The B cells make and release specific antibodies that bind to surface proteins on the pathogen, targeting it for destruction by a large group of plasma proteins known as complement. Glucocorticoids are bay far the most important mediators of immune system suppression. The body appears to actively work to disassemble the immune system. In what is currently the dominant theory, stressful emergencies are seen as times when the immune system is likely to be very active. Stress hormones thus serve the role of reining in the immune system.
Chronic stress suppresses immune function.
Immune systems whose functioning is suppressed cannot fight disease effectively. Thus, chronic stress should make a vast number of diseases more likely to occur and more damaging once they do occur. It has been difficult to prove this though. Most of the work has been done on cancers. For example, an episode of a major depression seems to increase cancer risk for decades afterward, independent of age, diet, smoking, and other risk factors.