Autoimmunity refers to what condition?

• A. The immune system attacks harmful foreign invaders
• B. The immune system mistakenly attacks the body's own cells
• C. The immune system has no response to foreign substances
• D. The immune system produces excessive antibodies

Answer: (B)

Autoimmunity is a condition where the immune system mistakenly identifies the body’s own cells and tissues as foreign invaders, leading to an inappropriate immune response that results in damage. This occurs when the mechanism that typically distinguishes between self and non-self fails, prompting the immune system to target its own components. The consequence of this misidentification is the development of autoimmune diseases, in which the body’s defenses mistakenly attack healthy cells, leading to inflammation and tissue damage.

In contrast, the other options describe different scenarios unrelated to autoimmunity. One option refers to the normal function of the immune system, where it effectively targets harmful foreign invaders. Another option describes a lack of immune response, which does not align with the activity characteristic of autoimmunity. Finally, the last option suggests excessive antibody production, which may be present in certain conditions but does not specifically define the fundamental process of autoimmunity itself.