CD47, also known as Integrin-Associated Protein (IAP), is a transmembrane protein involved in various cellular processes, including cell signaling, immune regulation, and cell adhesion. It is often referred to as a "don't eat me" signal because it helps cells avoid phagocytosis by interacting with SIRPα (Signal Regulatory Protein Alpha) on macrophages. CD47 has been implicated in cancer, where it can help tumor cells evade the immune system, and in various other diseases. ELISA kits for CD47 are used to measure its levels in biological samples, such as serum, plasma, and cell culture supernatants.

Overview of CD47 ELISA Kits

• Purpose: To detect and quantify CD47 levels in biological fluids. This measurement is useful for research in immune evasion mechanisms in cancer, cell signaling, and other diseases related to CD47 expression.
• Assay Principle: Typically a sandwich ELISA. The assay involves capturing CD47 with a specific antibody immobilized on a microtiter plate, followed by detection with a secondary antibody conjugated to an enzyme (usually HRP). The enzymatic reaction produces a color change that is proportional to the amount of CD47 present in the sample.
• Sensitivity: High sensitivity, often in the picogram per milliliter (pg/mL) range, allowing for the detection of low levels of CD47.
• Specificity: High specificity for CD47, minimizing cross-reactivity with other cell surface proteins or molecules.
• Sample Volume: Typically requires 50-100 µL of sample per well.

Content of a Standard CD47 ELISA Kit

• Microtiter Plate: Pre-coated with an anti-CD47 antibody.
• Standards: Recombinant CD47 protein at various concentrations to create a standard curve.
• Detection Antibody: Biotinylated or enzyme-conjugated anti-CD47 antibody.
• Enzyme Conjugate: Typically streptavidin-HRP, used to amplify the signal generated by the detection antibody.
• Substrate Solution: Usually TMB (3,3',5,5'-Tetramethylbenzidine), which undergoes a color change upon reaction with HRP.
• Stop Solution: Often sulfuric acid or hydrochloric acid, which halts the enzyme reaction and stabilizes the color change.

Key Steps in the Assay Procedure

• Sample/Standard Addition: Standards and samples are added to wells coated with an anti-CD47 antibody.
• Incubation: The plate is incubated to allow CD47 to bind to the capture antibody.
• Washing: Wells are washed to remove unbound components.
• Detection Antibody Addition: The detection antibody specific to CD47 is added, binding to the captured protein.
• Washing: Excess detection antibody is washed away.
• Enzyme Conjugate Addition: Enzyme-conjugated secondary antibody binds to the detection antibody.

Applications

• Research: Studying CD47's role in immune evasion, cell signaling, and its implications in cancer biology, as well as its involvement in other diseases where CD47 expression is altered.
• Clinical Diagnostics: Measuring CD47 levels to understand its role in disease mechanisms and to potentially guide therapeutic strategies, particularly in cancer where CD47-targeted therapies are being explored.

CD47 ELISA kits are valuable for researchers and clinicians to monitor CD47 levels, providing insights into immune regulation, cancer progression, and other pathological conditions. They help in understanding CD47's role in various diseases and developing targeted therapies.