What is the role of the tonsils?

• A. Protect against foreign substances inhaled or ingested
• B. Filter lymph
• C. Produce T-cells
• D. Regulate fluid balance

Answer: (A)

Tonsils act as a frontline immune sensor in the upper airway and digestive tract. They are part of mucosa-associated lymphoid tissue and form Waldeyer’s ring, ready to sample microbes that enter through the nose and mouth. When antigens are encountered, immune cells in the tonsils—B cells and T cells—are activated. B cells can produce antibodies, including secretory IgA, that help neutralize pathogens at the mucosal surface, while T cells participate in cellular immune responses. This local immune sampling and rapid response help prevent infection from inhaled or ingested materials.

Other options don’t fit because filtering lymph is the job of lymph nodes and the spleen, not the tonsils; producing T-cells is a function of the thymus; and regulating fluid balance is handled by the kidneys and the broader lymphatic system.