What is the difference between a primary antibody and a secondary antibody?
Posted June 30, 2022
Answer
| Basis of differentiation | Primary antibody | Secondary antibody | 
| Definition | Is an immunoglobulin that binds directly to a specific protein or other target biomolecule | Is designed to bind to the primary antibody, which is directly bound to the target antigen | 
| Use in immunoassays | Is necessary to bind to the target antigen | Is not always necessary | 
| Interaction with antigen | Interacts directly with the antigen | Interacts indirectly with the antigen by binding with the primary antibody | 
| Source | Host species of the primary antibody must be different from the species of the sample | Host species of the secondary antibody must be different from the host species of the primary antibody | 
| Function | Used as biomarkers for detecting diseases such as Alzheimer’s disease, cancer, Parkinson’s disease and diabetes. | Used in immunolabeling | 
| Advantages | No risk of secondary antibody cross-reactivity
More streamlined workflow & faster results
Improved experimental reproducibility
 | Multiplexing or multi-labeling capability
Extended access to a wider range of probes
More flexibility in assay design
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