Which of the following statements is true regarding superantigens?

• A. Superantigens are produced by the host's immune cells to enhance the immune response.
• B. Superantigens are specific to a single type of antigen and activate only a small subset of T cells.
• C. Superantigens are recognized by the immune system through the classical antigen-antibody interaction.
• D. Superantigens activate a large number of T cells by binding directly to the T-cell receptor and MHC class II molecules.

Answer: (D)

Verified step by step guidance

1. Understand the role of superantigens: Superantigens are a class of antigens that result in excessive activation of the immune system, particularly T cells.
2. Recognize the mechanism of action: Unlike typical antigens, superantigens bypass the normal antigen processing and presentation pathway.
3. Identify the interaction: Superantigens bind directly to the T-cell receptor (TCR) and major histocompatibility complex (MHC) class II molecules on antigen-presenting cells.
4. Acknowledge the effect: This direct binding leads to the activation of a large number of T cells, regardless of their antigen specificity.
5. Differentiate from other antigens: Unlike conventional antigens, superantigens do not require specific antigen recognition by the TCR, leading to a massive, non-specific T cell response.