Which term refers to any molecule that elicits an immune response in the host?

• A. Antigen
• B. Cytokine
• C. Antibody
• D. Pathogen

Answer: (A)

Verified step by step guidance

1. Understand the question: It asks for the term that describes any molecule capable of triggering an immune response in the host.
2. Recall definitions: An antigen is a molecule or molecular structure that the immune system recognizes as foreign and can provoke an immune response.
3. Differentiate from other options: Cytokines are signaling proteins released by cells to communicate during immune responses, antibodies are proteins produced by B cells that specifically bind to antigens, and pathogens are organisms that cause disease.
4. Identify the correct term: Since the question focuses on the molecule that elicits the immune response, the correct term is 'antigen'.
5. Summarize: The antigen is the key molecule recognized by the immune system, leading to activation of immune cells and production of antibodies.