Natural killer cell lytic activity and CD56dim and CD56bright cell distributions during and after intensive training

Decreased exercise-induced natural killer cell redistribution in multiple sclerosis

BACKGROUND

Exercise may have beneficial effects in MS, remaining controversial its possible disease-modifying effects and which mechanisms might be involved. We evaluated whether exercise-induced lymphocyte redistribution differ in MS patients as compared to controls.

METHODS

Exercise was assessed in 12 relapsing-remitting MS patients and 11 controls in a cycle ergometer, obtaining blood samples before exercise, at maximal exercise capacity (T1), and after resting (T2). Peripheral lymphocytes were evaluated by flow cytometry, assessing chemokine receptor expression to study cell trafficking properties.

RESULTS

Lymphocyte subsets in all cases increased after exercise and decreased at resting. However, total natural killer (NK) cells in patients as compared to controls had a lower exercise-induced redeployment at T1 (696 ± 581 cells/µL vs.1502 ± 641 cells/µL, p < 0.01). Evaluating NK cell subsets, CD56bright NK cells numbers decreased in peripheral blood in MS patients after resting (T2), contrasting with values remaining above baseline in healthy controls. NK cells mobilized after exercise at T1 in controls, as compared to patients, had a higher CX3CR1 expression (1402 ± 564/µL vs. 615 ± 548 cell//µL, p < 0.01).

CONCLUSION

Exercise-induced redeployment of NK cells may be reduced in MS patients, as well as their migration capabilities, pointing to potential immunological mechanisms to be enhanced by exercise training programs.

Effects of Ingesting Food Containing Heat-Killed Lactococcus lactis Strain Plasma on Fatigue and Immune-Related Indices after High Training Load: A Randomized, Double-Blind, Placebo-Controlled, and Parallel-Group Study

Lactococcus lactis strain Plasma (LC-Plasma) is a unique lactic acid bacterium that activates plasmacytoid dendritic cells (pDCs). We evaluated the effect of LC-Plasma on fatigue indices and dendritic cells activity in athletes after 14 days’ continuous exercise load. Thirty-seven participants were divided into two groups and consumed placebo (PL) or LC-Plasma capsules (containing 100 billion cells) daily for 14 days. Maturation markers on dendritic cells, blood parameters, physiological indices, and fatigue-related indices were recorded on days 1 and 15 (before and after exercise). Cumulative days of symptoms relating to physical conditions were also recorded during the continuous exercise period. We observed that CD86 as a maturation marker on pDCs was significantly higher and that cumulative days of fatigue were significantly fewer in the LC-Plasma group than in the Placebo group on day 15. We also conducted 2 h ergometer exercise on day 15 to evaluate fatigue. The results showed that autonomic fatigue parameters (LF/HF) were significantly lower in the LC-Plasma group. These results suggest that LC-Plasma supplementation alleviates fatigue accumulation and increases pDC activity caused by a continuous high training load.

Review on the Effect of Exercise Training on Immune Function

Exercise training is not only a necessary means to improve the level of exercise, but also an important means to improve the body's immunity. Different time, intensity, items, and forms of exercise training have different effects on the body's immune function. As a double-edged sword to improve the body's immune function, exercise training is a different reaction mechanism of different immune cells after exercise training. This paper combined with foreign scholars' studies on the immune function of the body of literature from different exercise intensity, different time, different sports, different movement forms, and different external environment such as angle of view for athletes body's immune cells and humoral immunity summarized the various indexes such as combing, in order to help academia, medicine, and sports. It provides enlightenment to the contemporary public on how to participate in sports training more healthily.

Exercise Training and Natural Killer Cells in Cancer Survivors: Current Evidence and Research Gaps Based on a Systematic Review and Meta-analysis

Background

Exercise training can positively impact the immune system and particularly natural killer (NK) cells, at least in healthy people. This effect would be of relevance in the context of cancer given the prominent role of these cells in antitumor immunity. In this systematic review and meta-analysis, we aimed to summarize current evidence on the effects of exercise training on the levels and function of NK cells in cancer survivors (i.e., from the time of diagnosis until the end of life).

Methods

Relevant articles were searched in PubMed, Scopus, Web of Science and Cochrane Central Register of Controlled Trials (until January 11, 2022). Randomized controlled trials (RCT) of exercise training (i.e., non-acute) interventions vs usual care conducted in cancer survivors and assessing NK number and/or cytotoxic activity (NKCA) before and upon completion of the intervention were included. Methodological quality of the studies was assessed with the PEDro scale, and results were meta-analyzed using a random effects (Dersimoian and Laird) model.

Results

Thirteen RCT including 459 participants (mean age ranging 11–63 years) met the inclusion criteria. Methodological quality of the studies was overall fair (median PEDro score = 5 out of 10). There was heterogeneity across studies regarding cancer types (breast cancer, non-small cell lung cancer and other solid tumors), treatment (e.g., receiving vs having received chemotherapy), exercise modes (aerobic or resistance exercise, Tai Chi, Yoga) and duration (2–24 weeks). No consistent effects were observed for NK number in blood (mean difference [MD]: 1.47, 95% confidence interval [CI] − 0.35 to 3.29, p = 0.113) or NKCA as assessed in vitro (MD: − 0.02, 95%CI − 0.17 to 0.14, p = 0.834). However, mixed results existed across studies, and some could not be meta-analyzed due to lack of information or methodological heterogeneity.

Conclusions

Current evidence does not support a significant effect of exercise training intervention on NK cells in blood or on their ‘static response’ (as assessed in vitro) in cancer survivors. Several methodological issues and research gaps are highlighted in this review, which should be considered in future studies to draw definite conclusions on this topic.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40798-022-00419-w.

Systematic review on the effects of physical exercise on cellular immunosenescence-related markers - An update

Immunosenescence is a remodeling of the immune system occurring with aging that leads to an increased susceptibility to auto-immunity, infections and reduced vaccination response. A growing consensus supports the view that physical exercise may counteract immunosenescence and improve the immune response. Unfortunately, evidence regarding the effects of exercise on markers of cellular immunosenescence lacked uniformity at the time of an extensive literature review in 2016. Moreover, exercise-induced effects in older adults were underrepresented compared to young adults or completely lacking, such as for senescent T-cells and apoptosis of T-lymphocytes. The aim of this systematic literature study was to collect and appraise newly available data regarding exercise-induced changes on immunosenescence-related markers of immune cells and compare this against data that was already available in 2016. Systematic reviewing of newly available data in the field of exercise immunology provides additional evidence for the effect of exercise on immunosenescence-related cellular markers. Importantly, this review provides evidence for the effect of long-term exercise on senescent T-lymphocytes in older adults. Additionally, newly retrieved evidence shows an acute exercise-induced mobilization of naïve and memory cells in older adults. In general, data regarding long-term exercise-induced effects in older adults remain scarce. Noteworthy was the high number of articles describing exercise-induced effects on regulatory T-cells. However exercise-induced effects on this cell type are still inconclusive as some articles reported an exercise-induced up- or downregulation, while others reported no effects at all. Numerous studies on Natural Killer cell counts did not provide uniformity among data that was already available. Recent data regarding dendritic cells mostly described an increase after exercise. Overall, our literature update highlights the major influence of the type and intensity of exercise on immunosenescence-related markers, especially in older adults.

Impact of exercise on the immune system and outcomes in hematologic malignancies

Exercise is increasingly recognized as important to cancer care. The biology of how exercise improves outcomes is not well understood, however. Studies show that exercise favorably influences the immune system in healthy individuals (neutrophils, monocytes, natural killer cells, T cells, and a number of cytokines). Thus, exercise in patients with hematologic cancer could significantly improve immune function and tumor microenvironment. We performed a literature search and identified 7 studies examining exercise and the immune environment in hematologic malignancies. This review focuses on the role of exercise and physical activity on the immune system in hematologic malignancies and healthy adults.

Does exercise attenuate age- and disease-associated dysfunction in unconventional T cells? Shining a light on overlooked cells in exercise immunology

Unconventional T Cells (UTCs) are a unique population of immune cells that links innate and adaptive immunity. Following activation, UTCs contribute to a host of immunological activities, rapidly responding to microbial and viral infections and playing key roles in tumor suppression. Aging and chronic disease both have been shown to adversely affect UTC numbers and function, with increased inflammation, change in body composition, and physical inactivity potentially contributing to the decline. One possibility to augment circulating UTCs is through increased physical activity. Acute exercise is a potent stimulus leading to the mobilization of immune cells while the benefits of exercise training may include anti-inflammatory effects, reductions in fat mass, and improved fitness. We provide an overview of age-related changes in UTCs, along with chronic diseases that are associated with altered UTC number and function. We summarize how UTCs respond to acute exercise and exercise training and discuss potential mechanisms that may lead to improved frequency and function.

Management and Treatment of Myocarditis in Athletes

Purpose of review

Myocarditis is an inflammation of the myocardium that can often be associated with cardiac dysfunction and arrhythmias, and is even one of the leading causes for sudden cardiac death (SCD) in athletes. This review aims to summarize the current evidence and treatment guidelines for the management of myocarditis in the active population.

Recent findings

Physical exertion is likely a trigger for dangerous arrythmias and further propagates myocardial damage in athletes with myocarditis. For this reason, abstinence from sports is a critical facet of management in the initial inflammatory period. The use of cardiac magnetic resonance imaging, specifically late gadolinium enhancement, to guide return to play decisions is becoming more common in clinical practice.

Summary

Establishing a stepwise approach for proper diagnosis and risk stratification, with an emphasis on contemporary cardiac magnetic resonance (CMR) imaging techniques, in myocarditis is critical. After a diagnosis of myocarditis is made, it is imperative for any athlete or highly active individual to refrain from physical exercise. Additionally, therapy for heart failure should be applied in cases of myocarditis with cardiac dysfunction. Undoubtedly, COVID 19, and its potential to cause myocarditis, is sure to change the landscape of management of this disease.

Obesity-Associated Alterations of Natural Killer Cells and Immunosurveillance of Cancer

Obesity is accompanied by a systemic chronic low-grade inflammation as well as dysfunctions of several innate and adaptive immune cells. Recent findings emphasize an impaired functionality and phenotype of natural killer (NK) cells under obese conditions. This review provides a detailed overview on research related to overweight and obesity with a particular focus on NK cells. We discuss obesity-associated alterations in subsets, distribution, phenotype, cytotoxicity, cytokine secretion, and signaling cascades of NK cells investigated in vitro as well as in animal and human studies. In addition, we provide recent insights into the effects of physical activity and obesity-associated nutritional factors as well as the reduction of body weight and fat mass on NK cell functions of obese individuals. Finally, we highlight the impact of impaired NK cell physiology on obesity-associated diseases, focusing on the elevated susceptibility for viral infections and increased risk for cancer development and impaired treatment response.

Alterations in the innate immune system due to exhausting exercise in intensively trained rats

It is known that intensive physical activity alters the immune system's functionality. However, the influence of the intensity and duration of exercise needs to be studied in more depth. We aimed to establish the changes in the innate immune response induced by two programmes of intensive training in rats compared to sedentary rats. A short training programme included 2 weeks of intensive training, ending with an exhaustion test (short training with exhaustion, S-TE). A second training programme comprised 5-week training including two exhaustion tests and three trainings per week. In this case, immune status was assessed before (T), immediately after (TE) and 24 h after (TE24) an additional final exhaustion test. Biomarkers such as phagocytic activity, macrophage cytokine and reactive oxygen species (ROS) production, and natural killer (NK) cell activity were quantified. S-TE was not enough to induce changes in the assessed innate immunity biomarkers. However, the second training was accompanied by a decrease in the phagocytic activity, changes in the pattern of cytokine secretion and ROS production by macrophages and reduced NK cell proportion but increased NK cytotoxic activity. In conclusion, a 5-week intense training programme, but not a shorter training, induced alterations in the innate immune system functionality.

Effects of Exercise on the Tumour Microenvironment

Epidemiological evidence suggests that exercise improves survival in cancer patients. However, much is still unknown regarding the mechanisms of this positive survival effect and there are indications that exercise may not be universally beneficial for cancer patients. The key to understanding in which situations exercise is beneficial may lie in understanding its influence on the tumour microenvironment (TME)-and conversely, the influence of the tumour on physical functioning. The TME consists of a vast multitude of different cell types, mechanical and chemical stressors and humoral factors. The interplay of these different components greatly influences tumour cell characteristics and, subsequently, tumour growth rate and aggression. Exercise exerts whole-body physiological effects and can directly and indirectly affect the TME. In this chapter, we first discuss the possible role of exercise capacity ('fitness') and exercise adaptability on tumour responsiveness to exercise. We summarise how exercise affects aspects of the TME such as tumour perfusion, vascularity, hypoxia (reduced oxygenation) and immunity. Additionally, we discuss the role of myokines and other circulating factors in eliciting these changes in the TME. Finally, we highlight unanswered questions and key areas for future research in exercise oncology and the TME.

Efficacy of heat-killed Lactococcus lactis JCM 5805 on immunity and fatigue during consecutive high intensity exercise in male athletes: a randomized, placebo-controlled, double-blinded trial

Background

Lactococcus lactis JCM 5805 (LC-Plasma) is a unique lactic acid bacteria (LAB) which activates plasmacytoid dendritic cells (pDC). We aimed to evaluate the effect of LC-Plasma on dendritic cell (DC) activity and subjective indices of upper respiratory tract infections (URTI) and fatigue in athletes under high intensity exercise.

Methods

We conducted a randomized, placebo-controlled, double-blinded trial. Fifty-one male subjects belonging to a university sports club were randomized into placebo (n = 25) and LC-Plasma (n = 26) groups. Individuals ingested placebo capsules containing cornstarch or LC-Plasma capsules containing 100 billion cells of heat-killed LC-Plasma per day for 13 days. During the intervention period, subjects performed high intensity exercise according to their sports club training regime. Blood and saliva sampling were obtained at days 1 and 14, and physical conditions were recorded in a diary. We investigated expression of maturation markers on DCs, muscle damage and stress markers and used student’s t test adjusted by Bonferoni’s method for multiple comparison between groups. These data were presented as mean ± SD. We also investigated cumulative days of symptoms regarding infections and fatigue and used Chi-square test for comparison between groups. These data were presented as cumulative number.

Results

CD86 as maturation marker on pDC was significantly increased in the LC-Plasma group at day 14 (Placebo: 296 ± 70 vs. LC-Plasma: 365 ± 115; Mean Fluorescent Intensity; p = 0.013). Cumulative days of URTI were significantly lower in the LC-Plasma group (Placebo: URTI positive 56, URTI negative 256 vs. LC-Plasma: URTI positive 39, URTI negative 299; days; p = 0.028) and symptoms like sneeze or running nose were significantly lower in the LC-Plasma group (Placebo: Symptom positive 52, Symptom negative 258, vs. LC-Plasma: Symptom positive 36, Symptom negative 301; days; p = 0.032). Moreover, the cumulative days of fatigue were significantly fewer in the LC-Plasma group (Placebo: Symptom positive 128, Symptom negative 182, vs. LC-Plasma: Symptom positive 110, Symptom negative 225; days; p = 0.032). Markers of muscle damage and stress markers were not significantly different between groups.

Conclusion

We consider that heat-killed LC-Plasma supplementation relieves morbidity and symptoms of URTI via activation of pDC and decreases fatigue accumulation during consecutive high intensity exercise in athletes. However, LC-Plasma ingestion did not affect markers of muscle damage and stress.

Trial registration

UMIN-CTR, UMIN000020372. Registered 28 December 2015.

Physical activity and autoimmune diseases: Get moving and manage the disease

Physical activity, by definition, is any skeletal muscle body movement that results in energy expenditure. In the last few decades, a plethora of scientific evidences have accumulated and confirmed the beneficial role of physical activity as a modifiable risk factor for a wide variety of chronic diseases including cardiovascular diseases (CVDs), diabetes mellitus and cancer, among others. Autoimmune diseases are a heterogeneous group of chronic diseases, which occur secondary to loss of self-antigen tolerance. With the advent of biological therapies, better outcomes have recently been noted in the management of autoimmune diseases. Nonetheless, recent research highlights the salient role of modifiable behaviors such as physical inactivity on various aspects of the immune system and autoimmune diseases. Physical activity leads to a significant elevation in T-regulatory cells, decreased immunoglobulin secretion and produces a shift in the Th1/Th2 balance to a decreased Th1 cell production. Moreover, physical activity has been proven to promote the release of IL-6 from muscles. IL-6 released from muscles functions as a myokine and has been shown to induce an anti-inflammatory response through IL-10 secretion and IL-1β inhibition. Physical activity has been shown to be safe in most of autoimmune diseases including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS), inflammatory bowel diseases (IBD), as well as others. Additionally, the incidence of RA, MS, IBD and psoriasis has been found to be higher in patients less engaged in physical activity. As a general trend, patients with autoimmune diseases tend to be less physically active as compared to the general population. Physically active RA patients were found to have a milder disease course, better cardiovascular disease (CVD) profile, and improved joint mobility. Physical activity decreases fatigue, enhances mood, cognitive abilities and mobility in patients with MS. In SLE patients, enhanced quality of life and better CVD profile were documented in more physically active patients. Physically active patients with type 1 diabetes mellitus have a decreased risk of autonomic neuropathy and CVD. Both fibromyalgia and systemic sclerosis patients report decreased disease severity, pain, as well as better quality of life with more physical activity. Further, SSc patients improve their grip strength, finger stretching and mouth opening with increased level of exercise. The purpose of this paper is to review the clinical evidence regarding the safety, barriers to engagement, and impact of physical activity on autoimmune diseases.

Unperturbed Cytotoxic Lymphocyte Phenotype and Function in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients

Myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS) is a debilitating disorder linked to diverse intracellular infections as well as physiological stress. Cytotoxic lymphocytes combat intracellular infections. Their function is attenuated by stress. Despite numerous studies, the role of cytotoxic lymphocytes in ME/CFS remains unclear. Prompted by advances in the understanding of defects in lymphocyte cytotoxicity, the discovery of adaptive natural killer (NK) cell subsets associated with certain viral infections, and compelling links between stress, adrenaline, and cytotoxic lymphocyte function, we reassessed the role of cytotoxic lymphocytes in ME/CFS. Forty-eight patients from two independent cohorts fulfilling the Canada 2003 criteria for ME/CFS were evaluated with respect to cytotoxic lymphocyte phenotype and function. Results were compared to values from matched healthy controls. Reproducible differences between patients and controls were not found in cytotoxic lymphocyte numbers, cytotoxic granule content, activation status, exocytotic capacity, target cell killing, or cytokine production. One patient expressed low levels of perforin, explained by homozygosity for the PRF1 p.A91V variant. However, overall, this variant was present in a heterozygous state at the expected population frequency among ME/CFS patients. No single patient displayed any pathological patterns of cellular responses. Increased expansions of adaptive NK cells or deviant cytotoxic lymphocyte adrenaline-mediated inhibition were not observed. In addition, supervised dimensionality reduction analyses of the full, multidimensional datasets did not reveal any reproducible patient/control discriminators. In summary, employing sensitive assays and analyses for quantification of cytotoxic lymphocyte differentiation and function, cytotoxicity lymphocyte aberrances were not found among ME/CFS patients. These assessments of cytotoxic lymphocytes therefore do not provide useful biomarkers for the diagnosis of ME/CFS.

PARÂMETROS IMUNOLÓGICOS E INFECÇÕES DO TRATO RESPIRATÓRIO SUPERIOR EM ATLETAS DE ESPORTES COLETIVOS

RESUMO Entre atletas e treinadores, existe uma percepção comum de que altas cargas de treinamento e competições, aplicadas de forma crônica, com controle nutricional e/ou períodos de recuperação inadequados, podem reduzir a resistência imunológica, aumentando a predisposição aos episódios de infecções, principalmente infecções do trato respiratório superior (ITRS). Nesse sentido, o presente estudo está centrado em revisar as interações entre os parâmetros imunológicos com a síndrome do sobretreinamento, especificamente em esportes coletivos, considerando a sua natureza intermitente. Assim, foi realizada uma revisão de periódicos nacionais e internacionais relacionados com o tema. As correlações entre exercício, sistema imunológico e suscetibilidade às ITRS têm sido avaliadas principalmente em esportes individuais e de resistência em comparação aos coletivos. As modulações dos leucócitos ao longo da temporada, frente ao efeito somatório das cargas de treinamento e competições, quando analisadas especificamente quanto aos neutrófilos e monócitos, possivelmente se relacionam com os processos de reparo tecidual e incidência de ITRS. As modulações relacionadas com os linfócitos parecem estar relacionadas mais diretamente com a incidência das ITRS. Ademais, o entendimento de todos os marcadores propostos, incluindo os imunológicos em associação com os indicadores de desempenho e controle do treinamento, parece ser um caminho mais promissor para o diagnóstico clínico do estado imunológico do atleta e da prevenção da síndrome do sobretreinamento do que necessariamente a busca por um marcador exclusivo de excesso de treinamento.

Influence of a Moderate-Intensity Exercise Program on Early NK Cell Immune Recovery in Pediatric Patients After Reduced-Intensity Hematopoietic Stem Cell Transplantation

Introduction: After allogeneic hematopoietic stem cell transplantation (HSCT), NK cell reconstitution, which is crucial for positive outcomes, is dominated by the CD56^bright subset with low NK cell cytotoxicity (NKCC) activity. Moderate exercise has been described as a potent NK cell stimulus in adults with cancer. Purpose: To determine the effects of a moderate-intensity exercise program on NK cell recovery early after HSCT and the feasibility of this intervention. Methods: Six children undergoing allogeneic HSCT were randomized to an exercise program (EP) or control (CT) group. The EP group performed a 10-week training combining in-hospital and home-based EP. Results: We observed a significant increase in the posttraining/pretraining ratio of the CD56^dim subset (EP = 1.27 ± 0.07; CT = 0.99 ± 0.08; P < .005) of the EP group. The ratio of NKCC was 8 times greater in the EP group. Conclusion: Data suggest that a moderate-intensity EP program performed early after HSCT is feasible and might redistribute the CD56^dim/CD56^brigh NK cell subset, improving NKCC. The results are still preliminary and must be interpreted with caution.

Immune cell changes in response to a swimming training session during a 24-h recovery period

Understanding the impact of training sessions on the immune response is crucial for the adequate periodization of training, to prevent both a negative influence on health and a performance impairment of the athlete. This study evaluated acute systemic immune cell changes in response to an actual swimming session, during a 24-h recovery period, controlling for sex, menstrual cycle phases, maturity, and age group. Competitive swimmers (30 females, 15 ± 1.3 years old; and 35 males, 16.5 ± 2.1 years old) performed a high-intensity training session. Blood samples were collected before, immediately after, 2 h after, and 24 h after exercise. Standard procedures for the assessment of leukogram by automated counting (Coulter LH 750, Beckman) and lymphocytes subsets by flow cytometry (FACS Calibur BD, Biosciences) were used. Subjects were grouped according to competitive age groups and pubertal Tanner stages. Menstrual cycle phase was monitored. The training session induced neutrophilia, lymphopenia, and a low eosinophil count, lasting for at least 2 h, independent of sex and maturity. At 24 h postexercise, the acquired immunity of juniors (15-17 years old), expressed by total lymphocytes and total T lymphocytes (CD3(+)), was not fully recovered. This should be accounted for when planning a weekly training program. The observed lymphopenia suggests a lower immune surveillance at the end of the session that may depress the immunity of athletes, highlighting the need for extra care when athletes are exposed to aggressive environmental agents such as swimming pools.

Exercise and the Regulation of Immune Functions

Exercise has a profound effect on the normal functioning of the immune system. It is generally accepted that prolonged periods of intensive exercise training can depress immunity, while regular moderate intensity exercise is beneficial. Single bouts of exercise evoke a striking leukocytosis and a redistribution of effector cells between the blood compartment and the lymphoid and peripheral tissues, a response that is mediated by increased hemodynamics and the release of catecholamines and glucocorticoids following the activation of the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis. Single bouts of prolonged exercise may impair T-cell, NK-cell, and neutrophil function, alter the Type I and Type II cytokine balance, and blunt immune responses to primary and recall antigens in vivo. Elite athletes frequently report symptoms associated with upper respiratory tract infections (URTI) during periods of heavy training and competition that may be due to alterations in mucosal immunity, particularly reductions in secretory immunoglobulin A. In contrast, single bouts of moderate intensity exercise are "immuno-enhancing" and have been used to effectively increase vaccine responses in "at-risk" patients. Improvements in immunity due to regular exercise of moderate intensity may be due to reductions in inflammation, maintenance of thymic mass, alterations in the composition of "older" and "younger" immune cells, enhanced immunosurveillance, and/or the amelioration of psychological stress. Indeed, exercise is a powerful behavioral intervention that has the potential to improve immune and health outcomes in the elderly, the obese, and patients living with cancer and chronic viral infections such as HIV.

Cortisol is not the primary mediator for augmented CXCR4 expression on natural killer cells after acute exercise

CXC-chemokine receptor 4 (CXCR4) and its ligand, stromal-derived factor 1α (SDF-1α; also known as CXCL12), are crucial for the redistribution of immune cells after acute exercise. We investigated the relationships between acute exercise and CXCR4 expression on natural killer (NK) cells. Peripheral blood mononuclear cells (PBMCs) were cultured with cortisol and analyzed for CXCR4 expression on CD3−/CD56+ NK cells and NK cell migration activity. To determine the effect of exercise, we isolated PBMCs from subjects before and after a 90-min exercise at 70% peak O2 uptake (V̇o2peak) and determined the changes in CXCR4 expression on NK cells after exercise. We cultured PBMCs with plasma obtained before and after exercise and with the glucocorticoid antagonist RU-486 to determine NK cell migration activity and the effects of cortisol on CXCR4 expression in vitro. Cortisol treatment increased CXCR4 expression ( P < 0.05) and migration activity ( P < 0.05) of NK cells. Exercise did not affect CXCR4 expression on NK cells, whereas incubating them with postexercise plasma significantly increased CXCR4 expression ( P < 0.05) and migration activity ( P < 0.05). RU-486 blocked cortisol-induced CXCR4 upregulation on NK cells, but only partially blocked (7%) CXCR4 upregulation when PMBCs were incubated with postexercise plasma. Thus acute exercise increases CXCR4 expression on NK cells and their migration activity and may contribute to NK cell redistribution after acute exercise; however, cortisol did not appear to be the primary mediator of augmented CXCR4 expression.

Acute exercise preferentially redeploys NK-cells with a highly-differentiated phenotype and augments cytotoxicity against lymphoma and multiple myeloma target cells

NK-cells undergo a "licensing" process as they develop into fully-functional cells capable of efficiently killing targets. NK-cell differentiation is accompanied by an increased surface expression of inhibitory killer immunoglobulin-like receptor (KIR) molecules, which is positively associated with cytotoxicity against the HLA-deficient K562 cell line. NK-cells are rapidly redeployed between the blood and tissues in response to acute exercise, but it is not known if exercise evokes a preferential trafficking of differentiated NK-cells or impacts NK-cell cytotoxic activity (NKCA) against HLA-expressing target cells. Sixteen healthy cyclists performed three 30-min bouts of cycling exercise at -5%, +5%, and +15% of lactate threshold. Blood samples obtained before, immediately after, and 1h after exercise were used to enumerate NK-cells and their subsets, and determine NKCA and degranulating subsets (CD107+) against cell lines of multiple myeloma (U266 and RPMI-8226), lymphoma (721.221 and 221 AEH), and leukemia (K562) origin by 4 and 10-color flow cytometry, respectively. Exercise evoked a stepwise redeployment of NK-cell subsets in accordance with differentiation status [highly-differentiated (KIR+/NKG2A-) >medium-differentiated (KIR+/NKG2A+)>low-differentiated (KIR-/NKG2A+)] that was consistent across all exercise intensities. NKCA per cell increased ∼1.6-fold against U266 and 221 AEH targets 1h post-exercise and was associated with a decreased proportion of NK-cells expressing the inhibitory receptor CD158b and increased proportion of NK-cells expressing the activating receptor NKG2C, respectively. We conclude that exercise evokes a preferential redeployment of NK-cell subsets with a high differentiation phenotype and augments cytotoxicity against HLA-expressing target cells. Exercise may serve as a simple strategy to enrich the blood compartment of highly cytotoxic NK-cell subsets that can be harvested for clinical use.

Brief Exercise Increases Peripheral Blood NK Cell Counts without Immediate Functional Changes, but Impairs their Responses to ex vivo Stimulation

Physical as well as psychological stress increases the number of circulating peripheral blood NK cells. Whereas some studies found a positive correlation between exercise and NK cell counts and cytotoxic activity, others showed that, for example, heavy training leads to a decrease in per cell NK cytotoxicity. Thus, the impact of exercise on NK cell function and eventually on altered immunocompetence remains to be elucidated. Here, we investigated whether a single bout of brief exercise, consisting in running up and down 150 stair-steps, affects the number and function of circulating NK cells. NK cells, obtained from 29 healthy donors, before and immediately after brief exercise, were assessed for numbers, phenotype, IFNγ production, degranulation, cytotoxicity, and in vitro response to stimulation with IL-2, IL-2/IL-12, or TLR2 agonists. Running resulted in a sixfold increase in the number of CD3⁻/CD56⁺ NK cells, but decreased the frequency of CD56^bright NK cells about twofold. Brief exercise did not significantly interfere with baseline IFNγ secretion or NK cell cytotoxicity. In vitro stimulation with IL-2 and TLR2 agonists (lipoteichoic acid, and synthetic triacylated lipopeptide Pam3CSK4) enhanced IFNγ-secretion, degranulation, and cytotoxicity mediated by NK cells isolated pre-exercise, but had less effect on NK cells isolated following exercise. There were no differences in response to combined IL-2/IL-12 stimulation. In conclusion, having no obvious impact on baseline NK functions, brief exercise might be used as a simple method to significantly increase the number of CD56^dim NK cell available for in vitro experiments. Nevertheless, the observed impaired responses to stimulation suggest an alteration of NK cell-mediated immunity by brief exercise which is at least in part explained by a concomitant decrease of the circulating CD56^bright NK cell fraction.

Changes in natural killer cell subpopulations over a winter training season in elite swimmers

Immune changes and increased susceptibility to infection are often reported in elite athletes. Infectious episodes can often impair training and performance with consequences for health and sporting success. This study monitored the occurrence of episodes of upper respiratory symptoms (URS) and the variation in circulating NK cells, CD56(bright) and CD56(dim) NK cells subpopulations, over a winter swimming season. Nineteen national elite swimmers and 11 non-athlete controls participated in this study. URS episodes were monitored using daily log books. Blood samples were taken at rest at four time points during the season: before the start of the season (t1--middle September), after 7 weeks of an initial period of gradually increasing training load (t2--early November), after 6 weeks of an intense training cycle (t3--late February) and 48 h after the main competition (t4--early April) and from the controls at three similar time points (t1--early November; t2--late February; t3--early April). In the swimmers, the occurrence of URS clustered around the periods of elevated training load (67 %). No URS were reported at equivalent time points in the non-athletes. Athletes showed a decrease in the percentage (t2 = 21 %; t3 = 27 %; t4 = 17 %) and absolute counts of circulating NK cells (t2 = 35 %; t3 = 22 %; t4 = 22 %), coinciding with the periods of increased training load, never recovering to the initial values observed at the start of the season. The reduction in the CD56(dim) and an increase in the CD56(bright) NK cell subpopulations were significant at t2 and t3 (p < 0.05). Concomitant with the fall in values of NK cells, in athletes that shown more than three URS episodes, a moderate correlation (r = 0.493; p = 0.036) was found between CD56(bright)/CD56(dim) ratio and the number of URS episodes after the more demanding training phase (t3). At t3, a lower value of CD56 cell counts was found in the group who reported three or more URS episodes (t = 2.239; p = 0.032). A progressive significant decrease in the expression of CD119, the receptor for IFN-γ, on the CD56(dim) cells was found over the season and an elevation in Granzyme B expression was coincident with the more demanding training phases. Periods of highly demanding training seem to have a negative impact on innate immunity mediated by NK cell subsets, which could partially explain the higher frequency of URS observed during these training phases.

Diferenças em populações de células exterminadoras naturais (Natural Killers-NK) sanguíneas periféricas entre atletas de caiaque e não atletas

INTRODUÇÃO: O exercício estressante prolongado tem sido associado a uma depressão transitória da função imune, com rotinas de treinamento e competição intensas e prolongadas capazes de levar os atletas a uma deficiência imune. OBJETIVO: O objetivo deste estudo foi observar se o treinamento cr ônico foi capaz de produzir diferenças sustentáveis no sangue periférico (SP) subpopulações de leucócitos (LEU, granulócitos, monócitos, linfócitos totais, linfócitos B e T, e células CD4+ e CD8+T e células natural killers) de atletas de caiaque de elite quando comparados com não atletas. MÉTODOS: A amostra incluiu 13 homens atletas de caiaque de elite, 20 ± 3 anos, 75,0kg ± 7,9 peso e 177,3 ± 7,1 cm estatura. O VO2max foi 58,3 ± 7,8mL.kg.min-1. O grupo de não atletas incluiu sete homens saudáveis, idade 18 ± 1 ano de idade, 81,3 ± 13,8Kg de peso corporal e 171,9 ± 4,5cm de estatura. As amostras de sangue dos atletas foram coletadas no início da temporada de treinamento, após um período fora do treinamento de seis semanas. Populações de células sanguíneas periféricas foram identificadas por análise de citometria de fluxo. Para identificar as diferenças entre os grupos de atletas e não atletas, o teste U de Mann-Whitney foi utilizado. RESULTADOS: N ão foram identificadas diferenças entre os atletas de caiaque treinados e não atletas em repouso, exceto para células natural killers (CD3-CD56+) e os valores da subpopulação CD3-CD56+CD8+ os quais foram mais baixos nos atletas. CONCLUSÃO: Nosso estudo encontrou que, após um período prolongado sem treinamento (seis semanas), somente a população de NK CD3-CD56+ e, em especial, a subpopulação de altamente citotóxica CD3-CD56+CD8+ apresentou níveis mais baixos nos atletas de elite quando comparados com os homens destreinados.

Exercise and the aging immune system

Aging is associated with a decline in the normal functioning of the immune system that is described by the canopy term "immunosenescence". This contributes to poorer vaccine responses and the increased incidence of infection and malignancy seen in the elderly. Regular exercise has been associated with enhanced vaccination responses, lower numbers of exhausted/senescent T-cells, increased T-cell proliferative capacity, lower circulatory levels of inflammatory cytokines ("inflamm-aging"), increased neutrophil phagocytic activity, lowered inflammatory response to bacterial challenge, greater NK-cell cytotoxic activity and longer leukocyte telomere lengths in aging humans, all of which indicate that habitual exercise is capable of regulating the immune system and delaying the onset of immunosenescence. This contention is supported by the majority of animal studies that report improved immune responses and outcomes to viral infections and malignancies due to exercise training. However, whether or not exercise can reverse, as well as prevent, immunosenescence is a contentious issue, particularly because most longitudinal exercise training studies do not report the same positive effects of exercise on immunity that have been widely reported in studies with a cross-sectional design. In this review, we summarize some of the known effects of exercise on immunosenescence, discuss avenues for future research, and provide potential mechanisms by which exercise may help rejuvinate the aging immune system.

Detailed analysis of peripheral blood natural killer cells in women with repeated IVF failure

PROBLEM

To analyse the peripheral blood NK cells in women with repeated IVF failure (RIF) and a fertile control group to determine which parameters best differentiate the two populations.

METHODS

Peripheral blood from the luteal phase of 171 women with RIF and 33 fertile controls was analysed by four-colour flow cytometry for NK cell concentration, subset differentiation and the activation marker CD69.

RESULTS

Women with RIF had significantly increased NK cell numbers as determined by concentration (P < 0.05) and percentage of lymphocytes (P < 0.001), increased concentration of the CD56(dim) subtype (P < 0.05), and increased concentration of activated CD56(dim) CD69(+) cells (P = 0.0001). There was no correlation between any NK cell parameters with the length of infertility or number of embryo transfer cycles.

CONCLUSIONS

Peripheral blood NK cell activity is significantly higher in women with RIF than in fertile controls. Future trials of immune therapy in women undergoing IVF should target those with high NK activity.

Immune responses, upper respiratory illness symptoms, and load changes in young athletes during the preparatory period of the training periodization

OBJECTIVE

The aim of this study was to investigate the immunological responses and the association between variation in exercise load and self-reported occurrence of upper respiratory illness (URI) symptoms in young basketball athletes.

MATERIALS AND METHODS

The sample was composed of twelve young male athletes aged 12.7 ± 0.6 years, with a height of 170 ± 10 cm, body mass of 57.6 ± 12.6 kg, and fat-free mass of 18.7 ± 5.9%. Daily training and occurrences of URI symptoms were recorded. Blood samples were collected at baseline (M1) and after 8 weeks (M2) of the preparatory period of periodization training to measure total and differential leukocyte counts, serum interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α).

RESULTS

There was a significant decrease in monocytes at M2 compared to M1 (P = 0.004). There were no significant alterations in total leukocytes (P = 0.07), neutrophils (P = 0.07), or lymphocytes (P = 0.09). No significant changes in plasma concentrations of TNF-α (P = 0.30) or IL-6 (P = 0.90) were found. The weekly load from week 6 was higher when compared with weeks 1, 2, 4, and 8 (P < 0.05), and week 8 was the lowest when compared with week 5 (P < 0.05). Self-reported URI incidences were highest at weeks 1 and 2.

CONCLUSION

Variations in weekly training load during the preparatory period were not correlated with changes in self-reported occurrence of URI incidences, suggesting that young athletes may have an attenuated response to exercise-induced perturbations to the immune system.

Immune parameters, symptoms of upper respiratory tract infections, and training-load indicators in volleyball athletes

Background

The control of immunological alterations becomes important during in-season training, as a result of increased incidence of infectious diseases, and may assist in avoiding interruptions to training due to illness.

Objective

The aim of the present study was to evaluate 28 weeks of chronic immune modulations in female volleyball athletes.

Methods

The sample was composed of twelve athletes aged 19.47 ± 2.49 years, height 1.78 ± 0.08 cm, and body mass 66.77 ± 7.8 kg. Leukocytes, individual immune cell count, interleukin (IL)-2, IL-6, and tumor necrosis factor (TNF)-α plasma cytokines were measured during the competitive period.

Results

Results revealed that immune variables were correlated with symptoms of upper respiratory tract infections and training-load indicators, indicating a possible marker of immune status. There was a statistically significant increase in total leukocytes, neutrophils, and monocyte count, a decrease in lymphocytes, and an increase in upper respiratory tract infection symptoms, with no change in IL-2, IL-6, and TNF-α. Correlations between subjective levels of tiredness, total leukocyte count, and neutrophils with upper respiratory tract infection symptoms were observed.

Conclusion

In conclusion, these correlations can represent important tools to access the immune status of an athlete during long training periods, preventing a possible immunosuppressive status.

Hypoxic exercise training promotes antitumour cytotoxicity of natural killer cells in young men

The cytotoxic functions of NKs (natural killer cells) are critical in enabling the immune system to cope efficiently with malignancy. In the present study, we compared how various exercise regimens without/with hypoxia influence phenotypic characteristics of NK subsets and cytotoxicity of NKs to NPCs (nasopharyngeal carcinoma cells). A total of 60 sedentary males were randomly divided into five groups. Each group (n=12) underwent one of five regimens: normoxic (21% O2) control (N-C), hypoxic (15% O2) control (H-C), normoxic exercise (50% maximal work rate under 21% O2; N-E), hypoxic relative exercise (50% maximal heart rate reserve under 15% O2; H-RE) or hypoxic absolute exercise (50% maximal work rate under 15% O2; H-AE) for 30 min/day, 5 days/week for 4 weeks. The results showed that hypoxic exercise regimens increased pulmonary ventilation and tissue oxygen utilization. Moreover, the H-RE regimen resulted in enhanced aerobic fitness at a less intensive training workload in the H-AE regimen. Before each regimen, strenuous exercise elevated NK perforin/granzyme B content and promoted cytotoxicity of NKs to NPCs. However, the percentage of NKs expressing homing (CD11a)/terminally differentiated (CD57)/inhibitory [KLRG1 (killer cell lectin-like receptor G1)] molecules that entered the bloodstream from peripheral tissues increased following this exercise. After 4 weeks, both the H-AE and H-RE regimens produced an up-regulated expression of memory (CD45RO)/activating (NKG2D) molecules and was accompanied by a decrease in CD57/KLRG1 levels on NKs at rest and after strenuous exercise. Furthermore, the two regimens increased resting and exercise NK perforin/granzyme B content and NK-induced phosphatidylserine exposure of NPCs. In contrast, no significant change in the phenotypic characteristics of blood NK subsets or NK-induced NPC apoptosis was observed in the N-C, H-C and N-E regimens. Therefore we conclude that 15% O2 exercise training reduces terminally differentiated NK subsets and up-regulates the expression of activating molecules and cytotoxic granule proteins in NKs, thereby enhancing the capacity of anti-NPC cytotoxicity by NKs. These findings could help to determine effective hypoxic exercise regimens for improving individual aerobic capacity and simultaneously promoting the natural cytotoxicity of NKs.

Physical activity and head and neck cancer risk

OBJECTIVE

To investigate the relation of physical activity to head and neck cancer.

METHODS

We prospectively examined the association between physical activity and head and neck cancer in 487,732 men and women, who, at baseline in 1995-1996, were 50-71 years old and free of cancer and emphysema. Follow-up occurred through 31 December 2003.

RESULTS

During follow-up, 1,249 participants developed head and neck cancer, of which 42.0%, 18.9%, and 32.5% were located in the oral cavity, pharynx, and larynx, respectively. In analyses adjusted for age and gender, the relative risks (RR) of head and neck cancer for increasing frequency of physical activity (0, < 1, 1-2, 3-4, and >or=5 times per week) were 1.0 (reference), 0.76, 0.66, 0.57, and 0.62 (95% CI = 0.52-0.74), respectively (p for trend < 0.001). After multivariate adjustment including smoking, the relation was attenuated and became statistically non-significant (RR comparing extreme physical activity categories = 0.89, 95% CI = 0.74-1.06; p for trend = 0.272). In analyses of head and neck cancer subtypes, the corresponding RRs for cancers of the oral cavity, pharynx, and larynx were 0.98 (95% CI = 0.75-1.29), 0.70 (95% CI = 0.45-1.08), and 0.82 (95% CI = 0.59-1.13), respectively.

CONCLUSIONS

Our findings suggest that physical activity is unlikely to play an important role in the prevention of head and neck cancer.

Evidence of sex-based differences in natural killer cell responses to exercise and carbohydrate intake in children

Distinct natural killer (NK) cell subsets (CD56bright and CD56dim) are mobilized with exercise and these cells may serve adaptive functions. We determined the distribution of NK cell subsets in response to exercise and carbohydrate (CHO) intake in young girls and compared these responses with previous findings in young boys of the same age. Twelve girls (12 years old) cycled for 60 min at 70% VO2max while drinking 6% CHO or flavoured water. Blood was collected at rest, during (30 and 60 min) and following (30 and 60 min) exercise to identify NK cells as CD3-CD56bright or CD3-CD56dim. CD69 expression on total CD3-CD56+ cells was also determined. A trend (P=0.07) was found for a trial x time interaction in CD56dim cell counts, with values lower with CHO than with water. CHO intake did not influence CD56bright responses (P>or=0.39). The CD56bright:CD56dim ratio increased during recovery from exercise (P<0.001), compared to rest, with no effect of CHO intake (P=0.48). CD69 expression was not different between exercise or recovery and rest. Like young boys, girls experience an elevated CD56bright:CD56dim ratio during recovery from exercise and CHO intake attenuates the exercise-induced CD56dim but not CD56bright cell response. Unlike young boys, girls do not experience a CHO-induced increase in the CD56bright:CD56dim ratio during recovery and CD69 expression does not increase on CD3-CD56+ cells during recovery. We conclude that even in young children sex-based differences exist in the NK cell response to exercise and CHO intake.

Effects of bovine colostrum supplementation on immune variables in highly trained cyclists

The aim of this study was to investigate the influence of low-dose bovine colostrum protein concentrate (CPC) supplementation on selected immune variables in cyclists. Twenty-nine highly trained male road cyclists completed an initial 40-km time trial (TT(40)) and were then randomly assigned to either a supplement (n = 14, 10 g bovine CPC/day) or placebo group (n = 15, 10 g whey protein concentrate/day). After 5 wk of supplementation, the cyclists completed a second TT(40). They then completed 5 consecutive days of high-intensity training (HIT) that included a TT(40), followed by a final TT(40) in the following week. Venous blood and saliva samples were collected immediately before and after each TT(40), and upper respiratory illness symptoms were recorded over the experimental period. Compared with the placebo group, bovine CPC supplementation significantly increased preexercise serum soluble TNF receptor 1 during the HIT period (bovine CPC = 882 +/- 233 pg/ml, placebo = 468 +/- 139 pg/ml; P = 0.039). Supplementation also suppressed the postexercise decrease in cytotoxic/suppressor T cells during the HIT period (bovine CPC = -1.0 +/- 2.7%, placebo = -9.2 +/- 2.8%; P = 0.017) and during the following week (bovine CPC = 1.4 +/- 2.9%, placebo = -8.2 +/- 2.8%; P = 0.004). Bovine CPC supplementation prevented a postexercise decrease in serum IgG(2) concentration at the end of the HIT period (bovine CPC = 4.8 +/- 6.8%, P = 0.88; placebo = -9.7 +/- 6.9%, P = 0.013). There was a trend toward reduced incidence of upper respiratory illness symptoms in the bovine CPC group (P = 0.055). In summary, low-dose bovine CPC supplementation modulates immune parameters during normal training and after an acute period of intense exercise, which may have contributed to the trend toward reduced upper respiratory illness in the bovine CPC group.

Puberty effects on NK cell responses to exercise and carbohydrate intake in boys

Previous research has demonstrated that younger versus older animals and humans experience smaller perturbations in natural killer (NK) cells in response to physiological stress.

PURPOSE

To determine whether the smaller perturbations in NK cells induced by strenuous exercise and carbohydrate (CHO) intake, previously reported in children, are influenced by puberty.

METHODS

Twenty 12-yr-old boys, distinguished as prepubertal (Tanner (T) 1, N = 7), early pubertal (T2, N = 7), or pubertal (T3-5, N = 6), cycled for 60 min at 70% VO(2max) while drinking 6% CHO (CT) or flavored water (WT). Blood was collected at rest and during (30 and 60 min) and following (30 and 60 min) exercise to identify NK cells as CD3(-)CD56(dim) or CD3(-)CD56(dim). CD69 expression on CD3(-)CD56(+) cells was also determined.

RESULTS

A puberty x CHO x exercise interaction was found for the proportion, but not number, of CD56(dim) cells (P = 0.06). CD56(dim) cell counts were lower in CT versus WT (P < 0.001). Responses of CD56(bright) proportions (P = 0.007) and counts (P = 0.03) depended on pubertal status, but not CHO. The CD56(bright):CD56(dim) ratio remained stable during exercise, but during recovery was higher in T1 and T3-5 versus T2 (P = 0.08) and in CT versus WT (P = 0.04). During recovery, CD3(-)CD56(+) cells expressed higher levels of CD69 (P = 0.01), with no change in the proportion of CD69(+) cells.

CONCLUSION

These results confirm the influence of puberty on the distribution of NK cell subsets in response to exercise and CHO intake. Increased CD69 expression suggests that NK cells increase activation status during recovery from physiological stress.

Sex-based effects on the distribution of NK cell subsets in response to exercise and carbohydrate intake in adolescents

Carbohydrate (CHO) supplementation and female sex independently influence the natural killer (NK) cell response to acute exercise. Consequently, this study sought to elucidate sex-based differences in the distribution of NK cell subsets (i.e., CD56dimand CD56bright) in response to exercise and CHO intake. Twenty-two healthy 14-yr-old girls ( n = 11) and boys ( n = 11) cycled for 60 min at 70% maximal oxygen consumption while drinking 6% CHO (CT) or flavored water (WT). Blood was collected at rest, during exercise (30 and 60 min), and during recovery (30 and 60 min) to identify CD3−CD56dimand CD3−CD56brightNK cells. The activation marker CD69 was also determined on CD3−CD56+cells. CD56dimresponses, expressed as proportions or cell counts, were greater ( P ≤ 0.01) in girls by 67 and 105%, respectively. CD56brightcell counts ( P = 0.006), but not CD56brightproportions ( P = 0.89), were greater in girls by 82%. Both CD56dimand CD56brightsubset responses, expressed as proportions or cell counts, were lower ( P ≤ 0.01) in CT vs. WT by 33–36%. The CD56bright-to-CD56dimratio decreased at 30 min of exercise but increased during recovery ( P < 0.001), with no effect of sex or CHO. Regardless of trial, CD3−CD56+cells expressed ∼18% higher levels of CD69 during recovery in girls but not boys ( P = 0.03), despite similar proportions and counts of CD69+cells. These results demonstrate sex-based differences in the distribution of NK cell subsets and activation status in response to exercise, but not CHO intake, and further support the need to control for sex in exercise immunology studies.

Polychromatic (eight-color) slide-based cytometry for the phenotyping of leukocyte, NK, and NKT subsets

BACKGROUND

Natural killer (NK) and NK T (NKT) cells are important in innate immune defense. Their unequivocal identification requires at least four antigens. Based on the expression of additional antigens, they can be further divided into functional subsets. For more accurate immunophenotyping and to describe multiple expression patterns of leukocyte subsets, an increased number of measurable colors is necessary. To take advantage of the technologic features offered by slide-based cytometry, repeated analysis was combined with sequential optical-filter changing.

METHODS

Human peripheral blood leukocytes from healthy adult volunteers were labeled with antibodies by direct or indirect staining. Tandem dyes of Cy7 (phycoerythrin [PE]-/allophycocyanin [APC]-Cy7), Cy5.5 (PE-/APC-Cy5.5), and PE-Cy5 and the fluorochromes fluorescein isothiocyanate (FITC), PE, and APC were tested alone and in combinations. Optical filters of the laser scanning cytometer were 555 DRLP/BP 530/30 nm for photomultiplier tube (PMT) 1/FITC, 605 DRLP/BP 580/30 nm for PMT 2/PE, 740 DCXR/BP 670/20 nm for PMT 3/Cy5/APC, and BP 810/90 nm for PMT 4/Cy7. Filter PMT 3 was replaced for detection of PE/Cy5.5 and APC/Cy5.5 by 740 LP/BP 710/20 nm and the sample was remeasured. Both data files were merged into one to combine the different information on a single-cell basis. The combination of eight antibodies against CD3, CD4, CD8, CD14, CD16, CD19, CD45, and CD56 was used to characterize NK and NKT cells and their subsets.

RESULTS

In this way Cy5.5 is measurable at 488-nm and 633-nm excitation. Further, with the two different filters it is possible to distinguish Cy5 from Cy5.5 in the same detection channel (PMT 3). With this method we identified NK and NKT cells, subsets of NK (CD3-16+56+, CD3-16+56-, CD3-16-56+) and NKT (CD3+16+56+, CD3+16-56+) and their CD4+8-, CD4-8+, CD4-8- and CD4+8+ subsets.

CONCLUSION

With our adaptations it is possible to discriminate tandem conjugates of Cy5, Cy5.5, and Cy7 for eight-color immunophenotyping. Using this method, novel rare subsets of NK and NKT cells that are CD4/CD8 double positive are reported for the first time.