Which of the following is NOT a function of antibodies?

• A. Activation of complement system
• B. Directly killing infected cells
• C. Opsonization for phagocytosis
• D. Neutralization of pathogens

Answer: (B)

Verified step by step guidance

1. Understand the primary functions of antibodies in the immune system. Antibodies are proteins produced by B cells that help identify and neutralize foreign objects like bacteria and viruses.
2. Review the process of opsonization. Antibodies can bind to pathogens and mark them for destruction by phagocytes, a process known as opsonization.
3. Examine how antibodies neutralize pathogens. Antibodies can bind to specific antigens on pathogens, preventing them from entering or damaging host cells.
4. Learn about the activation of the complement system. Antibodies can initiate the complement cascade, a series of protein activations that enhance the ability to clear pathogens.
5. Identify the function that antibodies do not perform. Antibodies do not directly kill infected cells; this is typically the role of cytotoxic T cells or natural killer cells.