Which of the following is not an antigen presenting cell?

Options

A. B-cell
B. Macrophage
C. Dendritic cell
D. T-cell

Answer

To determine which of the following is not an antigen presenting cell (APC), we need to analyze the options provided: B cells, macrophages, dendritic cells, and T cells.

### Step-by-Step Solution:

1. **Understanding Antigen Presenting Cells (APCs)**:
- APCs are crucial components of the immune system that present antigens to T cells. This process is essential for the activation of T cells, which then carry out immune responses.

2. **Identifying Common APCs**:
- The primary types of APCs include:
- **B cells**: These can present antigens to T cells and are considered APCs.
- **Macrophages**: These cells engulf pathogens and present their antigens to T cells, thus functioning as APCs.
- **Dendritic cells**: These are the most efficient APCs, known for their ability to capture and present antigens to T cells.

3. **Evaluating the Options**:
- **B cells**: They are APCs as they present antigens to T cells.
- **Macrophages**: They are also APCs, presenting antigens to T cells.
- **Dendritic cells**: These are well-known APCs.
- **T cells**: Unlike the others, T cells do not present antigens. Instead, they recognize and respond to antigens presented by APCs.

4. **Conclusion**:
- From the analysis, it is clear that T cells do not function as antigen presenting cells. Therefore, the correct answer to the question "Which of the following is not an antigen presenting cell?" is **T cells**.

### Final Answer:
**T cells** (Option D) are not antigen presenting cells.

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