Natural autoantibodies of IgG class to proteins S100b, glial fibrillar acidic protein (GFAP), and nerve growth factor (NGF) are presented in serum of healthy adults and those levels/affinities are relatively constant and may vary among individuals within narrow limits. In patients with depressive disorder, epilepsy, multiple sclerosis, and Parkinson's disease dispersion of such autoantibodies serum levels were often found beyond the normal ranges. Most of the patient groups include cases with significantly elevated as well as abnormally decreased immunoreactivity parameters. This leads us to assumption that changes in some basic mechanisms of individual immune state represent the common features of different forms of pathology of the nervous system.