Which feature characterizes innate immunity?

Which feature characterizes innate immunity?

• A. It requires clonal expansion of antigen-specific lymphocytes.
• B. It generates memory responses after exposure.
• C. It relies on preformed, constantly present defenses.
• D. It uses antibodies as primary effector mechanisms.

Answer: (C)

Innate immunity is the body's immediate, non-specific defense that is ready at all times. It relies on preformed, constantly present defenses such as physical barriers (skin and mucosal surfaces), resident phagocytes in tissues, natural killer cells, and components of the complement system. These elements respond quickly to a broad range of pathogens without needing prior exposure or antigen-specific training. Clonal expansion of antigen-specific lymphocytes describes adaptive immunity, which tailors a response to a specific pathogen and increases the pool of targeted lymphocytes. Memory responses are a hallmark of adaptive immunity, built after prior encounters to provide faster responses upon re-exposure. Antibodies are produced as part of adaptive humoral immunity and act as antigen-specific effectors, whereas innate defenses rely on more general mechanisms.

Innate immunity is the body's immediate, non-specific defense that is ready at all times. It relies on preformed, constantly present defenses such as physical barriers (skin and mucosal surfaces), resident phagocytes in tissues, natural killer cells, and components of the complement system. These elements respond quickly to a broad range of pathogens without needing prior exposure or antigen-specific training.

Clonal expansion of antigen-specific lymphocytes describes adaptive immunity, which tailors a response to a specific pathogen and increases the pool of targeted lymphocytes. Memory responses are a hallmark of adaptive immunity, built after prior encounters to provide faster responses upon re-exposure. Antibodies are produced as part of adaptive humoral immunity and act as antigen-specific effectors, whereas innate defenses rely on more general mechanisms.