What is an autoimmune disease?

An autoimmune disease is characterized by the immune system mistakenly identifying and attacking the body's own cells as if they were foreign invaders. This misdirected immune response leads to inflammation and damage to various tissues and organs, which can significantly impact normal physiological functions. Conditions such as rheumatoid arthritis, lupus, and type 1 diabetes exemplify autoimmune diseases, where the immune system targets specific cell types or tissues, believing them to be threats.

In contrast, other options present different immunological phenomena. For instance, a lack of immune responses refers to immunodeficiency disorders, where the body is unable to effectively fight infections. Attacking benign cells typically does not classify as an autoimmune response, since benign cells are generally not targeted in this way; instead, autoimmunity involves attacking the body's own healthy cells. Lastly, diseases caused by infectious agents pertain to infectious diseases rather than autoimmune conditions, which specifically involve the body's own immune system turning against its tissues.