5.1 From Psychoneuroimmunology and Neuroimmunology
to Present-Day Characterizations of the Dialogue between
the Nervous and the Immune Systems
Despite important preexisting research on interactions between the nervous and the
immune systems (relative to the blood–brain barrier, the idea of the brain as an
immune-privileged organ, and the role of microglia cells, in particular; more will be
said below about all these aspects), thefields of neuroimmunology and psychoneur-
oimmunology emerged in the 1970s and 1980s. The Neuroimmunology Branch of
the National Institute of Neurological Disorders and Stroke was established in 1975
(McFarland et al. 2017). The journalNeuroimmunologywas founded in 1981. Terms
such as neuroinflammatory were already in use in the early 1980s (e.g., (Hartung and
Toyka 1983)). Psychoneuroimmunology was also born in the second half of the
1970s, following the work of Robert Ader (1932–2011) and a few others. Thefirst
edition of the volumePsychoneuroimmunology, edited by Ader, was published in
1981 (Ader 1981) and several updated editions followed. In 1987 Ader founded the
journal Brain, Behavior, and Immunity, the official journal of the
Psychoneuroimmunology Research Society. Importantly, the domain of psycho-
neuroimmunology stemmed in part from psychosomatic medicine (Kiecolt-Glaser
et al. 2002).^1
Despite considerable overlap between neuroimmunology and psychoneuroim-
munology, neuroimmunology tends to investigate the interactions between the
nervous and the immune systems, particularly at the cellular and molecular levels,
while psychoneuroimmunology explores how behavior influences and is influenced
by the immune system. Historically, psychoneuroimmunology has focused on the
conditioning of immune responses, the role of immune factors in mental disorders
such as schizophrenia, and the effect of psychological factors such as stress on
immune responses (Ader 2000). Later, the role of neuroimmune interactions in
fatigue and sickness behavior (the feeling of fever and nausea, for example, when we
are sick, and which is mediated by pro-inflammatory cytokines such as IL-1β)
became important topics in thefield ( Dantzer et al. 2008). As early as the 1970s,
interactions under investigation included not just two but three actors: the nervous
and the immune system, but also the endocrine system (Besedovsky and Sorkin
1977)(foraretrospective,see(Besedovsky and Rey 2007)). This explains why some
researchers talk about“psycho-neuro-endocrino-immunology”(Sivik et al. 2002).
Neuroimmunology, psychoneuroimmunology, and psycho-neuro-endocrino-
immunology all pay attention to both the central nervous system (CNS) and the
(^1) I thank Jan Pieter Konsman for many discussions about the history of neuroimmunology and
psychoneuroimmunology.
Philosophy of Immunology 45