Double determinant immuno-polymerase chain reaction: a sensitive method for detecting circulating antigens in human...

Area of Science:

• Immunology
• Molecular Biology
• Biochemistry

Background:

• Enzyme-linked immunosorbent assay (ELISA) is a common method for antigen detection.
• Limitations exist in ELISA's sensitivity for detecting low-abundance antigens, particularly in complex biological samples like serum.

Purpose of the Study:

• To develop a highly sensitive method for antigen detection in sera.
• To improve upon the detection limits of conventional immunoassays.

Main Methods:

• Developed double determinant immuno-polymerase chain reaction (immuno-PCR) using two monoclonal antibodies (MoAbs) to "sandwich" antigens.
• Immobilized the first MoAb, followed by binding of a biotinylated second MoAb to the antigen.
• Used streptavidin to attach biotinylated DNA to the complex, which was then amplified by PCR.
• Analyzed PCR products via Southern blot hybridization after agarose gel electrophoresis.

Main Results:

• Double determinant immuno-PCR demonstrated a 10^3-fold higher sensitivity compared to ELISA for detecting soluble intercellular adhesion molecule-1 (sICAM-1).
• This enhanced sensitivity was observed in both cell culture supernatant and sera from gastric cancer patients.
• The method successfully detected antigens below the detection limit of traditional ELISA.

Conclusions:

• Double determinant immuno-PCR offers a significant advancement in antigen detection sensitivity.
• The technique is adaptable to any antigen-antibody system where two specific MoAbs are available.
• This method holds promise for early disease diagnosis and monitoring through sensitive biomarker detection.