Which cells initiate the immune response to N. meningitidis that can lead to meningitis?

• A. B cells
• B. Cytotoxic T cells
• C. Helper T cells
• D. Microglia

Answer: (D)

The initiation of the immune response to Neisseria meningitidis, which can lead to meningitis, primarily involves microglia. These are the resident immune cells of the central nervous system and play a crucial role in the brain's immune defense.

When Neisseria meningitidis enters the central nervous system, microglia are among the first responders. They can recognize pathogens through pattern recognition receptors and participate in the innate immune response. By detecting the bacterial components, microglia become activated, leading to the release of pro-inflammatory cytokines and chemokines that help recruit other immune cells to the site of infection. This activation is essential for mounting an effective immune response in the brain, an area that is typically protected by the blood-brain barrier.

In contrast, although B cells, cytotoxic T cells, and helper T cells play significant roles in adaptive immunity, they typically respond after the initial innate immune response is activated. B cells are responsible for antibody production, cytotoxic T cells kill infected host cells, and helper T cells facilitate the activation of other immune cells, but the immediate response to an infection like that caused by N. meningitidis begins with the action of microglia and other innate immune components. Thus, the role