[Recent perceptions on the development, assembly and function of the immune system]

The immune system developed through many stages during evolution. It is fascinating that none of the diverse defense mechanisms vanished in such a long period of nearly 3.5 billion years. They still function in the integrated immune system. The barrier system can be compared to the immune system. The immune system itself is subdivided in antigen-independent, paraspecific (primitive immune system) and antigen specific (specific immune system), restricted immune reactions. The role and use of the phylogenetically older, paraspecific mechanisms, that will react immediately after antigen exposure, are discussed in detail. The immune system is not autonomous. It is closely linked to the hormonal, circulatory, metabolic and nervous systems. Its function is comparable to a sensory organ. Psychoneuroimmunology as a new discipline is mentioned. Immunity and paramunity are not seen as opposing phenomena but are linked in their functions. The terminology of immunology is discussed.