In higher vertebrates, the immune system can distinguish self-cells and non-self. If this property is lost due to genetic abnormality and it attacks self-cells, then it leads to

Options

A. Auto-immune disease
B. Active immunity
C. Allergic response
D. Graft rejection

Explanation

**Step-by-Step Solution:**

1. **Understanding the Immune System**: The immune system in higher vertebrates has the ability to differentiate between self-cells (the body’s own cells) and non-self-cells (foreign invaders like pathogens). This distinction is crucial for maintaining health.

**Hint**: Recall the basic function of the immune system in recognizing self vs. non-self.

2. **Loss of Distinction**: If there is a genetic abnormality that causes the immune system to lose this ability to distinguish between self and non-self, it can lead to serious health issues.

**Hint**: Think about what happens when the immune system misidentifies its own cells.

3. **Consequences of Misidentification**: When the immune system mistakenly attacks self-cells, it results in the immune system targeting and damaging the body’s own tissues.

**Hint**: Consider the implications of the immune system attacking its own cells.

4. **Identifying the Condition**: This condition is known as an autoimmune disease. Autoimmune diseases occur when the immune system fails to recognize its own cells and instead attacks them, leading to various health problems.

**Hint**: Remember the term "autoimmune" and what it signifies regarding the immune response.

5. **Differentiating from Other Conditions**: It is important to distinguish autoimmune diseases from other immune responses such as allergic responses, graft rejection, and active immunity, which involve reactions to external agents rather than the body’s own cells.

**Hint**: Reflect on the definitions of allergic responses, graft rejection, and active immunity to see how they differ from autoimmune diseases.

**Final Answer**: The loss of the immune system's ability to distinguish self-cells from non-self-cells due to genetic abnormality leads to autoimmune diseases.

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