Which statement best describes immunoreactivity preservation during bone decalcification?

• A. Chelating agents like EDTA preserve immunoreactivity better than strong acids
• B. Immunoreactivity is not affected by decalcification
• C. Decalcification is unnecessary for immunohistochemistry
• D. Strong acids preserve immunoreactivity better than chelating agents

Answer: (A)

Preserving immunoreactivity during bone decalcification hinges on using a method that removes minerals without destroying antigenic sites. Chelating agents like EDTA remove calcium by chelation at near-neutral pH, softening bone while keeping protein epitopes intact enough for antibody binding. Strong acids, used for rapid decalcification, tend to hydrolyze proteins and alter epitopes, which diminishes or abolishes immunostaining. Because of this, EDTA-based or other milder chelation methods are preferred when the goal is reliable immunohistochemistry on bone. Keep in mind that overall results also depend on fixation, processing, and sometimes antigen retrieval steps to maximize signal.