Which of the following is associated with differentiation of cells of the immune system:

Options

A. Cortisol
B. Thyroxine
C. Thymosin
D. Steroid

Answer

To solve the question "Which of the following is associated with differentiation of cells of the immune system?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks which hormone is involved in the differentiation of immune system cells. This implies we need to identify a hormone that plays a crucial role in the development and maturation of immune cells.

2. **Identify the Options**: The options provided likely include various hormones. In the video transcript, thymosin is mentioned as a key hormone related to immune cell differentiation.

3. **Research the Role of Thymosin**: Thymosin is produced by the thymus gland, which is located just below the sternum. It is crucial for the maturation and differentiation of T-cells, which are essential components of the immune system.

4. **Evaluate Other Hormones**: The transcript mentions other hormones like cortisol and thyroxine.
- **Cortisol**: Secreted by the adrenal cortex, it generally suppresses immune function rather than promoting differentiation.
- **Thyroxine**: Primarily involved in metabolism and does not play a direct role in immune cell differentiation.
- **Steroids**: Similar to cortisol, they can suppress immune responses.

5. **Conclusion**: Based on the information gathered, thymosin is the hormone associated with the differentiation of immune system cells, particularly T-cells.

6. **Select the Correct Answer**: Therefore, the correct answer to the question is thymosin.

### Final Answer:
Thymosin is associated with the differentiation of cells of the immune system.

---