D89.8: Other specified disorders involving the immune mechanism, not elsewhere classified

The immune system protects the body from pathogens and foreign substances. The immune system can also destroy cells in the body that have pathologically changed. The body's immune system is made up of different types of immune cells. Some immune cells can destroy pathogens or foreign bodies themselves. Other immune cells produce certain antibodies. Some of the immune system’s antibodies can make pathogens and foreign substances visible to the immune system. Other antibodies attack pathogens or foreign substances directly.

When the immune system has a disorder, it may not create the right antibodies, for example. The immune system may also produce too many or the wrong antibodies, or certain defense cells may not be produced properly.

When there is a disorder in the immune system, the body finds it harder to protect against pathogens. So you become ill more easily. Your immune system may also attack your own body or inflammations can occur around the body. Then you can get fever, diarrhea or inflammations of the airways, for example. If the disorder is congenital, it can delay physical and mental development.