AffinityImmuno Products

Introduction

Syndecan-1 is a type I transmembrane heparan sulfate (and some chondroitin sulfate) proteoglycan that physically bridges the actin cytoskeleton to extracellular matrix proteins, giving cells a structural handle for adhesion, spreading, and migration. Beyond this scaffolding role, it helps direct exosome formation together with syndecan-binding partners and participates in receptor-mediated uptake of extracellular ligands, including facilitating entry of the HIV-1 Tat protein into cells. Its expression is altered across a range of solid tumors and hematologic malignancies, where changes in syndecan-1 levels have been associated with shifts in tumor cell invasiveness and metastatic behavior, and separately it has drawn interest as a marker of endothelial and vascular integrity in critical illness and tissue injury. A shed, soluble ectodomain of the protein circulates and can be measured in blood or other fluids as an indicator of these underlying cellular processes.

Shed syndecan-1 has become one of the most widely used markers of endothelial glycocalyx degradation in sepsis and critical-illness research, with recent meta-analyses linking it to shock severity, organ complications, and mortality — a fast-growing critical-care research use case alongside its established role as a marker in multiple myeloma and other malignancies.

Principle of the Assay

This kit employs a sandwich enzyme immunoassay format in which the microtiter plate wells are pre-coated with a capture antibody specific to human syndecan-1 (SDC1). During the assay, standards or samples are added to the appropriate wells together with a biotin-conjugated detection antibody that also recognizes human SDC1. Avidin conjugated to horseradish peroxidase (HRP) is then added to each well and allowed to incubate, completing the detection complex. Upon addition of TMB substrate solution, a colorimetric signal develops exclusively in wells containing human SDC1, the biotin-conjugated antibody, and avidin-HRP. The enzymatic reaction is stopped by the addition of a sulphuric acid stop solution, and absorbance is measured spectrophotometrically at 450 nm (± 10 nm). Sample concentrations are determined by comparing the optical density of each sample against a standard curve generated from the kit-provided standards.