This conceptual article addresses different underrecognized aspects of the immune system physiological activities. These ones include: the role of the immune system and physiologic autoimmunity in maintaining normal body’s own cell populations; its involvement in placen-tation and mother-to-fetus interactions; its embedding into immune-neuroendocrine com-municative and integrating apparatus designated first of all for support of unique multicellu-larity of the organism and for regulation of its somatic cells’ growth and life. Besides cytokines, a powerful instrument of somatic regulation is agonistic (functional) autoantibodies, able to act on their receptors in hormone-like manner. The regulatory potential of antiidiotypic im-munity is underappreciated. There is evidence, that anti-idiotypic antibodies can create inter-nal immunological images and copy the ligand properties of different bioregulators and even drugs. What makes the regulatory interactions even more complex is the fact that antibodies are capable of penetrating living cell membrane, permeating the nucleus and produce a wide spectrum of regulatory effects on transcription, translation and post-transcription modifica-tions.