The immune system, natural autoantibodies and general homeostasis in health and disease.

It is generally accepted that the destination of the immune system is not only to discriminate between self and non-self but also to mount responses against non-self. During the last decades, it became evident that weak self-reactivity is a necessary condition for immune homeostasis. Natural self reactivity and the internal image created by autoantibodies, participate greatly to the maintenance of homeostasis. Under conditions of increased or altered antigenic pressure, the homeostatic status is disrupted and the organism becomes vulnerable to the emergence of diseases. "Immunculus" is the self-reactive and interconnected entity of the immune system, provided by a complicated network of natural autoantibobies of different specificity, as a mosaic picture. Quantitative changes in each part of the image are related to variations of expression of relative antigens. The immune system takes in account image information from the continuous screening of the antigenic status and compares between presented state and the desired (optimal) one. Substantial and prolonged deviations from the optimal state, triggers the induction of compensatory and reparative processes, aiming to restore molecular and functional homeostasis. So, natural autoimmunity through the ability of natural a-Abs to induce mechanisms of natural and acquired immunity, aims to prevent pathogenic processes and maintain or restore health status.