL-36beta (Human IL1h), which binds the target analyte present in standards or samples added to each well. A biotin-conjugated detection antibody, also specific to IL-36beta, is then introduced to form a sandwich complex on any well containing the analyte. Avidin conjugated to horseradish peroxidase (HRP) is subsequently added and binds the biotin, completing the detection assembly. Upon addition of TMB substrate solution, only wells containing IL-36beta, the biotin-conjugated detection antibody, and avidin-HRP produce a colorimetric signal. The enzymatic reaction is stopped by the addition of sulphuric acid solution, and absorbance is measured spectrophotometrically at 450 nm (± 10 nm). IL-36beta concentrations in the samples are determined by comparing sample optical densities against a standard curve.