Sometimes the immune system overreacts, as in an allergic response. Sometimes it attacks self antigens, as in autoimmune disease. And sometimes it fails to act, or acts weakly, as in immune deficiency disease.
focus your learning
Allergic reactions, which can be immediate or delayed, result from an over-
Allergies can be treated by desensitization.
Autoimmunity occurs when T cells bind to antigen–
The study of HIV has led to the development of treatments for HIV.