Transplantation of tissues/organs to save certain patients often fails due to rejection of such tissues/organs by the patient. Which type of immune response is responsible for such rejections?

Options

A. Autoimmune response
B. Cell-mediated immune response
C. Humoral immune response
D. Physiological immune response

Answer

**Step-by-Step Solution:**

1. **Understanding the Context**: The question pertains to the rejection of transplanted tissues or organs by the patient's immune system. This is a common issue in organ transplantation.

2. **Identifying the Immune Response Types**: The options provided are:
- Autoimmune response
- Cell-mediated immune response
- Humoral immune response
- Physiological immune response

3. **Analyzing Autoimmune Response**: An autoimmune response occurs when the immune system mistakenly attacks the body’s own cells. This is not applicable in the case of organ transplantation where the organ is from another individual.

4. **Analyzing Humoral Immune Response**: The humoral immune response involves B cells producing antibodies against pathogens. While this response is important in fighting infections, it is not primarily responsible for the rejection of transplanted organs.

5. **Analyzing Physiological Immune Response**: The physiological immune response is related to innate immunity, which provides a general defense against pathogens. It does not specifically target transplanted tissues or organs.

6. **Identifying Cell-Mediated Immune Response**: The cell-mediated immune response involves T cells, particularly T cytotoxic cells, which can recognize and destroy foreign cells, including transplanted tissues. This is the primary mechanism responsible for organ rejection.

7. **Conclusion**: The type of immune response responsible for the rejection of transplanted tissues or organs is the **cell-mediated immune response**.

**Final Answer**: Cell-mediated immune response.

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