Immune network and autoimmunity

The concept of autoimmunity is regarded as the inability of the immune system to distinguish between self and non-self. This oversimplification of the concept is far from explaining the complex and perplexing mechanisms that are postulated to lead to its development. The transition from autoimmune state, in which no corresponding clinical manifestation exist, to an autoimmune disease, is further complicated by the evidence of multiple factors that participate in the evolution of the disease state. This article is written in a stepwise manner, initially reviewing the basic elements of the immune system, which are essential to understanding the fundamental processes underlying the occurrence of autoimmunity. Subsequently, a description of the factors involved in the etiopathogenesis and the presumed triggering events leading to the emergence of autoimmune diseases are described, with special emphasis on the important role of the idiotypic network, either in the maintenance of the normal immune response, or in the breakdown of self-tolerance eventuating in the autoimmune disease.