ABSTRACT
Since Ader and Cohen’s pioneering observations concerning the susceptibility of the immune system to behavioral conditioning (Ader & Cohen, 1975), there has been a dramatic increase in research dedicated to stress-neuroendocrine-immune interactions and their consequences for immunomodulation, i.e., the field of psychoneuroimmunology (PNI). Within this field, one area to have attracted considerable attention has been the phenomenon of stress-related immune impairment in humans. Multiple immunological changes have been reported. However, one of the major challenges to face human PNI research concerns the clinical significance of these immune alterations in people who experience psychological stress. In this regard, two main questions are evident:
What is the clinical significance of altered immunity, as measured by in vitro, ex vivo and in vivo humoral and cellular assays of immunity?; and
Is the magnitude of stress-associated immune changes sufficient to alter immunocompetence?
In this chapter we have aimed to review and evaluate some of the more frequently used in vitro, in vivo and ex vivo immunological techniques in the hope that a clearer understanding of what these assays can tell us will inform the discussion of the significance of stress-related immune impairment in humans. The chapter commences with a brief description of the immune system and this is followed by a review of the most commonly used in vitro, in vivo and ex vivo assays in PNI. The review of each assay includes: (1) a description of the rationale behind its use; (2) a commentary on the advantages and limitations of the assay; and (3), a consideration of their clinical relevance. The empirical work considered in this chapter has been conducted primarily with humans and, with the exception of the section on delayed hypersensitivity skin tests (DTH), focuses on sampling from peripheral blood.