AffinityImmuno Products

Introduction

PVR, better known by its surface designation CD155, is a single-pass membrane glycoprotein of the immunoglobulin superfamily that normally helps glue epithelial cells together at adherens junctions and lets cells grip the surrounding matrix through vitronectin. On immune cells it does double duty as a ligand: it engages the activating receptor CD226 and the inhibitory receptors TIGIT and CD96 on natural killer and T cells, and this competitive three-way interaction shapes whether those cells become cytotoxic or stand down, forming a stable contact point called the immunological synapse in the process. Many solid tumors upregulate CD155, which appears to help them dodge immune surveillance and can also promote tumor cell movement and invasion directly. The molecule is also historically notable as the entry point that poliovirus, and separately pseudorabies virus, use to infect human cells, a property confined to primates that gave the gene its original name.

CD155 sits at the center of a three-receptor immune checkpoint circuit — competing engagement of TIGIT, CD96, and CD226 on NK and T cells — that many solid tumors exploit by upregulating CD155 to suppress immune attack, making this assay a natural companion to our TIGIT, CD96, and CD226 ELISA kits for studying that axis as a unit.

Principle of the Assay

This kit utilizes a sandwich enzyme immunoassay format in which the microtiter plate wells are pre-coated with a capture antibody specific to human CD155 (PVR). During the assay, standards or samples are introduced into the appropriate wells along with a biotin-conjugated detection antibody that also recognizes human CD155. Avidin conjugated to horseradish peroxidase (HRP) is then added to each well and allowed to incubate, linking the enzymatic reporter to the captured analyte via the biotin–avidin interaction. Upon addition of TMB substrate solution, a colorimetric signal develops exclusively in wells containing human CD155, biotin-conjugated antibody, and avidin-HRP. The enzymatic reaction is stopped by the addition of a sulphuric acid stop solution, and the resulting color change is measured spectrophotometrically at 450 nm (± 10 nm). Sample concentrations are determined by comparing the optical density readings of each sample against a reference standard curve.