What is the avidin-biotin complex (ABC) method?

The avidin-biotin complex (ABC) method is a widely used technique in immunohistochemistry (IHC) and immunocytochemistry (ICC) for enhancing the detection of antigens. Essentially, the ABC method amplifies the signal generated by the primary antibody binding to the antigen, enhancing the sensitivity of antigen detection in tissue sections. The interaction between avidin and biotin is one of the strongest non-covalent interactions known. When biotin binds to avidin, the bond forms quickly and remains stable even in harsh conditions such as extremes in temperature, pH organic solvents, and other denaturing agents. The binding of avidin to biotin is nearly irreversible.