Which enzymes are used for intercellular antigen exposure?

• A. Pepsin and Bromelin
• B. Trypsin and Pepsin
• C. Proteinase K and Trypsin
• D. Bromelin alone

Answer: (A)

Intercellular antigen exposure relies on proteolytic enzymes to digest the proteins that mask epitopes between cells, freeing the sites for antibody access. Pepsin and bromelin (bromelain) are proteases commonly used for enzymatic antigen retrieval because they gently digest a broad range of extracellular and intercellular proteins without destroying the epitopes of many antigens. Pepsin, active in acidic conditions, helps reveal epitopes shielded by protein matrices, while bromelain digests a variety of proteins in the tissue’s intercellular spaces, expanding the set of antigens that can be exposed. Using them together provides a balanced digestion that can unmask intercellular epitopes more effectively than some other enzymes.

Other enzyme options can be either too harsh or too specific, risking over-digestion or failing to reveal certain intercellular epitopes. For example, trypsin is a strong protease that may degrade epitopes, and proteinase K is broad and aggressive, which can destroy delicate targets. Bromelain alone might not reveal all required epitopes.