Time course of natural killer cell activity and lymphocyte proliferation in response to two acute stressors in healthy men

Effects of Integrated Indirect Forest Experience on Emotion, Fatigue, Stress and Immune Function in Hemodialysis Patients

BACKGROUND

Most hemodialysis patients may experience physiological and psychological stress. Exposure to nature has been reported to reduce psychological and physiological stress levels and improve immune function. This study aimed to investigate psychological and physiological effects of integrated indirect forest experience on chronic renal failure patients undergoing hemodialysis.

METHODS

As a quasi-experiment, this study employed a nonequivalent control group, repeated measurements, and a non-synchronized design. In total, 54 participants were included: 26 and 28 patients in the experimental and control groups, respectively. During hemodialysis, five types of forest therapy stimuli (visual, auditory, olfactory, tactile, and motor) were applied 3 times per week for 4 weeks during 15 min sessions.

RESULTS

Positive, but not negative, emotion measures differed between the groups after the intervention. Fatigue and physiological stress levels were significantly reduced in the experimental group, whereas no significant difference was found between the groups with respect to measures of psychological stress. Activation of both the parasympathetic and sympathetic nervous systems was similar in both groups, as was the number of natural killer cells.

CONCLUSION

Integrated indirect forest experience may help increase positive emotions and reduce fatigue and stress levels during hemodialysis in patients with chronic renal failure.

Exposure to low temperatures suppresses the production of B-cell activating factor via TLR3 in BEAS-2B cells

Acute viral respiratory tract infections (RTIs) are commonly associated with cold weather; however, the mechanism behind this is still unclear. Secretory IgA (sIgA) mainly contributes to the immune response against pathogenic microorganisms in the respiratory tract. Certain pathogen-associated molecular patterns (PAMPs) induce the expression of B-cell activating factor (BAFF) in epithelial cells, macrophages, and dendritic cells. BAFF transforms B cells into plasma cells, which leads to the mass production of immunoglobulins, including IgA, on the mucosal epithelium. However, no studies have described the relationship between cold exposure and BAFF and/or sIgA in RTI. The aim of our study was to determine this relationship in vitro by investigating the effect of low temperature on BAFF production by BEAS-2B cells after the addition of toll-like receptor (TLR) ligands. We showed stimulation of polyinosinic:polycytidylic acid (poly I:C), which led BEAS-2B to produce interferon (IFN)-β. IFN-β itself induced BEAS-2B cells to produce BAFF. Janus kinase inhibitor I decreased the amount of BAFF produced in BEAS-2B cells upon stimulation with IFN-β and poly I:C. Significantly less BAFF was produced post-poly I:C stimulation in low-temperature conditions than in normal-temperature conditions (mean ± SD: 41.2 ± 23.3 [33 °C] vs. 138.3 ± 7.1 pg/mL [37 °C], P = 0.05). However, the low-temperature condition itself was not cytotoxic. The stimulation of poly I:C produced BAFF from BEAS2B cells via IFN-β production and the JAK/signal transducer and activator of transcription pathway played an important role in BAFF production in BEAS-2B cells. Cold exposure reduced BAFF production by BEAS2B cells after stimulation with the TLR3 ligand. Cold exposure may, therefore, suppress the production of BAFF, resulting in the inhibition of IgA secretion in the bronchial epithelium, which explains the increased frequency of RTIs in cold weather.

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Relationship between cold exposure and B-cell activating factor (BAFF) was assessed.

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BAFF produced post poly I:C stimulation was lesser under low-temperature conditions.

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Cold exposure may suppress BAFF production to inhibit IgA secretion.

Behavioral Symptoms after Breast Cancer Treatment: A Biobehavioral Approach

Being diagnosed and treated for breast cancer is emotionally and physically challenging. Breast cancer is the most commonly diagnosed cancer and the second leading cause of death for women in the United States. Accordingly, women with a breast cancer history are the largest group of female cancer survivors. Psychological stress substantially augments adverse autonomic, endocrine, and immune discharge, including enhanced production of proinflammatory cytokines. Importantly, inflammation is a key biological mechanism underlying the symptom cluster of pain, depression, fatigue, and sleep disturbances; there is also good evidence that inflammation contributes to breast cancer recurrence. Stress may exert direct effects on psychological and physiological risk processes. In this review, we take a biobehavioral approach to understanding predictors and mechanisms underlying somatic symptoms in breast cancer survivors.

Salivary cortisol and soluble tumor necrosis factor-α receptor II responses to multiple experimental modalities of acute pain

The present study compared cortisol and soluble tumor necrosis factor-α receptor II (sTNFαRII) responses provoked by cold pressor, hot water, ischemic, and neutral water (i.e., room temperature) modalities. Oral fluid samples were collected before, immediately after, and during recovery to assess physiological responses. From baseline, the cold pressor, but not hot water or ischemic modalities, produced a significant time-dependent elevation in cortisol, whereas cortisol significantly decreased for the neutral water task. When compared to baseline, the cold pressor, hot water, and ischemic modalities were associated with decreased sTNFαRII responses over time. The sTNFαRII response to neutral water initially decreased but returned to approximate baseline levels. Pain ratings were positively associated with cortisol increase from baseline and the overall cortisol response was negatively associated with the overall sTNFαRII response.

Regulation of lymphocytes redistribution via autonomic nervous activity during stochastic learning

Several studies reported that redistribution of lymphocyte subsets, especially CD3-CD16+CD56+ natural killer (NK) cells, was elicited by acute psychological stress tasks. It is known that lymphocyte redistribution was regulated based on active or passive emotional coping strategies, which can be elicited dependent on controllability of a stressor. Controllability can be evaluated gradually by learning of a contingency between actions and outcomes. Therefore, lymphocyte redistribution can be determined by learning of the contingency. To examine this issue, we used a stochastic learning task as an acute stress task and divided twenty healthy participants into reinforcement or yoked groups. Between the two groups, only whether they could learn the contingency was manipulated. As a result, patterns of changes in the NK cell numbers differed between the groups; NK cells remarkably increased at first and then gradually decreased to the baseline in the reinforcement group while the yoked group showed a moderate but sustained increase of NK cells. These patterns of changes in the NK cells were completely parallel with changes of the cardiovascular parameters but not with secretion of catecholamines. The present results suggest that cardiovascular and immune reactivity can be modulated along with progresses of adaptation for an acute stressor.

Acute stress exposure prior to influenza vaccination enhances antibody response in women

Animal studies have shown that an acute stressor in close temporal proximity to immune challenge can enhance the response to delayed-type hypersensitivity and antibody response to vaccination. The current study examined the effects of acute exercise or mental stress prior to influenza vaccination on the subsequent antibody response to each of the three viral strains. Sixty young healthy adults (31 men, 29 women) were randomly allocated to one of three task conditions: dynamic exercise, mental stress, or control. After an initial baseline, participants completed their allocated 45 min task and then received the influenza vaccine. Plasma cortisol and interleukin-6 were determined at the end of baseline, after the task, and after 60 min recovery. Antibody titres were measured pre-vaccination and at 4 weeks and 20 weeks post-vaccination follow-ups. For the A/Panama strain, women in both the exercise and mental stress conditions showed higher antibody titres at both 4 and 20 weeks than those in the control condition, while men responded similarly in all conditions. Interleukin-6 at +60 min recovery was found to be a significant predictor of subsequent A/Panama antibody response in women. In line with animal research, the current study provides preliminary evidence that acute stress can enhance the antibody response to vaccination in humans.

Immune, endocrine and cardiovascular responses to controllable and uncontrollable acute stress

This study, using a triadic-yoked design, clarified the effects of controllability of acute stress on responses of immune, cardiovascular (heart rate and blood pressure), and cortisol activities. Forty-three women in their follicular phase completed a mental arithmetic task as a stressor in which controllability was manipulated by correct or yoked-bogus feedback. The task decreased proportions of CD3+ T cells, CD4+ T cells, and CD19+ B cells, whereas it increased the numbers of white blood cells, lymphocytes, natural killer (NK) cells, and NK cell activity (NKCA). Our main hypothesis that greater immune and cardiovascular responses to the task would be obtained under the uncontrollable condition than under the controllable condition was not supported. However, the uncontrollable stress condition, but not the controllable situation, led to higher correlations between heart rate or blood pressure, and various immune parameters. On the other hand, parameters of heart rate variability reflecting sympathetic and parasympathetic activities showed significant correlations only with NKCA. These results suggest that immune responses were most directly associated with cardiovascular activities under the uncontrollable condition.

Visceral pain and public speaking stress: neuroendocrine and immune cell responses in healthy subjects

Whereas responses to psychological stressors are well-characterized, little is known regarding responses to painful visceral stimuli. We analyzed the emotional, cardiovascular, neuroendocrine, and cellular immune responses to painful rectal stimulation and psychological stress in healthy individuals. Eleven healthy subjects were studied in three conditions on separate days: painful rectal distension, public speaking stress, and rest. Blood was drawn for endocrinological and immunological analyses; heart rate and blood pressure were measured continuously; state anxiety was assessed with a questionnaire (STAI-S). Anxiety scores were highest in the rectal distension condition. This was evident following rectal distension (mean STAI-S scores: 44.2+/-3.5 post-distension vs. 36.6+/-3.8 post-speech, p<.05), but anxiety was also elevated at baseline (41.6+/-3.9 vs. 32+/-3.2 recovery, p<.01). This anticipatory effect was reflected by elevated baseline cortisol (p<.05) and baseline ACTH (p<.01) levels, as well as circulating lymphocytes and lymphocyte subsets, including decreased basal CD3+CD4+ cells (p<.05) and increased CD16+CD56+ cells (p=.06) compared to rest. Both public speech and rectal distension induced cardiovascular activation, but the effect was more pronounced following rectal distension (+63.8+/-9.4 mmHg in response to distension vs. +36.4+/-6.2 mmHg in response to speech for systolic BP, p<.05). Different response patterns were also observed in the distribution of circulating leukocytes and lymphocyte subsets, including CD16+CD56+ cells (p<.05). An acute visceral pain stimulus causes profound emotional, neuroendocrine, and immune cell responses, which are markedly affected by anticipatory anxiety. These findings may have implications for conditions associated with visceral hyperalgesia.

Temporal variation of acute stress responses in sympathetic nervous and immune systems

Sympathetic nervous activity plays a prominent role in acute stress responses in the immune system, enhancement of innate immunity and suppression of specific immunity. The present study was conducted to examine the temporal characteristics of such immune responses to acute stress and to determine their association with sympathetic activity in detail. For this purpose, 15 female undergraduates engaged in a continuous mental arithmetic task for 14 min, and we collected their blood samples for immune indices (CD3+ T cells, CD4+ T cells, NK cells) each 3 min during the task and saliva samples before and after the task. Our results showed that the proportion of Natural Killer cells (NK cells) increased even 2 min after initiation of the task, whereas proportions of CD3+ and CD4+ lymphocytes decreased 8 min after initiation of the task. Moreover, we found significant correlations between cardiovascular activity and the variations of immune indices.

Religiosity and the expansion of caregiver stress

We present a stress process framework as a model for understanding how religiosity may influence the expansion of stress. Survey data from informal caregivers to a spouse with Alzheimer's disease or a related dementia (n = 200) were analyzed to observe the relationships among three variables: (1) care-related stress, (2) religiosity, and (3) depression. This sample, which has a mean age of 73 years, demonstrates high rates of self-described religiosity, church attendance and frequency of prayer. Using these criteria, women and racial/ethnic minority caregivers are the most religious. In a series of multivariate analyses, we found strong evidence to suggest that there is an expansion of care-related stressors leading to depression in this sample. Religiosity, as measured here, appears to be largely unrelated to stress and stress expansion. We found no evidence to suggest that it moderates stress expansion. However, these data do suggest that one stressor--feelings of role overload--is correlated with greater levels of self-perceived religiosity, which among caregivers who have health problems of their own is associated with greater depressive symptomatology. Thus, for a sub-sample of these caregivers, we find weak evidence of a mediation effect wherein one subjective, non-organizational dimension of religiosity is a conduit of the harmful effects of stress (rather than a suppressor). Results and data limitations are discussed in relation to better assessing the role of religiosity and spirituality in the experience of the stress process.

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.

Reactivity of immune, endocrine and cardiovascular parameters to active and passive acute stress

This study clarified associations among immune, autonomic, and endocrine activities during mental arithmetic and cold pressor stress tasks in 26 women in the follicular phase. Both tasks decreased CD3+ T cells, CD4+ T cells, and CD19+ B cells, whereas they increased lymphocytes, granulocytes, NK cells, and NK cell activity (NKCA). The mental arithmetic task had a greater impact than the cold pressor task on changes in CD3+ T cells and in NK cells. Cardiovascular reactivity to active stress was associated with increased NK cells and decreased CD3+ T cells. Reduced cortisol levels during passive stress were associated with decreased CD19+ B cells and with increased NK cells. The merits of this study are that it controlled the following factors. Perceived stress during the two tasks was matched; both tasks lasted long enough to elicit high-magnitude responses; and the length of the intervening rest period minimized probable carryover effects between tasks.

The Effects of Therapeutic Back Massage on Psychophysiologic Variables and Immune Function in Spouses of Patients With Cancer

BACKGROUND

Spouses of patients with cancer are at risk for stress-related disorders and may experience a reduction in immune function. Therapeutic back massage (TBM) has been shown to enhance relaxation and thus, may reduce stress associated with caring for an ill partner.

OBJECTIVES

To determine if TBM's influences on psychosocial, physiologic, and immune function variables in spouses of patients with cancer, and explore the relationships between psychosocial variables and immune function in spouses of patients with cancer.

METHODS

This group experimental design measured the effects of a 20-minute TBM at three time points (preintervention, immediately postintervention, 20 minutes postintervention) on spouses of patients with cancer (N= 42) randomly assigned to either the experimental or control group. The major dependent variables including natural killer cell activity (NKCA), heart rate, systolic and diastolic blood pressure, mood, and perceived stress were measured at the three time points to examine the effects of TBM. Data collected on measures of mood and perceived stress were correlated with NKCA to examine their relationships. Prior to hypotheses testing, data collected on measures of depressive mood, loneliness, marital disruption, and health practices were also correlated with NKCA to ascertain any possible confounding variables.

RESULTS

Two-way repeated measures analysis of variance tests determined the effects of TBM over the two postintervention time points and resulted in significant group x time interactions on mood (F [2, 40]= 14.61, p=.0005) and perceived stress (F [2, 40]= 28.66, p=.001). Significant inverse relationships were found between mood and NKCA (r= -.41, p=.009, N= 42) and perceived stress and NKCA (r= -.37, p=.017, N= 42).

DISCUSSION

Findings suggest that TBM may enhance mood and reduce perceived stress in this population. Insight was gained into the psycho-immunologic relationships studied.

HIV-positive men differ in immunologic but not catecholamine response to an acute psychological stressor

Acute psychological stress in humans induces sudden alterations in catecholamine plasma levels and in the distribution of peripheral blood lymphocytes. The purpose of this study was to investigate whether infection with the human immunodeficiency virus (HIV) had an impact on the psychoneuroimmunologic axis. Twelve asymptomatic HIV-positive homo- or bisexual men (CD4 cell counts>400/mm3) and 13 healthy HIV-negative control subjects were exposed to an acute psychological stressor consisting of a 30 min semi-structured stress interview using emotion- and client-centered conversation techniques surrounded by two relaxation periods. Changes in neuroendocrine and immunological, as well as cardiovascular parameters, were intermittently monitored. Under the influence of the stressor plasma norepinephrine (NE) levels increased significantly in HIV-positive patients (+30.6%; p<0.05) and in HIV-negative individuals (+17.5%; n.s.). These changes were paralleled by significant increases in blood pressure and heart rate. Plasma cortisol decreased continuously from initially high levels during the entire experimental setting in both groups, compatible with an adaption reaction. Concomitantly, WBC and neutrophilic granulocytes increased significantly in HIV-negative subjects, while they were blunted in HIV-positive patients. Interestingly, NK cell increases were significantly higher during the stress experiment in HIV-positive patients than in HIV-negative controls. CD4+ and B cell counts remained unaffected by the stressor. These results suggest that catecholamine secretion induced by an acute psychological stressor is preserved in HIV-infected patients with the responsiveness of WBC and neutrophilic granulocytes being diminished, while NK cells showed an increased response.

Impact of stress of marital dissolution on skin barrier recovery: tape stripping and measurement of trans-epidermal water loss (TEWL)

BACKGROUND

Psychological stress of marital disruption is associated with significant increases in a variety of psychological and physical disorders. The effect of stress on the immune system is well documented and skin disorders have been reported to exacerbate during stressful situations. This study was designed to observe the effects of stress on skin barrier strength and recovery. Twenty-eight healthy females age 21-45 who were in the process of marital separation were tested for skin barrier strength and recovery. The panel was chosen on the basis of the intensity of self perceived stress. The control group was an age-matched group of self perceived 'happy' subjects. Servomed evaporimeter was used to measure trans-epidermal water loss (TEWL) from cheek area of the face, before and after removing stratum corneum layers with tape strippings. Skin barrier strength was defined as the number of tape strippings required to disrupt skin barrier, which is a TEWL of 18 g/m2/h or more. Barrier recovery was denoted by the level of TEWL, 3 h and 24 h after barrier disruption.

RESULTS

There was no correlation between the degree of stress and barrier strength. However, individuals with high stress recovered slower than the individuals with low stress after 3 h (R = 0.64) and 24 h (R = 0.74).

CONCLUSIONS

Psychological stress of marital dissolution does not appear to change skin barrier strength but has a negative impact on skin barrier recovery.

Cold exposure: human immune responses and intracellular cytokine expression

It is commonly believed that exposure to cold environmental temperatures depresses immune function and increases the risk for infection. This review paper will 1) present an overview of human physiological responses to cold exposure, 2) present the human studies examining the effects of cold exposure on immune responses, and 3) summarize recent experiments from our laboratories examining the effects of exercise and fatigue on immune responses during subsequent cold exposure. Based on the review of the literature, there is no support for the concept that cold exposure depresses immune function.

Heart rate, neuroendocrine, and immunological reactivity in response to an acute laboratory stressor

OBJECTIVE

The primary objective of the present study was to identify neuroendocrine and immunological correlates of cardiovascular reactivity to an acute laboratory stressor.

METHODS

Subjects were 56 healthy volunteers. Heart rate and blood pressure were assessed at regular intervals during a 30-minute adaptation period and a 6-minute videotaped speech task. Blood was drawn before and after the task and was assayed for natural killer cell activity (NKCA), cortisol production, in vitro interferon gamma (IFN-gamma) and interleukin 10 production by peripheral blood mononuclear cells (PBMC), and antibody titers to the Epstein-Barr virus. Psychological measures were also administered.

RESULTS

NKCA increased significantly in response to the task, and this increase was significantly and positively correlated with heart rate reactivity. IFN-gamma production by PBMC also increased in response to the task, but these increases were unrelated to heart rate reactivity. In addition, baseline cortisol levels were found to be predictive of heart rate reactivity. Finally, questionnaire data were modestly related to various aspects of stress-induced reactivity.

CONCLUSIONS

Consistent with the task-related increases in NKCA and IFN-gamma, acute stress may signal an increase in at least some aspects of the cell-mediated, or TH1-driven, immune response. Furthermore, the finding that heart rate reactivity was related in part to baseline individual differences in cortisol production suggests that short-term cardiovascular responses to stress may be directly related to longer-term neuroendocrine modulation. Finally, the present results also help to highlight the influence of both sympathetic and nonsympathetic pathways in the response to acute stressors and suggest tentative links between certain psychological traits and various aspects of stress-induced reactivity.

The relationship of daily mood and stressful events to symptoms in juvenile rheumatic disease

OBJECTIVES

The purpose of this study was 3-fold: 1) to assess the feasibility of a daily diary for use with children with juvenile rheumatic disease (JRD), 2) to describe daily variation in mood, stressful events, and symptoms in children with JRD, and 3) to examine the extent to which daily mood and daily stressful events predict daily symptoms in children with JRD.

METHODS

Twelve children with JRD completed a daily booklet for 7 days. The daily booklet included measures of daily mood, daily stressful events, daily symptoms, and daily function. The children also completed a visual analog scale for pain and the Children's Depression Inventory.

RESULTS

Subjects showed good compliance with scheduled completion and return of the daily diaries. Results indicated that children with JRD showed variability in daily mood, frequency of daily stressful events, and daily symptoms across days. Multilevel fixed effects models showed that more negative daily mood and more daily stressful events significantly predicted increased reports of fatigue, stiffness, and cutting back on daily activities. Negative daily mood also correlated with increases in daily reported pain.

CONCLUSIONS

These results indicate that daily diary research is both feasible and potentially informative in children with JRD. Our data emphasize the need for further investigation into the role of daily mood and daily stressful events on disease course in JRD.

Acute stress impairs NK cell adhesion and cytotoxicity through CD2, but not LFA-1

Using a nonhuman primate model, we examined the mechanisms by which acute social stress inhibits the ability of NK cells to form conjugates with, and lyse target cells. We examined the expression and role of the primary NK cell adhesion molecules, CD2 and LFA-1, in mediating conjugation to target cells. Acute stress induced a decrease in NK cell expression of CD2 (17+/-3%); and to a lesser degree induced a decrease in expression of LFA-1 (CD11a: 8+/-3%; CD18: 7+/-3%). Antibody blocking studies indicated that anti-LFA-1 significantly inhibited NK cell conjugate formation and cytotoxicity in both control (approximately 40% and approximately 50%, respectively) and stressed (approximately 20% and approximately 45%, respectively) conditions. However, anti-CD2 blocked conjugation and cytotoxicity in the control condition by approximately 50%, but had no capacity to further affect the inhibition of conjugation or cytotoxicity of NK cells induced by acute stress. These data indicate that there are differential effects of acute stress on the expression and function of LFA-1 and CD2, and that the stress-induced inhibition of NK cell adhesion and cytotoxicity is dependent upon modulation of adhesion and/or signalling through CD2.

Immune changes in humans during cold exposure: effects of prior heating and exercise

This study examined the immunological responses to cold exposure together with the effects of pretreatment with either passive heating or exercise (with and without a thermal clamp). On four separate occasions, seven healthy men [mean age 24.0 +/- 1.9 (SE) yr, peak oxygen consumption = 45.7 +/- 2.0 ml. kg(-1). min(-1)] sat for 2 h in a climatic chamber maintained at 5 degrees C. Before exposure, subjects participated in one of four pretreatment conditions. For the thermoneutral control condition, subjects remained seated for 1 h in a water bath at 35 degrees C. In another pretreatment, subjects were passively heated in a warm (38 degrees C) water bath for 1 h. In two other pretreatments, subjects exercised for 1 h at 55% peak oxygen consumption (once immersed in 18 degrees C water and once in 35 degrees C water). Core temperature rose by 1 degrees C during passive heating and during exercise in 35 degrees C water and remained stable during exercise in 18 degrees C water (thermal clamping). Subsequent cold exposure induced a leukocytosis and granulocytosis, an increase in natural killer cell count and activity, and a rise in circulating levels of interleukin-6. Pretreatment with exercise in 18 degrees C water augmented the leukocyte, granulocyte, and monocyte response. These results indicate that acute cold exposure has immunostimulating effects and that, with thermal clamping, pretreatment with physical exercise can enhance this response. Increases in levels of circulating norepinephrine may account for the changes observed during cold exposure and their modification by changes in initial status.

Health psychology: mapping biobehavioral contributions to health and illness

Our evolving understanding of how psychosocial and behavioral factors affect health and disease processes has been marked by investigation of specific relationships and mechanisms underlying them. Stress and other emotional responses are components of complex interactions of genetic, physiological, behavioral, and environmental factors that affect the body's ability to remain or become healthy or to resist or overcome disease. Regulated by nervous, endocrine, and immune systems, and exerting powerful influence on other bodily systems and key health-relevant behaviors, stress and emotion appear to have important implications for the initiation or progression of cancer, HIV, cardiovascular disease, and other illnesses. Health-enhancing and health-impairing behaviors, including diet, exercise, tobacco use, and protection from the sun, can compromise or benefit health and are directed by a number of influences as well. Finally, health behaviors related to being ill or trying to avoid disease or its severest consequences are important. Seeking care and adhering to medical regimens and recommendations for disease surveillance allow for earlier identification of health threats and more effective treatment. Evidence that biobehavioral factors are linked to health in integrated, complex ways continues to mount, and knowledge of these influences has implications for medical outcomes and health care practice.

Selective reduction in CD2 expression on CD2bright/CD8+ lymphocytes from cynomolgus monkeys (Macaca fascicularis) in response to acute stress

Numerous reports have demonstrated a link between stressful stimuli and immune suppression. However, the cellular mechanisms by which stress impairs immune function are largely unknown. We have examined the effects of an acute stressor on the T cell population, specifically, the number and phenotype of T cells in a nonhuman primate model. In nonstressed adult monkeys, we found differences in the level of expression of CD2 on T cells, revealing two distinct subsets of T cells, CD2dim and CD2bright cells, with CD2bright cells predominately coexpressing CD8. In response to acute stress, we observed a significant loss in the number and percent of CD2bright/CD8+ cells, with percent of CD2bright cells returning to pre-stress values within 24 h.

Experimental induction and termination of acute psychological stress in human volunteers: effects on immunological, neuroendocrine, cardiovascular, and psychological parameters

The present research investigated the effects of controlled experimental manipulations of stress on biological and psychological reactions. Fifty young adult male volunteers were exposed to a 12-min period of stress induced by the threat of an unavoidable, painful electric shock. A 12-min period without this threat preceded or followed the stress period. Blood was drawn during the 4th and the 12th minute of each period. Anticipatory threat led to significant elevations in the proportions and cytotoxic activity of natural killer (NK) lymphocytes, plasma epinephrine levels, pulse rate, and reported level of tension, and to a reduction in the CD4/CD8 ratios. The no-threat period induced a return to baseline values for epinephrine, pulse rate, and tension, and lower than baseline levels for cytotoxic activity of NK lymphocytes, within a similarly short time span. The findings underline the rapidity with which physiological changes may transpire in the course of a brief and acute period of psychological stress, and the rapidity of their reversal upon relief from the stressor.

Chronic stress and natural killer cell activity after exposure to traumatic death

OBJECTIVE

The present study examined the effects of working at the crash site of USAir Flight 427 on psychological, cardiovascular, and immunological sequelae of stress within 2 months of the recovery work and again 6 months after the crash.

METHOD

A total of 159 workers at the crash site and 41 controls were examined within 2 months of the crash and again 6 months after the crash. Subjects were initially grouped according to whether they had contact with human remains. For a finer-grained analysis of exposure to bodies, subjects were also grouped by degree of exposure, determined by the area in which the workers were stationed. Dependent measures included intrusive thoughts, coping styles, and symptom reporting, as well as heart rate and blood pressure, and NK cell number and activity.

RESULTS

Workers exposed to body parts at the actual crash site, and those who were exposed to remains without expecting to be, exhibited more symptoms of stress than workers who saw bodies and body parts at the morgue and those who did not see human remains. Non-morgue workers who were exposed to bodies or body parts had the highest levels of intrusive thoughts at both time points, and the highest NK cell activity at Time 1. NK activity in this group decreased to levels comparable with other groups at Time 2.

CONCLUSIONS

Increased NK activity is unusual in chronic stress situations, and may be because of acute stress experienced as a result of being asked to talk and think about the crash. The finding that the more one was exposed to human remains the less distress he or she reported is discussed in terms of adaptation, expectancy, and control.