IMMUNOLOGY DISCOVERS PHYSIOLOGY

Not so long ago, it was believed that the brain is totally devoid of i mmunologic reactions, that cytokines derived from activated leukocytes serve only as communication molecules between leukocytes and that the immune system is regulated solely by intrinsic mechanisms. One by one , these old-time, traditional views have fallen by the wayside as neur oscientists, endocrinologists and pharmacologists have begun to explor e immunology. The old view was that the immune system is autonomous be cause it neither affects nor is it affected by other physiologic syste ms. The new view is that cells of the immune system are inextricably l inked with other physiological systems, including the neuroendocrine, cardiovascular, reproductive and central nervous systems (CNS). Change s in one system evoke changes in the other, and it is likely that comm unication loops have evolved between cells of the immune system and th ose of other tissues to coordinate and regulate functional activities aimed at preserving homeostasis during inflammation. The integrated vi ew of immunophysiologists that cells of the immune system interact wit h the entire body, rather than existing as a separate physiologic syst em that operates autonomously, should help to unravel a number of myst eries in immunoregulation, such as the well-recognized redundant and p leiotropic properties of cytokines. Unfortunately, very few of these i deas have been incorporated into studying immunity of domestic animals . A complete understanding of immunobiology will be achieved only afte r this new field of immunophysiology is integrated into current immuno logical thinking. The purpose of this short article is to describe new discoveries which provide insights into how leukocytes discriminate b etween self and non-self by enlisting the aid of neuroendocrine and CN S and to document what is known about the immunophysiology of pigs.