Legionella uses C3b receptors to enter monocytes. This
a. prevents phagocytosis.
b. degrades complement.
c. inactivates complement.
d. prevents inflammation.
e. prevents cytolysis.

Verified step by step guidance

1. Understand the role of C3b in the immune system: C3b is a component of the complement system that tags pathogens for destruction and facilitates phagocytosis by binding to complement receptors on phagocytes.
2. Recognize that Legionella is a bacterium that can cause Legionnaires' disease and is known for its ability to survive and replicate within macrophages, a type of monocyte.
3. Consider how Legionella's use of C3b receptors might affect the normal immune response: By binding to C3b receptors, Legionella can enter monocytes, which are cells that typically engulf and destroy pathogens.
4. Analyze the options given: a) prevents phagocytosis, b) degrades complement, c) inactivates complement, d) prevents inflammation, e) prevents cytolysis.
5. Determine which option aligns with Legionella's strategy to survive within monocytes: Since Legionella uses C3b receptors to enter monocytes, it likely prevents the normal process of phagocytosis, allowing it to avoid being destroyed.

Key Concepts

C3b and Complement System

C3b is a component of the complement system, which is part of the immune response. It plays a crucial role in opsonization, marking pathogens for destruction by phagocytes. Understanding how C3b interacts with receptors on immune cells, such as monocytes, is essential for grasping how Legionella can evade immune responses.

Phagocytosis

Phagocytosis is the process by which certain immune cells, like monocytes and macrophages, engulf and digest pathogens. Legionella's ability to use C3b receptors to enter monocytes suggests a mechanism to avoid being destroyed, highlighting the importance of this process in the immune defense against infections.

Inflammatory Response

The inflammatory response is a critical part of the immune system that helps to eliminate pathogens and initiate healing. By understanding how Legionella might manipulate immune responses, such as preventing inflammation, we can better comprehend its pathogenic strategies and the implications for disease progression.