Elevated HbA(1c) levels and the accumulation of differentiated T cells in CMV(+) individuals

AIMS/HYPOTHESIS

Biological ageing of the immune system, or immunosenescence, predicts poor health and increased mortality. A hallmark of immunosenescence is the accumulation of differentiated cytotoxic T cells (CD27(-)CD45RA(+/-); or dCTLs), partially driven by infection with the cytomegalovirus (CMV). Immune impairments reminiscent of immunosenescence are also observed in hyperglycaemia, and in vitro studies have illustrated mechanisms by which elevated glucose can lead to increased dCTLs. This study explored associations between glucose dysregulation and markers of immunosenescence in CMV(+) and CMV(-) individuals.

METHODS

A cross-sectional sample of participants from an occupational cohort study (n = 1,103, mean age 40 years, 88% male) were assessed for HbA(1c) and fasting glucose levels, diabetes, cardiovascular risk factors (e.g. lipids), numbers of circulating effector memory (EM; CD27(-)CD45RA(-)) and CD45RA re-expressing effector memory (EMRA; CD27(-)CD45RA(+)) T cells, and CMV infection status. Self-report and physical examination assessed anthropometric, sociodemographic and lifestyle factors.

RESULTS

Among CMV(+) individuals (n = 400), elevated HbA(1c) was associated with increased numbers of EM (B = 2.75, p < 0.01) and EMRA (B = 2.90, p < 0.01) T cells, which was robust to adjustment for age, sex, sociodemographic variables and lifestyle factors. Elevated EM T cells were also positively associated with total cholesterol (B = 0.04, p < 0.05) after applying similar adjustments. No associations were observed in CMV(-) individuals.

CONCLUSIONS/INTERPRETATION

The present study identified consistent associations of unfavourable glucose and lipid profiles with accumulation of dCTLs in CMV(+) individuals. These results provide evidence that the impact of metabolic risk factors on immunity and health can be co-determined by infectious factors, and provide a novel pathway linking metabolic risk factors with accelerated immunosenescence.

Progenitor cells are mobilized by acute psychological stress but not beta-adrenergic receptor agonist infusion

OBJECTIVES

Stimuli that activate the sympathetic nervous system, such as acute psychological stress, rapidly invoke a robust mobilization of lymphocytes into the circulation. Experimental animal studies suggest that bone marrow-derived progenitor cells (PCs) also mobilize in response to sympathetic stimulation. Here we tested the effects of acute psychological stress and brief pharmacological β-adrenergic (βAR) stimulation on peripheral PC numbers in humans.

METHODS

In two studies, we investigated PC mobilization in response to an acute speech task (n=26) and βAR-agonist (isoproterenol) infusion (n=20). A subset of 8 participants also underwent the infusion protocol with concomitant administration of the βAR-antagonist propranolol. Flow cytometry was used to enumerate lymphocyte subsets, total progenitor cells, total haematopoietic stem cells (HSC), early HSC (multi-lineage potential), late HSC (lineage committed), and endothelial PCs (EPCs).

RESULTS

Both psychological stress and βAR-agonist infusion caused the expected mobilization of total monocytes and lymphocytes and CD8(+) T lymphocytes. Psychological stress also induced a modest, but significant, increase in total PCs, HSCs, and EPC numbers in peripheral blood. However, infusion of a βAR-agonist did not result in a significant change in circulating PCs.

CONCLUSION

PCs are rapidly mobilized by psychological stress via mechanisms independent of βAR-stimulation, although the findings do not exclude βAR-stimulation as a possible cofactor. Considering the clinical and physiological relevance, further research into the mechanisms involved in stress-induced PC mobilization seems warranted.

Developing the Model for Optimal Learning and Transfer (MOLT) following an evaluation of outdoor groupwork skills programmes

Purpose

– This paper aims to evaluate the perceived efficacy of outdoor groupwork skills programmes for the undergraduate and postgraduate students, and the factors that influence its success. It also illustrates the use of Kirkpatrick’s (1994) 4-level model of training evaluation as a framework for qualitative investigation of learning and transfer, from the perspective of key stakeholders.

Design/methodology/approach

– Over 24 hours of recorded data were collected using a video diary room, one-to-one interviews and focus group discussions. Participants were current students (n = 66), alumni (n = 12), outdoor education instructors (n = 6) and academic staff (n = 5). The data were transcribed, and then analysed by conducting conventional content analysis. Prolonged engagement, triangulation, peer debriefing and referential adequacy were used to establish the trustworthiness and reliability of the analyses.

Findings

– Outdoor groupwork skills programmes were widely viewed as being effective for developing interpersonal skills, attitudes and knowledge that were then further developed and applied during degree courses and later in the workplace. Four of the main perceived benefits were increased social integration amongst peers, academic success, personal development and employability. A range of psychological and environmental factors were reported to influence the extent of skill development and transfer, and are presented in the Model for Optimal Learning and Transfer.

Practical implications

– This study supports outdoor groupwork skills programmes as an effective method of groupwork skills training during higher education, and offers recommendations for promoting learning and transfer following training courses.

Originality/value

– This is the first study to systematically evaluate the long-term impact of outdoor groupwork skills programmes in higher education. A novel methodological approach is also demonstrated, which can be replicated in other contexts of training evaluation.

Consistent associations between measures of psychological stress and CMV antibody levels in a large occupational sample

Cytomegalovirus (CMV) is a herpes virus that has been implicated in biological aging and impaired health. Evidence, largely accrued from small-scale studies involving select populations, suggests that stress may promote non-clinical reactivation of this virus. However, absent is evidence from larger studies, which allow better statistical adjustment for confounding and mediating factors, in more representative samples. The present study involved a large occupational cohort (N=887, mean age=44, 88% male). Questionnaires assessed psychological (i.e., depression, anxiety, vital exhaustion, SF-12 mental health), demographic, socioeconomic (SES), and lifestyle variables. Plasma samples were analyzed for both the presence and level of CMV-specific IgG antibodies (CMV-IgG), used as markers for infection status and viral reactivation, respectively. Also assessed were potential biological mediators of stress-induced reactivation, such as inflammation (C-reactive protein) and HPA function (awakening and diurnal cortisol). Predictors of CMV infection and CMV-IgG among the infected individuals were analyzed using logistic and linear regression analyses, respectively. Confirming prior reports, lower SES (education and job status) was positively associated with infection status. Among those infected (N=329), higher CMV-IgG were associated with increased anxiety (β=.14, p<.05), depression (β=.11, p=.06), vital exhaustion (β=.14, p<.05), and decreased SF-12 mental health (β=-.14, p<.05), adjusting for a range of potential confounders. Exploratory analyses showed that these associations were generally stronger in low SES individuals. We found no evidence that elevated inflammation or HPA-function mediated any of the associations. In the largest study to date, we established associations between CMV-IgG levels and multiple indicators of psychological stress. These results demonstrate the robustness of prior findings, and extend these to a general working population. We propose that stress-induced CMV replication warrants further research as a psychobiological mechanism linking stress, aging and health.

Rudimentary signs of immunosenescence in Cytomegalovirus-seropositive healthy young adults

Ageing is associated with a decline in immune competence termed immunosenescence. In the elderly, this process results in an accumulation of differentiated 'effector' phenotype memory T cells, predominantly driven by Cytomegalovirus (CMV) infection. Here, we asked whether CMV also drives immunity towards a senescent profile in healthy young adults. One hundred and fifty-eight individuals (mean ± SD; age 21 ± 3 years, body mass index 22.7 ± 2.7 kg m(2)) were assessed for CMV serostatus, the numbers/proportions of CD4(+) and CD8(+) late differentiated/effector memory cells (i.e. CD27(-)CD28(-)/CD45RA(+)), plasma interleukin-6 (IL-6) and antibody responses to an in vivo antigen challenge (half-dose influenza vaccine). Thirty percent (48/158) of participants were CMV(+). A higher lymphocyte and CD8(+) count (both p < 0.01) and a lower CD4/CD8 ratio (p < 0.03) were observed in CMV(+) people. Eight percent (4/58) of CMV(+) individuals exhibited a CD4/CD8 ratio <1.0, whereas no CMV(-) donor showed an inverted ratio (p < 0.001). The numbers of CD4(+) and CD8(+)CD27(-)CD28(-)/CD45RA(+) cells were ~ fourfold higher in CMV(+) people (p < 0.001). Plasma IL-6 was higher in CMV(+) donors (p < 0.05) and showed a positive association with the numbers of CD8(+)CD28(-) cells (p < 0.03). Finally, there was a significant negative correlation between vaccine-induced antibody responses to the A/Brisbane influenza strain and CMV-specific immunoglobulin G titres (p < 0.05). This reduced vaccination response was associated with greater numbers of total CD8(+) and CD4(+) and CD8(+)CD27(-)CD28(-)/CD45RA(+) cells (p < 0.05). This study observed marked changes in the immune profile of young adults infected with CMV, suggesting that this virus may underlie rudimentary aspects of immunosenescence even in a chronologically young population.

Vaccination response following aerobic exercise: can a brisk walk enhance antibody response to pneumococcal and influenza vaccinations?

High intensity acute exercise at the time of vaccination has been shown to enhance the subsequent antibody response. This study examines whether an acute moderate intensity aerobic intervention prior to vaccination can enhance antibody response to pneumonia and half dose influenza vaccination. Sixty young (age (SD)=22.0 (6.1) years) and 60 older (age (SD)=57.5 (6.5) years) adults attended the laboratory on two separate occasions. At the first session, baseline antibody titres were determined, before participants completed either a brisk walk around campus at >55% of their age-predicted heart rate maximum, or a resting control condition, for 45 min. After the intervention, all participants received a full-dose pneumococcal vaccination and a half-dose influenza vaccination. Four weeks later, participants returned for a follow up blood sample. Multivariate ANOVA revealed an increase in total antibody titres against the influenza vaccine (F((12,106))=25.76, p<.001, η(2)=.75) and both the IgM (F((12,106))=17.10, p<.001, η(2)=.66) and IgG (F((12,106))=25.76, p<.001, η(2)=.75) antibody titres against the pneumococcal vaccine. However, there were no significant Time×Group interactions (p's all >.15), indicating that a 45 min brisk walk prior to vaccination did not affect antibody response to either the influenza or pneumonia vaccine. The results suggest that higher intensity exercise is necessary to augment antibody response to vaccination.

Using vaccinations to assess in vivo immune function in psychoneuroimmunology

Finding clinically relevant measures of immune function is an important challenge in psychoneuroimmunological research. Here, we discuss the advantages of the vaccination model, and provide guidance on the methodological decisions that are important to consider in the use of this technique. These include the choice of vaccination, timing of assessments, and the available outcome measures.

Basic psychological need satisfaction, stress-related appraisals, and dancers' cortisol and anxiety responses

Self-determination theory (Deci & Ryan, 2000) posits basic psychological need satisfaction (BPNS) as essential for optimal functioning and health. Grounded in this framework, the current study examined the role of BPNS in dancers' cognitive appraisals and hormonal and emotional responses to performance stress. Dancers reported their degree of BPNS 1 month before a solo performance. Threat and challenge appraisals of the solo were recorded 2 hr before the performance. Salivary cortisol and anxiety were measured 15 min before, and 15, 30, 45, and 60 min postperformance. Higher BPNS was associated with lower cortisol responses and anxiety intensity. Challenge appraisals mediated the association between BPNS and cortisol. Threat appraisals mediated the BPNS-anxiety intensity relationship. These findings point to the potential importance of performers' BPNS for optimal emotional and hormonal homeostasis in performance conditions.

Phenotypic characterization of gammadelta T cells mobilized in response to acute psychological stress

Gamma-delta (gammadelta) T lymphocytes are versatile cells that play key roles in bacterial clearance, wound repair, and delayed-type hypersensitivity reactions. Recently we showed that these cells are mobilized into the blood during acute psychological stress. gammadelta T lymphocytes are a heterogeneous population of cells, and the current study aimed to characterize the effects of stress on distinct gammadelta T cell populations. Twenty-nine healthy participants completed a 12min speech task. Blood samples were taken after a resting baseline, during the last two minutes of the task, and after a 15min recovery period. Flow cytometry was used to investigate the response of memory phenotypes (i.e. Naïve, Central memory, Effector Memory, and CD45RA(+) Effector Memory (EMRA)) within the delta1 and delta2 gammadelta T cell populations. Cells were further analysed on expression of adhesion molecules (CD11a, CD62L) and the NK-receptor CD94. Both the delta1 and delta2 subsets were mobilized during stress, and for both subsets, EMRA cells were mobilized to a much greater extent than the other memory phenotypes. Analysis of migration markers revealed that mobilized cells had a predominantly tissue migrating phenotype (CD11a(hi)CD62L(lo/neg)) and expressed high levels of the NK-receptor CD94. The current findings indicate that stress primarily mobilizes gammadelta memory cells that have high cytotoxic capability, tissue homing potential, and the capacity for rapid, innate-like target recognition. This selective mobilization possibly provides protection in contexts when tissue damage and antigen exposure are more likely to occur.

The effects of vaccine timing on the efficacy of an acute eccentric exercise intervention on the immune response to an influenza vaccine in young adults

An acute bout of exercise prior to vaccination can improve the antibody and cell-mediated responses to influenza vaccination. The mechanisms underpinning this adjuvant effect remain unclear, and further investigation to determine the optimal exercise protocol is warranted. The aim of the current study was to determine whether exercise augmented the immune response to vaccination, and whether the timing of exercise relative to vaccination affected the efficacy of the intervention. One hundred and fifty-six (76 men) healthy participants were randomly assigned to a control group or one of three intervention groups who exercised immediately, 6h or 48 h prior to administration of a standard trivalent influenza vaccine. The exercise groups performed 50 repetitions of the eccentric portion of both the bicep curl and lateral raise movements at an intensity eliciting 85% of each participant's pre-determined concentric one repetition maxima. Antigen-specific serum antibody titres were measured at baseline and 28 days post-vaccination as indicators of the humoral response. All three viral strains elicited strong antibody responses; however, eccentric exercise did not further augment any antibody responses compared to the control group. Cell-mediated immunity at 28 days post-vaccination was determined by measuring the IFN-gamma response to in vitro stimulation of the blood with whole vaccine. There were no differences in cell-mediated immunity among the groups. Although these null findings were unexpected, they are consistent with previous research showing that exercise-induced immunoenhancement was only observed when the control group had relatively poor responses. In conclusion, it is likely that the robust immune responses to the vaccine observed in this study may have limited any further immune enhancement by exercise.

Antibody response to vaccination as a marker of in vivo immune function in psychophysiological research

The hunt for novel tools to investigate empirical questions is ever present in psychophysiological research. Antibody response to vaccination has received increasing attention over recent years as a useful measure of in vivo immune function. There is now considerable evidence that the magnitude of the antibody response to vaccination is associated with a wide range of psychosocial factors. Further, there are preliminary indications that manipulating psychosocial variables, using both chronic and acute interventions, can also alter the efficacy of the vaccination. This review will discuss the theoretical and clinical relevance of the vaccine model in this context, and will address key methodological considerations for researchers considering adopting this approach. The review will also address how the strategic use of this model could help researchers further elucidate some of the remaining theoretical issues.

Mobilization of gammadelta T lymphocytes in response to psychological stress, exercise, and beta-agonist infusion

The mobilization of cytotoxic lymphocytes, such Natural Killer (NK) cells and CD8(+) T cells, during stress and exercise is well documented in humans. However, humans have another cytotoxic lymphocyte subset that has not been studied in this context: the Gamma Delta (gammadelta) T lymphocyte. These cells play key roles in immune processes including the elimination of bacterial infection, wound repair and delayed-type hypersensitivity reactions. The current study investigated the effects of stress, exercise, and beta-agonist infusion on the mobilization of gammadelta T lymphocytes. Three separate studies compared lymphocytosis in response to an acute speech stress task (n=29), high (85%W(max)) and low (35%W(max)) intensity concentric exercise (n=11), and isoproterenol infusion at 20 and 40 ng/kg/min (n=12). Flow cytometric analysis was used to examine lymphocyte subsets. gammadelta T lymphocytes were mobilized in response to all three tasks in a dose-dependent manner; the extent of mobilization during the speech task correlated with concomitant cardiac activation, and was greater during higher intensity exercise and increased dose of beta-agonist infusion. The mobilization of gammadelta T lymphocytes was greater (in terms of % change from baseline) than that of CD8(+) T lymphocytes and less than NK cells. This study is the first to demonstrate that gammadelta T cells are stress-responsive lymphocytes which are mobilized during psychological stress, exercise, and beta-agonist infusion. The mobilization of these versatile cytotoxic cells may provide protection in the context of situations in which antigen exposure is more likely to occur.

Acute exercise mobilises CD8+ T lymphocytes exhibiting an effector-memory phenotype

An acute bout of exercise evokes mobilisation of lymphocytes into the bloodstream, which can be largely attributed to increases in CD8+ T lymphocytes (CD8TLs) and natural killer (NK) cells. Evidence further suggests that, even within these lymphocyte subsets, there is preferential mobilisation of cells that share certain functional and phenotypic characteristics, such as high cytotoxicity, low proliferative ability, and high tissue-migrating potential. These features are characteristic of effector-memory CD8TL subsets. The current study therefore investigated the effect of exercise on these newly-identified subsets. Thirteen healthy and physically active males (mean+/-SD: age 20.9+/-1.5 yr) attended three sessions: a control session (no exercise); cycling at 35% Watt(max) (low intensity exercise); and 85% Watt(max) (high intensity exercise). Each bout lasted 20 min. Blood samples were obtained before exercise, during the final min of exercise, and +15, and +60 min post-exercise. CD8TLs were classified into naïve, central memory (CM), effector-memory (EM), and CD45RA+ effector-memory (RAEM) using combinations of the cell surface markers CCR7, CD27, CD62L, CD57, and CD45RA. In parallel, the phenotypically distinct CD56(bright) 'regulatory' and CD56(dim) 'cytotoxic' NK subsets were quantified. The results show a strong differential mobilisation of CD8TL subsets (RAEM>EM>CM>naïve); during high intensity exercise the greatest increase was observed for RAEM CD8Tls (+450%) and the smallest for naïve cells (+84%). Similarly, CD56(dim) NK cells (+995%) were mobilised to a greater extent than CD56(bright) (+153%) NK cells. In conclusion, memory CD8TL that exhibit a high effector and tissue-migrating potential are preferentially mobilised during exercise. This finding unifies a range of independent observations regarding exercise-induced phenotypic and functional changes in circulating lymphocytes. The selective mobilisation of cytotoxic tissue-migrating subsets, both within the NK and CD8TL population, may enhance immune-surveillance during exercise.

Cardiovascular activity and the antibody response to vaccination

OBJECTIVE

To examine the relationship between cardiovascular activity in response to acute psychological stress and the antibody response to vaccination.

METHODS

Fifty-seven healthy participants were vaccinated with the trivalent influenza vaccine and meningococcal A+C polysaccharides. Antibody levels were measured at baseline and 5-weeks post-vaccination. Cardiovascular activity was measured at rest, during, and following a mental arithmetic stress task in 54 participants.

RESULTS

Participants demonstrating a fourfold increase in antibody titre to the A/Panama and B/Shangdong influenza strains and to meningococcal A showed greater blood pressure reactions toward the end of the acute stress task. In addition, there was some evidence of delayed diastolic blood pressure recovery in those who were responders to A/Panama and B/Shangdong influenza strains.

CONCLUSION

The present results suggest that heightened cardiovascular reactivity to stress and delayed recovery may not necessarily be detrimental to all aspects of health and may be associated with an enhanced immune response to antigen challenge.

The Acute Stress-Induced Immunoenhancement Hypothesis

Acute stress, such as a bout of exercise, is accepted to cause an array of immunologic changes. Recently, it has been proposed that acute stress activation of the innate immune system might be harnessed as an adjuvant to enhance immune responses to antigen challenge. This review develops the acute stress-induced immunoenhancement hypothesis and its possible role as a vaccine adjuvant.

Stress and exercise: Getting the balance right for aging immunity

Age-related immunological and endocrinological changes may have implications for resilience to stress in older adults. We hypothesize that the combination of adrenopause and immunosenescence may leave this population particularly vulnerable to the negative effects of stress on immunity. We propose that exercise may be an effective intervention to limit the impact of stress on immunity in chronically stressed older populations.

Eccentric exercise as an adjuvant to influenza vaccination in humans

The immune response to vaccination in animals can be enhanced by exposure to acute stress at the time of vaccination. The efficacy of this adjuvant strategy for vaccination in humans requires investigation. The current study employed a randomised controlled trial design to examine the effects of eccentric exercise prior to influenza vaccination on the antibody and cell-mediated responses. Sixty young healthy adults (29 men, 31 women) performed eccentric contractions of the deltoid and biceps brachii muscles of the non-dominant arm (exercise group) or rested quietly (control group), and were vaccinated 6h later in the non-dominant arm. Change in arm circumference and pain were measured to assess the physiological response to exercise. Antibody titres were measured pre-vaccination and at 6- and 20-week follow-ups. Interferon-gamma in response to in vitro stimulation by the whole vaccine, an index of the cell-mediated response, was measured 8 weeks post-vaccination. Interferon-gamma responses were enhanced by exercise in men, whereas antibody titres were enhanced by eccentric exercise in women but not in men. Men showed greater increase in arm circumference after eccentric exercise than women but there was no difference in reported pain. The interferon-gamma response was positively associated with the percentage increase in arm circumference among the exercise group. Eccentric exercise exerted differential effects on the response to vaccination in men and women, with enhancement of the antibody response in women, but enhancement of the cell-mediated response in men. Eccentric exercise of the muscle at the site of vaccine administration should be explored further as a possible behavioural adjuvant to vaccination.

Individual differences in the interleukin-6 response to maximal and submaximal exercise tasks

The inflammatory responsive cytokine interleukin-6 (IL-6) helps regulate immune responses to exercise. Evidence suggests that increases in IL-6 are related to exercise duration and intensity. However, the moderating effect of sex and underlying mediators have received limited attention. We compared plasma IL-6 responses to two cycling tasks with a resting control in young male (n = 12) and female (n = 12) recreationally active adults. Both 45 min tasks comprised an incremental test, either maximal or submaximal, followed by steady-state exercise at 55% peak power output. Interleukin-6 was elevated above baseline immediately after the maximal but not the submaximal task. Compared with the control condition, IL-6 was increased at 30 and 60 min after both exercise tasks. The IL-6 response was greater in women than men at 60 min after maximal exercise. Cortisol increased in both tasks compared with the control condition, the increase being greater after maximal than submaximal exercise. No associations were found between IL-6 responses and cortisol, heart rate, fitness or body mass index. The results show that 45 min of moderate-intensity exercise can increase IL-6 and suggest that the inclusion of maximal effort may accelerate this response. The finding that women showed a greater IL-6 response to maximal exercise may reflect a gender dimorphism in the immune response to stress.

Bereavement and marriage are associated with antibody response to influenza vaccination in the elderly

Stressful life events exposure including bereavement, an event commonly experienced by elderly people, social support, marital status, and satisfaction were examined in relation to antibody response to the annual trivalent influenza vaccination in an elderly community sample (N=184). Antibody response was assessed at baseline, and at 1 and 12 months following vaccination. Taking into account baseline antibody titer, overall life events exposure and social support were not associated with response to any of the influenza strains. However, bereavement in the year prior to vaccination was negatively associated with the 1-month response to the A/Panama and B/Shangdong strains. Being married and having higher marital satisfaction was also associated with higher peak responses to the A/Panama influenza strain at 1 month. The positive association between marital satisfaction and A/Panama response was particularly evident in the younger half of the married sample. These associations largely withstood adjustment for potential confounders. Thus, in the elderly, peak antibody response was associated with bereavement and marriage, and not the more general factors, life events and social support, related to antibody response in student samples. This suggests the importance of taking a life course approach to examining relationships between psychosocial factors and immunity, and that interventions to modify the impact of these factors should address those most salient for each age group.

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.

Sex differences in the interleukin-6 response to acute psychological stress

Interleukin-6 (IL-6), an immune regulator that helps coordinate the inflammatory response, may mediate inflammatory disease exacerbation associated with stress. Twenty men and twenty women completed a single session, comprising baseline (20 min), mental arithmetic task (8 min), and recovery (60 min). Blood samples, taken at baseline, immediately after the task, and at +30 and +60 min recovery were analysed for plasma IL-6. Overall, IL-6 increased linearly from baseline to +60 min recovery, and a sex difference was found in the IL-6 response, with men peaking earlier than women. These findings confirm a small delayed IL-6 increase after acute laboratory stress, and reveal sex differences in the profile of the IL-6 response.

Factors influencing influenza vaccination uptake in an elderly, community-based sample

This study investigated predictors of influenza vaccination uptake since the introduction of the policy to target over 65s. Four hundred and forty-four participants completed a cross-sectional structured interview. The predictors of vaccination uptake were: having a doctor or nurse who explained why the vaccination is important and possible side effects; living with others; higher occupational status; and having a car or being able to walk to the GPs rather than reliant on others or public transport. Most participants who had received the vaccination reported having done so in response to reminders or advice from medical professionals. The most common explanations given by those who had chosen not to receive the vaccination were fear of side effects and concerns regarding vaccination efficacy. Current national campaigns and general practitioners' reminder programmes appear to have been successful in improving awareness; however, these results suggest that a more informational campaign, focused on the evidence that the vaccine is efficacious and that side effects are limited, may further improve uptake.

The association between life events, social support, and antibody status following thymus-dependent and thymus-independent vaccinations in healthy young adults

This study determined whether stressful life events and social support were related to antibody status following both thymus-dependent and thymus-independent vaccinations. Life events in the previous year and customary social support were measured in 57 healthy students at baseline. Antibody status was also assessed at baseline and at five weeks and five months following vaccination with the trivalent influenza vaccine and the meningococcal A+C polysaccharide vaccine. Taking into account baseline antibody titre, high life events scores prior to vaccination were associated with lower responses to the B/Shangdong influenza strain at both five weeks and five months and meningococcal C at five weeks. Life event scores were not associated with response to the other two influenza viral strains nor response to meningococcal A. Those with high social support scores had stronger 5-week and 5-month antibody responses to the A/Panama influenza strain, but not to any of the other strains. These associations could not be accounted for by demographic or health behaviour factors, and also emerged from analyses comparing those who exhibited a fourfold increase in antibody titre from baseline with those who did not. Life events and social support were related to antibody status following influenza vaccination in distinctive ways that may be partly determined by vaccine novelty and prior naturalistic exposure. Life events also predicted poor antibody response to meningococcal C polysaccharide vaccination after previous meningococcal C conjugate vaccination. Neither psychosocial factor was associated with response to primary meningococcal A polysaccharide vaccination.

Neuroticism, cortisol reactivity, and antibody response to vaccination

This study examined whether neuroticism was related to the antibody response to influenza vaccination and whether the relationship was mediated by cortisol reactions to acute laboratory mental stress. Antibody status was assessed at baseline and to a trivalent influenza vaccination in 57 students at 5-week and 5-month follow-up. Neuroticism was also measured at baseline. Cortisol was measured at rest and in response to a pressurized mental arithmetic task. At both follow-ups, higher neuroticism scores were associated with poorer A/Panama antibody response, following adjustment for baseline antibody titer. Higher neuroticism scores were also associated with blunted cortisol reactivity, and blunted cortisol reactivity was associated with poorer A/Panama antibody response, but only at 5 months. However, there was no conclusive evidence that cortisol reactivity mediated the association between neuroticism and antibody response.

Mental stress-induced hemoconcentration: Sex differences and mechanisms

Given the possible role of hemoconcentration in myocardial infarction and apparent sex differences in susceptibility, three studies examined sex differences in mental stress-induced hemoconcentration, and explored possible underlying mechanisms. Blood pressure, heart rate, and hematocrit were monitored at rest and in response to a mental stress task that was contrived to be increasingly provocative across the three studies. This was confirmed by self-report, performance, and cardiovascular reactivity data. The most convincing evidence for hemoconcentration effects and sex differences in hemoconcentration emerged from exposure to the more provocative of the stress tasks, with men also showing greater hemoconcentration than women. Blood pressure reactivity was a strong and consistent predictor of stress-induced hemoconcentration. These findings may help to explain sex differences in susceptibility to myocardial infarction.

Reductions in secretory immunoglobulin A to cold pressor stress are not influenced by timing of saliva sampling

Acute psychological stress has been shown to alter secretory immunity, principally secretory immunoglobulin A (S-IgA). Most acute stress tasks result in increases in S-IgA, but decreases have been reported in response to the cold pressor. However, the evidence is mixed, with increases and no changes in S-IgA in response to the cold pressor also being reported. It was hypothesised that differences in the timing of saliva sampling may provide an explanation for these discrepant results. Participants completed two 4-min cold pressor tasks, each preceded by a rest period in which baseline S-IgA was measured. In one condition, S-IgA was assessed during the final 2 min of the cold pressor; in the other, it was measured immediately after completion of the task. S-IgA decreased from baseline to task, regardless of timing of saliva sampling. It was concluded that differences in timing of sampling do not account for the mixed reports in the literature.

Life events, perceived stress and antibody response to influenza vaccination in young, healthy adults

OBJECTIVES

Chronic stress has been associated with impaired response to influenza vaccination in the elderly. This study investigated whether mild, intermittent stress experienced by young, healthy adults has a similar effect.

METHODS

Antibody and psychological status were determined prevaccination and 5 weeks and 5 months later; a fourfold increase in antibody to at least one viral strain was considered protective.

RESULTS

At 5 months, unprotected participants reported significantly more life events and tended to report more perceived stress than those who were protected.

CONCLUSIONS

Psychological stress is detrimental to long-term maintenance of antibody levels following vaccination in young, healthy adults.

Antibody response to vaccination and psychosocial stress in humans: relationships and mechanisms

The purpose of this review is to determine the effects of psychosocial stress on antibody response to vaccination in humans, consider possible mechanisms, and identify agenda for future research. Studies of the association between stress and vaccination response in humans were reviewed. There is evidence of a negative association between stress and antibody response to vaccination, which is most apparent with thymus-dependent vaccines and when measured at extended times after vaccination. Preliminary findings implicate the hypothalamic-pituitary-adrenal axis and sympathetic nervous system as potential mechanisms, although a role for unhealthy behaviours cannot be discounted at this stage. Results to date are sufficiently indicative to direct future research to untangling their theoretical ramifications, as well as realising their clinical implications.

Perceived stress and psychological well-being are associated with antibody status after meningitis C conjugate vaccination

OBJECTIVE

Psychological stress has been associated with reduced immune response to a variety of vaccinations. This study is the first to examine antibody status after vaccination with a conjugate vaccine, in which a polysaccharide antigen is conjugated to a protein to elicit a thymus-dependent antibody response.

METHODS

Sixty undergraduate students, who had received the meningitis C conjugate vaccine before recruitment, attended a single testing session. They provided a blood sample and completed a battery of questionnaires, including the Life Events Scale for Students, Perceived Stress Scale, and General Health Questionnaire (GHQ-28). Both meningitis C-specific antibody titer and the serum bactericidal assay titer to whole meningitis C bacteria were assayed.

RESULTS

High perceived stress, but not life events stress, was associated with low antibody titers. Poor antibody titers were also predicted by relatively low levels of psychological well-being as measured by the GHQ-28. Of the GHQ-28 subscales, anxiety/insomnia and social dysfunction were associated with antibody status. No psychological variables emerged from bivariate analyses as predictive of the adequacy of bactericidal titer.

CONCLUSIONS

This study provides the first evidence that antibody status after a conjugate vaccination may be susceptible to psychological influences.

Shifting hemodynamics of blood pressure control during prolonged mental stress

The present study examined the hemodynamics underlying blood pressure elevations for evidence of a shift in the control of blood pressure during prolonged mental stress. Mean arterial pressure (MAP), cardiac output (CO), and total peripheral resistance (TPR) were measured at rest, during a 28-min mental arithmetic stress task, and during recovery, in 30 young healthy men and women. The stress task elicited a sustained increase in MAP: CO rose during the first half of the task but returned to baseline levels during the last quarter of the task, whereas TPR increased as the task progressed. When participants' hemodynamic reactions were classified as cardiac, vascular, or neither, there were more cardiac reactors early relative to late in the task, whereas there were more vascular reactors late relative to early. Thus, the sustained pressor response was initially supported mainly by cardiac mechanisms but subsequently by predominantly vascular mechanisms.

Cortisol and cardiovascular reactions to mental stress and antibody status following hepatitis B vaccination: a preliminary study

This study examined possible neuroendocrine mechanisms underlying the association between stress and antibody response to vaccination. Hepatitis B antibody titers were obtained, and salivary cortisol and cardiovascular activity measured during baseline, mental arithmetic, and recovery in 30 undergraduates. It was hypothesised that higher reactivity would be associated with poorer antibody status. Compared to individuals with high antibody titers, those with low titers had significantly lower cortisol levels throughout, exhibited a significantly attenuated end-of-task reduction in cortisol relative to resting baseline, and had larger cardiac output and inotropic reactions, but smaller increases in total peripheral resistance, to mental arithmetic. In sum, variations in indices of both hypothalamic pituitary adrenocortical axis and sympathetic nervous system activity were associated with individual differences in immune response to vaccination.

Stress, coping, and hepatitis B antibody status

OBJECTIVE

The present study investigated the association between exposure to stressful life events, coping style, and antibody status after hepatitis B vaccination.

METHODS

Two hundred sixty medical school undergraduates, who had received the three-dose hepatitis B vaccine before recruitment to this study, completed questionnaires measuring exposure to stressful life events during the past year, customary coping strategies, and health behaviors. Antibodies against hepatitis B surface antigen were determined; levels <100 mIU/ml were deemed inadequate.

RESULTS

Two participant cohorts were identified: those vaccinated within the last year and those vaccinated earlier. In the early vaccination cohort, participants with greater-than-average stress exposures had a more than two-fold increased risk of having an inadequate antibody titer. Coping by accepting the reality of stressful situations proved protective, whereas coping by substance use increased the risk of having an inadequate antibody count in this cohort. These associations remained significant after adjustment for possible mediators. Furthermore, the effects of stress and coping were largely independent of one another. Neither stress nor coping was significantly associated with antibody status in the recently vaccinated cohort.

CONCLUSIONS

The present study confirms that the immune system is sensitive to variations in psychological factors. Stressful life events and coping strategy seem to have a continuing impact on hepatitis B antibody status.

The effects of competition and competitiveness on cardiovascular activity

Cardiovascular activity was measured at resting baseline and in response to a car racing game, undertaken in competition or in cooperation with an experimenter, or individually. Competitiveness and win and goal orientations were assessed by questionnaire. Competition provoked increases in blood pressure and heart rate, and a significant shortening of the preejection period, an index of enhanced beta-adrenergic influences on the heart. The cooperation task was largely without effect, and although the solo task affected cardiovascular activity, it did so to a lesser extent and much less consistently than did the competition task. The three task conditions, then, were largely distinguishable by their capacity to activate beta-adrenergic processes. Participants high in competitiveness and desire to win showed higher blood pressure reactions and greater shortening of the preejection period to competition than those low in these characteristics.

Cardiovascular and secretory immunoglobulin A reactions to humorous, exciting, and didactic film presentations

Secretory immunoglobulin A (sIgA) in saliva and cardiovascular activity were measured at rest and in response to three film extracts varying in affective content. Subjective ratings of film impact confirmed a priori assumptions; the humorous film was rated as funnier than the other two films, the didactic film as more boring than the other two films, and the exciting film as more exciting and more stressful than the other two films. The films elicited distinct patterns of cardiovascular autonomic activity. The exciting film provoked changes characteristic of beta-adrenergic activation: increased systolic blood pressure (SBP); heart rate (HR); cardiac output (CO); and shortened pre-ejection period (PEP). The didactic film had little impact on cardiovascular activity. While an increase in total peripheral resistance (TPR) occurred, the humorous film was largely notable for a reduction in beta-adrenergic drive, as evidenced by reduced CO and a lengthening of PEP. In contrast to previous research reporting a rise in sIgA particular to humorous exposures, the sIgA secretion rate, although enhanced by exposure to the films, did not vary with film content.

Factors influencing teenage mothers' participation in unprotected sex

OBJECTIVE

To study the values, beliefs, and lived experiences of 8 teenage mothers who participated in unprotected sex at the time their babies were conceived, in order to enhance understanding of adolescent sexual behavior from a nursing science perspective.

DESIGN

A qualitative, heuristic approach that subscribed to the basic tenets of descriptive phenomenology, in which teenagers were allowed to discuss in their own words the sentiments, opinions, ideologies, and intentions that affected their sexual decision-making.

SETTING

Data collection consisted of a series of audiotaped interviews conducted by the researcher in the participants' homes over an 8-week period from November 1997 through January 1998.

PARTICIPANTS

A convenience sample of 8 teenage mothers who met the inclusion criteria for having participated in unprotected sex at the time of conception, recruited from a facility specializing in education, support, and intervention for teenage parents.

MAIN OUTCOME MEASURES

Thematic analysis of transcribed text began once the first interview was completed and continued throughout the data collection process. The process included open coding of key words and phrases, bracketing out conventional knowledge, and immersion in the data in order to identify prevalent and recurring themes.

RESULTS

Results are reported in terms of the six prevalent themes that emerged from the interview data relevant to factors which contributed to the teenagers' participation in unprotected sexual intercourse: Desiring Pregnancy, Handing It Over to Fate, Lacking a Plan, Doubting the Chances, Fearing Harm, and Fearing Loss.

CONCLUSIONS

Key themes identified in this study represent a foundational step in achieving a more cogent view of the issues involved in adolescent sexual decision-making. Awareness of these experiences and intentions can be used to enhance meaningful interaction between adolescents and the health care system as well as to serve as a resource in the development and implementation of programs designed to prevent adolescent pregnancy. Further studies are required before specific practice applications can be identified.