Innate immune system defenses include
A T cells.
B phagocytosis.
C plasma cells.
D B cells.
The correct answer and explanation is:
The correct answer is B. phagocytosis.
The innate immune system is the body’s first line of defense against pathogens. Unlike the adaptive immune system, which develops over time and adapts to specific pathogens, the innate immune system is present from birth and responds to a broad range of invaders in a non-specific manner.
Phagocytosis is the process by which certain white blood cells, such as macrophages and neutrophils, engulf and digest pathogens like bacteria, viruses, and dead or dying cells. These cells recognize foreign particles through pattern recognition receptors (PRRs) that detect common features of pathogens, such as bacterial cell wall components. Once a pathogen is detected, the immune cell surrounds it and internalizes it in a vesicle called a phagosome. The phagosome then fuses with a lysosome, where enzymes break down the pathogen.
Phagocytosis plays a crucial role in the innate immune response by quickly clearing infections, limiting the spread of pathogens, and stimulating inflammation. It also helps in activating the adaptive immune system by presenting antigens from the pathogen to T cells, thereby linking both branches of immunity.
In contrast, T cells (option A) and B cells (option D) are part of the adaptive immune system and are responsible for more specific, long-term immune responses. Plasma cells (option C) are derived from B cells and produce antibodies, which are a key part of the adaptive immune response, not the innate immune defense.
Thus, while phagocytosis is a central defense mechanism of the innate immune system, T cells, B cells, and plasma cells are more involved in adaptive immunity.