AAT Bioquest

What are the main differences between a primary antibody and a secondary antibody?

Posted June 27, 2022

Basis of DifferentiationPrimary AntibodySecondary Antibody
DefinitionIs 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 immunoassaysIs necessary to bind to the target antigenIs not always necessary 
Interation with antigenInteracts directly with the antigenInteracts indirectly with the antigen by binding with the primary antibody 
SourceHost species of the primary antibody must be different from the species of the sampleHost species of the secondary antibody must be different from the host species of the primary antibody
FunctionUsed as biomarkers for detecting diseases such as Alzheimer’s disease, cancer, Parkinson’s disease and diabetes. Used in immunolabeling
  • No risk of secondary antibody cross-reactivity
  • More streamlined workflow & faster results
  • Improved experimental reproducibility
  • Increased sensitivity
  • Multiplexing or multi-labeling capability
  • More versatile 
  • Extended access to a wider range of probes
  • More flexibility in assay design
Additional resources

Therapeutic Antibodies: An Overview

Buccutite™ Peroxidase (HRP) Antibody Conjugation Kit *Optimized for Labeling 1 mg Protein*

Antibody and Protein Labeling