Increase In Natural Killer Activity Research Articles

Antinutrient Phytic acid: Can be proved to be a Boon for Colorectal Cancer

Phytic acid also known as inositol hexa-phosphate, is a simple ringed bioactive sugar molecule with six phosphate groups attached to each carbon. Cereals, pulses, and oil seeds contain considerable amounts of Phytic acid. Phytic acid is known as a potent anti-nutrient that binds with the minerals and forms chelates thus leading to mineral deficiency diseases if administered in excess dosage. The phytase (enzyme) containing foods can reverse the reaction and increase the bioavailability of minerals. In-spite of having anti-nutritional properties, phytic acid can be a boon for colorectal cancer. Colorectal cancer, the third most often malignant carcinoma, progresses sporadically in the setting of hereditary cancer syndromes, or on the basis of inflammatory bowel disease. Nutrients can directly affect the fundamental cellular processes and is considered as the most important risk factors in colorectal cancer. Colorectal Cancer occurs with the formation of polyps. Various mechanisms have been proposed for Phytic Acid as anti-tumorigenic abilities that are antioxidant properties, gene alteration, increase natural killer activity and cell cycle inhibition. Different studies suggest phytic acid can suppress tumour growth and prevent colorectal cancer. Phytic acid supplementation with its potential anti-inflammatory, antioxidant activity, and metal chelation capacity are of great deal of interest to improve the anticarcinogenic activity of chemotherapeutic drugs in combination or alone. Further studies are needed to establish the safe dosage of phytic acid in daily diet as well as for preventing colorectal cancer.

Human IL-15 Inhibits NK Cells Specific for Human NK-92 Cells

Recent studies have indicated that natural killer (NK) cells present in peripheral blood mononuclear cells (PBMCs) might be responsible for the somewhat poor outcome of clinical trials conducted with the NK cell line NK-92, as well as chimeric antigen receptor-modified NK-92 cells against leukemias and lymphomas. These NK cells and how their cytotoxic profiles can be altered by some common gamma chain receptor-dependent cytokines or by removal of CD4+ cells have been addressed herein. A time-resolved fluorometric assay using 2.2':6'.2"-terpyridine-6.6"-dicarboxylic acid-labeled NK-92 or K562 as target cells was used for measuring the cytotoxic activity of cytokine-treated PBMCs and purified NK cells. Pre-incubation with 25 ng/ml interleukin 12 (IL-12), IL-15 or IL-21 for 72 h increased NK cell activity against K562 cells by more than 90% (1:25 target:effector ratio), whereas the corresponding NK cell activity against NK-92 cells was reduced by 15.9±0.1% by IL-12 and 50.6±2.9% by IL-15 compared to cells treated with medium alone. IL-7, on the other hand, increased NK activity against K562 to a much smaller extent (10.4±0.4%) and inhibited NK-92 cell lysis by 15.2±0.3%. Interestingly, similar amounts of IL-2 potentiated NK cell activity against both K562 and NK-92 cells by 50.9±0.5% and 14.3±0.9%, respectively. Purification of NK cells with magnetic beads demonstrated that NK cells indeed were responsible for the observed cytotoxic activity against both NK-92 cells (58.5±9.10%, 1:100 target:effector ratio) and K562 cells (81.6±9.57%, 1:100 target:effector ratio). Elimination of CD4+ cells from PBMCs did not alter the NK activity profile. This study highlights a problem that might arise with immune-based NK-92 and chimeric antigen receptor-transduced NK-92 cell therapies and pinpoints the need for evaluating new NK-like cell lines.

Benefits of A Three-Day Bamboo Forest Therapy Session on the Psychophysiology and Immune System Responses of Male College Students.

Forest therapy is a fast-growing treatment approach, as it has the potential to alleviate stressful life events and to improve psychological well-being and physical health. Bamboo forests are widespread in southwestern China. Nevertheless, a knowledge gap on the specific health benefits of bamboo forest (BF) therapy still exists. To explore the psycho-physiologic responses of participants to the effects of BF therapy, 60 male adults aged between 19 and 24, with similar healthy conditions, were selected to participate in this study. A one-group pretest–posttest design was used for the BF sites and the city site (CS) to compare the difference in the psycho-physiologic responses of participants before and after the test. Participants at the BF sites participated in a three-day bamboo forest therapy session, and those at the CS participated in a three-day urban program. Blood pressure, heart rate, and peripheral oxygen saturation were measured as the physical signs, and the profile of mood state (POMS) questionnaire was completed by the participants for the psychological evaluation. Blood was sampled, and natural killer (NK) activity, the number of NK cells, and the levels of corticosterone, granulysin, perforin, and granzyme A/B in peripheral blood lymphocytes (PBLs) were measured. All the measurements mentioned above were performed at 08:00 on the first and fourth days within the test. Results indicated that the three-day BF therapy was capable of enhancing positive mood states and also reducing negative mood states in the male participants. The blood pressure and heart rates of the male participants decreased, while the peripheral oxygen saturation increased after the three-day BF therapy session. Furthermore, BF therapy significantly increased NK activity and the number of NK cells and perforin-, granulysin-, and granzyme A/B-expressing cells and significantly decreased the corticosterone level in PBLs in the male participants. The three-day BF therapy session improved the psychological and physiological well-being and enhanced the immune functions of the male college students.

Changes in Both CD4+CD25+Foxp3+ Regulatory T Cells and CD3-CD56+ NK Cells in Patients with Chronic Myeloid Leukemia Treated with a Tyrosine Kinase Inhibitor

Background: The immunological graft-versus-leukemia effects associated with chronic myeloid leukemia (CML) are well-established. Both regulatory T cells (Treg) and natural killer (NK) cells play a role in the maintenance of CML. In this study, we examined changes in the number of circulating Treg and NK cells and the NK activity in CML patients before and after treatment with a tyrosine kinase inhibitor (TKI). Our goal was to evaluate the clinical significance of this treatment on these two different cell types. Moreover, the levels of these cells suggest that there is a need to make the TKI more effective as an immunotherapy.Patients and Methods: Treg and NK cells were characterized and quantified by flow cytometry in 27 newly diagnosed CML patients, 19 newly diagnosed patients with other myeloproliferative neoplasms (MPN), and 15 healthy controls (HC-group). CML patients, who were diagnosed as chronic phase and initially treated with a TKI between September 2007 and July 2017 and were followed up for more than 12 months were enrolled in the study. The molecular response was analyzed by quantitative PCR of the BCR-ABL fusion genes at approximately 6-month intervals after the initiation of treatment. After obtaining informed consent, peripheral blood (PB) was drawn from all patients at their initial diagnosis and at 6-month intervals thereafter. CD4+CD25+Foxp3+ Treg cells, CD3+CD4+T cells, CD3+CD8+ T cells, and CD3-CD56+ NK cells were analyzed using flow cytometry, and the absolute numbers of these cells were calculated. The NK activity was measured by the standard 51Cr release assay at an effector:target (E:T) ratio of 20:1.Results: The median age for CML patients was 65 years (range: 44-85), and 17 out of 27 of the patients were male. The median period of observation was 656 days. After 12 months, 12 CML patients (MMR-group) had a major molecular response (MMR), and 15 patients (NR-group) did not have a MMR. Treg% values in the PB before treatment in the CML-group (0.39±0.30%) were significantly lower than that in the HC-group (0.70±0.29%, p<0.01). Before treatment, the percentage of Treg cells in the NR-group (0.25±0.24%) was significantly lower than that in MMR-group and HC-group (0.57±0.29, 0.69±0.29%, p<0.01, p<0.01, respectively), although the absolute number of Treg cells did not differ. The changes in Treg% values in the PB before treatment to 6 months after treatment in the CML patients significantly increased from 0.39±0.30 to 0.60 ±0.49% (p=0.026). However, the absolute number of Treg cells significantly decreased from 37.1±18.6 to 28.3±20.0/μL (p<0.01). Similarly, comparing before and at 1 year after treatment, the absolute number of Treg cells significantly decreased from 37.1±18.6 to 17.0±14.2/μL in the CML patients (p<0.01) and from 39.2±14.7 to 14.6±6.6/μL in the MMR-group (p<0.01). The Treg% values in the MMR-group also decreased from 0.57±0.29 to 0.31±0.18% (p=0.033). However, even 6 months after treatment, the absolute number of Treg cells was significantly higher in both the CML-group (28.3±20.0/μL) and the NR-group (29.4±15.2/μL) than that in the MPN-group (14.5±10.1/μL, p<0.01, p<0.01, respectively). The absolute numbers and percentages of CD3-CD56+ NK cells and NK activity before treatment as well as after treatment did not differ between each group. However, the absolute number of CD3-CD56+ NK cells before treatment in the CML patients (427.5±424.4/μL) was significantly higher than that in the MPN patients (192.6±87.7/μL, p=0.022). The NK activity before treatment in the MMR-group (26.5±20.5%) was significantly lower than that in the HC-group (41.7±4.1%, p<0.01), whereas the NK activity increased with time and was no longer different from that in the HC-group.Conclusions: The absolute number of Treg cells in the CML patients decreased remarkably after treatment. The absolute number and the percentage of Treg cells decreased remarkably after treatment especially among the CML patients in the MMR-group. Although the number of NK cells did not change in the MMR-group compared to that in the HC-group, the NK activity was significantly lower and tended to approach the value of the normal control group after treatment. These data suggest that patients with CML have a more profound remission by treatment with a TKI resulting in decreased levels of Treg cells and increased NK activity. Immunological control via T cells and NK cells is very important in the treatment of CML. DisclosuresSuzumiya:Chugai-Roche: Research Funding, Speakers Bureau; Kyowa Hakko Kirin: Research Funding, Speakers Bureau; Pfizer: Research Funding; SymBio: Research Funding; Ono: Speakers Bureau; Nippon Shinyaku: Speakers Bureau; Eisai: Research Funding, Speakers Bureau; Shire Japan: Speakers Bureau; Taiho: Research Funding, Speakers Bureau; Toyama Chemical: Research Funding; Celltrion: Research Funding; Takeda: Research Funding, Speakers Bureau; Zenyaku Kogyo: Consultancy; Abbvie: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Sumitomo Dainioppon: Research Funding, Speakers Bureau; Astellas: Research Funding, Speakers Bureau; Bristol Myers Squibb: Speakers Bureau; Ohtsuka: Speakers Bureau.

Differential effect of dietary vitamin D supplementation on natural killer cell activity in lean and obese mice

Vitamin D has an immunoregulatory effect on both innate and adaptive immunity. Contradictory results regarding vitamin D and natural killer (NK) cell functions have been reported with in vitro studies, but little is known about this in vivo. We investigated whether vitamin D levels (50, 1000 or 10,000 IU/kg of diet: DD, DC or DS) affect NK cell functions in mice fed a control or high-fat diet (10% or 45% kcal fat: CD or HFD) for 12 weeks. The splenic NK cell activity was significantly higher in the CD-DS group than the HFD-DS group, and the CD-DS group showed significantly higher NK cell activity compared with the CD-DD and CD-DC groups. However, no difference in NK cell activity was observed among the HFD groups fed different levels of vitamin D. The splenic population of NK cells was significantly higher in the CD-DS group than the HFD-DS group. There was no difference in the intracellular expression of IFN-γ and the surface expression of NKG2D and CD107a in NK cells by both dietary fat and vitamin D content. The splenic mRNA expression of Ifng and Ccl5 was significantly lower in the HFD groups compared with the CD groups, but there was no difference in the mRNA levels of Vdup1 and Vdr among the groups. Taken together, these results suggest that dietary vitamin D supplementation can modulate innate immunity by increasing NK activity in control mice but not in obese mice. This effect might be mediated through alternation of the splenic NK cell population.

Biobran/MGN-3, an arabinoxylan rice bran, enhances NK cell activity in geriatric subjects: A randomized, double-blind, placebo-controlled clinical trial.

Aging is associated with a decline in natural killer (NK) and natural killer T (NKT) cell function that may contribute to increased susceptibility to malignancy and infection. A preliminary investigation was conducted examining the hypothesis that arabinoxylan rice bran (Biobran/MGN-3), a denatured hemicellulose with known immunomodulatory activity, could counteract this decline in NK/NKT cell activity in geriatrics. A total of 12 healthy geriatric subjects of both sexes and over 56 years old, participated in a randomized, double-blind, placebo-controlled clinical trial. A total of six subjects served as control and six subjects ingested Biobran/MGN-3 (500 mg/day) for 30 days. The effect of Biobran/MGN-3 supplementation on NK/NKT cell activity was assessed using the degranulation assay. All study subjects were monitored for the development of any inadvertent side effects. In addition, the pharmacological effects of Biobran/MGN-3 on blood cell components and liver and kidney functions were also assessed. Results demonstrated that Biobran/MGN-3 had no effect on the total percentage of NK cells, however it enhanced the cytotoxic activity of induced NK cell expression of cluster of differentiation 107a, when compared with baseline values and with the placebo group (P<0.05). Furthermore, there were no side effects observed, indicating that Biobran/MGN-3 supplementation was safe at the utilized dosage and for the duration of administration. Various additional beneficial effects were observed, including improved mean corpuscular volume and reduced hepatic aspartate aminotransferase enzyme levels, which suggested improved liver function. It was concluded that Biobran/MGN-3 induces a significant increase in NK activity which may increase resistance to viral infections and cancers in the geriatric population. However, additional clinical trials should be conducted in the future to verify these findings.

Augmentation of natural killer cell activity in vitro and in vivo by sericin-derived oligopeptides

This study investigated the effects of sericin-derived oligopeptides on natural killer (NK) activity. In vitro exposure of human peripheral blood mononuclear cells with sericin-derived oligopeptides resulted in an augmentation of NK cell activity against K562 target cells and the effects appeared to be dose-related. Experiments designed to examine whether enhanced NK activity was due to direct or indirect activation of NK cells revealed that sericin oligopeptides did not induce activity of purified NK cells, and that sericin oligopeptides augmented NK activity indirectly by inducing the production of IL-2 and IFN-γ cytokines. In in vivo experimentation where mice were orally administered with sericin oligopeptides and splenic mononuclear cells tested against YAC-1 target cells, significant increase in NK activity was obtained compared to control mice. Elevated levels of IL-2 were also evident in all oligopeptides-treated groups. As demonstrated both in vitro and in vivo, these results indicate that sericin-derived oligopeptides have efficient NK-enhancing activity and suggest the potential therapeutic applications of such oligopeptides for functional improvement of NK cells, and possibly for treatment of tumor and infectious diseases in which NK activity contributes to host defense.

Reduced IL‐10 production contributes to impaired NK cytotoxicity in old mice fed a high folic acid diet (638.3)

Natural killer (NK) cells are important for immunity against malignant and virally infected cells. High folic acid intake, which may be linked with higher risk of colon cancer, was associated with lower NK activity in older women. To study the underlying mechanisms, we created a mouse model and found that aged mice fed a high folic acid (HFA) diet had reduced NK activity. In this study, we determined if expression of cytokines that are known to activate NK activity (IL‐10, IFN‐γ, TNF‐α) are affected by a HFA diet in aged mice.Female C57BL/6 mice (16 mo) were fed a control (1x RDA folic acid) or a HFA diet (20x RDA folic acid) for 3 months. Splenocytes were collected and stimulated with LPS for 24 h for ex vivo production of IL‐10, IFN‐γ, and TNF‐α determined by cytometric bead array.In HFA mice, IL‐10 production was 50.7% less than that of the control mice (P=0.028) but no differences were found in IFN‐γ and TNF‐α production. Since IL‐10 activates NK cells, we examined whether addition of IL‐10 to the splenocyte cultures would restore NK activity in the HFA group. We found that NK activity increased for both groups (P&lt;0.01), but the HFA group had larger percent increase in NK activity as compared to control mice (P=0.058). These results indicate that IL‐10 restored the lower NK activity in aged mice fed a HFA diet.These findings suggest the decreased NK activity due to a high folic acid diet may in part be due to impaired IL‐10 secretion.Grant Funding Source: Supported by USDA contract # 51520‐008‐045 and HNRCA Pilot grant

MGN-3 arabinoxylan rice bran modulates innate immunity in multiple myeloma patients.

Dendritic cells (DCs) and natural killer (NK) cells are central components of innate immunity for controlling tumor growth. The therapeutic effects of certain anti-myeloma drugs are partially mediated by targeting the innate immune response. In addition, novel types of natural compounds have been developed that efficiently modulate the activity of both the cellular and humoral compartments of immunity. MGN-3 is known as an activator of natural killer cells, inducer of apoptosis and cytokine production, and modulator of dendritic cell maturation and differentiation in vitro. We have performed a randomized, placebo-controlled study to examine the effects of MGN-3 on innate immune system parameters in 48 multiple myeloma patients. We performed immunophenotypic analysis of peripheral blood samples, determined NK cell activity, and assessed the cytokine profiles of plasma before and during 3 months of treatment. The results demonstrate a clear increase in NK activity in MGN-3-treated patients compared to the placebo group, an increased level of myeloid DCs in peripheral blood, and augmented concentrations of T helper cell type 1-related cytokines. The present study suggests that MGN-3 may represent an immunologically relevant product for activating innate immunity in multiple myeloma patients and warrants further testing to demonstrate clinical efficacy.

Daily intake ofLactobacillus caseiShirota increases natural killer cell activity in smokers

Dietary probiotics supplementation exerts beneficial health effects. Since cigarette smoking reduces natural killer (NK) activity, we evaluated the effect of Lactobacillus casei Shirota (LcS) intake on NK cytotoxic activity in male smokers. The double-blind, placebo-controlled, randomised study was conducted on seventy-two healthy Italian blue-collar male smokers randomly divided for daily intake of LcS powder or placebo. Before and after 3 weeks of intake, peripheral blood mononuclear cells were isolated and NK activity and CD16⁺ cells' number were assessed. Daily LcS intake for 3 weeks significantly increased NK activity (P < 0.001). The increase in NK activity was paralleled by an increase in CD16⁺ cells (P < 0.001). Before intake, NK cytotoxic activity inversely correlated with the number of cigarettes smoked (R - 0.064). LcS intake prevented the smoke-dependent expected NK activity reduction. The analysis of the distribution of changes in smoke-adjusted NK activity demonstrated that the positive variations were significantly associated with LcS intake, while the negative variations were associated with placebo intake (median value of distributions of differences, 20.98 lytic unit (LU)/10⁷ cells for LcS v. - 4.38 LU/10⁷ cells for placebo, P = 0.039). In conclusion, 3 weeks of daily LcS intake in Italian male smokers was associated with a higher increase in cytotoxic activity and CD16⁺ cells' number in comparison to the placebo intake group.

Cytotoxicity of human cord blood natural killer cells is enhanced by recombinant interleukin-15.

Hematopoietic cord blood (CB) stem cell transplantation has more advantages to other cell sources because of lower Graft Versus Host Disease (GVHD). Interleukin-15(IL-15) is an immunoregulatory cytokine, known to enhance cytolytic function of cord Natural Killer (NK) cells. The aim of this study was to investigate the effect of IL-15 on NK cytotoxicity simultaneously in different cell death stages. We compared the ability of IL-15 to enhance the NK cytotoxicity of CB in comparison to adult blood Mononuclear Cells (MNCs) against K562 target cells by co-staining with AnnexinV-FITC and Propidium Iodide after 3.5 h incubation at 37 °C and 5% CO₂ by using flow cytometric method. We also evaluated phenotypic changes after treatment by IL-15 in both cell sources. Our results indicated that CB samples had lower level of apoptosis, while necrosis was negligible; also by escalating Effector: Target (E: T), we got higher level of apoptosis and necrosis in peripheral blood (PB). NK activity of cord and adult MNCs was enhanced by incubation with IL-15 (10 ng/ml) for 72 h with significantly higher results of PB in comparison to CB (p<0.0001). Moreover, IL-15 increased the percentage of CD3-/CD56+ and CD25+ cells after 72 h incubation. Results showed incubation with human recombinant (hr) IL-15 for 3 days increased NK activity. Taken together, these results indicated that NK cytotoxicity of CB MNCs could be augmented by human recombinant (hr) IL-15, but this activity did not reach to same level of PB counterparts. We established that CD25 expression on CB MNCs could be increased with IL-15, in 72-hour cultures, but to a lesser degree compared to that on corresponding adult PB MNCs.

Does analgesia and condition influence immunity after surgery? Effects of fentanyl, ketamine and clonidine on natural killer activity at different ages

Cellular immunity varies in the perioperative period. We evaluated the effects of fentanyl, clonidine and ketamine at different time points after surgery and in animals in different conditions (young vs. old). Rats undergoing laparotomy under sevoflurane anaesthesia were assigned to receive saline, fentanyl (40 microg kg(-1)), clonidine (10 microg kg(-1)) or ketamine (10 mg kg(-1)) 1 h before surgery. Natural killer (NK) activity was quantified at different time points (immediately or after 18, 24, 48, 72 h and 8 days) in vitro by the lysis of YAC-1 cells. In-vivo assessment included counting the number of lung metastases induced by the MADB-106 cells. During the first 24 h after surgery, a rapid increase in NK activity was noted, followed by a significant depression returning to baseline at 8 days. Analgesics show specific effects: fentanyl depressed NK activity with or without surgery. Clonidine depressed NK activity in nonoperated animals and during the first 24 h after surgery. Ketamine depressed NK activity in nonoperated animals but, after surgery, this activity varied with the same time course as saline. Ketamine and clonidine significantly reduced the number of lung metastases in operated animals. Ketamine significantly reduced the number of metastases in old nonoperated animals. Finally, ageing has a significant negative influence. Surgery, analgesics and co-existing conditions significantly influence cellular immunity. The importance of these changes varies with time. Fentanyl had a worse influence than clonidine and ketamine, but seemed equally protective against the development of metastases.

Enhancement of Murine NK cell Activity in vitro by Red Ginseng Acidic Polysaccharide

The in-vitro immunomodulatory function of the activity of murine natural-killer (NK) cells induced by redginseng acidic polysaccharide (RGAP) was examined. RGAP induced the significant enhancement of NK cell activity against the Yac-1 tumor cells. The treatment of splenocytes cultured with RGAP for 16 h resulted in a significant increase in NK activity at the E:T ratio of 100:1, and in a 239 and 250% increase at 10 and l00 ㎍/㎖, respectively. We also demonstrate that RGAP treatment increased the production of interferon (IFN)-γ (17-125%) and tumor necrosis factor (TNF)-α (15-100%), suggesting that the increase in NK cell cytotoxicity could be due to the enhancement of the NK cell production of both cytokines. In addition, RGAP had a stimulating effect on lymphocyte proliferation in the presence of mitogens. Overall, these results suggest that RGAP has an immunopotentiating effect on NK cells, which can support the development of clinical studies on RGAP.

Effect of Phytoncide from Trees on Human Natural Killer Cell Function

We previously reported that the forest environment enhanced human natural killer (NK) cell activity, the number of NK cells, and intracellular anti-cancer proteins in lymphocytes, and that the increased NK activity lasted for more than 7 days after trips to forests both in male and female subjects. To explore the factors in the forest environment that activated human NK cells, in the present study we investigate the effect of essential oils from trees on human immune function in twelve healthy male subjects, age 37-60 years, who stayed at an urban hotel for 3 nights from 7.00 p.m. to 8.00 a.m. Aromatic volatile substances (phytoncides) were produced by vaporizing Chamaecyparis obtusa (hinoki cypress) stem oil with a humidifier in the hotel room during the night stay. Blood samples were taken on the last day and urine samples were analysed every day during the stay. NK activity, the percentages of NK and T cells, and granulysin, perforin, granzyme A/B-expressing lymphocytes in blood, and the concentrations of adrenaline and noradrenaline in urine were measured. Similar control measurements were made before the stay on a normal working day. The concentrations of phytoncides in the hotel room air were measured. Phytoncide exposure significantly increased NK activity and the percentages of NK, perforin, granulysin, and granzyme A/B-expressing cells, and significantly decreased the percentage of T cells, and the concentrations of adrenaline and noradrenaline in urine. Phytoncides, such as alpha-pinene and beta-pinene, were detected in the hotel room air. These findings indicate that phytoncide exposure and decreased stress hormone levels may partially contribute to increased NK activity.

Effect of forest bathing trips on human immune function

In Japan, a forest bathing trip, called "Shinrinyoku" in Japanese, is a short, leisurely visit to a forest; it is regarded as being similar to natural aromatherapy. This review focuses on the effects of forest bathing trips on human immune function. Beginning in 2005, adult Japanese individuals, both male and female, participated in a series of studies aimed at investigating the effect of forest bathing trips on human immune function. The subjects experienced a 3-day/2-night trip to forest areas, and blood and urine were sampled on days 2 (the first sampling during each trip) and 3 (the second sampling during each trip), and on days 7 and 30 after the trips. Natural killer (NK) activity, the numbers of NK, granulysin-, perforin-, and granzymes A/B-expressing lymphocytes in the blood, and the concentration of urinary adrenaline were measured. The same measurements were made before the trips on a normal working day as a control. The mean values of NK activity and the numbers of NK, granulysin-, perforin-, and granzymes A/B-expressing cells on forest bathing days were significantly higher than those on the control days, whereas the mean values of the concentration of urinary adrenaline on forest bathing days were significantly lower than that on the control days in both male and female subjects. The increased NK activity lasted for more than 30 days after the trip, suggesting that a forest bathing trip once a month would enable individuals to maintain a higher level of NK activity. In contrast, a visit to the city as a tourist did not increase NK activity, the numbers of NK cells, or the level of intracellular granulysin, perforin, and granzymes A/B. These findings indicate that forest bathing trips resulted in an increase in NK activity, which was mediated by increases in the number of NK cells and the levels of intracellular granulysin, perforin, and granzymes A/B.

Differential augmentation ofin vivonatural killer cytotoxicity in normal primates with recombinant human interleukin-1 and granulocyte-macrophage colony-stimulating factor

The effect of recombinant human interleukin-1 (IL-1) alpha, granulocyte-macrophage colony-stimulating factor (GM-CSF), and combined factor therapy (CFT) on Rhesus monkey peripheral blood natural killer (NK) activity in vivo was compared. During a 14-day treatment period, IL-1-treated animals demonstrated a 170% increase in NK activity against K562 target cells by day 4, reaching maximal levels (300%) at day 16, and returning to baseline by day 30. NK activity of GM-CSF-treated monkeys increased slightly (60-100%) during days 4-12, as did saline-treated monkeys, but returned to baseline values by day 16. A delayed increase in NK activity resulted after GM-CSF treatment, reaching a peak (260%) on day 23 and remaining elevated through day 39. CFT resulted in a bimodal response pattern, with two peaks of NK activity: one at day 16 and a second at day 39. The first peak of activity (223%) was significantly less than the activity attained with IL-1 alone; the second peak (300%) was of greater duration and occurred later than the peak observed in GM-CSF-treated monkeys. Unlike IL-1, GM-CSF treatment did not lead to a immediate stimulation of NK activity; augmentation was delayed by more than 7 days post treatment. CFT results suggest that GM-CSF reduced the direct NK response to IL-1; while IL-1 led to an enhanced delayed NK response. Therefore, IL-1 and GM-CSF augment NK activity through different but interrelated pathways.

In Vivo Tumor Inhibitory Effects of Nutritional Rice Bran Supplement MGN-3/Biobran on Ehrlich Carcinoma-Bearing Mice*

This study was undertaken to investigate the in vivo anti-tumor activity of MGN-3/Biobran, a modified arabinoxylan rice bran. Swiss albino mice were inoculated intramuscularly in the right thigh with Ehrlich ascites carcinoma (EAC) cells. On Day 8, mice bearing a solid Ehrlich carcinoma (SEC) tumor were treated with MGN-3 via intraperitoneal injection. Tumor growth, cytokine production, and apoptotic effect of MGN-3 were examined. MGN-3 caused a highly significant delay in both tumor volume (63.27%) and tumor weight (45.2%) as compared to controls (P < 0.01). The mechanisms by which MGN-3 exerts its antitumor effect seem to involve its ability to induce apoptosis and immune modulation. MGN-3 induced a 1.8-fold increase in the percentage of apoptotic SEC cells as determined by flow cytometry and the histopathological examination. In addition, MGN-3 influenced plasma cytokine production by increasing the levels of tumor necrosis factor-α and interferon-γ, while downregulating levels of the immune suppressing cytokine interleukin-10. Data also showed that non-tumor-bearing mice intramuscularly injected with MGN-3 resulted in a twofold increase in natural killer activity. No adverse side effects due to MGN-3 treatment were observed; all animals displayed normal feeding/drinking and life activity patterns. These data may have clinical implications for the treatment of solid cancers.

Immunotoxicity of nivalenol after subchronic dietary exposure to rats

Immunobiological effects of nivalenol (NIV), a trichothecene mycotoxin produced by Fusarium nivale, were examined in male F344 rats after 90-day dietary exposure at doses of 0, 0.4, 1.5, and 6.9 mg/kg body weight/day (0, 6.25, 25 and 100 ppm, respectively) in a subchronic toxicity study. With regards to the serum immunoglobulin levels, a slight increase of IgM was observed only at 6.9 mg/kg (26% increase), while levels of IgG and IgA did not fluctuate at any dose. Flow cytometric analysis of splenic cells revealed a dose-dependent decrease of T lymphocyte/B lymphocyte (CD3 +/B220 +) ratio from 1.5 mg/kg and an elevated CD4 +helper/CD8 +cytotoxic T lymphocyte ratio at 6.9 mg/kg. Furthermore, increases of natural killer (NK) activity of splenic lymphocytes against YAC-1 target cells were observed at all doses, while the magnitude of changes was similar between 1.5 and 6.9 mg/kg. At 6.9 mg/kg, the reduction of the ratio of NKR-P1A + splenic cells, which is an indicator of NK cells in the spleen, was apparent. As with other previous studies of NIV, decreased body weight was observed from 1.5 mg/kg during the experiment in the present study. In summary, NIV affected immune function in rats after 90-day dietary exposure, the effects being apparent from 0.4 mg/kg judging from the increase of NK activity, although nutritional suppression might have influenced the immunological changes appeared from 1.5 mg/kg.

Forest Bathing Enhances Human Natural Killer Activity and Expression of Anti-Cancer Proteins

In order to explore the effect of forest bathing on human immune function, we investigated natural killer (NK) activity; the number of NK cells, and perforin, granzymes and granulysin-expression in peripheral blood lymphocytes (PBL) during a visit to forest fields. Twelve healthy male subjects, age 37-55 years, were selected with informed consent from three large companies in Tokyo, Japan. The subjects experienced a three-day/two-night trip in three different forest fields. On the first day, subjects walked for two hours in the afternoon in a forest field; and on the second day, they walked for two hours in the morning and afternoon, respectively, in two different forest fields. Blood was sampled on the second and third days, and NK activity; proportions of NK, T cells, granulysin, perforin, and granzymes A/B-expressing cells in PBL were measured. Similar measurements were made before the trip on a normal working day as the control. Almost all of the subjects (11/12) showed higher NK activity after the trip (about 50 percent increased) compared with before. There are significant differences both before and after the trip and between days 1 and 2 in NK activity. The forest bathing trip also significantly increased the numbers of NK, perforin, granulysin, and granzymes A/B-expressing cells. Taken together, these findings indicate that a forest bathing trip can increase NK activity, and that this effect at least partially mediated by increasing the number of NK cells and by the induction of intracellular anti-cancer proteins.

Supplementation with active hexose correlated compound increases the innate immune response of young mice to primary influenza infection.

The emergence of H5N1 avian influenza and the threat of new or adapted viruses in bioterrorism have created an urgent interest in identifying agents to enhance the immune response to primary virus infection. Active hexose correlated compound (AHCC) is a natural mushroom extract reported to increase natural killer (NK) cell activity, survival, and bacterial clearance in young mice. However, the effects of AHCC on the response to viral infections have not been studied. In this study, young C57BL/6 mice were supplemented with 1 g AHCC/(kg body weight x d) for 1 wk prior to and throughout infection with influenza A (H1N1, PR8). Supplementation increased survival, decreased the severity of infection, and shortened recovery time following intranasal infection with flu, as determined by the recovery of body weight and epithelial integrity in the lungs. AHCC increased NK activity in lungs at d 1 (P < 0.05) and d 4 (P < 0.01) and in the spleen at d 2 postinfection (P < 0.01). Supplementation increased the percentage (P < 0.05) and number (P < 0.01) of NK1.1+ cells in the lung and reduced the infiltration of lymphocytes and macrophages compared with controls (P < 0.01). These data suggest that AHCC supplementation boosts NK activity, improves survival, and reduces the severity of influenza infection in young mice. Bolstering innate immunity with dietary bioactives may be one avenue for improving the immune response to primary flu infection.