Why are autoimmune diseases called degenerative diseases?

Explanation

### Step-by-Step Solution:

1. **Understanding Autoimmune Diseases**:
- Autoimmune diseases occur when the immune system mistakenly attacks the body's own cells. Normally, the immune system functions to protect the body from foreign invaders like bacteria and viruses. However, in autoimmune diseases, this protective mechanism turns against the body itself.

2. **Role of the Immune System**:
- The immune system identifies and responds to foreign particles. It does this by producing antibodies and activating immune cells to eliminate these threats. In a healthy immune response, the body protects itself without harming its own cells.

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