A pathogenic bacterium that is able to avoid binding with the complement protein C3b would most likely protect itself from which of the following immune responses?

• A. Cell lysis of the bacterium.
• B. Opsonization.
• C. Triggering an inflammatory response.
• D. Antibodies binding to the bacterium.

Answer: (B)

Verified step by step guidance

1. Understand the role of complement protein C3b in the immune system. C3b is part of the complement system, which enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells.
2. Recognize that C3b is involved in opsonization, a process where pathogens are marked for destruction by phagocytes. C3b binds to the surface of pathogens, making them more recognizable to immune cells.
3. Consider how a bacterium avoiding binding with C3b would affect opsonization. If C3b cannot bind, the bacterium is less likely to be marked for phagocytosis, thus avoiding this immune response.
4. Evaluate the other immune responses listed: cell lysis, triggering an inflammatory response, and antibodies binding to the bacterium. These processes may involve other components of the immune system, not solely dependent on C3b.
5. Conclude that the bacterium's ability to avoid binding with C3b would most likely protect it from opsonization, as this process directly involves C3b marking the pathogen for destruction by phagocytes.