Helper T cells are distinguished from cytotoxic T-cells due to presence of

Options

A. `CD_(2)`
B. `CD_(4)`
C. `CD_(3)`
D. IL- 2 receptor

Answer

**Step-by-Step Text Solution:**

1. **Understanding T-Cells**: T-cells are a type of white blood cell that play a crucial role in the immune response. They are primarily divided into two main types: Helper T cells and Cytotoxic T cells.

2. **Identifying Helper T Cells**: Helper T cells, also known as T_H cells, are responsible for activating other immune cells, including B cells and cytotoxic T cells, through the secretion of cytokines.

3. **Identifying Cytotoxic T Cells**: Cytotoxic T cells, or T_C cells, are primarily involved in directly killing cancer cells and cells infected by viruses.

4. **Key Receptor Differences**: The main distinguishing feature between Helper T cells and Cytotoxic T cells is the type of surface receptors they possess:
- Helper T cells have CD4 receptors.
- Cytotoxic T cells have CD8 receptors.

5. **Understanding MHC Recognition**: The CD4 receptor on Helper T cells recognizes Major Histocompatibility Complex (MHC) class II molecules, while the CD8 receptor on Cytotoxic T cells recognizes MHC class I molecules.

6. **Analyzing the Options**: Given the options:
- CD2: Not specific to either type.
- CD4: Present in Helper T cells but absent in Cytotoxic T cells.
- CD3: Not specific to either type.
- IL-2: Related to interleukin-2 receptors, not distinguishing.

7. **Conclusion**: The correct answer is CD4, as it is the receptor that distinguishes Helper T cells from Cytotoxic T cells.

**Final Answer**: Helper T cells are distinguished from cytotoxic T cells due to the presence of CD4 receptors.

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