What condition occurs when antibodies develop against a person's own cells?

The condition where antibodies develop against a person's own cells is known as an autoimmune disease. In autoimmune diseases, the immune system mistakenly identifies the body’s own healthy cells as foreign invaders, leading to an immune response that attacks these cells. This can result in inflammation and damage to various tissues and organs in the body. Common examples of autoimmune diseases include rheumatoid arthritis, lupus, and type 1 diabetes.

In contrast, an allergic reaction refers to an inappropriate immune response to a harmless substance, such as pollen or certain foods. An infection occurs when pathogens like bacteria or viruses invade the body, leading to illness. Immunodeficiency describes a state where the immune system is weakened or unable to respond adequately to infections, which is quite different from the autoimmunity that occurs when the immune system is actively attacking the body’s own cells.