All of the following cells are examples of cellular barriers , except

Options

A. Natural killer cells (NK cells)
B. Macrophages
C. Lymphocytes
D. Neutrophils

Answer

To solve the question, we need to identify which of the listed cells are not examples of cellular barriers. The options provided are:

A. Natural killer cells (NK cells)
B. Macrophages
C. Lymphocytes
D. Neutrophils

### Step-by-Step Solution:

1. **Understand the Types of Immunity**:
- The immune system is divided into two main types: innate immunity and adaptive immunity.
- Innate immunity provides immediate defense against infections and includes various cellular barriers.
- Adaptive immunity is a more specialized response that develops over time and involves memory.

2. **Identify the Role of Each Cell Type**:
- **Natural Killer (NK) Cells**: These are part of the innate immune system and act as a first line of defense against infected or cancerous cells. They are considered a cellular barrier.
- **Macrophages**: These cells are also part of the innate immune system. They engulf and digest pathogens and dead cells, serving as a cellular barrier.
- **Lymphocytes**: This group includes B cells and T cells, which are part of the adaptive immune system. They are not considered cellular barriers because they respond to specific antigens and develop memory.
- **Neutrophils**: These are another type of innate immune cell that responds quickly to infections and are considered cellular barriers.

3. **Determine the Correct Answer**:
- Since NK cells, macrophages, and neutrophils are all part of the innate immune response and serve as cellular barriers, while lymphocytes belong to the adaptive immune response, the correct answer is **C. Lymphocytes**.

### Final Answer:
C. Lymphocytes

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