How does the brain know the body is sick? New approaches to an old problem in medicine.
The physiological significance of a widespread distribution of lymphoid cells throughout most of the organ systems in the body is thought to represent the general tissue requirement for protection and vigilance against foreign invaders and certain other disease states. More recently, this distribution has also been viewed as a group of immune system transducers capable of extending the sensory capabilities of the central nervous system. The information monitors the internal state of the body in relation to the external environment including potential invaders, malignant transformations of body cells, and certain other disease-causing agents. This kind of information is clearly on a sensory scale or wavelength not otherwise available to the central nervous system. The information consists of chemical messengers rather than energy, which is monitored by sensory pathways that have been conceptualized and studied over a much longer period of time.