Which of the following statements is true regarding humoral and cellular immune defenses in the context of innate immunity?

• A. Humoral defenses involve soluble factors like complement proteins, while cellular defenses involve phagocytic cells such as neutrophils and macrophages.
• B. Both humoral and cellular defenses in innate immunity require prior exposure to specific pathogens.
• C. Humoral defenses are exclusively mediated by antibodies produced by B cells.
• D. Cellular defenses in innate immunity are only provided by T lymphocytes.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the distinction between humoral and cellular immune defenses within innate immunity. Humoral defenses refer to soluble factors present in body fluids, while cellular defenses involve immune cells that act directly against pathogens.
2. Step 2: Identify examples of humoral defenses in innate immunity. These include complement proteins, cytokines, and antimicrobial peptides, which are soluble molecules that help neutralize or destroy pathogens without prior exposure.
3. Step 3: Recognize the cellular components of innate immunity. Key cells include phagocytic cells such as neutrophils and macrophages, which engulf and destroy pathogens nonspecifically, as well as natural killer (NK) cells that target infected or abnormal cells.
4. Step 4: Clarify that innate immunity does not require prior exposure to specific pathogens, unlike adaptive immunity. Therefore, statements suggesting that innate humoral or cellular defenses require prior exposure are incorrect.
5. Step 5: Differentiate innate immunity from adaptive immunity by noting that antibodies produced by B cells and T lymphocytes are part of adaptive immunity, not innate. Hence, humoral defenses in innate immunity are not exclusively antibody-mediated, and cellular defenses are not solely provided by T lymphocytes.