Simple immunohistochemical staining method using large sized gold colloid conjugated secondary antibody.

Area of Science:

• Biotechnology
• Immunohistochemistry
• Nanotechnology

Background:

• Semiquantitative immunohistochemical staining (IHC) is crucial for antigen quantification.
• Enzyme-based IHC methods can be limited by signal stability and differentiation.
• Large-sized gold conjugated secondary antibodies (gold-2° Ab) offer potential advantages for IHC.

Purpose of the Study:

• To evaluate the feasibility of semiquantitative IHC using large-sized gold-2° Ab.
• To compare the performance of gold-2° Ab IHC with traditional enzyme IHC.
• To assess the stability and distinguishability of signals generated by gold-2° Ab.

Main Methods:

• Utilized beads coated with known amounts of primary antibody (mouse IgG).
• Employed secondary antibodies conjugated with gold colloid particles (20 and 40 nm).
• Compared signal intensity and stability with enzyme IHC using DAB substrate.

Main Results:

• Six distinct color intensity levels were observed with graded amounts of IgG, readily distinguishable.
• Gold-2° Ab produced immediate and stable color signals for up to 1 week.
• Enzyme IHC showed minimal pigment after 5 minutes of DAB incubation.
• Gold-2° Ab provided strong signals on cell surfaces and was effective on paraffin-embedded tissues.
• The bright red color from gold-2° Ab was easier to differentiate from hemosiderin pigment than enzyme IHC signals.

Conclusions:

• Gold IHC with large-sized gold-2° Ab is superior to enzyme IHC for antigen quantification.
• This method offers enhanced signal stability, intensity, and differentiation.
• Gold IHC is particularly recommended for analyzing tissues rich in macrophages, such as bone marrow and spleen.