Natural Killer (NK) cells are lymphocytes that respond to pathogens and cancer cells. Where do they primarily circulate?

Natural Killer (NK) cells are lymphocytes that respond to pathogens and cancer cells. Where do they primarily circulate?

• A. Blood
• B. Lymph nodes
• C. Spleen
• D. Bone marrow

Answer: (A)

Natural killer cells patrol the body by circulating in the bloodstream. They mature in the bone marrow, then enter peripheral blood to survey for virus-infected or cancerous cells. This bloodstream distribution lets them reach sites of infection or transformation quickly. They can migrate into tissues like the spleen, liver, or lymph nodes as needed, but the largest circulating pool is in the blood. Thus, blood is their primary circulation route.

Natural killer cells patrol the body by circulating in the bloodstream. They mature in the bone marrow, then enter peripheral blood to survey for virus-infected or cancerous cells. This bloodstream distribution lets them reach sites of infection or transformation quickly. They can migrate into tissues like the spleen, liver, or lymph nodes as needed, but the largest circulating pool is in the blood. Thus, blood is their primary circulation route.