Psychoneuroimmunology

Description of the Strategy

Historically, the immune system was thought to operate autonomously, without input from other bodily systems. However, interdisciplinary research in the 1980s began to suggest interactions between the nervous and immune systems, thus leading to the development of the field of psychoneuroimmunology (PNI). Research in the area of PNI examines the interrelationships among brain, behavior, and immunity. The finding that immune system activity could be altered by external influences led to studies demonstrating that both increases and decreases in immune activity could be conditioned. Subsequent research has begun to examine the extent to which interventions could be developed to positively impact immune system activity in various disease populations such as cancer and HIV patients. Furthermore, the immune system has been repeatedly examined as a mechanism through which behavioral interventions (e.g., relaxation therapy and cognitive-behavioral stress management) may slow disease progression. The present entry will review the literature examining the impact of behavioral interventions on immunity, focusing on studies in which immune components are used as the primary dependent variables as well as studies examining immunity as a mechanism for altered disease progression.

Overview of the Immune System

Prior to reviewing the PNI literature, it is necessary to first provide a brief overview of immune system functioning. The immune system is extremely complex, involving the interplay of numerous cellular and chemical components. Therefore, a comprehensive review of the workings of the immune system is well beyond the scope of this entry. Rather, we will briefly review the activity of the immune cells and components that are most commonly examined in the PNI literature.

The primary purpose of the immune system is to fight against infection and disease by identifying and eliminating foreign pathogens (e.g., bacteria, fungi, viruses) and mutated self-cells. This is accomplished through the activity of the two branches of the immune system: acquired (specific) and innate (nonspecific) immunity. Although these branches are discussed separately, they do not operate independently. The two branches communicate with each other, influence each other, and to some extent, control each other.