VMC 221: Veterinary Immunology and Serology (1+1)

IMMUNOPEROXIDASE TEST (IPT)

• Used to detect antigen in tissue sections. Similar to immunofluorescence test or direct or indirect ELISA.
• Here enzyme labeled immunoglobulin is used and the chromogenic substrate is DAB.
• Positive reactions indicated by presence of brown deposit at site of antigen.

IPT - Brown colour  in the cytoplasm indicates positive reaction

• Unlike in FAT, this deposition can be visualized by light microscopy and paraffine embedded and resin embedded sections can be used.
• Horse raddish peroxidase and alkaline phosphatase are the enzymes most often used.
• A disadvantage is that endogenous peroxidase present in the cells may produce false positives.