Article

Natural killer cell activity following 6 weeks of strength training in healthy young males with/without testosterone enanthate administration

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Abstract

There is limited information on the acute immune response to resistance-training programs in combination with short-term administration of the anabolic androgenic steroid, testosterone enanthate (TE), in healthy young males. Eighteen healthy young men were match-paired and randomly assigned in a double-blind manner to either a TE or a placebo (PG) group. All subjects performed a structured resistance-training program while receiving injection of either TE at the dosage of 3.5 mg per kilogram body mass, or saline as placebo, once weekly for 6 weeks. A 10-second all-out cycle sprint test was conducted at the beginning (Week 0) and end (Week 6) of the treatment period. NK, B and T lymphocyte populations were counted and natural killer cytotoxic activity (NKCA) was measured prior to and 5 minutes post the cycle sprint at Weeks 0 and 6. The TE group significantly increased their total work in the 10-second cycle sprint test from Week 0 to Week 6 (p< 0.04), while there was no significant increase for total work in the PG group. There was a significant increase in NKCA from Week 0 to Week 6 (p < 0.05) in the PG group. A significantly higher NKCA in the PG group than in the TE group was found in the post exercise sample in Week 6 (p < 0.04). No significant differences were found between groups for the lymphocyte subsets. The 6-week strength training increased acute NKCA response to anaerobic type of exercise as shown in the PG group. Although dosing of TE enhanced anaerobic performance, the NKCA response in the TE group was lower than that in the PG group. The impact of this altered immune response on athletes' health requires further investigation.

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... The immunological analysis involved the assessment of NK cell numbers, function and phenotypes, CD4 + /CD8 + numbers and further assessment examined cytokine production by Th1 and Th2 cells – (IL-2, IL-4, IL-6, IL-10, tumour necrosis factor (TNF)-α and interferon (IFN)-γ). All methods were performed using previously described methods (Marshall Gradisnik, et al., 2008). Whole blood was collected into either heparinised or EDTA blood collection tubes and PBMC were isolated from using Ficoll–Hypaque density gradient centrifugation (Amersham Pharmacia Biotech AB, Uppsala, Sweden). ...
... Whole blood was collected into either heparinised or EDTA blood collection tubes and PBMC were isolated from using Ficoll–Hypaque density gradient centrifugation (Amersham Pharmacia Biotech AB, Uppsala, Sweden). Determination of the lymphocyte phenotypic subsets (CD4 + /CD8 + ) was performed using IMK lymphocyte test kit (Becton Dickinson Immunocytometry Systems, California, USA) as previously described (Marshall-Gradisnik, et al., 2008). List mode parameters were collected for 10,000 cells within the lymphocyte gate and positive staining was calculated based on the subsets control specimens. ...
... Lymphocytes populations were identified by forward and side-scatter analyses. The NK lymphocyte cytotoxicity was assessed as previously described (Marshall-Gradisnik, et al., 2008). Briefly, PBMCs were isolated from whole blood using ficoll-Hypaque (GE Healthcare) through density gradient centrifugation. ...
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... The T cell granules contain perforins, cytolysins, proteases, and granulolysins that are all designed to degrade a cell [128]. The main focus of the review is pro-inflammatory CD8 + and CD4 + (T h 1, T h 2, and T h 17) and immunosuppressive regulatory CD4 + (T reg ) cells as they relate to muscle physiology; however, B cells and Natural Killer cells have been found in myopathies and post-exercise, respectively [132][133][134]. ...
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... On other hand, there is limited information concerning the influence of ST on NK cells. Marshall-Gradisnik et al (169) performed a 10-s all-out cycle sprint test in healthy young males at week 0 and at week 6 and found a significant increase in NK cytotoxic activity (NKCA), whilst the NK number did not significantly increase. Another recent study found that the recruitment of NK cells depends on the levels of lactic acid, higher levels of lactate increase NK cell activity and number after four sprint intervals accumulating to 1,000 meters at 85% of a subject's maximal velocity in 53 sprinters (aged 22.2 ± 1.1 years) (167). ...
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... Testosterone is reported to inhibit proliferation and differentiation of lymphocytes, dehydroepiandrosterone (DHEA) seems either to inhibit or enhance T cell expansion and reduce IL-4 and IL-10 release [102,103]. Upon androgen administration NK cell cytotoxic activity is inhibited and immunoglobulins suppressed [104]. Considering that the male population shows higher levels of androgens, and males show a lower autoimmune incidence, the common hypothesis is that androgens confer protection against autoimmunity. ...
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... I.e., T cell expansion is both inhibited or enhanced by dehydroepiandrosterone (DHEA) [67], whereas T cell proliferation and differentiation is counteracted by testosterone [68][69][70]. Also, supraphysiological doses of androgens are able to decrease natural killer (NK) cells cytotoxic activity and suppress immunoglobulins [65,71,72]. Albeit some controversial reports, it is generally accepted that androgens confer protection against autoimmunity, considering that androgens are higher in males who, in turn, show a lower autoimmune incidence. ...
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... Testosterone reduces the proliferation and differentiation of lymphocytes (Sakiani et al., 2013;Sthoeger et al., 1988;Wyle and Kent, 1977), and the use of androgens may suppress immunoglobulins, and in particular IgA (Calabrese et al., 1989;Hirota et al., 1976). Androgens, including supraphysiological doses of testosterone may inhibit the cytotoxic activity of NK cells (Callewaert et al., 1991;Marshall-Gradisnik et al., 2008;Sulke et al., 1985). Given that the effects of androgens may vary considerably relative to the level of exposure, and that multiple factors may contribute to the immune profile in females, the potential role of endogenous androgens in gender specific immune function remains unknown. ...
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Natural killer cell cytotoxic activity (NKCA) and the proportion of circulating natural killer (NK) cells were compared in 10 weight trainers versus 10 sedentary controls. Height, weight, and percent body fat did not differ significantly between the two groups. The average subject in the weight training group was able to squat 1.8 times his body weight, lifted weight more than 6 hours a week, and had been a weight trainer for nearly 9 years. NKCA did not differ between the weight training and control groups (166 +/- 33 vs. 155 +/- 27 lytic units, respectively), and the proportion of NK cells was the same (15.1 +/- 1.9% vs. 15.1 +/- 1.3%, respectively). The results of this cross-sectional study of long-term weight trainers and sedentary controls indicate no significant differences in NKCA. The two groups did not differ in the distribution of lymphocytes or natural killer cells, lending strength to this conclusion. (C) 1994 National Strength and Conditioning Association
Article
Little is understood about the immune responses to heavy resistance exercise. The purpose of this investigation was to determine the influence of physical strength and the ability to do more total work on lymphocyte proliferation after an acute bout of heavy resistance exercise. A group of 50healthy but non-strength trained women were recruited for the study and tested for their one repetition maximum (i.e. 1RM or maximal mass lifted once). From the normal distribution of strength the top and bottom 8women [mean age 22.5(SD3.1)years] were asked to volunteer to define our two groups (i.e. high strength and low strength). The two groups were significantly different (P<0.05) in 1RM squat strength [low strength 39.9(SD4.6)kg, 0.65(SD0.08)kg·kg body mass–1 and high strength 72.2(SD10.7)kg, 1.1(SD0.12)kg·kg body mass–1] but were not significantly different in body mass, age, activity levels, and menstrual status (all in same phase). Each performed a resistance exercise protocol consisting of six sets of 10RM squats with 2min rest between the sets. The 10RM loads and total work were significantly greater in the high strength group than in the low strength group. Blood samples were obtained pre-exercise and immediately post-exercise for test for lactate (significant increase with exercise) and cortisol (no changes) concentrations with no differences noted between groups. Immunological assays on the blood samples determined the incorporation of tritiated thymidine by lymphocytes in responses to concanavalin A (ConA), phytohemagglutinin (PHA), and pokeweed mitogen (PWM). Following the squat exercise, there was a significant decrease in lymphocyte responsiveness to PWM in the high strength but not in the low strength group for both total proliferation and proliferation adjusted per B or T cell. On the other hand, lymphocytes from the low strength group proliferated to a significantly greater extent (adjusted per T cell) in response to ConA and PHA. These data indicate that the heavy resistance exercise protocol reduced the lymphocyte proliferative responses only in the stronger group of subjects. This effect may have been due to the high absolute total work and the greater exercise stress created by the resistance exercise protocol in the high strength group. Therefore, individuals performing at the same relative exercise intensity (i.e. 10RM) in a resistance exercise protocol may have different immune responses stemming from differences in absolute total work performance.
Article
Use of testosterone enanthate has been shown to significantly increase strength within 6–12 weeks of administration (2, 9), however, it is unclear if the ergogenic benefits are evident in less than 6 weeks. Testosterone enanthate is classified as a prohibited substance by the World Anti-Doping Agency (WADA) and its use may be detected by way of the urinary testosterone/epitestosterone (T/E) ratio (16). The two objectives of this study were to establish (a) if injection of 3.5 mg·kg−1 testosterone enanthate once per week could increase muscular strength and cycle sprint performance in 3–6 weeks; and (b) if the WADA-imposed urinary T/E ratio of 4:1 could identify all subjects being administered 3.5 mg·kg−1 testosterone enanthate. Sixteen healthy young men were match-paired and were assigned randomly in a double-blind manner to either a testosterone enanthate or a placebo group. All subjects performed a structured heavy resistance training program while receiving either testosterone enanthate (3.5 mg·kg−1) or saline injections once weekly for 6 weeks. One repetition maximum (1RM) strength measures and 10-second cycle sprint performance were monitored at the pre (week 0), mid (week 3), and post (week 6) time points. Body mass and the urinary T/E ratio were measured at the pre (week 0) and post (week 6) time points. When compared with baseline (pre), 1RM bench press strength and total work during the cycle sprint increased significantly at week 3 (p < 0.01) and week 6 (p < 0.01) in the testosterone enanthate group, but not in the placebo group. Body mass at week 6 was significantly greater than at baseline in the testosterone enanthate group (p < 0.01), but not in the placebo group. Despite the clear ergogenic effects of testosterone enanthate in as little as 3 weeks, 4 of the 9 subjects in the testosterone enanthate group (44%) did not test positive to testosterone under current WADA urinary T/E ratio criteria.
Article
Female mice were given a single intraperitoneal injection of testosterone immediately after irradiation and marrow reconstitution. Thirty days later testosterone had no suppressive effect on the recovery of thymus and spleen weights. Testosterone had no effect on the graft-versus-host reaction. Testosterone had no influence on the survival of the skin homografts. However, the plaque-forming cell response to sheep erythrocytes in the spleen was dramatically suppressed by testosterone. Histological observations revealed marked inhibition of lymphoid regeneration selectively in the thymus-independent areas of the peripheral lymphoid tissues. These results suggest that testosterone would act mainly on the differentiation of stem cells toward the population of bone marrow-derived B lymphocytes. The immune response to sheep erythrocytes was restored completely 90 days after testosterone administration. Testosterone given to normal adult mice can also have suppressive activity on the immune system 30 days after a single intraperitoneal injection.
Article
Human PMNs have well-described responses to beta-adrenergic catecholamines; these include elevation of cellular levels of cyclic AMP and inhibition of the release of lysosomal contents. Using the radioactive beta-adrenergic antagonist (-)-[3H]DHA in direct ligand-binding studies, we have identified and characterized beta-adrenergic receptors on particulate preparations of PMNs. These particulates bind DHA rapidly (t1/2 less than 1 min) and reversibly (t1/2 = 8 to 9 min). DHA binding is saturable and of high affinity (dissociation constant = 1 to 5 nM) and low capacity (870 +/- 128 receptors/cell, mean +/- S.D.) to a single class of binding sites. Competition for DHA binding sites by both beta-adrenergic agonists and antagonists is stereoselective [(-)-isomers more potent that (+)-isomers]. The rank order of potency of adrenergic agents in such competition studies indicates that these receptors are of the beta2 type. Since PMNs can be obtained in high purity with relative ease, the combined use of pharmacologic and ligand-binding studies in PMNs provide a useful system for studying beta-adrenergic receptors and their function in human subjects.
Article
Ten healthy males (mean age 22.3 +/- 0.8 yr) pedaled with maximal effort for 30 s against a workload adjusted prior to the start of the test to 0.98 N.kg body mass-1. Blood samples were collected before, and 3 min and 1 h following exercise. Peak and average power mean values were 1020 +/- 51 and 738 +/- 34 W, respectively. Total leukocytes increased 40% in response to the exercise bout, but were 16% below pretest levels after 1 h of recovery (F = 123, P < 0.001). Neutrophils and lymphocytes represented approximately 60% and 30% of the leukocytosis, respectively. Lymphocytes increased 30% following exercise, but were 36% below pretest levels after 1 h recovery (F = 56.4, P < 0.001). The post-test lymphocytosis can be explained primarily from the 176% increase in natural killer cells (NK) and 28% increase in cytotoxic/suppressor T cells, while the 1-h recovery lymphopenia occurred because of a sharp decrease in total T cells and a moderate decrease in NK cells. No significant changes in lymphocyte proliferative response or serum immunoglobulin levels were found when appropriate adjustments for changes in plasma volume or lymphocyte subset changes were made. Plasma epinephrine increased 300% in response to the exercise bout, and best explains the measured changes in circulating levels of lymphocyte subsets. These results demonstrate that changes in circulating levels of leukocyte and lymphocyte subsets, especially NK cells, occur rapidly in response to 30 s of brief, heavy exertion.
Article
The present study was designed to test the hypothesis that the changes in natural killer (NK) cell activity in response to physical exercise were mediated by increased epinephrine concentrations. Eight healthy volunteers 1) exercised on a bicycle ergometer (60 min, 75% of maximal O2 uptake) and 2) on a later day were given epinephrine as an intravenous infusion to obtain plasma epinephrine concentrations comparable with those seen during exercise. Blood samples were collected in the basal state, during the last minutes of exercise or epinephrine infusion, and 2 h later. The NK cell activity (lysis/fixed number of mononuclear cells) increased during exercise and epinephrine infusion and dropped below basal levels 2 h afterward. The increased NK cell activity during exercise and the epinephrine infusion resulted from an increased concentration of NK (CD16+) cells in the peripheral blood. On the other hand, the decreased NK cell activity demonstrated 2 h after exercise and epinephrine infusion did not simply reflect preferential removal of NK cells from the blood, because the proportion of CD16+ cells was normalized. On the basis of the finding that indomethacin abolished the suppressed NK cell activity in vitro and the demonstration of a twofold increase in the proportion of monocytes (CD14+ cells) 2 h after exercise and epinephrine infusion, we suggest that, after stress, prostaglandins released by monocytes are responsible for downregulation of NK cell function. Our findings support the hypothesis that increased plasma epinephrine during physical stress causes a redistribution of mononuclear subpopulations that results in altered function of NK cells.
Article
The majority of human NK cells express low affinity IgG Fc receptors (CD16+), whereas a minor subset of NK cells lack Fc receptor expression (CD16-). In contrast to CD16+ NK cells that express only p75 IL-2 receptors, CD16- NK cells constitutively co-express both p75 and p55 IL-2 receptors in vivo and preferentially respond to low concentrations of IL-2 with increased cytolytic activation and proliferation. Scatchard analysis demonstrated the presence of approximately 1,200 high affinity (approximately 25 pM kD) and approximately 9,600 intermediate affinity (approximately 2 nM kD) IL-2 receptors on CD16- NK cells. CD16+ NK cells expressed only a single intermediate affinity IL-2 receptor of approximately 1.9 nM kD (approximately 9,000 sites per cell). The IL-2 binding data thus substantiated the phenotypic and functional studies and definitively show that the differential responsiveness of CD16- and CD16+ NK cells to IL-2 is manifested through different affinity IL-2 receptors.
Article
Dynamic exercise increases the number of beta-adrenergic receptors in mixed lymphocytes by a mechanism that is incompletely understood. In a set of in vivo studies, we have investigated the effects of dynamic exercise on the subset distribution of circulating lymphocytes and on the number of beta-adrenergic receptors in each of these subsets in two groups of patients. In healthy subjects, exercise increased plasma norepinephrine and epinephrine and caused lymphocytosis. Whereas the number of Thelper cells increased only modestly, the number of Tsuppressor/cytotoxic and natural killer cells more than tripled. The number of beta-adrenergic receptors varied among subsets but was not significantly altered by dynamic exercise in any subset except natural killer cells (35% increase, p = 0.0302). In a group of patients with congestive heart failure, dynamic exercise increased plasma norepinephrine but did not alter plasma epinephrine and did not cause significant lymphocytosis. We did not detect any significant alterations of circulating leukocyte subsets or beta-adrenergic receptors in any of these subsets after exercise. A combined analysis of healthy patients and heart failure patients revealed a significant correlation between increases in plasma epinephrine and increases in circulating lymphocytes. We conclude that the exercise-induced increase in beta-adrenergic receptors of mixed lymphocytes is predominantly caused by a redistribution of circulating cell subsets that differ in their beta-adrenergic receptor number. This appears to be mediated by epinephrine rather than norepinephrine.
Article
As an untoward effect of chronic anabolic steroid use, immunologic alterations may be induced. To evaluate this possibility five commercially available steroids with various types of structural differences were studied in male Sprague-Dawley rats. Animals were divided into five groups and treated with testosterone (Group 1), testosterone propionate (Group 2), testolactone (Group 3), oxandrolone (Group 4), and stanozolol (Group 5). Androgenic anabolic steroids were administered daily, subcutaneously dissolved in oil, at a dose of 1.1 mg/kg. Immune alterations were assessed by skin-test responses to phytohemagglutinin. After five days of treatment (1.1 mg/kg/day) a significant immuno-suppression was observed with all groups. However, by day 10, groups 3, 4, and 5 showed an immuno-stimulation. Using oxandrolone as the model stimulant, serum testosterone levels were significantly suppressed, while castration abolished the stimulatory effect. These observations indicate that immune alterations do occur with anabolic steroids which are immuno-suppressive when the steroid nucleus is intact and immuno-stimulatory with nuclear alterations. It appears that these changes are associated with altered gonadal testosterone release.
Article
The immune response was assessed in 13 competitive bodybuilders self-administering anabolic-androgenic steroids and ten competitive bodybuilders not administering these drugs. Laboratory assessment included the number and relative distribution of T-cells, T-helper/inducer cells, T-cytotoxic/suppressor cells, activated T-cells, lymphocyte transformation to the mitogens, pokeweed mitogen (PWM), phytohemagglutinin (PHA), Concanavalin-A (CON-A), Staphylococcus aureus Cowan strain I (SAC), serum immunoglobulins, and natural killer (NK) activity. There were no significant differences in T-cell subsets among steroid users and non-users, but lymphocyte transformation studies revealed that the anabolic-androgenic steroid-using group had enhanced proliferative ability to the B-cell mitogen, SAC, in comparison to non-bodybuilding controls. NK activity was significantly (P less than 0.05) augmented in the anabolic-androgenic steroid users but not in the non-using bodybuilders. Serum immunoglobulin levels, in particular IgA, were significantly (P less than 0.017) lower in the steroid-using group. Four of 13 steroid users and three of eight non-steroid-using bodybuilders had detectable antinuclear antibodies. These studies indicate that 1) anabolic-androgenic steroid use as practiced by contemporary athletes is a potent modulator of immune responsiveness and 2) autoantibodies are prevalent in strength-trained men even in the absence of anabolic steroid use.
Article
The present study was designed to examine the effect of physical exercise on human natural killer (NK) cells. Six healthy volunteers underwent two different acute physical exercise tests with an interval of at least 1 week: (1) 60 min bicycle exercise at 80% of maximal oxygen uptake (VO2max) and (2) 60 min back-muscle training at up to 29% 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 NK cell activity (lysis/fixed number of mononuclear cells) increased during bicycle exercise, dropped to a minimum 2 h later and returned to pre-exercise levels within 24 h. Back-muscle exercise did not significantly influence NK cell activity. Plasma levels of adrenaline, noradrenaline, and cortisol were elevated during bicycling, but not during back-muscle exercise, indicating that exercise intensity is a determinant of NK cell activity. During bicycle exercise the NK cell subset (CD16- cells) of mononuclear cells increased significantly. Furthermore an improved interleukin 2 (IL-2) boosting of the NK cell activity was found during work as compared to IFN-alpha and indomethacin-enhanced NK cell activity. These results indicate that NK cells with a high IL-2 response capacity are recruited to the peripheral blood during exercise. The decreased NK cell activity demonstrated 2 h after work was probably not due to fluctuations in size of the NK cell pool, since the proportion of CD16+ cells was normal. The finding that indomethacin fully restored the suppressed NK cell activity in vitro and the demonstration of a twofold increase in monocyte (CD20+ cells) proportions 2 h after work, strongly indicate that prostaglandins released by monocytes during the heavy physical exercise are responsible for the down-regulation of the NK cells.
Article
To examine the relationship between stress and upper respiratory tract infection, 235 adults aged 14-57 years, from 94 families affiliated with three suburban family physicians in Adelaide, South Australia, participated in a six-month prospective study. High and low stress groups were identified by median splits of data collected from the Life Events Inventory, the Daily Hassles Scale, and the General Health Questionnaire, which were administered both before and during the six months or respiratory diary data collection. Using intra-study stress data, the high stress group experienced significantly more episodes (mean of 2.71 vs. 1.56, p < 0.0005) and symptom days (mean of 29.43 vs. 15.42, p = 0.005) of respiratory illness. The two groups were almost identical with respect to age, sex, occupational status, smoking, passive smoking, exposure to air pollution, family size, and proneness to acute respiratory infection in childhood. In a multivariate model with total respiratory episodes as the dependent variable, 21% of the variance was explained, and two stress variables accounted for 9% of the explained variance. Significant, but less strong relationships were also identified between intra-study stress variables and clinically 'definite' episodes and symptom days in both clinically definite and total respiratory episodes. Pre-study measures of stress emphasized chronic stresses and were less strongly related to measures of respiratory illness than those collected during the study. However, significantly more episodes (mean of 2.50 vs. 1.75, p < 0.02) and symptom days (mean of 28.00 vs. 17.06, p < 0.03) were experienced in the high stress group. In the multivariate analyses, pre-study stress remained significantly associated with total respiratory episodes and symptom days in total and 'definite' respiratory episodes. In all of the multivariate analyses performed, sex (female) and age also appeared as important correlates of respiratory illness.
Article
The lymphokine interleukin-2 (IL-2; also termed T-cell growth factor) causes the proliferation of activated T-cell clones1,2. Effector T-cell lines exhibiting suppressor, helper and cytotoxic activities have been established by growth of appropriately stimulated cells in IL-2-containing medium3,4. In addition, IL-2 has been shown to provide requisite T-cell `help' in a number of in vitro immune response assays, including the generation of cytotoxic T cells from thymocyte (and nude spleen cell) cultures5 and the induction of erythrocyte-specific antibody in T cell-deficient populations6. We report here a further activity of IL-2, one previously attributed solely to interferon-the ability to augment the cytotoxic activity of natural killer (NK) cells. This conclusion was reached from the observation that preparations of IL-2, which lacked interferon, caused a rapid increase in NK cell activity. This ability to augment cytotoxity was removed from IL-2 preparations, not only by absorption with IL-2 receptor bearing cells, but also by precipitation with a monoclonal antibody directed against IL-2.
Article
The proliferative response of murine natural killer (NK) cells to a T cell growth factor, interleukin 2 (IL 2) was investigated by using the NK-enriched, low-density fractions (F.1) and NK-depleted, T cell-enriched, and high-density fractions (F.3) of normal spleen cells after Percoll-discontinuous density gradient centrifugation. When F.1 and F.3 cells were cultivated with IL 2-containing medium without addition of any other factors, like lectins, feeder layer, or macrophage products, F.1 but not F.3 cells showed an IL 2-dependent proliferative response. Growing populations showed a potent NK activity and consisted largely of cells with a morphology of large granular lymphocyte (LGL) and a surface marker profile characteristic for murine NK cells. By limiting dilution in the liquid culture and colony formation in the soft agar medium, F.1 but not F.3 cells showed a high frequency of clonal replication in IL 2. Almost all growing colonies in either medium showed a typical morphology of LGL. Further, F.1 cells treated with anti-asialo GM1 antibody and C, from which NK cells and cytolytic activity were almost completely abrogated and for which T cells were enriched, conversely formed a few IL 2-dependent colonies. From the colonies in soft agar, 11 clones, all of which showed a typical morphology (LGL), a typical surface profile with the exception of lacking IgG-Fc receptors for NK cells (Thy-1 +/-, Ly-5+, ASGM1+, Lyt-1-, Lyt-2-, Fc gamma R-), and a cytotoxic activity of activated nature, were established and maintained for a period of longer than 1 yr in the medium containing IL 2 alone. These results indicate that a major population in the naive spleens of normal mice that respond directly to IL 2 and clonally replicate without other stimulating factors may be NK cells.
Article
Thymosin fraction 5, an immunopotentiating thymic preparation, significantly increases the cytotoxic capacity of NK cells isolated from the spleen. This stimulation is inhibited by testosterone and estradiol.
Article
The main methods for the evaluation of natural killer (NK, CD16+ CD56+) cells, interleukins and related subsets of lymphocytes are briefly described. Moderate endurance exercise causes either no change or an increase in lymphocyte and NK cell counts, total T cell (CD3+) count, the ratio of T helper (CD3+ CD4+) to T suppressor (CD3+ CD8+) cells, mitogen-induced lymphocyte proliferation, serum immunoglobulin levels and in vitro immunoglobulin production. Plasma levels of interleukin-1 increase but interleukin-2 (IL-2) levels generally fall. Decreases in plasma IL-2 levels reflect increased expression of beta (CD122) receptors for IL-2, and thus increased binding of IL-2, changes in cell distribution or a lesser production of IL-2 by peripheral blood mononuclear cells. Exercise to exhaustion induces adverse changes in many of these indices of immune function, particularly if the physical activity is accompanied by psychological or environmental stress. Moderate, appropriately graded training reduces the adverse reactions initially associated with a given bout of exhausting exercise, and cross-sectional comparisons show an increased expression of beta IL-2 receptors on the peripheral blood mononuclear cells of trained individuals. However, excessive training, nutrient deficiency and/or muscle damage has adverse consequences for both the production of interleukins and the response of the immune system to these cytokines.
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.
Article
The effect of 45 min of high- (80% VO2max) vs moderate- (50% VO2max) intensity treadmill exercise on natural killer cell cytotoxic activity (NKCA) was investigated in 10 well-conditioned (66.0 +/- 1.9 ml.kg-1.min-1), young males (22.1 +/- 1.3 yr). Blood samples were taken before and immediately after exercise, with three more samples taken during 3.5 h of recovery, and analyzed for proportion of NK cells (CD3-CD16+CD56+) and NKCA. Exercise at 80% vs 50% VO2max resulted in a greater immediate postexercise increase in proportion of NK cells, followed by a 1-h and 2-h decrease below preexercise levels for both intensity conditions. NKCA rose significantly above preexercise levels following high- but not moderate-intensity exercise. For both exercise intensity conditions, NKCA tended to drop below preexercise levels by 1 h postexercise, rising back to preexercise levels by 3.5 h postexercise. When NKCA was expressed on a per-NK cell basis, however, no change relative to preexercise levels occurred following moderate-intensity exercise, while a significant increase occurred after 2-h recovery from high-intensity exercise. These data demonstrate that both high- and moderate-intensity exercise are associated with significant shifts in circulating proportions of NK cells which significantly influence interpretation of NKCA data based on assays using separated mononuclear cells.
Article
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.
Article
Anabolic androgenic steroids (AS) have recently been placed on the Food and Drug Administration's (FDA's) list of controlled substances, because of the adverse effects seen in athletes taking accelerated dosages in attempts to enhance performance. Reported deleterious effects on abusers include sterility, gynecomastia in males, acne, balding, psychological changes, and increased risks of heart disease and liver neoplasia. Considering the roles of the immune and neuroendocrine systems and their interactions in many of these pathologies, it is important to determine the effects of these derivitized androgens on this connection. Little is known in this respect. We therefore determined the effects of anabolic steroids on certain immune responses and their effects on the extrapituitary production of corticotropin by lymphocytes. We present evidence that (1) both 17-beta and 17-alpha esterified AS, nandrolone decanoate and oxymethenelone, respectively, significantly inhibited production of antibody to sheep red blood cells in a murine abuse model; (2) the control androgens testosterone and dehydroepian-drosterone (DHEA) or sesame seed oil vehicle had no significant effects on antibody production; (3) nandrolone decanoate and oxymethenelone directly induced the production of the inflammatory cytokines IL-1 beta and TNF-alpha from human peripheral blood lymphocytes but had no effect on IL-2 or IL-10 production; (4) control androgens had no direct cytokine inducing effect; (5) nandrolone decanoate significantly inhibited IFN production in human WISH and murine L-929 cells; and (6) nandrolone decanoate significantly inhibited the production of corticotropin in human peripheral blood lymphocytes following viral infection. These data indicate that high doses of anabolic steroids can have significant effects on immune responses and extrapituitary production of corticotropin. Furthermore, the mouse model should provide an effective means by which to study other deleterious effects of anabolic steroid abuse in humans.
Article
To examine the effects of verbal encouragement on the peak force of the elbow flexors during an isometric muscle action. A crossover design whereby 20 subjects were divided into 10 2 x 2 Latin squares was undertaken. Peak forces were measured on a Kin-Com dynamometer, and electromyographic (EMG) activity was also recorded from the biceps brachii. All subjects completed trials with and without verbal encouragement. Mean peak force increased (P < 0.05) from 296 to 311 N (5%) when verbal encouragement was presented. A spectral analysis of the EMG activity showed no changes (P > 0.05) to the median frequency in the condition where verbal encouragement was present. These findings have ramifications for training and exercise therapy. An awareness of the effects of verbal encouragement is important when motivating athletes and patients to attain maximum performance during exercise.
Article
Acute muscular exercise induces an increased neutrophil count concomitant with recruitment of natural killer (NK), B and T cells to the blood as reflected by an elevation in the total lymphocyte count. Meanwhile, following intense exercise of long duration the lymphocyte count declines, non-MHC-restricted cytotoxicity is suppressed, but the neutrophil concentration increases. In relation to eccentric exercise involving muscle damage, the plasma concentrations of interleukin-1, interleukin-6 and the tumor necrosis factor are elevated. In this review we will propose a model based on the possible roles that stress hormones play a mediating the exercise- related immunological changes: adrenaline and to a lesser degree noradrenaline are responsible for the immediate effects of exercise on lymphocyte subpopulations and cytotoxic activities. The increase in catecholamines and growth hormone mediate the acute effects of exercise on neutrophils, whereas cortisol may be responsible for maintaining lymphopenia and neutrocytosis after exercise of long duration. Lastly, the role of beta-endorphin is less clear, but the cytokine response is closely related to muscle damage and stress hormones do not seem to be directly involved in the elevated cytokine level. Other possible mechanisms of exercise-induced immunomodulation may include the so-called glutamine hypothesis, which is based on the fact that skeletal muscle is an important source of glutamine production and that lymphocytes are dependent on glutamine for optimal growth. Furthermore, physiological changes during exercise, e.g. increased body temperature and decreased oxygen saturation may also in theory contribute to the exercise-induced immunological changes.
Article
T cells are considered to be unresponsive to testosterone due to the absence of androgen receptors (AR). Here, we demonstrate the testosterone responsiveness of murine splenic T cells in vitro as well as the presence of unconventional cell surface receptors for testosterone and classical intracellular AR. Binding sites for testosterone on the surface of both CD4(+) and CD8(+) subsets of T cells are directly revealed with the impeded ligand testosterone-BSA-FITC by confocal laser scanning microscopy (CLSM) and flow cytometry, respectively. Binding of the plasma membrane impermeable testosterone-BSA conjugate induces a rapid rise (<5 s) in [Ca2+]i of Fura-2-loaded T cells. This rise reflects influx of extracellular Ca2+ through non-voltage-gated and Ni2+-blockable Ca2+ channels of the plasma membrane. The testosterone-BSA-induced Ca2+ import is not affected by cyproterone, a blocker of the AR. In addition, AR are not detectable on the surface of intact T cells when using anti-AR antibodies directed against the amino and carboxy terminus of the AR, although T cells contain AR, as revealed by reverse transcription-polymerase chain reactions and Western blotting. AR can be visualized with the anti-AR antibodies in the cytoplasm of permeabilized T cells by using CLSM, though AR are not detectable in cytosol fractions when using the charcoal binding assay with 3H-R1881 as ligand. Cytoplasmic AR do not translocate to the nucleus of T cells in the presence of testosterone, in contrast to cytoplasmic AR in human cancer LNCaP cells. These findings suggest that the classical AR present in splenic T cells are not active in the genomic pathway. By contrast, the cell surface receptors for testosterone are in a functionally active state, enabling T cells a nongenomic response to testosterone.
Article
To determine the effect the steroid, testosterone enanthate (TE) had on upper body strength, body composition and health. Twenty one male weight training subjects were randomly assigned in a double blind method to either a 3.5 mg(-1) x kg(-1) TE (n=11) or placebo (n=10) weight training group. The subjects were monitored during a 12 week administration phase and a subsequent 12 week follow up phase. Subjects were tested on a number of strength and size measurements, whilst having their health monitored. The results from the study revealed that the testosterone/weight training group improved significantly (p<0.05) more than the placebo/weight training group during and immediately after the administration phase on a 1 repetition maximum bench press. With regards to body composition, body weight, arm girth and rectus femoris circumference all increased significantly greater in the TE group compared to the placebo. Furthermore, the abdomen skinfold showed significant decreases in the TE group compared to the placebo group at post testing, follow up mid testing and the follow up post testing occasions. With the exception of the abdomen skinfold no within or between group differences were evident following a cycling off period of 12 weeks. Changes to baseline health indicators were reported in some subjects following testosterone usage. This included an average elevation in systolic blood pressure in all TE subjects by 10 mm Hg, a mild increase in hereditary frontal alopecia, increased muscle tightness (hamstrings and pectorals), a mild increase in libido over the first two weeks with a subsequent fall to normal, mild acne, subjective changes to personality including an increase in aggression, irritability and positive mood responses. Consequently, moderate doses of TE combined with weight training can result in short term significant changes in upper body strength and body composition, with corresponding changes to baseline health in some individuals.
Article
The change of plasma catecholamine concentration correlates with the change of natural killer (NK) activity and NK cell number in peripheral blood mononuclear cells (PBMC) during and after moderate exercise. We studied the causal relation between exercise-induced catecholamine and expression of adhesion molecules on NK cells during and after exercise. The expression of CD44 and CD18 on CD3(-)CD56(+) NK cells was significantly reduced during exercise (P < 0.01). When PBMC were stimulated with 10(-8)M norepinephrine in vitro, the expression of these adhesion molecules on CD3(-)CD56(+) NK cells was downmodulated within 30 min. The binding capacity of NK cells to a CD44 ligand, hyaluronate, was reduced by the stimulation with norepinephrine (P < 0.01). The intravenous injection of norepinephrine in mice decreased the expression of CD44 and CD18 on CD3(-)NK1.1(+) cells (P < 0.01) and increased the number of CD3(-)NK1.1(+) cells in PBMC (P < 0.01). These findings suggest that exercise-induced catecholamines modulate the expression of adhesion molecules on NK cells, resulting in the mobilization of NK cells into the circulation.
Natural killer cells: modulation by intensity and duration of exercise
  • Ga Gannon
  • Pn Shek
  • Rj Shephard
Gannon GA, Shek PN, Shephard RJ (1995). Natural killer cells: modulation by intensity and duration of exercise. Exerc Immunol Rev 1: 26-48.
Effect of high versus moderate intensity exercise training on natural killer cell activity
  • Dc Nieman
  • Ar Miller
  • Da Hensen
  • Bj Warren
  • G Gusewitch
  • Rl Johnson
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