Neuroendocrine-immune interactions.

Over the past 15 years, the mechanisms by which the brain communicates with the immune system and the immune system with the brain have been elucidated. Increasingly, we are beginning to realize that cytokines within the brain are no scientific oddity, but rather are an important component of normal brain functioning. They are able to alter behaviour, memory, stress responses, brain injury and are increasingly being linked to psychiatric disorders. Hormones, peptides and neurotransmitters regulate the immune system. Understanding the complex interactions of these systems is a challenge for the 21st century.