AffinityImmuno Products

Introduction

CD163, also called the hemoglobin scavenger receptor or M130, is a macrophage- and monocyte-restricted membrane protein that clears hemoglobin-haptoglobin complexes from the circulation through calcium- and pH-dependent endocytosis, protecting tissue from the oxidative damage that free hemoglobin can cause and allowing macrophages to recycle the iron released during heme breakdown. Receptor engagement also triggers intracellular calcium signaling and secretion of interleukin-6 and CSF1, and separate work indicates CD163 can act as an innate sensor that helps trigger local inflammatory responses to bacteria. Inflammatory stimuli such as bacterial LPS trigger proteolytic shedding of the receptor’s extracellular domain by membrane metalloproteinases, releasing a soluble form, sCD163, into plasma; this cleaved fragment appears to dampen inflammation while also serving as a practical readout of how active tissue macrophages are. Circulating sCD163 has consequently been explored as a biomarker of macrophage activation across a wide range of conditions, including atherosclerosis, sepsis, chronic liver disease, and insulin resistance.

Because sCD163 shedding tracks how active tissue macrophages are, it’s used as a practical readout of macrophage activation across a notably wide range of research areas — atherosclerosis, sepsis, chronic liver disease, and insulin resistance — making this one of the more broadly applicable inflammation-biomarker kits in the catalog.

Principle of the Assay

This kit uses a sandwich enzyme immunoassay format to measure Human sCD163. Microtiter plate wells are pre-coated with a capture antibody specific to Human sCD163. Standards or samples are added to the appropriate wells along with a biotin-conjugated detection antibody that also recognizes Human sCD163. Avidin conjugated to horseradish peroxidase (HRP) is then added to each well and allowed to incubate. Upon addition of TMB substrate solution, a colorimetric signal develops exclusively in wells where Human sCD163, the biotin-conjugated antibody, and the avidin-HRP conjugate are all present. The enzymatic reaction is stopped by the addition of a sulphuric acid solution, and the resulting color change is measured spectrophotometrically at 450 nm (± 10 nm). Sample concentrations are determined by comparing the optical density of each sample against a standard curve.