Immune protection vs. immunopathology vs. autoimmunity: a question of balance and of knowledge.

Immunological mechanisms have been suspected and have been shown to be involved in many acute or chronic, and also in some neurological diseases. However, in most cases it is unclear whether disease is caused by insufficient immunity, delayed immunity against infectious agents or by autoimmunity (i.e., reactivity to a "normal" self). The present summary is a biased view of immunological pathogenic principles that may explain some of the questions henceforth. Two proposals will be illustrated. Firstly, T cell mediated immune protection is mediated by cell destruction, i.e., pathology, therefore both beneficial and harmful effects of T cell responses against foreign, mostly infectious, antigens will be the result of the balance between kinetics of immune response and infectious agents. Secondly, if one knows the causative agent, the immunologically mediated disease is called "immunopathological" whereas if a new or trivial causative agent is not recognized the disease is called "autoimmune".