Types of Ligand Binding Assays

After ingesting biotechnology drugs, the body will produce different degrees of immune response based on the immunogenicity of the drug. The drug stimulates the body to form specific anti-drug antibodies (ADA) for the immunogenicity of the drug, allergies, autoimmunity and different The pharmacokinetic characteristics of the drug are anti-drug antibody reactions, which can cause various clinical adverse reactions such as drug neutralization, abnormal biodistribution, and enhanced drug clearance, which may change the efficacy of the drug. Ligand binding assay is the main and commonly used bioanalysis method for biotechnology drugs. Today, let’s take a brief look at this method.

Biotechnology drugs can cause a certain anti-drug antibody response, that is, an immune response. The body’s immune response to biological drugs may affect the safety and effectiveness of the product, but the clinical effects of the immune response are highly variable, and some are completely healthy. There is no impact, and some will cause extremely harmful effects. Neutralizing antibody refers to a type of anti-drug antibody that can directly bind to the drug’s binding site or through steric hindrance, so that the drug loses its ability to bind to its target, thereby blocking and neutralizing drug treatment Active antibodies. Neutralizing antibodies can affect the safety and effectiveness of the drug by affecting the exposure level of the drug in the body. The ligand binding assay can be used to evaluate neutralizing antibodies. The ligand binding assay methods mainly include enzyme-linked immunosorbent assay, radioimmunoassay, and time-resolved fluorescence immunoassay.

Types of Ligand Binding Assays

Ligand binding assay method Incubate the radiolabeled antibody, overshooting unlabeled ligand and the receptor to be tested at the same time, determine the amount of labeled ligand in the bound and free state, and calculate the maximum number of binding sites and dissociation constant for the receptor to be tested Methods of analysis. Medicilon Bioanalysis Department can provide FDA/CFDA GLP-compliant macromolecular drug bioanalysis services to support the screening and development of protein drugs, antibody drugs, vaccines and biomarkers, as well as preclinical and clinical research.

❖ELISA

Enzyme-linked immunosorbent assay, also called ELISA, can detect the content of antigen or antibody in the sample. The basic method is to adsorb the known antigen or antibody on the surface of a solid-phase carrier (polystyrene microreaction plate) to make the enzyme-labeled antigen The antibody reaction is carried out on the surface of the solid phase, and the free components in the liquid phase are washed away by the washing method. In the research and development of biotechnology drugs, this technology can be used to detect macromolecular antigens and specific antibodies, etc. It has the advantages of rapid, sensitive, simple, and easy to standardize the carrier. According to the connection and application form of the immunosorbent, conjugate and the test substance during the experiment, ELISA mainly includes sandwich method, indirect method, competition method and other types.

❖RIA

The immune response caused by drugs is an important indicator of drug safety and effectiveness, which is also the common concern of regulatory agencies, manufacturers, clinicians and patients. Radioimmunoassay is also a method to analyze the immunogenicity of antibody drugs. This method uses the sensitivity and accuracy of radionuclide detection and the specificity of antigen-antibody reaction combined with an immunological technique, including the principle of competitive binding reaction. Two methods of radioimmunoassay (RIA) and non-competitive combined immunoradioassay (IRMA). Radioimmunoassay technology is often used in the determination of trace substances such as various hormones, trace proteins, tumor markers and drugs.

❖TRFIA

Time-resolved fluorescence immunoassay (TRFIA) is a non-isotopic immunoassay technique developed on the basis of fluorescence analysis (FIA). This method uses lanthanide elements to label antigens or antibodies. According to the luminescence characteristics of lanthanide chelates, time-resolved technology is used to measure fluorescence. The two parameters of wavelength and time are simultaneously detected for signal resolution, which can effectively eliminate the interference of non-specific fluorescence. . It can be used to analyze hormones, viral hepatitis markers, tumor-associated antigens, pepsinogen (PG), drugs and peptides.

Ligand Binding Test Biological Analysis

Overview of LBA Test Methods in Bioanalysis