Which antibody function involves blocking pathogens from interacting with host cells?

• A. Opsonization
• B. Neutralization
• C. Complement activation
• D. Agglutination

Answer: (B)

Neutralization blocks pathogens from interacting with host cells. When antibodies bind to viral surface proteins or bacterial toxins, they physically cover the sites needed for attachment or entry, preventing the pathogen or toxin from sticking to and entering the host cell. This stops infection or toxin action before it can happen. For example, a neutralizing antibody against a virus can prevent the virus from binding to its cellular receptor, while an antibody against a toxin can keep the toxin from engaging its receptor on the cell surface.

Other antibody functions include opsonization, which coats a pathogen to promote phagocytosis by immune cells; complement activation, which can lead to lysis of the pathogen or enhanced clearance; and agglutination, which clumps pathogens together to limit spread and make them easier to remove.