The immune system plays an important role in
(a) Recognition of foreign antigens
(b) Responds to antigens and remembers them
(c ) Allergic -immune diseases
( e) Organ transplantation

Options

A. b, c and e
B. a and b only
C. a, b, c and d
D. a, b, c, d and e

Answer

To answer the question about the roles of the immune system, we will analyze each option step by step:

### Step-by-Step Solution:

1. **Recognition of Foreign Antigens**:
- The immune system is responsible for identifying foreign substances (antigens) that enter the body. This includes pathogens like bacteria and viruses.
- The immune cells, such as macrophages and lymphocytes, recognize these foreign antigens and initiate a response to eliminate them.
- **Conclusion**: This statement is correct.

2. **Responds to Antigens and Remembers Them**:
- The immune system not only responds to antigens but also has a memory component.
- After the initial exposure to a pathogen, the immune system creates memory cells that "remember" the specific antigens.
- If the same pathogen attacks again, the immune system can mount a faster and stronger response due to this memory.
- **Conclusion**: This statement is correct.

3. **Allergic-Immune Diseases**:
- The immune system can also be involved in allergic reactions, which are inappropriate responses to harmless substances (allergens).
- In these cases, the immune system overreacts, leading to symptoms such as sneezing, itching, and swelling.
- **Conclusion**: This statement is correct.

4. **Organ Transplantation**:
- The immune system plays a crucial role in organ transplantation.
- It can recognize transplanted organs as foreign and may reject them unless there is a proper match between the donor and recipient (tissue typing).
- This is why immunosuppressive drugs are often required after a transplant to prevent rejection.
- **Conclusion**: This statement is correct.

### Final Conclusion:
All the options provided (a, b, c, d, e) are correct regarding the roles of the immune system. Therefore, the correct answer is that the immune system plays an important role in all of the mentioned aspects.