Improving the specificity of immunological detection in aged human brain tissue samples

Area of Science:

• Neuroscience
• Immunology
• Biochemistry

Background:

• Immunological analyses of aged human brain tissues are crucial for understanding brain aging and neurological diseases like Alzheimer's.
• Primary antibodies for these analyses often come from rabbit or mouse.
• Lipofuscin, a pigment associated with aging, can interfere with immunological detection.

Purpose of the Study:

• To investigate unexpected cross-immunoreactivity in aged human brain tissues.
• To identify the cause of non-specific immunostaining signals.
• To develop methods to mitigate this cross-reactivity for improved research accuracy.

Main Methods:

• Immunoblotting analysis of aged human brain samples.
• Immunohistochemical localization of cross-reactive proteins.
• Testing modifications including sodium borohydride pretreatment and Tween-20 addition.

Main Results:

• Anti-rabbit secondary antibody alone showed significant cross-reactivity (~180 kDa) with lipofuscin-associated proteins in aged human brain tissue.
• Anti-mouse secondary antibody did not exhibit this cross-reaction.
• Pretreatment with sodium borohydride and/or Tween-20 significantly reduced or abolished the non-specific staining without affecting specific signals like phospho-tau pT231.

Conclusions:

• Anti-rabbit antibodies can lead to misinterpretation of results in aged human brain tissue due to cross-reactivity with lipofuscin.
• Protocol modifications are essential to minimize non-specific binding and ensure reliable immunological analyses.
• Researchers should exercise caution when using rabbit polyclonal antibodies in aged brain tissue studies.