- The correct answer is Macrophage because it is an innate immune cell that responds non-specifically to pathogens without requiring antigen-specific receptors.
- Unlike B and T lymphocytes, macrophages recognize pathogens through pattern recognition receptors (PRRs) that detect common microbial structures.
- This allows macrophages to initiate an immediate immune response, phagocytose microbes, and activate inflammation without prior sensitization.
- In contrast, B lymphocytes, T helper cells, and cytotoxic T cells depend on antigen-specific receptors and are part of the adaptive immune response.

Reference: Janeway’s Immunobiology, 9th Edition, Volume 1, Chapter 2