Which of the following functions is/are performed by complement proteins?
a. Cell lysis
b. Opsonization
c. Enhancing inflammation
d. Only a and b
e. All of the above

Verified step by step guidance

1. Step 1: Understand the role of complement proteins in the immune system. Complement proteins are part of the innate immune system and help defend the body against pathogens by enhancing various immune responses.
2. Step 2: Define the term 'cell lysis.' Complement proteins can form a membrane attack complex (MAC) that creates pores in the membranes of pathogens, leading to their destruction through cell lysis.
3. Step 3: Define 'opsonization.' Complement proteins can coat the surface of pathogens, making them easier for phagocytes (like macrophages) to recognize and engulf. This process is called opsonization.
4. Step 4: Explain how complement proteins enhance inflammation. Complement proteins can stimulate the release of inflammatory mediators, such as histamine, which increases blood flow and attracts immune cells to the site of infection.
5. Step 5: Evaluate the options provided in the question. Since complement proteins perform all three functions (cell lysis, opsonization, and enhancing inflammation), the correct answer would include all of the above functions.

Key Concepts

Complement System

The complement system is a part of the immune system consisting of proteins that enhance the ability of antibodies and phagocytic cells to clear pathogens from an organism. It plays a crucial role in immune responses, including opsonization, cell lysis, and inflammation. Understanding how these proteins function helps in grasping their importance in both innate and adaptive immunity.

Opsonization

Opsonization is a process where pathogens are marked for destruction by immune cells. Complement proteins bind to the surface of pathogens, making them more recognizable to phagocytes like macrophages and neutrophils. This enhances the efficiency of the immune response, allowing for quicker and more effective clearance of infections.

Cell Lysis

Cell lysis refers to the destruction of a cell's membrane, leading to its death. In the context of the complement system, certain complement proteins form a membrane attack complex that creates pores in the target cell's membrane, causing it to burst. This mechanism is particularly effective against bacteria and is a key function of the complement system in combating infections.