Graft rejection is due to which immunity?

Options

A. Cellular barrier of innate immunity only
B. Cell mediated immunity.
C. Humoral immunity
D. Innate immunity.

Answer

**Step-by-Step Solution:**

1. **Understanding Graft Rejection:**
- Graft rejection is a process where the recipient's immune system recognizes the transplanted tissue (graft) as foreign and mounts an immune response against it, leading to the destruction of the graft tissue.

2. **Defining Immunity:**
- Immunity is the ability of an organism to recognize and fight off pathogens or foreign cells. It can be categorized into different types, including innate immunity and adaptive immunity.

3. **Analyzing the Options:**
- **Cellular barrier of innate immunity only:** This refers to the non-specific immune response that includes cells like leukocytes and monocytes. While these cells can destroy foreign cells, they are not specifically responsible for graft rejection.
- **Cell-mediated immunity:** This type of immunity is specifically mediated by T lymphocytes (T cells), which can recognize and destroy foreign cells, including grafts. This is the correct answer as it is responsible for graft rejection.
- **Humoral immunity:** This involves antibodies produced in the blood (like IgA and IgG) that target pathogens. However, humoral immunity is not primarily responsible for graft rejection.
- **Innate immunity:** This is a non-specific immune response that cannot distinguish between different types of foreign cells, making it ineffective for graft rejection.

4. **Conclusion:**
- The correct answer is **cell-mediated immunity**, as it specifically involves T lymphocytes that recognize and attack foreign graft tissues.