What causes body to fight against itself?

The body can mistakenly attack itself due to autoimmune diseases, where the immune system fails to distinguish between foreign invaders and its own healthy tissues. Factors such as genetic predisposition, environmental triggers, infections, and hormonal changes may contribute to this dysregulation. In these conditions, the immune system produces antibodies or immune cells that target the body's own cells, leading to inflammation and damage. This misguided response can result in a variety of health issues, depending on which tissues or organs are affected.