Which of the following hormones regulates humoral immunity ?

Options

A. Thyroxine
B. Insulin
C. Glucagon
D. Thymosin

Answer

To determine which hormone regulates humoral immunity, we can follow these steps:

### Step 1: Understand Humoral Immunity
Humoral immunity is a type of immune response that is mediated by antibodies. It is also referred to as antibody-mediated immunity. The primary role of humoral immunity is to produce antibodies that help in fighting off pathogens.

**Hint:** Focus on the role of antibodies in the immune system.

### Step 2: Identify the Cells Involved
Humoral immunity is primarily mediated by B lymphocytes (B cells), which are responsible for the production and secretion of antibodies. T lymphocytes (T cells) also play a role, particularly in the activation of B cells.

**Hint:** Remember the key players in humoral immunity: B cells and T cells.

### Step 3: Know the Origin of B and T Cells
B cells are produced and matured in the bone marrow, while T cells are produced in the bone marrow but mature in the thymus gland.

**Hint:** Distinguish between the maturation sites of B cells and T cells.

### Step 4: Identify the Hormone Involved
The thymus gland produces a hormone called thymosine, which is crucial for the differentiation and maturation of T cells. These T cells are essential for the activation of B cells, which then produce antibodies.

**Hint:** Focus on the role of thymosine in T cell maturation.

### Step 5: Evaluate the Options
- **Thyroxin**: Secreted by the thyroid gland, regulates metabolism (not related to immunity).
- **Insulin and Glucagon**: Regulate blood glucose levels (not related to immunity).
- **Thymosine**: Produced by the thymus gland, regulates T cell differentiation and thus plays a role in humoral immunity.

**Hint:** Compare the functions of each hormone with the requirements of humoral immunity.

### Conclusion
Based on the above analysis, the hormone that regulates humoral immunity is **thymosine**.

**Final Answer:** Thymosine.