Acquired Immunity mediated by which of the following

Options

A. Antibody formation by T-lymphocytes
B. Antibody formation by B- lymphocytes
C. HCl by stomach
D. Bite by snake

Answer

To solve the question regarding which mechanism mediates acquired immunity, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Acquired Immunity**:
- Acquired immunity is the immunity that an individual develops over their lifetime after exposure to pathogens. It is different from innate immunity, which is present from birth.

2. **Types of Acquired Immunity**:
- Acquired immunity can be classified into two types:
- **Active Immunity**: This occurs when the body is exposed to a pathogen and produces antibodies in response.
- **Passive Immunity**: This occurs when antibodies are transferred from one individual to another, such as through breast milk or antiserum.

3. **Evaluate the Options**:
- **Option A: Antibody formation by T lymphocytes**:
- T lymphocytes do not directly produce antibodies; they help in the immune response. This option is incorrect.
- **Option B: Antibody formation by B lymphocytes**:
- B lymphocytes are responsible for producing antibodies. When activated, they differentiate into plasma cells that secrete antibodies. This option is correct.
- **Option C: HCl by stomach**:
- Hydrochloric acid (HCl) in the stomach is part of innate immunity, not acquired immunity. This option is incorrect.
- **Option D: Bite by snake**:
- A snake bite may require antivenom, which is a form of passive immunity but does not represent the mechanism of acquired immunity itself. This option is incorrect.

4. **Conclusion**:
- The correct answer is **Option B: Antibody formation by B lymphocytes**, as they are the cells responsible for the production of antibodies in acquired immunity.

### Final Answer:
**Acquired immunity is mediated by antibody formation by B lymphocytes.**