What is the role of complement system?

Options

A. It interferes with viral replication
B. It is involved with antibody production
C. It aids antigen presentation
D. It causes cell lysis

Answer

### Step-by-Step Solution:

1. **Understanding the Complement System**: The complement system is a part of the immune system that enhances the ability of antibodies and phagocytic cells to clear pathogens from an organism. It consists of a series of proteins that work together to fight infections.

2. **Roles of the Complement System**:
- **Enhancement of Antibody Function**: The complement system enhances the effectiveness of antibodies in opsonization, which marks pathogens for destruction by phagocytes.
- **Promotion of Inflammation**: It promotes inflammation, which is crucial for recruiting immune cells to the site of infection.
- **Cell Lysis**: One of the primary roles of the complement system is to cause lysis (destruction) of pathogens by forming a membrane attack complex that creates pores in the pathogen's cell membrane.

3. **Evaluating the Options**:
- **Option 1: Interferes with Viral Replication**: This is incorrect. The complement system does not directly interfere with viral replication.
- **Option 2: Involved with Antibody Production**: This is also incorrect. While the complement system enhances antibody function, it does not produce antibodies.
- **Option 3: Aids Antigen Presentation**: This is incorrect as well. Antigen presentation is primarily the role of Major Histocompatibility Complex (MHC) molecules, not the complement system.
- **Option 4: Causes Cell Lysis**: This is correct. The complement system can directly cause the lysis of pathogens.

4. **Conclusion**: The primary role of the complement system is to enhance the immune response, promote inflammation, and cause cell lysis of pathogens.

### Final Answer:
The correct role of the complement system is that it causes cell lysis.

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