Which of the following cells is NOT a part of cellular barriers ?

Options

A. Interferons
B. Natural killer cell
C. kupffer cell
D. Polymorphonuclear lymphocytes

Answer

To solve the question "Which of the following cells is NOT a part of cellular barriers?", we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Cellular Barriers**:
- Cellular barriers are components of the immune system that help protect the body from pathogens. They include various types of cells that play a role in the immune response.

2. **Analyzing Option 1: Interferons**:
- Interferons are proteins produced by host cells in response to viral infections. They are not cells themselves but rather signaling molecules that help other cells prepare to fight off infections. Therefore, they do not form a part of the cellular barriers.
- **Conclusion**: Interferons are NOT a part of cellular barriers.

3. **Analyzing Option 2: Natural Killer Cells**:
- Natural Killer (NK) cells are a type of lymphocyte that play a crucial role in the innate immune response. They can directly kill virus-infected cells and are indeed part of the cellular barriers.
- **Conclusion**: Natural Killer cells ARE part of cellular barriers.

4. **Analyzing Option 3: Cover Cells**:
- Cover cells, also known as Kupffer cells, are specialized macrophages located in the liver. They help in maintaining liver function and provide a barrier against bacterial infections. Thus, they are part of the cellular barriers.
- **Conclusion**: Cover cells ARE part of cellular barriers.

5. **Analyzing Option 4: Polymorphonuclear Lymphocytes**:
- Polymorphonuclear lymphocytes (PMNs), which include neutrophils, are essential components of the immune system that respond to infections and inflammation. They help in forming cellular barriers against pathogens.
- **Conclusion**: Polymorphonuclear lymphocytes ARE part of cellular barriers.

6. **Final Answer**:
- Based on the analysis, the correct answer to the question is **Option 1: Interferons**, as they are not cells and do not constitute a part of cellular barriers.