Which of the following primarily mediates the adaptive (specific) defense system in humans?

• A. Macrophages
• B. Natural killer (NK) cells
• C. Lymphocytes (B cells and T cells)
• D. Neutrophils

Answer: (C)

Verified step by step guidance

1. Understand the two main branches of the human immune system: the innate (nonspecific) defense system and the adaptive (specific) defense system.
2. Recall that the innate immune system includes cells like macrophages, natural killer (NK) cells, and neutrophils, which respond quickly but non-specifically to pathogens.
3. Recognize that the adaptive immune system is characterized by its ability to recognize specific antigens and remember them for a stronger response upon re-exposure.
4. Identify that lymphocytes, specifically B cells and T cells, are the primary mediators of the adaptive immune response because they have antigen-specific receptors and can generate immunological memory.
5. Conclude that among the options given, lymphocytes (B cells and T cells) are responsible for the adaptive (specific) defense system, while macrophages, NK cells, and neutrophils belong mainly to the innate immune system.