[Main issues of psychoneuroimmunology: Part II].

In psychoneuroimmunology links between psyche and the body are examined in the context of neurotransmitter, hormone and immuno-transmitter interaction. This allows for construction of models which show empirically verifiable links between the nervous, endocrine and immune systems. The earlier concepts of stress by Cannon and Selye focused on the physical and mental strain influence on the action of the nervous and endocrine systems. Ursin, Olff and Schedlowski introduced the concept of stress extended by an immune system reaction, which is an integral part of the alarm phase. A change in the amount of NK cells and their stress-influenced activity is an important defense mechanism of the body. It constitutes a component of the preparation for defense against potential pathogen penetration.