Which of the following best describes the membrane attack stage of the complement cascade?

• A. Formation of a pore in the target cell membrane by the assembly of complement proteins
• B. Activation of B cells to produce antibodies
• C. Opsonization of pathogens to enhance phagocytosis
• D. Release of histamine from mast cells

Answer: (A)

Verified step by step guidance

1. Understand that the complement cascade is a part of the innate immune system that helps clear pathogens through a series of protein activations.
2. Recall that the cascade has multiple stages, including activation, opsonization, inflammation, and membrane attack.
3. Focus on the membrane attack stage, which involves the assembly of complement proteins to form a complex called the Membrane Attack Complex (MAC).
4. Recognize that the MAC creates pores in the target cell's membrane, leading to cell lysis and death.
5. Compare this with other options: activation of B cells relates to adaptive immunity, opsonization enhances phagocytosis, and histamine release is part of inflammation, none of which describe the membrane attack stage.