Which of the following best describes the role of antigen-presenting cells (APCs) in adaptive immunity?

• A. They process antigens and present them on major histocompatibility complex (MHC) molecules to T cells.
• B. They directly produce antibodies against pathogens.
• C. They destroy infected cells by releasing cytotoxic granules.
• D. They activate complement proteins to lyse pathogens.

Answer: (A)

Verified step by step guidance

1. Understand the role of antigen-presenting cells (APCs) in the immune system, specifically within adaptive immunity.
2. Recall that APCs capture and process foreign antigens from pathogens or infected cells.
3. Recognize that after processing, APCs present these antigens on their surface using major histocompatibility complex (MHC) molecules.
4. Know that this antigen-MHC complex is recognized by T cells, which is crucial for activating the adaptive immune response.
5. Differentiate this function from other immune activities such as antibody production, cytotoxic killing, or complement activation, which are performed by other immune cells or mechanisms.