The assessment of the emotional and immunological consequences of examination stress

A corticoid-sensitive cytokine release assay for monitoring stress-mediated immune modulation

The human immune system is orchestrated in a complex manner and protects the host against invading organisms and controls adequate immune responses to different antigen challenges in an endo-, auto- and paracrine-regulated fashion. The variety and intensity of immune responses are known to be dependent on stress-sensitive neural, humoral and metabolic pathways. The delayed-type hypersensitivity (DTH) skin test was a validated and standardized measure applied in clinical studies to monitor the integral function of cellular immune responses in vivo. The DTH skin test was, however, phased out in 2002. To obtain insight into the mechanisms of stress-sensitive immune reactions, we have developed an alternative in-vitro assay which allows the evaluation of antigen-dependent cellular immune responses triggered by T lymphocytes. The change in the concentration of proinflammatory cytokines in supernatant of the blood-antigen mixture is of particular interest to mirror the degree and adequacy of cellular immune responses. In this study we report that the proinflammatory cytokines interleukin (IL)-2, interferon (IFN)-γ and tumour necrosis factor (TNF)-α show a time-dependent increase upon ex-vivo bacterial, viral and fungal antigen stimulations. Furthermore, evidence is provided that this assay is sensitive to mirror stress hormone-mediated immune modulation in humans as shown either after hydrocortisone injection or after acute stress exposure during free fall in parabolic flight. This in-vitro test appears to be a suitable assay to sensitively mirror stress hormone-dependent inhibition of cellular immune responses in the human. Because of its standardization and relatively simple technical handling, it may also serve as an appropriate research tool in the field of psychoneuroendocrinology in clinical as in field studies.

Psychological stress and wound healing in humans: a systematic review and meta-analysis

OBJECTIVE

The current review aims to synthesize existing knowledge about the relationship between psychological stress and wound healing.

METHODS

A systematic search strategy was conducted using electronic databases to search for published articles up to the end of October 2007. The reference lists of retrieved articles were inspected for further studies and citation searches were conducted. In addition, a meta-analysis of a subset of studies was conducted to provide a quantitative estimation of the influence of stress on wound healing.

RESULTS

Twenty-two papers met the inclusion criteria of the systematic review and a subsample of 11 was included in a meta-analysis. The studies assessed the impact of stress on the healing of a variety of wound types in different contexts, including acute and chronic clinical wounds, experimentally created punch biopsy and blister wounds, and minor damage to the skin caused by tape stripping. Seventeen studies in the systematic review reported that stress was associated with impaired healing or dysregulation of a biomarker related to wound healing. The relationship between stress and wound healing estimated by the meta-analysis was r=-0.42 (95% CI=-0.51 to -0.32) (P<.01).

CONCLUSION

Attention now needs to be directed towards investigating potential moderators of the relationship, mediating mechanisms underpinning the association, as well as the demonstration of a causal link by the development of experimental interventions in healthy populations.

The interaction of social network size and stressful life events predict delayed-type hypersensitivity among women with metastatic breast cancer

This study examined relationships between social support, stressful life events and antigen-specific cell-mediated immunity. Participants were 72 women with documented metastatic breast carcinoma, who completed self-report measures of social support and life stress. Immune response was assessed using the delayed type hypersensitivity (DTH) skin test. Number of positive antigens was significantly related to the interaction of social network size and stressful life events (p<0.05). Number of positive antigens was greater for women who had experienced a high frequency of stressful life events but who reported a larger network of support. However, social network size was inversely related to DTH response among women who had experienced fewer stressful life events. Average induration size was not significantly related to the quality of social support, life stress per se, or their interactions. The relationship between social network size and immune response in women with metastatic breast cancer depends on prior stressful life experience.

Psychological stress and the human immune system: a meta-analytic study of 30 years of inquiry

The present report meta-analyzes more than 300 empirical articles describing a relationship between psychological stress and parameters of the immune system in human participants. Acute stressors (lasting minutes) were associated with potentially adaptive upregulation of some parameters of natural immunity and downregulation of some functions of specific immunity. Brief naturalistic stressors (such as exams) tended to suppress cellular immunity while preserving humoral immunity. Chronic stressors were associated with suppression of both cellular and humoral measures. Effects of event sequences varied according to the kind of event (trauma vs. loss). Subjective reports of stress generally did not associate with immune change. In some cases, physical vulnerability as a function of age or disease also increased vulnerability to immune change during stressors.

Influences of distress and alcohol consumption on the development of a delayed-type hypersensitivity skin test response

OBJECTIVE

This paper reports the effects of naturally occurring levels of distress on the development of delayed-type hypersensitivity (DTH) skin test responses. These in vivo measures provide a biologically relevant assessment of cellular immune competence.

METHODS

Subjects (N = 166) were immunized (baseline) with the novel antigen, keyhole limpet hemocyanin (KLH), and DTH skin test responses against KLH were assessed 3 weeks later (follow-up). The CMI Multitest (Merieux, France), which evaluates DTH responses to a panel of seven antigens, was also administered at follow-up. Emotional distress was assessed at baseline and follow-up by the Profile of Mood States.

RESULTS

Distress levels at baseline were associated with a reduced likelihood of developing DTH responses against KLH at follow-up (r = -0.22, p =.01). There was no relationship between distress at follow-up and cutaneous DTH in response to KLH (r = 0.09, p =.24) or in the Multitest (r = -0.03, p =.70). In addition, higher levels of alcohol consumption at baseline (r = -0.19, p =.02) and at follow-up (r = -0.20, p =.01) were associated with a decreased likelihood of developing cutaneous DTH against KLH.

CONCLUSIONS

Everyday levels of distress predicted the capacity of the cellular arm of the immune system to exhibit recall responses to an antigen, when the experimental paradigm allowed the assessment of distress at the time of antigen sensitization. Moderate alcohol consumption independently affected cutaneous DTH.

Psychological stress and the human immune system: a meta-analytic study of 30 years of inquiry

The present report meta-analyzes more than 300 empirical articles describing a relationship between psychological stress and parameters of the immune system in human participants. Acute stressors (lasting minutes) were associated with potentially adaptive upregulation of some parameters of natural immunity and downregulation of some functions of specific immunity. Brief naturalistic stressors (such as exams) tended to suppress cellular immunity while preserving humoral immunity. Chronic stressors were associated with suppression of both cellular and humoral measures. Effects of event sequences varied according to the kind of event (trauma vs. loss). Subjective reports of stress generally did not associate with immune change. In some cases, physical vulnerability as a function of age or disease also increased vulnerability to immune change during stressors.

The relationship between distress and the development of a primary immune response to a novel antigen

Forty-five medical students were recruited to examine the effects of distress on the development of an immune response to the novel antigen, keyhole limpet hemocyanin (KLH). The subjects' level of distress was manipulated by immunizing them either at the time of an important viva voce examination (n=22) or during examination-free term time (n=23). This manipulation increased variance amongst the subjects, but the emphasis in this research was on individual distress as a predictor of immune function. In the group as a whole, the likelihood of developing DTH skin responses to KLH was reduced in the more distressed subjects (r=-.45; p=.002), independently of a number of behavioral (e.g., sleep disturbance) and demographic (e.g., sex) variables. Proliferation of T cells against KLH in vitro and the development of anti-KLH IgG antibodies were not related to levels of distress. Thus, cellular, rather than humoral, immune responses in vivo appear susceptible to the influence of distress. This immunization model provides the opportunity to further dissect the basis of these stress-immune pathways.

Use and abuse of academic examinations in stress research

Previous research suggests that certain types of academic examinations can have a significant impact on psychological and physical health. However, there has not been adequate discussion about the methodological and statistical issues associated with using academic examinations as a model for short-term stress in the context of psychoneuroimmunology research. Limitations of the model are presented with recommendations for appropriate use. Specific suggestions include use of subjective and objective measures of test difficulty, within-subjects designs including measurements during the examination itself, statistical models for testing interactions of continuous variables, and participants with clinical conditions.

The measurement of stress-related immune dysfunction in psychoneuroimmunology

In recent years there has been a dramatic increase in research dedicated to the psycho-behavioural modulation of immune function, i.e. the field of Psychoneuroimmunology (PNI). This has led, necessarily, to the use of several in vitro and in vivo techniques in attempts to delineate the relationship between these two phenomena. However, since the field's inception, considerable uncertainty has existed over the significance of the immune outcomes detected and this has been compounded by the equivocal nature of some of the published data. A great deal of this uncertainty could, however, be overcome if a clearer understanding was achieved on the advantages and limitations conferred by the manifold immune assays described in the literature. This would, in turn, encourage their more appropriate use within PNI. Hence, in this review we describe the rationale behind, and offer an evaluation of, some of the more frequently used in vitro and in vivo immunological and virological techniques. We hope that a clear understanding of the rationale behind such assays and their inherent advantages and limitations will inform the discussion of the significance of stress-related immune impairment.

Physiological and emotional response to psychological stressors in psychiatric and psychosomatic disorders

Deviations from emotional and physiological homeostasis in humans occur under episodic, chronic, or traumatic stress experiences. These dysregulations can provoke emotional and physical disturbances that may result in stress-related psychiatric or psychosomatic disorders. This brief review discusses a variety of both naturally occurring and experimental stressors and the complexity of intervening variables on cardiovascular and hormonal dysregulations of the hypothalamic-pituitary-adrenal (HPA) axis. In addition to the type, intensity, and duration of the stressor, subject variables such as dispositional factors (e.g., age and sex), personality traits, and coping styles are considered. Finally, emotional and physiological stress responses to naturally occurring stressors and psychological challenge tests in depressed patients and anxiety disorder patients are presented and discussed. Stressors in humans induce emotional arousal, which leads to physiological activation of the central nervous system, an increase of hormones of the HPA axis, and coping reactions on the psychological and behavioral level. Depending on the type, intensity, and duration of the stressor, on personal and psychosocial resources of the individual, stressful situations may provoke emotional and physical disturbances. These dysfunctions may result in psychosomatic or psychiatric disorders. The following brief review intends to discuss a variety of stressors that have been examined in humans in order to gain insight into the complex relationship between physiological and behavioral stress reactions and the occurrence or maintenance of stress related psychosomatic and psychiatric disorders.