Which statement best describes the implications of autoimmune diseases on immune system function?

Autoimmune diseases happen when the immune system mistakenly attacks the body’s own cells, treating them like foreign invaders. This misdirected activity depletes normal immune resources and can damage healthy tissues, making the body vulnerable to infections and reducing overall immune efficiency. Because the immune system is busy fighting itself, it has less capacity to respond quickly to real threats, which can lead to chronic illness and a higher chance of infections. For example, in rheumatoid arthritis, the immune system attacks joint tissues, causing pain and swelling while weakening the body’s ability to fight off other diseases. Thus, autoimmune diseases not only harm tissues but also compromise the immune system’s normal protective function.