Adjuvants act by which of the following mechanisms?

• A. Protects antigen from being degraded
• B. Facilitates rapid escape from the tissues
• C. Limits the area of the immune response
• D. Decreases number of APCs

Answer: (A)

Adjuvants boost vaccine effectiveness by keeping the antigen around longer and helping the immune system notice and respond to it. Protecting the antigen from degradation is a key way this happens: adjuvants can create a depot at the injection site or shield the antigen from proteolysis, so the immune system has time to take up the antigen, process it, and present it to T cells. This sustained presence enhances the overall immune response.

The idea of rapid escape from tissues doesn’t fit how adjuvants work—the goal is often to retain antigen and promote continued exposure, not speed its removal. Adjuvants also don’t purposefully limit the area of the immune response or decrease the number of antigen-presenting cells; they typically recruit and activate APCs to improve antigen presentation and activation of adaptive immunity. So protecting the antigen from degradation best matches the mechanism.