autoimmunity

"Autoimmunity is the presence of antibodies (which are made by B lymphocytes) and T lymphocytes directed against normal components of a person (autoantigens).

These components are called autoantigens or self-antigens and typically consist of proteins (or proteins complexed to nucleic acids). The antibodies and T lymphocytes that recognize autoantigens are called "autoantibodies" and "autoreactive T cells"."

Source:  https://pathology.jhu.edu/autoimmune/definitions 

Any disease resulting from this type of immune response is termed an "autoimmune disease".