Effect of pig-specific cytokines on mobilization of hematopoietic progenitor cells in pigs and on pig bone marrow engraftment in baboons

Mixed hematopoietic chimerism has been found to be a requirement for achieving specific immunologic hyporesponsiveness. Some of the requirements for in vitro and in vivo coexistence of discordant hematopoietic systems in the pig-to-baboon (or human) model have been investigated. We have tested the efficacy of pig-specific cytokines (PSC) (IL3, SCF, GM-CSF) in the mobilization of porcine bone marrow (BM) progenitors in vivo (i) in the pig and (ii) in baboons that underwent a conditioning regimen and porcine BM transplantation. In a preliminary in vitro study, porcine BM cells were incubated in various media to assess the effect of human plasma on pig progenitors in a colony-forming unit (CFU) assay. In in vivo studies, four pigs received PSC and one control pig did not. Six baboons underwent natural antibody removal, with subsequent pig BM transplantation. Four of these six underwent nonmyeloablative (n=2) or myeloablative (n=2) conditioning and all received PSC treatment. Two baboons did not receive PSC, one of which underwent a nonmyeloablative regimen. Sequential blood samples and BM biopsies in pigs and baboons were analyzed by CFU assay for the detection of porcine cells. Baboon samples were analyzed by polymerase chain reaction (PCR) to detect porcine DNA. In the case of the in vitro tests, colony forming by porcine progenitors was not inhibited by media containing human plasma and for the in vivo tests, PSC increased the number of progenitors in pig BM; mobilization of progenitors into the peripheral blood was observed. PSC-treated baboons which experienced transient depletion of leukocytes < 1,000/ml (as an effect of the conditioning regimen) had porcine BM cells detectable by PCR for as long as day 316 after BM transplantation. In conclusion we found that: (i) under the conditions of these studies, in vitro porcine progenitor cell growth was not inhibited by human plasma containing natural antibody and complement; (ii) PSC treatment led to an increased number of progenitors in pig BM and peripheral blood; (iii) the combination of an effective conditioning regimen and treatment with PSC was capable of inducing long-term survival of pig progenitors in baboons, although only a low level of engraftment was achieved.

Porcine kidney and heart transplantation in baboons undergoing a tolerance induction regimen and antibody adsorption

BACKGROUND

Xenotransplantation would provide a solution to the current shortage of organs for transplantation. Our group has been successful in inducing tolerance in mice and monkey models of allogeneic transplantation. The present study attempts to extend the same tolerance-inducing regimen to a pig-to-baboon organ transplantation model.

METHODS

Nine baboons underwent a conditioning regimen (consisting of nonmyeloablative or myeloablative whole body and thymic irradiation, splenectomy, antithymocyte globulin, pharmacologic immunosuppression and porcine bone marrow transplantation [BMTx]), which has previously been demonstrated to induce donor-specific allograft tolerance in monkeys. In addition, immunoadsorption of anti-alphaGal antibody (Ab) was performed. Four of the nine baboons received pig kidney transplants (KTx), and one also underwent repeat transplantation with an SLA-matched kidney. Two received heterotopic pig heart transplants (HTx). Three baboons underwent conditioning without organ transplantation for long-term studies of natural Ab kinetics.

RESULTS

In the three baboons that received the conditioning regimen without an organ transplant, immunoadsorption reduced Ab by approximately 90%, but recovery of Ab to pretreatment level or higher occurred within 7 days. In contrast, the level of Ab remained low after organ transplant. No Ab to pig antigens other than alphaGal was detected in any baboon before or after BMTx, KTx, or HTx. No graft succumbed to hyperacute rejection. KTx function began to deteriorate within 3-6 days, with oliguria and hematuria progressing to anuria, and the kidneys were excised after 3, 6, 9, 11, and 14 days, respectively. One HTx ceased functioning at 8 days; the second baboon died with a contracting HTx at 15 days. Features of coagulopathy and thrombocytopenia developed in all six transplanted baboons (high D-dimer, prolonged prothrombin time and partial thromboplastin time, and falling fibrinogen) resulting in serious bleeding complications in two baboons, one of which died on day 9. Donor organs showed progressive acute humoral rejection with deposits of IgM, IgG, and complement; a focal mononuclear cellular infiltrate was also observed. The ureter was the earliest structure of the KTx affected by rejection, with progression to necrosis.

CONCLUSIONS

This conditioning regimen prevented hyperacute rejection but was ineffective in preventing the return of Ab, which was associated with the development of acute humoral rejection with features of coagulopathy. No baboon developed anti-pig Ab other than alphaGal Ab. Further modifications of the protocol directed toward suppression of production of Ab are required to successfully induce tolerance to pig organs in baboons.

Psychological influences on surgical recovery. Perspectives from psychoneuroimmunology

Greater fear or distress prior to surgery is associated with a slower and more complicated postoperative recovery. Although anxiety presumably interferes with recuperation through both behavioral and physiological mechanisms, the pathways have been unclear. Recent work in psychoneuroimmunology (PNI) has demonstrated that stress delays wound healing. In addition, a second line of research has illustrated the adverse effects of pain on endocrine and immune function. A biobehavioral model is described that is based on these and other data; it suggests a number of routes through which psychological and behavioral responses can influence surgery and post-surgical outcomes. Clinical and research implications are highlighted.

Psychological influences on surgical recovery. Perspectives from psychoneuroimmunology

Greater fear or distress prior to surgery is associated with a slower and more complicated postoperative recovery. Although anxiety presumably interferes with recuperation through both behavioral and physiological mechanisms, the pathways have been unclear. Recent work in psychoneuroimmunology (PNI) has demonstrated that stress delays wound healing. In addition, a second line of research has illustrated the adverse effects of pain on endocrine and immune function. A biobehavioral model is described that is based on these and other data; it suggests a number of routes through which psychological and behavioral responses can influence surgery and post-surgical outcomes. Clinical and research implications are highlighted.

Stress-associated immune modulation: relevance to viral infections and chronic fatigue syndrome

The frequent association of an active viral infection with the symptoms of CFS led researchers to hypothesize that chronic fatigue syndrome (CFS) is induced by a virus. Results of these studies indicated that despite clinical support for this hypothesis, there were no clear data linking viruses to CFS. In this overview, we will explore the interrelation of the immune, endocrine, and central nervous systems, and the possibility that stress and/or the reactivation/replication of a latent virus (such as Epstein Barr virus) could modulate the immune system to induce CFS. Relevant research conducted in the developing field of psychoneuroimmunology will be reviewed, with a particular focus on cytokine synthesis, natural killer (NK) cell activity, and T-lymphocyte function, as they relate to CFS.

Human osteoblast-like cells respond not only to the extracellular calcium concentration but also to its changing rate

The effect of extracellular calcium on human osteoblast-like cells (HOS) has been demonstrated. An experimental setup was used for applying defined rates of change in the extracellular calcium concentration. The intracellular calcium concentration was monitored using the fluorescence dye fura-2. HOS cells showed qualitatively different responses of the intracellular calcium concentration to changes of the extracellular calcium concentration depending on its changing rate. A small rate caused only a small and slow increase of the intracellular calcium concentration, whereas faster changes are able to cause a rapid transient increase followed by a sustained elevation of the internal calcium level. Surprisingly, both an increasing as well as a decreasing external calcium concentration is able to cause cellular responses. These signals could be reduced by the IP3-inhibitor neomycin. We propose that the G-protein dependent signalling pathway of HOS cells can not only sense the extracellular calcium concentration but also its time derivative.

Anti-Gal(alpha)1-3Gal antibody response to porcine bone marrow in unmodified baboons and baboons conditioned for tolerance induction

BACKGROUND

Mixed lymphohematopoietic chimerism can provide an effective means of inducing longterm immunological tolerance and has been documented in a monkey allograft model. A conditioning regimen including nonmyeloablative or myeloablative irradiation and splenectomy has been used to induce chimerism in a pig-to-primate transplantation model. Since the presence of anti-Gal(alpha)1-3Gal (alphaGal) natural antibodies leads to the hyperacute rejection of pig organs transplanted into primates, extracorporeal immunoaffinity adsorption (EIA) of anti-alphaGal antibodies is also included in the regimen. The effect of the tolerance induction protocol on the anti-alphaGal antibody response has been assessed.

METHODS

Anti-alphaGal antibody was measured after the EIA of plasma through an alphaGal immunoaffinity column in baseline studies involving two unmodified baboons, one splenectomized baboon, and one baboon that received a challenge with porcine bone marrow (BM), and in three groups of baboons (n=2 in each group) that received different conditioning regimens for tolerance induction. Group 1 received a nonmyeloablative conditioning regimen without porcine BM transplantation. Group 2 received nonmyeloablative conditioning with pig BM transplantation and pig cytokine therapy. Group 3 received myeloablative conditioning, an autologous BM transplant (with BM depleted of CD2+ or CD2+/CD20+ cells), and pig BM transplantation.

RESULTS

In the baseline studies, a single EIA of anti-alphaGal antibodies in an unmodified animal initially depleted anti-alphaGal antibody, followed by a mild rebound. Nonmyeloablative conditioning (group 1) in the absence of pig cell exposure reduced the rate of anti-alphaGal antibody return. Pig BM cells markedly stimulated anti-alphaGal antibody production in an unmodified baboon (alphaGal IgM and IgG levels increased 40- and 220-fold, respectively). This response was significantly reduced (to an only 2- to 5.5-fold increase of IgM and IgG) in baboons undergoing nonmyeloablative conditioning (group 2). A myeloablative conditioning regimen (group 3) prevented the antibody response to pig BM, with the reduction in response being greater in the baboon that received autologous BM depleted of both CD2+ and CD20+ cells. No new antibody directed against pig non-aGal antigens was detected in any baboon during the 1 month follow-up period.

CONCLUSIONS

(i) EIA of anti-alphaGal antibody in unmodified baboons results in a transient depletion followed by a mild rebound of antibody; (ii) exposure to pig BM cells results in a substantial increase in anti-alphaGal antibody production; (iii) a nonmyeloablative conditioning regimen reduces the rate of antibody return and (iv) markedly reduces the response to pig BM cells; (v) the anti-alphaGal response is completely suppressed by a myeloablative regimen if CD2+ and CD20+ cells are eliminated from the autologous BM inoculum. Furthermore, (vi) challenge with pig BM cells appears to stimulate only an anti-alphaGal antibody response without the development of other (non-alphaGal) anti-pig antibodies. We conclude that regimens used for T-cell tolerance induction can be beneficial in reducing the anti-alphaGal antibody response to porcine BM.

I-symmetry, the highest chiral point group, and the icosahedral structure of virus particles

Small molecules exhibiting I-symmetry, the member of highest order amongst the five chiral point groups, have yet to be made. However, many virus particles such as the human adenovirus exhibit icosahedral symmetry. The handedness of the subunits being exchanged or permutated by symmetry operations in these supramolecular structures remain invariant since their protein constituents contain L-amino acids. This is only consistent with the existence of symmetry operations of the first kind, and thus these chiral icosahedral ensembles provide suitable examples of I-symmetry.

Social stress and the reactivation of latent herpes simplex virus type 1

Psychological stress is thought to contribute to reactivation of latent herpes simplex virus (HSV). Although several animal models have been developed in an effort to reproduce different pathogenic aspects of HSV keratitis or labialis, until now, no good animal model existed in which application of a psychological laboratory stressor results in reliable reactivation of the virus. Reported herein, disruption of the social hierarchy within colonies of mice increased aggression among cohorts, activated the hypothalamic-pituitary-adrenal axis, and caused reactivation of latent HSV type 1 in greater than 40% of latently infected animals. However, activation of the hypothalamic-pituitary-adrenal axis using restraint stress did not activate the latent virus. Thus, the use of social stress in mice provides a good model in which to investigate the neuroendocrine mechanisms that underlie behaviorally mediated reactivation of latent herpesviruses.

Chronic stress modulates the virus-specific immune response to latent herpes simplex virus type 1

We compared 71 family caregivers of dementia sufferers and 58 control subjects on three different immune measures relevant to latent herpes simplex virus Type 1 (HSV-1) infection: neutralizing antibody titers, antibody titers to a total viral antigen, and a proliferative memory T-cell response. Caregivers had significantly higher antibody titers to the total viral antigen and a poorer HSV-1 specific T-cell response than controls, but no significant difference in neutralizing antibody titers between groups was observed. These data provide additional evidence that psychological stress can modulate a virus-specific immune response associated with caregiving.

Cellular immune responses to acute stress in female caregivers of dementia patients and matched controls

This study investigated whether the stress of caregiving alters cellular immune responses to acute psychological stressors. Twenty-seven women caring for a spouse with a progressive dementia (high chronic stress) and 37 controls matched for age and family income performed a 12-min laboratory stressor. Cellular immune function was assessed by both functional and quantitative measures taken before (low acute stress), immediately after (high acute stress), and 30 min after (recovery from stress) exposure to the laboratory stressors. The laboratory challenges were associated with diminished proliferative responses but elevated natural killer (NK) cell cytotoxicity; however, subsequent analyses suggested that this elevated cytotoxicity was largely attributable to an increase in the number of NK cells in peripheral blood. The results suggest that although the stress of caregiving diminishes cellular immune function, caregiving appears to have little effect on cellular immune responses to or recovery from brief psychological challenges.

Cardiovascular and immune responses to acute psychological stress in young and old women: a meta-analysis

OBJECTIVE

To describe the relationships between cardiovascular and natural killer (NK) cell number changes on acute psychological stress in women.

METHOD

Data from eight different studies were analyzed. A total of 128 healthy female subjects, 85 younger (18-45 years) and 43 older (49-87 years), had been subjected to a speech stressor (N = 80) or a mental effort stressor (N = 48), mental arithmetic, or the Stroop test. Correlations between changes in NK cell numbers, systolic (SBP) and diastolic (DBP) blood pressure, and heart rate (HR) were computed. Meta-analysis programs were used to study correlations across studies and to examine whether correlations differed with stressors or age.

RESULTS

In all studies, significant increases over baseline were observed for each variable. Across studies, the mean weighted r between changes in HR, DBP, and SBP was medium (rw = .25) to large (rw = .64). A medium to large average correlation between HR and NK changes (rw = .37) was observed, whereas average correlations of changes in NK cell numbers with blood pressure changes were small to medium (rw < or = .23). Correlations between changes in NK cell numbers and cardiovascular variables were homogeneous across studies, whereas mutual correlations between cardiovascular variables were heterogeneous. One moderator variable showed itself: correlations between HR and DBP reactions were larger in studies with older than younger subjects.

CONCLUSION

NK cell changes and HR responses induced by acute stress in women are regulated, to some extent, by the same mechanisms. Neither the type of stressor nor age seem to be very important when considering correlations between NK cell and cardiovascular changes. This study integrates information about NK cell and cardiovascular responses in women that can be used as reference material in future studies.

The influence of psychological stress on the immune response to vaccines

We compared virus-specific antibody and T-cell responses to influenza virus vaccination in 32 caregivers of Alzheimer's disease (AD) patients and matched control subjects. Caregivers showed a poorer antibody response and virus-specific T-cell response following vaccination compared to the control subjects as measured by fourfold increases in antibody titers to the vaccine and lower levels of virus-induced IL-2 levels in vitro. We performed a second study in which forty-eight medical students were inoculated with a series of three injections of the hepatitis-B (HEP-B) vaccine to coincide with the third day of three, three-day examination blocks. Twelve of the 48 medical students seroconverted after the first injection; these students were characterized by falling into the lower stressed/lower anxiety group of students. Students who reported greater social support and lower anxiety and stress demonstrated a higher antibody response to the vaccine and a more vigorous T-cell response to HEP-B surface antigen at the end of the third examination experience. The differences in antibody and T-cell responses to HEP-B and influenza virus vaccinations provide a demonstration of how stress may be able to alter both the cellular and humoral immune responses to vaccines and novel pathogens in both younger and older adults.

Autonomic, neuroendocrine, and immune responses to psychological stress: the reactivity hypothesis

We examined the effects of brief psychological stressors on cardiovascular, neuroendocrine, and cellular immune response in 22 older women to investigate the common effects of stress across systems. Results revealed that psychological stressors heightened cardiac sympathetic activation, elevated plasma catecholamine concentrations, and affected the cellular immune response (ps < 0.05). In a replication and extension, 27 women caring for a spouse with a progressive dementia (high chronic stress) and 37 controls category matched for age and family income (low chronic stress) performed the 12-min laboratory stressor. Measures were taken before (low acute stress) and immediately following (high acute stress) exposure to the laboratory stressors as well as 30 min after termination of the stressor (recovery period). Acute stress again heightened cardiac sympathetic activation, elevated plasma catecholamine concentrations, and affected cellular immune responses (ps < 0.05), whereas chronic stress was associated with higher reports of negative affect, enhanced cardiac sympathetic activation, elevated blood pressure and plasma levels of ACTH, and diminished production of interleukin-1 beta (ps < 0.05). Correlational analyses in both studies further suggested that individuals who showed the greatest stress-related changes in HPA activation also exhibited the greatest diminution in cellular immune response.

Stress-induced neuroendocrine modulation of viral pathogenesis and immunity

Physical restraint (RST) was used to examine the interactions among the hypothalamic-pituitary-adrenal (HPA) axis, sympathetic nervous system, and the immune response to infection. In these studies, mice were infected with either herpes simplex virus (HSV) or influenza A/PR8 virus so that the impact of neuroendocrine activation could be assessed on disease pathophysiology and anti-viral immunity. RST suppressed lymphadenopathy in draining lymph nodes, reduced mononuclear cellular infiltration in the lungs, and suppressed virus-specific cytokine and cytolytic T-cell responses. Blockade of type II glucocorticoid receptors (by RU486) restored cellularity and cytokine responses to both organs in restraint-stressed, infected mice. Thus, the HPA axis modulated cell trafficking and T-cell cytokine responses. However, RU486 treatment failed to restore cytolytic T-cell responses. Blockade of beta-adrenergic receptors (by nadolol), in combination with RU486 treatment, fully restored cytolytic T-cell responses, suggesting that catecholamines were involved in suppressing the virus-specific CD8+ cytolytic T-cell response. RST also modulated the local development or expression of antibody-secreting cells (ASC) in the lungs draining lymph nodes, and spleen following infection of restrained mice. RST significantly suppressed the number of virus-specific ASC (IgM, IgG and subclasses IgG1 and IgG2a) in the lungs, mediastinal (MLN) lymph nodes and spleen, while it enhanced the responses in the superficial cervical (SCV) lymph nodes. This observation of differential modulation of ASC responses in the MLN and SCV lymph nodes supports the concept of tissue-specific immunoregulation in response to stress.

Marital stress: immunologic, neuroendocrine, and autonomic correlates

Ninety newlywed couples (mean age = 25), selected on the basis of extremely stringent mental and physical health criteria, were admitted to a hospital research unit for 24 hours to provide a detailed assessment of conflict-resolution behaviors and changes in autonomic, endocrine, and immune function. Among these newlyweds, negative or hostile behaviors during marital conflict (coded from videotaped interactions) were associated with increased levels of epinephrine, norepinephrine, growth hormone, and ACTH as well as greater immunological change over the subsequent 24 hours. Wives demonstrated greater and more persistent physiological changes related to marital conflict than husbands. To assess the generalizability of these physiological changes, a similar laboratory paradigm was used with 31 older couples (mean age = 67) who had been married an average of 42 years. Consistent with the data from newlyweds, both endocrinological and immunological data showed significant relationships to negative behavior during marital conflict in these older couples. These findings suggest that abrasive marital interactions have important endocrinological and immunological correlates.

Epstein-Barr virus growth-transformed cells are converted to malignancy following transfection of a 1.3-kb CATR1 antisense construct independent of a change in the level of c-myc expression followed by a 8;14 chromosomal translocation

The AGLCL Epstein-Barr virus (EBV) growth-transformed cell line is incapable of inducing tumors in nude mice. When the cells were transfected with a 1.3-kb CATR1 antisense cDNA construct, progressively growing lymphomas could be induced in nude mice. Chromosome analysis of the parental, transfected, and tumor cells revealed that a chromosomal translocation t(8;14)(q24.1;q32) had occurred in the transfected cells and was retained in cells derived from tumors. Moreover, enhanced c-myc expression, usually associated with this translocation, was either unchanged or under-expressed. These data suggest that the malignant transformation of the EBV growth-transformed cells was independent of c-myc expression and suggest that the CATR1 gene may act synergistically with the chromosomal translocation facilitating the conversion of AGLCL cells from a growth-transformed state to a malignant phenotype.

Cellular immune responses to acute stress in female caregivers of dementia patients and matched controls

This study investigated whether the stress of caregiving alters cellular immune responses to acute psychological stressors. Twenty-seven women caring for a spouse with a progressive dementia (high chronic stress) and 37 controls matched for age and family income performed a 12-min laboratory stressor. Cellular immune function was assessed by both functional and quantitative measures taken before (low acute stress), immediately after (high acute stress), and 30 min after (recovery from stress) exposure to the laboratory stressors. The laboratory challenges were associated with diminished proliferative responses but elevated natural killer (NK) cell cytotoxicity; however, subsequent analyses suggested that this elevated cytotoxicity was largely attributable to an increase in the number of NK cells in peripheral blood. The results suggest that although the stress of caregiving diminishes cellular immune function, caregiving appears to have little effect on cellular immune responses to or recovery from brief psychological challenges.

Stress and immune responses after surgical treatment for regional breast cancer

BACKGROUND

Adults who undergo chronic stress, such as the diagnosis and surgical treatment of breast cancer, often experience adjustment difficulties and important biologic effects. This stress can affect the immune system, possibly reducing the ability of individuals with cancer to resist disease progression and metastatic spread. We examined whether stress influences cellular immune responses in patients following breast cancer diagnosis and surgery.

METHODS

We studied 116 patients recently treated surgically for invasive breast cancer. Before beginning their adjuvant therapy, all subjects completed a validated questionnaire assessing the stress of being cancer patients. A 60-mL blood sample taken from each patient was subjected to a panel of natural killer (NK) cell and T-lymphocyte assays. We then developed multiple regression models to test the contribution of psychologic stress in predicting immune function. All regression equations controlled for variables that might exert short- or long-term effects on these responses, and we also ruled out other potentially confounding variables.

RESULTS

We found, reproducibly between and within assays, the following: 1) Stress level significantly predicted lower NK cell lysis, 2) stress level significantly predicted diminished response of NK cells to recombinant interferon gamma, and 3) stress level significantly predicted decreased proliferative response of peripheral blood lymphocytes to plant lectins and to a monoclonal antibody directed against the T-cell receptor.

CONCLUSIONS

The data show that the physiologic effects of stress inhibit cellular immune responses that are relevant to cancer prognosis, including NK cell toxicity and T-cell responses. Additional, longitudinal studies are needed to determine the duration of these effects, their health consequences, and their biologic and/or behavioral mechanisms.

Postmenopausal hormone replacement: effects on autonomic, neuroendocrine, and immune reactivity to brief psychological stressors

OBJECTIVE

Postmenopausal status increases some aspects of women's physiological responses to psychological stress; however, the influences of chronic hormone replacement with estrogen and progestogen on these responses are not known. We investigated possible effects of long-term estrogen replacement therapy (ERT), both with and without progestogen, on physiological reactivity to brief laboratory stressors.

METHOD

We studied three groups of postmenopausal women: 16 on estrogen alone, 14 on estrogen and progestogen, and 25 control participants receiving no replacement therapy. Cardiovascular, neuroendocrine, and immune data were collected at baseline and after speech and math tasks.

RESULTS

In all groups, the stressors reduced vagal cardiac control (indexed by respiratory sinus arrhythmia); increased heart rate and plasma epinephrine, adrenocorticotropic hormone, and cortisol levels; and altered T lymphocyte response (measured by mitogen-induced cell proliferation), natural killer cell lysis, and circulating leukocyte subsets. Women on either type of ERT had higher total cortisol levels (reflecting an estrogen effect on cortisol binding globulin) and greater mitogen-induced blastogenesis across measurement periods than controls. They also showed greater vagal withdrawal and less decline in mitogen-stimulated blastogenesis in response to the stressors. Combined estrogen and progestogen was associated with higher epinephrine and lower circulating total lymphocytes, T cells, and CD4+ T cells across measurement periods, and with intermediate levels of vagal withdrawal in response to the stressors.

CONCLUSIONS

Long-term ERT was associated with enhanced parasympathetic responsiveness to stress, suggesting possible reduced demand for potentially detrimental sympathetic activation; and with higher overall levels and smaller stress-induced reductions of mitogen-stimulated blastogenesis, suggesting up-regulated T cell function.

Differential effects of estrogen and medroxyprogesterone on basal and stress-induced growth hormone release, IGF-1 levels, and cellular immunity in postmenopausal women

We evaluated the influence of continual estrogen replacement therapy (ERT) as presently practiced by postmenopausal women with conjugated estrogens and medroxyprogesterone acetate (MPA) on the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis and cellular immunity. Thirty-nine postmenopausal women were evaluated (12 on no replacement, 14 on estrogen only, and 13 on estrogen and MPA). In the women receiving only conjugated estrogens, increased GH levels and decreased IGF-1 levels were found, which replicated previous research and probably reflected estrogen inhibition of hepatic IGF-1 production with a secondary increase in GH release because of reduced feedback inhibition. In women taking both MPA and estrogen, GH was increased and the previously observed estrogen induced decrease in IGF-1 levels was inhibited. In order to determine the influence of ERT on psycho-social stress-induced GH release, math (mental stress) and speech (social stress) challenges were utilized, and they produced significant increases in heart rate in all three groups. The heart rate following stress was significantly enhanced by estrogen replacement. These stressors also led to increased GH secretion in the women taking estrogen and MPA, but not in the other two groups. Gonadal steroids and GH can influence cellular immunity. We observed that ERT in both groups was associated with significantly enhanced lymphocyte responsiveness to the T-cell mitogens phytohemaglutinin (PHA) and Conconavalin A (Con A), and basal GH levels were correlated with the PHA response in the estrogen only group. ERT did not influence natural killer (NK) cell activity. We also found significant differences in the steady-state expression of latent Epstein-Barr virus (EBV) with increased antibody titers in the women in the estrogen only group and lower antibody titers in the MPA plus estrogen group. GH levels were correlated with EBV antibody titers in the estrogen plus MPA group. This study supports the hypothesis that GH and immune modulation can be influenced by ERT in postmenopausal woman. Given the extant literature on the immune-enhancing effects of GH, these data suggest that ERT may slow the decline of GH secretion with aging, an event that has been implicated in immunosenescence.

Predictors of risk for different stages of adolescent smoking in a biracial sample

This investigation was designed to identify the risk factors associated with different stages of cigarette use in a large biracial adolescent sample. A questionnaire assessing smoking habits and variables thought to be related to smoking was administered to 6,967 7th graders. Analysis revealed that the best predictor of experimentation with cigarettes was the perception that they were easily available. Regular smoking appeared to be heavily influenced by cost. Social influences contributed to both experimental and regular smoking, but the impact of social models varied with ethnicity and gender. Analysis further revealed that weight-related variables were closely tied to regular smoking. Implications of the findings for smoking prevention programs are discussed.

Predictors of risk for different stages of adolescent smoking in a biracial sample

This investigation was designed to identify the risk factors associated with different stages of cigarette use in a large biracial adolescent sample. A questionnaire assessing smoking habits and variables thought to be related to smoking was administered to 6,967 7th graders. Analysis revealed that the best predictor of experimentation with cigarettes was the perception that they were easily available. Regular smoking appeared to be heavily influenced by cost. Social influences contributed to both experimental and regular smoking, but the impact of social models varied with ethnicity and gender. Analysis further revealed that weight-related variables were closely tied to regular smoking. Implications of the findings for smoking prevention programs are discussed.

Marital conflict in older adults: endocrinological and immunological correlates

OBJECTIVE

To assess endocrinological and immunological correlates of marital conflict and marital satisfaction, 31 older couples (mean age 67 years) who had been married an average of 42 years were studied.

METHOD

Couples were admitted to the Clinical Research Center and a catheter was placed in each subject's arm. Blood was drawn on entry for immunological assays; for hormone analyses, five blood samples were drawn during a 30-minute conflict discussion and a 15-minute recovery session. The conflict session was recorded on videotapes that were later coded for problem-solving behaviors using the Marital Interaction Coding System (MICS).

RESULTS

Among wives, escalation of negative behavior during conflict and marital satisfaction showed strong relationships to endocrine changes, accounting for 16% to 21% of the variance in the rates of change of cortisol, adrenocorticotropic hormone (ACTH), and norepinephrine (but not epinephrine). In contrast, husbands' endocrine data did not show significant relationships with negative behavior or marital quality. Both men and women who showed relatively poorer immunological responses across three functional assays (the blastogenic response to two T-cell mitogens and antibody titers to latent Epstein-Barr virus) displayed more negative behavior during conflict; they also characterized their usual marital disagreements as more negative than individuals who showed better immune responses across assays.

CONCLUSION

Abrasive marital interactions may have physiological consequences even among older adults in long-term marriages.