PubMed Health⌕ Search

Biomedical subjects

B K Pedersen

Publications and source records attributed to B K Pedersen.

At least 181 records · Page 10Linked to original sources
PubMed1994

Bicycle exercise enhances plasma IL-6 but does not change IL-1 alpha, IL-1 beta, IL-6, or TNF-alpha pre-mRNA in BMNC.

The present study investigated the effect of concentric exercise on cytokine plasma levels and cytokine pre-mRNA in blood mononuclear cells (BMNCs). Healthy young moderately trained men performed ergometer bicycle exercise for 1 h at 75% of maximal oxygen uptake. The levels of plasma interleukin (IL)-6 increased significantly during exercise, but plasma levels of IL-1 alpha, IL-1 beta, and tumor necrosis factor-alpha (TNF-alpha) were below the detection limit in most subjects. Pre-mRNA for IL-1 alpha, IL-1 beta, IL-6, and TNF-alpha could be detected in BMNCs, but the amounts did not change in relation to exercise. These results indicate that, although the absolute number of monocytes increases during exercise and the percentage of CD14+/HLA-DR+ and CD14+/HLA-DR- monocytes increases after exercise, the increased plasma levels of IL-6 during exercise is not likely to be a result of activated monocytes in peripheral blood.

Adult↗
PubMed1994

NK cell response to physical activity: possible mechanisms of action.

Natural killer (NK) cells are highly influenced by physical exercise. The possible important mechanisms behind exercise-induced changes in NK cell function are cytokines, hyperthermia, and stress hormones, including catecholamines, growth hormone, cortisol, and beta-endorphins. Infusion studies mimicking stress hormone levels in blood during exercise indicate that increased plasma-adrenaline accounts for at least part of the exercise-induced modulation of NK cell function. During moderate as well as severe acute exercise, the NK cell activity is enhanced, but severe exercise is followed by immunodepression, at least in part caused by prostaglandins. Elite athletes have at rest elevated NK cell activity. However, due to frequent severe exercise the NK cell function is often temporarily severely depressed. It is suggested that during the time of immunodepression microorganisms, especially virus, invade the host, whereby infections can be established. However, in those who perform regular moderate exercise the immune system will often be temporarily enhanced and this will protect these from infections.

Cytokines↗
PubMed1994

The effect of acute exercise on lymphocyte subsets, natural killer cells, proliferative responses, and cytokines in HIV-seropositive persons.

Eight healthy men infected with human immunodeficiency virus, type 1 (HIV) and eight HIV seronegative age- and sex-matched controls exercised on a bicycle ergometer (75% of VO2max, 1 h). The percentages of CD4+, CD4+45RA+, and CD4+45RO+ cells did not change, whereas the absolute number of CD4+ cells increased twofold during exercise and fell below prevalues 2 h after. The neutrophil count increase was more pronounced after exercise in the controls compared with in HIV-seropositive subjects. The percent CD16+ cells, and the natural killer (NK) and lymphokine activated killer (LAK) cell activity increased during exercise, but this increase was significantly less pronounced in the HIV-seropositive group. The results suggest that in response to physical stress, HIV-seropositive subjects have an impaired ability to mobilize neutrophils, NK and LAK cells to the blood. Furthermore, because the total number of CD4+ cells, but not the percentage of CD4+ cells, changed in response to exercise, this study further strengthens the idea that the percentage of CD4+ cells is preferable to the number of CD4+ cells in monitoring patients seropositive for HIV.

Adult↗
PubMed1994

Chronic fatigue syndrome--a controlled cross sectional study.

OBJECTIVE: To look for signs of immunodeficiencies and/or longstanding infections underlying chronic fatigue syndrome (CFS). METHODS: Twenty-one patients fulfilling the Centers for Disease Control criteria for CFS were compared to 21 age and sex matched controls. A number of viral antibodies as well as the following tests evaluating the immune system were studied: autoantibody profile, cell surface markers on isolated blood mononuclear cells, cytokine production, lymphocyte proliferative responses, natural killer cell activity and quantitation of immunoglobulin secreting cells. RESULTS: Production in vitro of the predominantly T cell derived cytokines interleukin 2 and interferon gamma was significantly higher in patients with CFS compared to the control group. Furthermore, the serum concentrations of IgA and IgE were lower in patients with CFS; however, this difference was caused by a larger number with values of IgA and IgE above the upper limit of the normal range among the controls than among the patients with CFS. All other variables were similar in the 2 groups. CONCLUSION: A pathogenically significant imbalance of the immune system in patients with CFS cannot be excluded. However, evidence of a causal link between abnormal immunity and CFS was not obtained.

Adolescent↗
PubMed1993

[The immune system and physical training].

The effects on the immune system of sudden physical exercise and degree of training are reviewed. During moderate as well as strenuous physical exercise natural killer (NK) cells especially, but also T and B cells are released into the blood. A few hours after moderate physical exercise the immune system is back to the pre-exercise state, but following strenuous exercise the lymphocyte concentration and the NK and B cell functions are suppressed. The immune suppression following strenuous exercise is at least partly due to release of prostaglandins from an elevated number of monocytes in the circulation. The importance of stress hormones for mediating the immune modulation is discussed. Examination of trained persons at rest show that these have elevated NK cell activity when compared to matched controls. There are sporadic reports in the literature, showing that persons who train moderately have fewer infections, while persons who train very hard have increased risk of upper respiratory diseases. These findings are in accordance with the observed immune modulation on moderate versus strenuous exercise. The effects of physical training in relation to acute and chronic diseases are evaluated.

Endorphins↗
PubMed1993

Natural killer cell function and number of peripheral blood are not altered in recurrent aphthous ulceration.

Natural killer cell activity against K562 target cells was measured during active disease (within 48 hours after symptom debut, day 0), and in remission stages (days 14 and 28) of 10 patients with recurrent aphthous ulceration. Ten healthy sex- and age-matched persons with a negative history of recurrent aphthous ulceration served as controls. Baseline, interferon-alpha- and interleukin-2-boosted natural killer cell activity was not significantly different between patients and controls at any of the three time periods. Furthermore, the percentages of peripheral CD16+, CD56+, and CD14+ cells were at no time significantly different between patients and controls. This study supports other investigations with respect to a systemic T-cell imbalance in which a decreased CD3+ and CD4+ fraction is encountered among patients with recurrent aphthous ulceration; however, the previously reported increase in the CD8+ subsets was not confirmed in the present study. Although no quantitative or nonspecific functional alterations of circulating peripheral natural killer cells were observed in patients with recurrent aphthous ulceration, this does not preclude NK cell involvement in the lesion sites. Furthermore, with recent studies that suggest a possible implication of varicella zoster virus or cytomegalovirus in recurrent aphthous ulceration, studies of varicella zoster virus and cytomegalovirus specific killer activity in this patient population are hereby encouraged.

Adult↗
PubMed1993

Effects of an acute bolus growth hormone infusion on the human immune system.

This study was performed to examine the in vivo effects of a bolus of recombinant human growth hormone (r-hGH) on the human immune system. In a double blind placebo controlled cross over study, healthy volunteers were given 2 IU r-hGH as an intravenous infusion. r-hGH did not influence the subpopulations of blood mononuclear cells (BMNC), natural killer cell activity, in vitro proliferative responses or production of interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-2, IL-6, IL-8, tumor necrosis factor alpha (TNF alpha), TNF beta or interferon gamma in supernatants from BMNC stimulated with either lipopolysaccharide or phytohemagglutinin. However, two h after infusion a significant neutrocytosis occurred. It is concluded that a bolus infusion of r-hGH to healthy volunteers exerts only minor effects on the human immune system.

Adult↗
PubMed1993

The effect of light, moderate and severe bicycle exercise on lymphocyte subsets, natural and lymphokine activated killer cells, lymphocyte proliferative response and interleukin 2 production.

The purpose of the present study was to evaluate the effect of acute bicycle exercise at different exercise intensities on the immune system. Six healthy volunteers exercised on a bicycle ergometer for 1 h at 25%, 50% and 75% of VO2max with an interval of 2 to 3 weeks. Blood samples were collected in the basal state, at the end of exercise and 2 h later. The absolute concentrations of all lymphocyte subsets increased during and fell after exercise at 50% and 75% of VO2max, but did not change significantly at 25% of VO2max. However, at all exercise levels, the percentage of CD3+ blood mononuclear cells decreased due to a decline in the fraction of CD4+ cells. This decline was most pronounced at 75% of VO2max. The fraction of NK cells expressing either the CD16 or the CD56 marker increased during exercise and declined to prevalues 2 h later, however the changes were most pronounced at 75% of VO2max. The natural killer (NK) cell and lymphokine activated killer (LAK) cell activities (lysis per fixed number of mononuclear cells) were increased during all exercise intensities, but were only suppressed below basal levels after exercise at 75% of VO2max. Indomethacin in vitro abolished the post-exercise suppression of NK cell activity and the proportion of CD14+ monocytes increased 2 h after exercise only at 75% of VO2max. These findings indicate that after exercise NK cell function is inhibited by prostaglandins released by monocytes. During exercise at 50% and 75% of VO2max the proliferative response of blood mononuclear cells (BMNC) following stimulation with phytohaemagglutinin A (PHA) decreased, whereas that following stimulation with interleukin-2 (IL-2) was enhanced. The IL-2 production by BMNC in vitro was markedly decreased during and after exercise at 75% of VO2max and this inhibition could be abolished by indomethacin in vitro. In conclusion, the response of the immune system to exercise depends on exercise intensity. In essence, the response is enhanced during exercise, however, after heavy exercise it is suppressed due to an increased level of prostaglandins produced by the elevated number of monocytes.

Adult↗
PubMed1993

Influence of in vivo hypobaric hypoxia on function of lymphocytes, neutrocytes, natural killer cells, and cytokines.

We have investigated the effects of short-term hypoxia in vivo on the human cellular immune system. Seven young healthy volunteers were placed in a decompression chamber (380 Torr) for 20 min with or without supplemental O2. The leukocyte concentration increased during hypobaric conditions because of an increased concentration of lymphocytes. The absolute and relative concentration of CD16+ natural killer (NK) cells increased markedly during hypoxia and returned to pretest values after 2 h of recovery. The NK cell activity of blood mononuclear cells (BMNC, %lysis/fixed no. of BMNC) boosted with interferon-alpha, interleukin-2 (IL-2), and indomethacin rose in parallel with unboosted NK cell activity during hypoxia. The percentage of CD4+ and CD8+ cells declined during hypoxia, whereas the absolute concentration of both CD8+ cells and CD14+ monocytes increased. Although the BMNC composition varied, the proliferative responses of BMNC after stimulation with phytohemagglutinin, purified derivative of tuberculin, and IL-2 did not change significantly. The in vitro production of interleukin-1 beta and IL-2 in supernatants obtained after stimulation of BMNC with phytohemagglutinin or lipopolysaccharide was not affected. The chemiluminescence response of neutrocytes increased 2 h after hypoxia. It was concluded that acute hypoxia induced marked alterations in the immune system and that the NK cells are especially sensitive to the hypoxic stimulus.

Adult↗
PubMed1993

Effect of 8 wk of bicycle training on the immune system of patients with rheumatoid arthritis.

The effect of 8 wk of progressive bicycle training on the immune system was evaluated in a controlled study on 18 patients with rheumatoid arthritis and moderate disease activity. Maximal O2 uptake increased significantly, whereas heart rate at stage 2 and rate of perceived exertion decreased significantly, in the training group compared with the controls. Resting levels of a number of immune parameters were measured before and after 4 and 8 wk of training. Training did not induce changes in blood mononuclear cell subpopulations, proliferative response, or natural killer cell activity. Furthermore the plasma concentrations of interleukin-1 alpha, interleukin-1 beta, and interleukin-6 did not change in response to training. It is concluded that 8 wk of bicycle training does not influence the immune system of patients with rheumatoid arthritis.

Aged↗
PubMed1993

Natural killer cell activity during head-up tilt-induced central hypovolemia in humans.

Changes in immunological competent blood cells were evoked in seven humans during passive head-up tilt (50 degrees anti-Trendelenburg's position maintained until appearance of presyncopal symptoms). Blood samples were collected after 60 min of rest, when presyncopal symptoms appeared during tilt, and 105 min after tilt-down. Natural killer (NK) cell activity increased during head-up tilt due to a three to four-fold increase in CD16+ NK cells in blood. In support NK cell activity boosted with interferon-alpha and interleukin 2 (IL-2) rose in parallel with unboosted NK cell activity. This effect on NK cells disappeared during recovery but was not suppressed when compared to prevalues. Lymphocyte concentration also increased during head-up tilt. Concentrations of CD3+ and CD4+ T cells were almost stable during head-up tilt, whereas the percentage of CD3+ T cells in relation to blood mononuclear cell (BMNC) concentration decreased, due to a diminished percentage of CD4+ T cells and the marked simultaneous increase in the percentage of CD16+ NK cells. Although changes in the BMNC composition occurred, the proliferative responses of BMNC following stimulation with phytohemagglutinin, purified derivative of tuberculin, or IL-2 did not change significantly. We conclude that head-up tilt induced marked changes in subpopulations of BMNC, especially the CD16+ NK cells, as they were recruited to the blood.

Adult↗
PubMed1992

Levels of complement receptor type one (CR1, CD35) on erythrocytes, circulating immune complexes and complement C3 split products C3d and C3c are not changed by short-term physical exercise or training.

The effect of heavy short-term physical exercise on the levels of complement receptor type one (CR1, CD35) on erythrocytes, the concentrations of circulating immune complexes (IC), and the complement C3 split products C3c and C3d were examined in young healthy males. Fourteen untrained volunteers underwent a 60-min bicycle exercise test at 75% of maximal oxygen uptake (VO2max). Six of the volunteers were exercised twice with an interval of at least one month. Before the second bicycle test they received oral indomethacin. With an interval of at least 1 week, 6 also went through a 60-min back-muscle exercise at up to 30% of VO2max. Blood samples were collected before and during the last few minutes of exercise as well as 2 h and 24 h afterwards. The same parameters were examined once in 29 highly trained racing cyclists. There were no consistent or significant exercise-induced changes in the levels of erythrocyte CR1, circulating IC, C3c nor C3d as measured by an enzyme-linked immunosorbent assay, polyethylene glycol precipitation complement consumption method, and by intermediate gel rocket immunoelectrophoresis, respectively. Neither did these parameters differ from controls in the highly trained group. The results indicate that CR1 on erythrocytes, circulating immune complexes and complement cleavage products C3c and C3d in healthy subjects remain unaffected by short-term heavy physical activity and training.

Adult↗
PubMed1991

Effect of physical exercise on in vitro production of interleukin 1, interleukin 6, tumour necrosis factor-alpha, interleukin 2 and interferon-gamma.

The present study was designed to examine the effect of physical exercise on production of interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-alpha), interleukin-2 (IL-2) and interferon-gamma (IFN-gamma). Ten young, healthy volunteers underwent 60-min bicycle exercise at 75% of maximal oxygen uptake (VO2max). Blood samples were collected before and during the last minutes of exercise, as well as 2 h and 24 h later. Blood mononuclear cells (BMNC) were stimulated in vitro with either bacterial lipopolysaccharide or phytohaemagglutinin, and the supernatants were tested for the above-mentioned cytokines using bioassays as well as ELISA techniques. The production of IL-6 increased significantly 2 h after exercise, furthermore the production of IL-1 alpha and IL-1 beta was enhanced, although only borderline significant. TNF-alpha, IL-2 and IFN-gamma did not fluctuate in relation to exercise. The increased amounts of IL-1 and IL-6 in the supernatants generated from a fixed number of BMNC are most likely explained by the increased percentage and absolute number of blood monocytes 2 h after exercise. IL-2 and IFN-gamma are mainly produced by CD4+ and CD16+ cells. During exercise the CD4+ subset decreases, while the CD16+ subset increases. The finding of unchanged production of IL-2 and IFN-gamma was therefore expected.

Adult↗
PubMed1991

Influence of physical activity on the cellular immune system: mechanisms of action.

This review deals with the effect of acute physical exercise and training status on different components of the immune system. Predominantly studies in humans are mentioned. In relation to acute physical exercise (75% of VO2max, 1 hour) the leukocyte concentration increased; following exercise the neutrophils increased fourfold. The lymhphocyte concentration increased during and decreased following exercise. The percentage of CD3+ cells (pan T cells) declined during exercise, mainly due to a fall in the %CD4+ cells. The %CD16+ cells (NK cells) increased two-fold and returned to prevalue two hours after exercise. The %CD20+ cells (B cells) did not change in relation to exercise, whereas the %CD14+ cells (monocytes) increased two to threefold following exercise. The NK cell activity increased during but decreased following exercise. These increases were due to recruitment of NK cells with a high IL-2 response capacity, whereas the decreased NK activity post-exercise was due to downregulation by prostaglandins released by the elevated concentration of monocytes. During severe, moderate as well as light exercise, the NK cell activity increased, but the post-exercise suppression of the NK cell function was found only following severe exercise, and not after moderate or light exercise, furthermore, only following severe exercise, an increased monocyte concentration was demonstrated. The IL-2-stimulated lymphocyte proliferative response increased due to stimulation of CD16+ cells and did not reflect expression of IL-2 receptors.

Cytokines↗
PubMed1991

Effects of in vivo hyperthermia on natural killer cell activity, in vitro proliferative responses and blood mononuclear cell subpopulations.

This work was designed to test the hypothesis that elevations in body temperature of humans induce immunostimulation. Eight healthy volunteers were immersed in a water bath (water temperature 39.5 degrees C) for 2 h, during which their rectal temperature rose to 39.5 degrees C. On a later day they served as their own controls, being immersed into thermoneutral water (34.5 degrees C) for 2 h. Blood samples were collected before immersion, at body temperatures of 38 degree C, 39 degree C and 39.5 degree C, and 2 h after water immersion. The interleukin-2 (IL-2) enhanced natural killer (NK) cell activity (lysis per fixed number of mononuclear cells), as well as the proportion and total number of NK cells (CD16+ cells), increased significantly during hyperthermia compared with control values. The lymphocyte proliferative responses did not differ significantly between hyperthermia and thermoneutral conditions. The proportion of pan-T (CD3+) cells was maximally depressed 2 h after water immersion. The decreased proportion of CD3+ cells was mainly due to a decreased percentage of CD4+ cells (not significant). The proportion of B cells (CD19+ cells) did not fluctuate significantly, while a marked and significant increase in monocyte proportion (CD14+ cells) was found 2 h after hyperthermia. Two hours after hot water immersion the lymphocyte concentration declined while the neutrophil and monocyte concentrations were augmented. Induced hyperthermia causes significantly increased serum cortisol, plasma norepinephrine and plasma epinephrine concentrations compared to controls. It is possible that the altered immune functions induced by elevated body temperature can be ascribed to altered composition and function of blood mononuclear cells induced by elevated levels of stress hormones.

Adult↗