Immuno-PCR: An ultrasensitive immunoassay for biomolecular detection

Techniques that combine nucleic acid amplification with an antibody-based assay can dramatically increase the sensitivity of conventional immunoassays. This review summarizes the methodology and applications of one such protein detection technique that has been used for the past 23 years—the immuno-polymerase chain reaction (usually referred to as immuno-PCR or IPCR). The key component of an immuno-PCR is a DNA–antibody conjugate that serves as a bridge to link the solid-phase immunoreaction with nucleic acid amplification. The efficiency of immuno-PCR enables a 10- to 10⁹-fold increase in detection sensitivity compared with that of ELISA. Advancements in immuno-PCR have included improvements of production of the DNA–antibody conjugate, assay formats, and readout methods. As an ultrasensitive protein assay, immuno-PCR has a broad range of applications in immunological research and clinical diagnostics.