Natural killer cell activity for IFN-gamma production as a supportive diagnostic marker for gastric cancer

Interferon-Gamma Secretion Is Significantly Decreased in Stage III Breast Cancer Patients

Even though some studies have shown possible clinical relationship between molecular subtypes and tumor infiltrating natural killer (NK) cells around tumors, there are few studies showing the clinical relevance of peripheral NK cell activity at diagnosis in female patients with invasive breast cancer. A total of 396 female invasive breast cancer patients who received curative surgical treatment from March 2017 to July 2021 were retrospectively analyzed. NK cell activation-induced interferon-gamma (IFN-γ) secretion measured by enzyme-linked immunosorbent assay was used to measure the activity of peripheral NK cells. Statistical analyses were performed to determine clinical relationships with major clinicopathologic parameters. Quadripartite NK cell activity measured by induced interferon-gamma showed significant relevance with staging and body mass index, and some of the inflammatory serological markers, namely N/L (neutrophil/lymphocyte), P/N (platelet/neutrophil), and P/L (platelet/lymphocyte), showed significantly different NK activity in each interval by univariate analysis. A binary subgroup analysis, setting the IFN-γ secretion cut-off at 100 pg/mL, showed that stage III was significantly increased and axillary lymph node metastasis positivity was increased in the group of IFN-γ < 100 pg/mL, and IFN-γ secretion decreased with an increasing N stage, increased BMI (body mass index), and decreased production of IFN-γ. Following this, the same binary analysis, but with the IFN-γ secretion cut-off at 250 pg/mL, also showed that secretion in stage III was increased in those concentrations with <250 pg/mL, axillary lymph node positivity appeared to be correlated, and BMI ≥ 30 increased in prevalence. Additional ANOVA post hoc tests (Bonferroni) were performed on some serological markers that tended to be somewhat inconsistent. By subgroup analysis with Bonferroni adjustment between the IFN-γ secretion and TNM stage, no significant difference in IFN-γ secretion could be identified at stages I, II, and IV, but at stage III, the IFN-γ secretion < 100 pg/mL was significantly higher than 250 ≤ IFN-γ secretion < 500 pg/mL or IFN-γ secretion ≥ 500 pg/mL. According to this study, stage III was significantly associated with the lowest IFN-γ secretion. Compared to a higher level of IFN-γ secretion, a lower level of IFN-γ secretion seemed to be associated with increased body mass index. Unlike when IFN-γ secretion was analyzed in quartiles, as the IFN-γ secretion fell below 100 pg/mL, the correlation between axillary lymph node positivity and increased N stage, increased BMI, and increased N/L and P/L, which are suggested poor prognostic factors, became more pronounced. We think a peripheral IFN-γ secretion test might be convenient and useful tool for pretreatment risk assessment and selecting probable candidates for further treatment such as immunotherapy in some curable but high-risk invasive breast cancer patients, compared to other costly assaying of tissue NK cell activity at diagnosis.

The Immune-Stimulating and Anti-Diabetic Effects of Allium hookeri Leaves Grown in a Plant Factory with Artificial Lights in Immunosuppressed Obese C57BL/6 Mice

We investigated the immune-stimulating and anti-diabetic effects of Allium hookeri leaves grown in a plant factory with artificial lights. The immunomodulatory effects of A. hookeri leaves' ethanol extracts were evaluated with immune-related hematological factors in blood, the proliferation of splenocytes, NK cell activity, IgG and cytokine levels, and their mechanisms in immunosuppressed obese mice. Anti-diabetic effects were determined by the inhibitory activity against α-amylase and α-glucosidase in vitro and fasting blood glucose levels and biochemical factors in the serum of immunosuppressed obese mice. A. hookeri leaf extracts increased WBC and LYM counts, the proliferation of splenocytes, and serum IgG and IL-1β concentrations compared to those of the NC group, which was used as a negative control. A. hookeri leaf extracts also improved serum HDL levels while they decreased the activities of digestive enzymes, fasting blood glucose, and biochemical factors (ALT, AST, T-Chol, TG, LDL, and GLU). The expressions of IL-1β, JNK, c-Jun, p65, and iNOS in the thymus of immunosuppressed mice were activated by the treatment of A. hookeri leaf extracts. The results suggest that A. hookeri leaves grown in a plant factory with artificial lights also have immune-stimulatory and anti-diabetic effects and can be used as novel functional supplements to control related diseases and to improve public health.

Mediastinal lymph node removal modulates natural killer cell exhaustion in patients with non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death globally. In this study, the effect of complete removal of mediastinal lymph nodes by video-assisted mediastinoscopic lymphadenectomy (VAMLA) on natural killer (NK) cell phenotype and functions in patients with NSCLC was evaluated. The study included 21 NSCLC patients (cIA-IVA) undergoing VAMLA staging and 33 healthy controls. Mononuclear cells were isolated from peripheral blood of all participants and mediastinal lymph nodes of the patients. NK cells were analyzed by flow cytometry to define NK subsets, expressions of PD-1, CTLA-4, activating/inhibitory receptors, granzyme A, and CD107a. The plasma levels of soluble PD-1, PDL-1, and CTLA-4 were measured by ELISA. Mediastinal lymph nodes of NSCLC patients had increased ratios of exhausted NK cells, increased expression of PD-1 and IL-10, and impaired cytotoxicity. Mediastinal lymph nodes removal increased CD56dimCD16bright cytotoxic effector phenotype and reduced exhausted NK cells. PD-1+ NK cells were significantly more abundant in patients' blood, and VAMLA significantly reduced their ratio as well. The ratio of IL-10 secreting regulatory NK cells was also reduced after VAMLA. Blood NK cells had increased cytotoxic functions and spontaneous IFN-γ secretion, and these NK cell functions were also recovered by VAMLA. Mediastinal lymph node removal reversed NK cell exhaustion, reduced regulatory NK cells, and improved antitumoral functions of NK cells. Tumor-draining lymph nodes may contribute to tumor evasion from antitumoral immune responses. The role of their removal needs to be further studied both to better understand this mechanism and as a potential immunotherapeutic approach.

The role of natural killer cell activity as a milestone in oncologic outcome after curative resection of pancreatic adenocarcinoma

BACKGROUND

The objective of this study was to investigate differences in oncologic outcomes of patients with pancreas cancer according to natural killer cell activity (NKA).

METHODS

A total of 118 patients who underwent curative resection for primary pancreas cancer in two hospitals were analyzed. NKA change pattern was analyzed. Difference in disease-free survival or overall survival was investigated by dividing subjects into two groups based on a normal NKA value for each period.

RESULTS

NKA value decreased after surgery compared to the value measured at admission. It recovered to normal levels at 5 weeks postoperatively. The low NKA (less than 250 pg/mL) group at admission, 5 weeks postoperatively, and before 1st chemotherapy had significantly poorer disease-free survival than the normal NKA group. In multivariate analysis, NKA values less than 250 pg/mL at admission (odds ratio = 2.267, p = 0.023) and N 1 or N2 category (odds ratio = 2.478, p = 0.023) were significant factors associated with recurrence after curative resection.

CONCLUSIONS

NKA in patients with pancreatic cancer demonstrated noticeable changes after surgery. Immunologically predisposed patients with a low NKA value had a high risk of early recurrence and a poor prognosis, although pancreatic cancer was surgically removed.

Modified Rice Bran Arabinoxylan by Lentinus edodes Mycelial Enzyme as an Immunoceutical for Health and Aging-A Comprehensive Literature Review

Rice bran arabinoxylan compound (RBAC) is derived from defatted rice bran enzymatically treated with Lentinus edodes mycelium. This review explores biologically active compounds and mechanisms of action that support RBAC as an immunomodulating nutraceutical in generally healthy and/or aging individuals. Thirty-seven (n = 37) primary research articles fulfilled the selection criteria for review. Most research is based on Biobran MGN-3, which consists of complex heteropolysaccharides with arabinoxylan as its primary structure while also containing galactan and glucan. RBAC was found to invoke immunological activities through direct absorption via the digestive tract and interaction with immune cells at the Peyer's patches. RBAC was shown to promote innate defence by upregulating macrophage phagocytosis and enhancing natural killer cell activity while lowering oxidative stress. Through induction of dendritic cell maturation, RBAC also augments adaptive immunity by promoting T and B lymphocyte proliferation. RBAC acts as an immunomodulator by inhibiting mast cell degranulation during allergic reactions, attenuating inflammation, and downregulating angiogenesis by modulating cytokines and growth factors. RBAC has been shown to be a safe and effective nutraceutical for improving immune health, notably in aging individuals with reduced immune function. Human clinical trials with geriatric participants have demonstrated RBAC to have prophylactic benefits against viral infection and may improve their quality of life. Further research should explore RBAC's bioavailability, pharmacodynamics, and pharmacokinetics of the complex heteropolysaccharides within. Translational research to assess RBAC as a nutraceutical for the aging population is still required, particularly in human studies with larger sample sizes and cohort studies with long follow-up periods.

Higher cytotoxic activities of CD8+ T cells and natural killer cells from peripheral blood of early diagnosed lung cancer patients

INTRODUCTION

Cytotoxic (CD8+) and natural killer (NK) cells play critical roles in anti-tumor immunity. Dysfunction in these cells is considered as one of the extrinsic mechanisms for tumor relapse.

AIM

We aimed in this study to assess cytotoxic activities of CD8 + T and NK cells in the peripheral blood from lung cancer patients before and after induction of chemotherapy.

SUBJECTS AND METHODS

Healthy (n = 5) volunteers and lung cancer patients (n = 15:5 before, 5 during, and 5 after induction of chemotherapy) were recruited. Flow cytometry was used to analyze the numbers of CD8 + T cells, NK and CD56+T cells and their intracellular expression of granzyme B (GzB) in fresh peripheral blood mononuclear cells (PBMCs) and after 72 h of their culture in vitro and stimulation with 5 µg/ml Concanavalin A (Con A) and 50ng/ml IL-2). In addition, the plasma levels of inflammatory cytokines were measured using luminex.

RESULTS

After culture, significant increases in the number of GzB expressing cells gated on CD3+, CD4+, CD8 + and NKCD8 + T cells in the PBMCs from lung cancer patients before induction of chemotherapy as compared to control individuals as well as patients during and after induction of chemotherapy. Serum levels of IL-1 and CXCL8 in patients before induction of chemotherapy showed 37- and 40-fold increases, respectively, as compared to control individuals. Both GzB expression and cytokines levels in patients during and after chemotherapy were similar.

CONCLUSION

Polyclonal stimulation of PBMCs can restore the cytolytic activities of cytotoxic CD8 and NK cells from lung cancer patients even after chemotherapy.

Low Muscle and High Fat Percentages Are Associated with Low Natural Killer Cell Activity: A Cross-Sectional Study

This study aimed to investigate whether body fat and muscle percentages are associated with natural killer cell activity (NKA). This was a cross-sectional study, conducted on 8058 subjects in a medical center in Korea. The association between the muscle and fat percentage tertiles and a low NKA, defined as an interferon-gamma level lower than 500 pg/mL, was assessed. In both men and women, the muscle mass and muscle percentage were significantly low in participants with a low NKA, whereas the fat percentage, white blood cell count, and C-reactive protein (CRP) level were significantly high in those with a low NKA. Compared with the lowest muscle percentage tertile as a reference, the fully adjusted odd ratios (ORs) (95% confidence intervals (CIs)) for a low NKA were significantly lower in T2 (OR: 0.69; 95% CI: 0.55-0.86) and T3 (OR: 0.74; 95% CI: 0.57-0.95) of men, and T3 (OR: 0.76; 95% CI: 0.59-0.99) of women. Compared with the lowest fat percentage tertile as a reference, the fully adjusted OR was significantly higher in T3 of men (OR: 1.31; 95% CI: 1.01-1.69). A high muscle percentage was significantly inversely associated with a low NKA in men and women, whereas a high fat percentage was significantly associated with a low NKA in men.

Monalizumab efficacy correlates with HLA-E surface expression and NK cell activity in head and neck squamous carcinoma cell lines

PURPOSE

NKG2A, an inhibitory receptor expressed on NK cells and T cells, leads to immune evasion by binding to HLA-E expressed on cancer cells. Here, we investigated the relationship between HLA-E surface expression on head and neck squamous cell carcinoma (HNSCC) cell lines and the efficacy of monalizumab, an NKG2A inhibitor, in promoting NK cell activity.

METHODS

Six HNSCC cell lines were used as target cells. After exposure to IFN- γ, HLA-E surface expression on HNSCC cell lines was measured by flow cytometry. Peripheral blood mononuclear cells (PBMCs) from healthy donors and isolated NK cells were used as effector cells. NK cells were stimulated by treatment with IL-2 and IL-15 for 5 days, and NK cell-induced cytotoxicity was analyzed by CD107a degranulation and 51Cr release assays.

RESULTS

We confirmed that HLA-E expression was increased by IFN-γ secreted by NK cells and that HLA-E expression was different for each cell line upon exposure to IFN-γ. Cell lines with high HLA-E expression showed stronger inhibition of NK cell cytotoxicity, and efficacy of monalizumab was high. Combination with cetuximab increased the efficacy of monalizumab. In addition, stimulation of isolated NK cells with IL-2 and IL-15 increased the efficacy of monalizumab, even in the HLA-E low groups.

CONCLUSION

Monalizumab efficacy was correlated with HLA-E surface expression and was enhanced when NK cell activity was increased by cetuximab or cytokines. These results suggest that monalizumab may be potent against HLA-E-positive tumors and that monalizumab efficacy could be improved by promoting NK cell activity.

Relationship between Serum Cortisol, Dehydroepiandrosterone Sulfate (DHEAS) Levels, and Natural Killer Cell Activity: A Cross-Sectional Study

The adrenal steroid hormones, cortisol and dehydroepiandrosterone sulfate (DHEAS), are associated with the immune system in opposite actions. This study aimed to investigate the relationship between cortisol and DHEAS serum concentrations, their ratio (CDR), and natural killer cell activity (NKA). This cross-sectional study included 2275 subjects without current infection or inflammation in the final analyses. NKA was estimated by measuring the amount of interferon-gamma (IFN-γ) released by activated natural killer cells; low NKA was defined as IFN-γ level < 500 pg/mL. Cortisol, DHEAS levels, and CDRs were categorized by quartiles in men, premenopausal women, and postmenopausal women. Compared with the lowest quartile as reference, the adjusted odd ratios (ORs) and 95% confidence intervals (CIs) for low NKA of the highest cortisol and CDR group were 1.66 (1.09-2.51) and 1.68 (1.11-2.55) in men, 1.58 (1.07-2.33) and 2.33 (1.58-3.46) in premenopausal women, and 2.23 (1.28-3.87) and 1.85 (1.07-3.21) in postmenopausal women. Only in premenopausal women, the highest DHEAS group showed significantly lower risk of low NKA (OR: 0.51, 95% CI: 0.35-0.76). HPA axis activation indicated as high cortisol level, CDR was significantly associated with low NKA, while high DHEAS levels were inversely associated with low NKA in premenopausal women.

Anti-Inflammatory Klotho Protein Serum Concentration Correlates with Interferon Gamma Expression Related to the Cellular Activity of Both NKT-like and T Cells in the Process of Human Aging

Klotho is a beta-glucuronidase that reveals both anti-inflammatory and anti-oxidative properties that have been associated with mechanisms of aging. The study aimed to analyze the relationships between the serum concentration of soluble α-Klotho and cellular activity of two populations of lymphocytes; T and NKT-like cells corresponding to the level of cytokine secretion; i.e., IFN-γ, TNF-α, and IL-6. The studied population comprised three age groups: young individuals ('young'), seniors aged under 85 ('old'), and seniors aged over 85 ('oldest'). Both NKT-like and T cells were either non-cultured or cultured for 48 h and stimulated appropriately with IL-2, LPS or PMA with ionomycin to compare with unstimulated control cells. In all studied age groups non-cultured or cultured NKT-like cells revealed higher expressions of TNF-α, IL-6, and IFN-γ than T cells. α-Klotho concentration in serum decreased significantly in the process of aging. Intriguingly, only IFN-γ expression revealed a positive correlation with α-Klotho protein serum concentration in both non-cultured and cultured T and NKT-like cells. Since IFN-γ is engaged in the maintenance of immune homeostasis, the observed relationships may indicate the involvement of α-Klotho and cellular IFN-γ expression in the network of adaptive mechanisms developed during the process of human aging.

Intersections between innate immune response and gastric cancer development

Worldwide, gastric cancer (GC) is the fifth most commonly diagnosed malignancy. It has a reduced prevalence but has maintained its poor prognosis being the fourth leading cause of deaths related to cancer. The highest mortality rates occur in Asian and Latin American countries, where cases are usually diagnosed at advanced stages. Overall, GC is viewed as the consequence of a multifactorial process, involving the virulence of the Helicobacter pylori (H. pylori) strains, as well as some environmental factors, dietary habits, and host intrinsic factors. The tumor microenvironment in GC appears to be chronically inflamed which promotes tumor progression and reduces the therapeutic opportunities. It has been suggested that inflammation assessment needs to be measured qualitatively and quantitatively, considering cell-infiltration types, availability of receptors to detect damage and pathogens, and presence or absence of aggressive H. pylori strains. Gastrointestinal epithelial cells express several Toll-like receptors and determine the first defensive line against pathogens, and have been also described as mediators of tumorigenesis. However, other molecules, such as cytokines related to inflammation and innate immunity, including immune checkpoint molecules, interferon-gamma pathway and NETosis have been associated with an increased risk of GC. Therefore, this review will explore innate immune activation in the context of premalignant lesions of the gastric epithelium and established gastric tumors.

INTERLEUKIN-6 AND NKG2D AS PROGNOSTIC FACTORS IN IRAQI FEMALES WITH PITUITARY GAND ADENOMA: A LONGITUDINAL STUDY

OBJECTIVE

The aim: To assess the role of circulating IL-6 & NKG2D in the prognosis of pituitary adenoma.

PATIENTS AND METHODS

Materials and methods: Thirty female with new diagnosis of prolactinoma (pituitary gland adenoma) were enrolled in the study. ELISA test was used to evaluate the level of IL6 and NKG2D. ELISA tests were conducted before the initiation of treatment and six months later.

RESULTS

Results: There are significant differences in mean levels of IL-6 and NKG2D, and the anatomical type (tumor size) (-418.7 & 418.9, p<0.001) of anatomical tumor (-373.72 & -373.920, p=0.001). There is a significant difference between the two immunological markers (IL-6 & NKG2D) (-0.305; p<0.001). The IL-6 markers significantly decreased in means on follow up (-197.8; p-value≤0.0001) while the reverse occur in NKG2D, which increased in levels post-treatment compared with baseline measurement. The high expression of IL-6 positively correlated with the risk of macroadenoma (>10 microns) and poor resonse to treatment and vice versa (p<0.024). High expression of NKG2D significantly (p<0.005) correlated with good prognosis and increased chance for tumor response to medicine and shrinkage in size compared with low concentration.

CONCLUSION

Conclusions: The higher the level of IL-6, the larger the size of adenoma (macroadenoma) and the poorer the response to treatment. The higher the level of NKG2D indidcate a better prognosis, therefore, IL-6 and NKG2D correlate negatively in prolactinoma patients.

Enhanced anticancer efficacy of primed natural killer cells via coacervate-mediated exogenous interleukin-15 delivery

Effective exogenous delivery of interleukin (IL)-15 to natural killer (NK) cells with subsequent anticancer efficacy could be a promising immune cell-based cancer immunotherapy. For the protection of encapsulated cargo IL-15 while maintaining its bioactivity under physiological conditions, we utilized a coacervate (Coa) consisting of a cationic methoxy polyethylene glycol-poly(ethylene arginyl aspartate diglyceride) (mPEG-PEAD) polymer, anionic counterpart heparin, and cargo IL-15. mPEGylation into the backbone cation effectively preserved the colloidal stability of Coa in harsh environments and enhanced the protection of cargo IL-15 than normal Coa without mPEGylation. Proliferation and anticancer efficacy of primed NK cells through co-culture with multiple cancer cell lines were enhanced in the mPEG-Coa group due to the maintained bioactivity of cargo IL-15 during the ex vivo expansion of NK cells. These facilitated functions of NK cells were also supported by the increased expression of mRNAs related to anticancer effects of NK cells, including cytotoxic granules, death ligands, anti-apoptotic proteins, and activation receptors. In summary, our Coa-mediated exogenous IL-15 delivery could be an effective ex vivo priming technique for NK cells with sustained immune activation that can effectively facilitate its usage for cancer immunotherapy.

Natural killer cell activity as a biomarker for the diagnosis of lung cancer in high-risk patients

Objective

Natural killer (NK) cells play an essential role in the immune response against cancer. However, immune escape mechanisms may cause inferior NK cell activity (NKA) in patients with cancer. This prospective study examined the relationship between NKA and lung cancer in a high-risk cohort.

Methods

In a cohort study, 250 participants referred by their general practitioner for suspicion of lung cancer were included. Before clinical investigation, blood was collected into NK Vue tubes, and the level of interferon gamma after 24 hours served as a surrogate marker for NKA.

Results

Among 250 patients, 79 were diagnosed with lung cancer. No difference in NKA was found between patients with lung cancer and control participants in which lung cancer was ruled out (median 226 pg/mL vs. 450 pg/mL). However, there was a significant difference in NKA between patients with late-stage lung cancer and controls (median 161 pg/mL vs. 450 pg/mL). A linear regression model showed that NKA was not influenced by age, sex or smoking status.

Conclusions

The significantly lower NKA in patients with late-stage lung cancer warrants further investigation combining NKA with other biomarkers and examining the potential role of NKA as a marker of disseminated disease.

A Case-Control Study on the Changes in Natural Killer Cell Activity following Administration of Polyvalent Mechanical Bacterial Lysate in Korean Adults with Recurrent Respiratory Tract Infection

Polyvalent mechanical bacterial lysate (PMBL) is used for the treatment and prevention of recurrent respiratory tract infections. Although PMBL is an immunostimulant, it remains unknown whether treatment with PMBL influences natural killer cell activity (NKA). Hence, this case-control study compared the changes in IFN-γ levels (surrogate index for NKA) following PMBL treatment or time passing between the PMBL-treated group and controls. The treatment group included adults who had a PMBL prescription for three months against recurrent respiratory tract infection from an outpatient clinic, while the control group had healthy adults visiting the health promotion center for periodic health check-ups. The control group (N = 506) showed no change in IFN-γ levels, while the treatment group (N = 301) showed a significant increase in mean from 462.8 to 749.3 pg/mL after PMBL treatment. In the subgroup with IFN-γ <500 pg/mL, IFN-γ levels significantly increased in both groups. However, the change in the treatment group (287 ± 822 pg/mL) was greater than that in the control group (58 ± 809 pg/mL), and the interaction between the visit and case/control was significant (p = 0.030) in a generalized estimating equation model. In conclusion, NKA increased in the subjects with recurrent respiratory tract infections with PMBL treatment.

Identification of nafamostat mesylate as a selective stimulator of NK cell IFN-γ production via metabolism-related compound library screening

Natural killer (NK) cells play important roles in controlling virus-infected and malignant cells. The identification of new molecules that can activate NK cells may effectively improve the antiviral and antitumour activities of these cells. In this study, by using a commercially available metabolism-related compound library, we initially screened the capacity of compounds to activate NK cells by determining the ratio of interferon-gamma (IFN-γ)⁺ NK cells by flow cytometry after the incubation of peripheral blood mononuclear cells (PBMCs) with IL-12 or IL-15 for 18 h. Our data showed that eight compounds (nafamostat mesylate (NM), loganin, fluvastatin sodium, atorvastatin calcium, lovastatin, simvastatin, rosuvastatin calcium, and pitavastatin calcium) and three compounds (NM, elesclomol, and simvastatin) increased the proportions of NK cells and CD3⁺ T cells that expressed IFN-γ among PBMCs cultured with IL-12 and IL-15, respectively. When incubated with enriched NK cells (purity ≥ 80.0%), only NM enhanced NK cell IFN-γ production in the presence of IL-12 or IL-15. When incubated with purified NK cells (purity ≥ 99.0%), NM promoted NK cell IFN-γ secretion in the presence or absence of IL-18. However, NM showed no effect on NK cell cytotoxicity. Collectively, our study identifies NM as a selective stimulator of IFN-γ production by NK cells, providing a new strategy for the prevention and treatment of infection or cancer in select populations.

Cross-Sectional and Time-Dependent Analyses on Inflammatory Markers Following Natural Killer Cell Activity

The function of natural killer (NK) cells in inflammation has not been explored enough in large-scale population studies. The cross-sectional and time-dependent relationship between NK cell activity (NKA) and inflammatory markers was examined. Methods: A total of 7031 subjects were involved in the cross-sectional analyses. Non-linear relationship between NKA and inflammatory indices was analyzed using generalized additive models. The time-dependent changes were analyzed in 1005 subjects with repeated measurement in 3–6 months. The changes in inflammatory markers were analyzed based on the changes in NKA. Results: As NKA reduces to a very low level, the white blood cell (WBC) and neutrophil counts increase sharply, and the lymphocyte count exhibits a slow decline. With increasing NKA larger than about 500 pg/mL, WBC and neutrophil-lymphocyte ratio (NLR) reduces in a mild slope. Among the subjects with repeated measurements, the follow-up NKA was increased with advancing baseline NKA levels. The subjects with a reduction in NKA indicated increment in WBC count, neutrophil count, and NLR, and decrease in lymphocyte count. Conclusions: Very low levels of NKA suggest a high inflammatory immune response. The changes in NKA may interact with the balance between neutrophils and lymphocytes.

Postoperative Natural Killer Cell Dysfunction: The Prime Suspect in the Case of Metastasis Following Curative Cancer Surgery

Surgical resection is the foundation for the curative treatment of solid tumors. However, metastatic recurrence due to the difficulty in eradicating micrometastases remain a feared outcome. Paradoxically, despite the beneficial effects of surgical removal of the primary tumor, the physiological stress resulting from surgical trauma serves to promote cancer recurrence and metastasis. The postoperative environment suppresses critical anti-tumor immune effector cells, including Natural Killer (NK) cells. The literature suggests that NK cells are critical mediators in the formation of metastases immediately following surgery. The following review will highlight the mechanisms that promote the formation of micrometastases by directly or indirectly inducing NK cell suppression following surgery. These include tissue hypoxia, neuroendocrine activation, hypercoagulation, the pro-inflammatory phase, and the anti-inflammatory phase. Perioperative therapeutic strategies designed to prevent or reverse NK cell dysfunction will also be examined for their potential to improve cancer outcomes by preventing surgery-induced metastases.

Changes in natural killer cell activity after surgery and predictors of its recovery-failure

BACKGROUND AND OBJECTIVES

We evaluated the changes in natural killer cell activity (NKA) during the entire treatment period of patients with resectable biliopancreatic cancers and investigated the predictors of the failure of recovery of NKA after surgery.

METHODS

A total of 202 patients who underwent curative resection for biliopancreatic cancer were enrolled in the study. NKA levels were measured six times during the treatment period. We investigated whether there was any difference in postoperative NKA recovery according to the period-by-time NKA value.

RESULTS

NKA decreased after surgery (mean, 40 pg/ml) compared to the NKA value at admission (200.2 pg/ml), then began to increase from 3 weeks after surgery (139.7 pg/ml) and rose to normal NKA levels at 5 weeks (217.1 pg/ml). The pattern of NKA changes was distinct according to the NKA values at admission. In multivariate analysis, NKA values of less than 250 pg/ml at admission (odds ratio = 5.898, p = 0.044) were a predictor of NKA recovery failure 5 weeks after surgery.

CONCLUSIONS

NKA rapidly decreased after curative surgery for biliopancreatic cancer and recovered to normal levels about 5 weeks later. Clinicians should be aware and cautious that patients with low NKA at admission may fail to recover NKA postoperatively.

Vitamin D and Exercise Are Major Determinants of Natural Killer Cell Activity, Which Is Age- and Gender-Specific

Background

The coronavirus-19 disease (COVID-19) pandemic reminds us of the importance of immune function, even in immunologically normal individuals. Multiple lifestyle factors are known to influence the immune function.

Objective

The aim was to investigate the association between NK cell activity (NKA) and multiple factors including vitamin D, physical exercise, age, and gender.

Methods

This was a cross-sectional association study using health check-up and NKA data of 2,095 subjects collected from 2016 to 2018 in a health check-up center in the Republic of Korea. NKA was measured using the interferon-γ (IFN-γ) stimulation method. The association of NKA with 25-(OH)-vitamin D (25(OH)D) and other factors was investigated by multiple logistic regression analysis.

Results

The average age of subjects was 48.8 ± 11.6 years (52.9% of subjects were female). Among 2,095 subjects, 1,427 had normal NKA (NKA ≥ 500 pg IFN-γ/mL), while 506 had low NKA (100 ≤ NKA < 500 pg/mL), and 162 subjects had very low NKA (NKA < 100 pg/mL). Compared to men with low 25(OH)D serum level (< 20 ng/mL), vitamin D replete men (30–39.9 ng/mL) had significantly lower risk of very low NKA (OR: 0.358; 95% CI: 0.138, 0.929; P = 0.035). In women, both low exercise (OR: 0.529; 95% CI: 0.299, 0.939; P = 0.030) and medium to high exercise (OR: 0.522; 95% CI: 0.277, 0.981; P = 0.043) decreased the risk compared to lack of physical exercise. Interestingly, in men and women older than 60 years, physical exercise significantly decreased the risk. Older-age was associated with increased risk of very low NKA in men, but not in women.

Conclusion

Physical exercise and vitamin D were associated with NKA in a gender- and age-dependent manner. Age was a major risk factor of very low NKA in men but not in women.

Interferon-γ: teammate or opponent in the tumour microenvironment?

Cancer immunotherapy offers substantive benefit to patients with various tumour types, in some cases leading to complete tumour clearance. However, many patients do not respond to immunotherapy, galvanizing the field to define the mechanisms of pre-existing and acquired resistance. Interferon-γ (IFNγ) is a cytokine that has both protumour and antitumour activities, suggesting that it may serve as a nexus for responsiveness to immunotherapy. Many cancer immunotherapies and chemotherapies induce IFNγ production by various cell types, including activated T cells and natural killer cells. Patients resistant to these therapies commonly have molecular aberrations in the IFNγ signalling pathway or express resistance molecules driven by IFNγ. Given that all nucleated cells can respond to IFNγ, the functional consequences of IFNγ production need to be carefully dissected on a cell-by-cell basis. Here, we review the cells that produce IFNγ and the different effects of IFNγ in the tumour microenvironment, highlighting the pleiotropic nature of this multifunctional and abundant cytokine.

Prognostic effects of cytokine levels on patients treated with taxane and zoledronic acid for metastatic breast cancer in bone (BEAT-ZO) (KCSG BR 10-13)

Advanced breast cancer frequently metastasizes to the skeleton causing major mobility issues and hazards to quality of life. To manage osteolytic bone metastasis, bone-modifying agents and chemotherapy are recommended as the standard of care. Here, we investigated serologic biomarkers that might be associated with prognosis in breast cancer patients treated with zoledronic acid (ZA) and taxane-based chemotherapy. We collected serum samples from breast cancer patients with bone metastasis who received taxane plus ZA as palliative treatment. Fourteen biomarkers of angiogenesis, immunogenicity, and apoptosis were assessed, and the correlation between serum cytokine levels and patient's prognosis was statistically analyzed. Sixty-six patients were enrolled, and samples from 40 patients were analyzed after laboratory quality control. Patients with low baseline PDGF-AA, high IFN-γ, low MCP-2, low TGF-β1, and low TNF-α were significantly associated with longer progression-free survival (PFS). Decreasing VEGF and TNF-α and increasing FGF-2 and PDGF-AA in the early treatment phase indicated longer PFS. In univariate and multivariate analyses, low TGF-β1 and TNF-α and high IFN-γ at baseline were associated with a significantly low hazard ratio for disease progression. Further, we designed a risk score with TGF-β1, TNF-α, and IFN-γ levels, which could prognosticate patients for PFS. In conclusion, serum cytokine level, such as TGF-β1, TNF-α, and IFN-γ, could be a potential prognostic biomarker for breast cancer patients with bone metastasis treated with ZA and taxane-based chemotherapy.

A Flow Cytometry-Based Whole Blood Natural Killer Cell Cytotoxicity Assay Using Overnight Cytokine Activation

Background: Measurement of natural killer (NK) cell function has important clinical utility in several diseases. Although the flow cytometry (FC)-based 4-h NK cytotoxicity assay using peripheral blood mononuclear cells (PBMCs) in the clinical laboratory has been used for this purpose, this assay requires large amounts of blood and a rapid PBMC isolation step. Here, we developed an FC-based overnight NK cytotoxicity assay using whole blood (WB), and applied it to patients with liver diseases.

Methods: Peripheral blood of healthy volunteers (n = 28) and patients with liver diseases, including hepatocellular carcinoma (n = 19) and liver cirrhosis (n = 7), was analyzed for complete blood count, absolute NK cell count, and NK cell activity (NKA). NKA was evaluated in three assay types: an FC-based overnight WB NK cytotoxicity assay using carboxyfluorescein diacetate succinimidyl ester-labeled K562 cells in the presence of various cytokine combinations [including interleukin (IL)-2, IL-18, and IL-21], an FC-based 4-h PBMC NK cytotoxicity assay, and an FC-based CD107a degranulation assay using WB and PBMCs.

Results: Optimal cytokine combinations for NK cell activation in WB were determined (IL-2/IL-18, IL-2/IL-21, and IL-2/IL-18/IL-21). A good correlation was observed between WB and PBMC NK cytotoxicity assays; absolute NK cell counts were better correlated with the WB NK cytotoxicity assay than with the PBMC NK cytotoxicity assay. This WB NK cytotoxicity assay showed that patients with liver diseases had significantly lower NK cytotoxicity than healthy volunteers, under stimulation with various cytokines (p < 0.001).

Conclusion: The proposed FC-based overnight WB NK cytotoxicity assay correlates well with the conventional 4-h PBMC NK cytotoxicity assay, demonstrating future potential as a supportive assay for clinical laboratory research and observational studies.

Delayed NK Cell Reconstitution and Reduced NK Activity Increased the Risks of CMV Disease in Allogeneic-Hematopoietic Stem Cell Transplantation

Cytomegalovirus (CMV) infection has a significant impact in patients after allogeneic hematopoietic stem cell transplantation (HSCT). We investigated natural killer (NK) cell reconstitution and cytotoxic/cytokine production in controlling CMV infection, especially severe CMV disease in HSCT patients. Fifty-eight patients with acute myeloid leukemia (AML) who received allo-HSCT were included. We monitored NK reconstitution and NK function at baseline, 30, 60, 90, 120, 150, and 180 days after HSCT, and compared the results in recipients stratified on post-HSCT CMV reactivation (n = 23), non-reactivation (n = 24) versus CMV disease (n = 11) groups. The CMV disease group had a significantly delayed recovery of CD56dim NK cells and expansion of FcRγ-CD3ζ+NK cells started post-HSCT 150 days. Sequential results of NK cytotoxicity, NK cell-mediated antibody-dependent cellular cytotoxicity (NK-ADCC), and NK-Interferon-gamma (NK-IFNγ) production for 180 days demonstrated delayed recovery and decreased levels in the CMV disease group compared with the other groups. The results within 1 month after CMV viremia also showed a significant decrease in NK function in the CMV disease group compared to the CMV reactivation group. It suggests that NK cells' maturation and cytotoxic/IFNγ production contributes to CMV protection, thereby revealing the NK phenotype and functional NK monitoring as a biomarker for CMV risk prediction, especially CMV disease.

Impact of Smoking on Human Natural Killer Cell Activity: A Large Cohort Study

Some studies have reported a decrease in the natural killer (NK) cell activity in smokers. However, large-scale data on the relationship between NK cell activity and smoking are unavailable. A cross-sectional study was performed on 12,249 asymptomatic examinees who underwent an NK cell activity test, between January 2016 and May 2017. The test quantitated the amount of interferon-γ secreted into the plasma by NK cells, using a patented stimulatory cytokine. The mean age of the study population was 39.1 years, and the proportions of “never”, “former”, and “current” smokers were 65.5%, 20.9%, and 13.6%, respectively. Current smokers (1,422 pg/mL) had a lower median level of NK cell activity than never smokers (1,504 pg/mL, P = 0.039) and former smokers (1,791 pg/mL, P < 0.001). Among current smokers, NK cell activity decreased with increase in the number of cigarettes smoked among current smokers (median, 1,537, 1,429, and 1,175 pg/mL at <10, 10-19, and ≥ 20 pack-years, respectively; P < 0.001). Additionally, it decreased linearly with increasing quartiles of cotinine levels (median, 1,707, 1,636, 1,348, and 1,292 pg/mL at cotinine levels < 292, 292-879, 880-1,509, and ≥ 1,510 ng/mL, respectively; r = –0.122, P < 0.001). NK cell activity was lower in current smokers. It also decreased with an increase in the number of cigarettes smoked, and it was negatively correlated with cotinine levels among current smokers. Our findings indicate a clear relationship between smoking and decreased NK cell activity.

A gastric cancer cell derived extracellular compounds suppresses CD161+CD3- lymphocytes and aggravates tumor formation in a syngeneic mouse model

Evasion of the immune system is often associated with malignant tumors. The cancer cell microenvironment plays an important role in tumor progression, but its mechanism is largely unknown. Here we show that an extracellular compound derived from gastric cancer (GC-EC) selectively suppresses CD161⁺CD3^- natural killer (NK) cells. Splenocytes treated with GC-EC showed considerable proliferation and the CD161⁺CD3^- NK cell population was time-dependently suppressed. Intracellular staining of IFN-γ was shown to be down-regulated in concert with granzyme B and perforin. A cytotoxicity assay of splenocytes treated with GC-EC against K-562 cells showed a significant reduction in cytolytic activity. Further, the immune-suppressive effect of GC-EC was more evident in a syngeneic tumor model in C57BL/6 mice. Animals treated with B16 F10 and GC-EC exhibited more aggravated tumor formation than animals treated with B16 F10 only. We demonstrated that inhibition of apoptosis while increasing PI3 K/AKT levels may provoke tumor formation by GC-EC. A cytokine array revealed the presence of several cytokines in GC-EC that negatively regulate immune cytolytic activity and could be potential candidates for immune-suppressive effects.

Natural Killer Cell Function Tests by Flowcytometry-Based Cytotoxicity and IFN-γ Production for the Diagnosis of Adult Hemophagocytic Lymphohistiocytosis

Although natural killer (NK) cell function is a hallmark of hemophagocytic lymphohistiocytosis (HLH), there is no standard method or data on its diagnostic value in adults. Thus, we performed a single-center retrospective study of 119 adult patients with suspected HLH. NK cell function was determined using both flowcytometry-based NK-cytotoxicity test (NK-cytotoxicity) and NK cell activity test for interferon-gamma (NKA-IFNγ). NK cell phenotype and serum cytokine levels were also tested. Fifty (42.0%) HLH patients showed significantly reduced NK cell function compared to 69 non-HLH patients by both NK-cytotoxicity and NKA-IFNγ (p < 0.001 and p = 0.020, respectively). Agreement between NK-cytotoxicity and NKA-IFNγ was 88.0% in HLH patients and 58.0% in non-HLH patients. NK-cytotoxicity and NKA-IFNγ assays predicted HLH with sensitivities of 96.0% and 92.0%, respectively. The combination of NKA-IFNγ and ferritin (>10,000 µg/L) was helpful for ruling out HLH, with a specificity of 94.2%. Decreased NK-cytotoxicity was associated with increased soluble IL-2 receptor levels and decreased CD56dim NK cells. Decreased NKA-IFNγ was associated with decreased serum cytokine levels. We suggest that both NK-cytotoxicity and NKA-IFNγ could be used for diagnosis of HLH. Further studies are needed to validate the diagnostic and prognostic value of NK cell function tests.

Natural Killer Cell Therapy: A New Treatment Paradigm for Solid Tumors

In treatments of solid tumors, adoptive transfer of ex vivo expanded natural killer (NK) cells has dawned as a new paradigm. Compared with cytotoxic T lymphocytes, NK cells take a unique position targeting tumor cells that evade the host immune surveillance by down-regulating self-antigen presentation. Recent findings highlighted that NK cells can even target cancer stem cells. The efficacy of allogeneic NK cells has been widely investigated in the treatment of hematologic malignancies. In solid tumors, both autologous and allogeneic NK cells have demonstrated potential efficacy. In allogeneic NK cell therapy, the mismatch between the killer cell immunoglobulin-like receptor (KIR) and human leukocyte antigen (HLA) can be harnessed to increase the antitumor activity. However, the allogeneic NK cells cause more adverse events and can be rejected by the host immune system after repeated injections. In this regard, the autologous NK cell therapy is safer. This article reviews the published results of clinical trials and discusses strategies to enhance the efficacy of the NK cell therapy. The difference in immunophenotype of the ex vivo expanded NK cells resulted from different culture methods may affect the final efficacy. Furthermore, currently available standard anticancer therapy, molecularly targeted agents, and checkpoint inhibitors may directly or indirectly enhance the efficacy of NK cell therapy. A recent study discovered that NK cell specific genetic defects are closely associated with the tumor immune microenvironment that determines clinical outcomes. This finding warrants future investigations to find the implication of NK cell specific genetic defects in cancer development and treatment, and NK cell deficiency syndrome should be revisited to enhance our understanding. Overall, it is clear that NK cell therapy is safe and promises a new paradigm for the treatment of solid tumors.

Relationship between natural killer cell activity and glucose control in patients with type 2 diabetes and prediabetes

AIMS/INTRODUCTION

Natural killer (NK) cells are cytotoxic lymphocytes critical to human immunity. Previous studies showed correlations between NK cell function and blood glucose concentrations. The purpose of the present study was to assess the NK cell activity and various metabolic parameters in people with type 2 diabetes, prediabetes and normal glucose tolerance.

MATERIALS AND METHODS

A total of 49 participants were enrolled in the study. Anthropometric and biochemical parameters including age, sex, body mass index, smoking status, blood pressure, fasting plasma glucose, C-peptide, insulin, glycated hemoglobin, total cholesterol, triglyceride, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol were assessed. The 75 g oral glucose tolerance test was carried out for 2-h postload glucose level. Homeostatic model assessment was calculated for insulin resistance and β-cell function. NK cell activity was measured by detecting the circulating interferon-gamma level secreted from NK cells.

RESULTS

NK cell activity was lower in patients with type 2 diabetes (768.01 ± 650.35) compared with those with prediabetes (2,396.08 ± 653.76, P < 0.001) and normal glucose tolerance (2,435.31 ± 633.22, P < 0.001). In patients with type 2 diabetes, there was a significant inverse linear relationship between NK cell activity and fasting plasma glucose, glycated hemoglobin, and 2-h postload glucose level (all P < 0.001). Multiple regression analysis showed glycated hemoglobin to be an independent predictor of NK cell activity in patients with type 2 diabetes.

CONCLUSIONS

Compared with individuals with normal glucose tolerance or prediabetes, type 2 diabetes patients have a reduced NK cell activity, and it is significantly related to glucose control.

Innate Lymphoid Cells in Mucosal Immunity

Innate lymphoid cells (ILCs) are innate counterparts of T cells that contribute to immune responses by secreting effector cytokines and regulating the functions of other innate and adaptive immune cells. ILCs carry out some unique functions but share some tasks with T cells. ILCs are present in lymphoid and non-lymphoid organs and are particularly abundant at the mucosal barriers, where they are exposed to allergens, commensal microbes, and pathogens. The impact of ILCs in mucosal immune responses has been extensively investigated in the gastrointestinal and respiratory tracts, as well as in the oral cavity. Here we review the state-of-the-art knowledge of ILC functions in infections, allergy and autoimmune disorders of the mucosal barriers.

Preventive Effect of the Herbal Preparation, HemoHIM, on Cisplatin-Induced Immune Suppression

We determined the functional effect of the herbal preparation, HemoHIM, on the immune system, by examining the immunomodulatory activities of HemoHIM using immunocompromised mice. In this study, to examine the effect on the restoration of immune cells and balance in the immune system, we utilized a cisplatin-induced immunosuppression mouse model. Mice were injected intraperitoneally with cisplatin, an immunosuppressive anticancer, and then received oral doses of 100, 250, and 500 mg/kg of HemoHIM for 14 days. The HemoHIM prevented the cisplatin-induced loss of body and organ weight. In terms of innate immunity, natural killer (NK) cell activity and phagocytosis increased in the HemoHIM group compared to the cisplatin control group. The HemoHIM group also showed a significantly higher expression of Th1-mediated cytokines (interferon gamma (IFN-γ), interleukin-2 (IL-2), and tumor necrosis factor alpha (TNF-α)) and inhibited the production of Th2-mediated cytokine interleukin-4 (IL-4) compared to cisplatin control group. These findings indicate that HemoHIM enhances immune activity by modulating immune cell activity and cytokine secretion in immune-suppressed mice.

Clinical utility of a novel natural killer cell activity assay for diagnosing non-small cell lung cancer: a prospective pilot study

Purpose

Although decreased natural killer cell activity (NKA) has been observed in many solid cancers, clinical implication of NKA has been scarcely investigated in lung cancer. The objective of this study was to evaluate the potential of using NKA to support diagnosis of non-small cell lung cancer (NSCLC).

Materials and methods

We prospectively evaluated and compared peripheral blood NKA using a novel interferon-gamma releasing assay in healthy population (n=40), patients with benign lung disease (n=40), and those with NSCLC (n=71). We explored the correlation between NKA and clinical parameters and assessed diagnostic performance of NKA for NSCLC using receiver operating characteristic curve analysis.

Results

Median NKA values in healthy population, patients with benign lung disease, and those with NSCLC were 1,364.2, 1,438.2, and 406.3 pg/mL, respectively. NKA in NSCLC patients was significantly lower than that in the other two control groups (both P<0.001). At a cutoff value of NKA at 391.0 pg/mL, the area under the curve was 0.762 (95% CI: 0.685–0.838, P<0.001), with a sensitivity of 52.3%, a specificity of 91.0%, a positive predictive value of 85.3%, and a negative predictive value of 65.4% for the diagnosis of NSCLC. Multivariate analysis demonstrated that diagnosis of NSCLC is the only clinical parameter that was significantly associated with NKA (P<0.001).

Conclusion

This pilot study showed that patients with low NKA were more likely to have lung cancer. Further studies are warranted in order to establish the clinical utility of NKA test for diagnosing lung cancer.

Ex Vivo Interferon Gamma Production by Peripheral Immune Cells Predicts Survival in Lung Adenocarcinoma

BACKGROUND

Lung cancer is one of the most lethal malignancies, with a 5-year survival rate < 20% in patients with stage IV lung cancer. Impaired host immunity is associated with lung cancer pathogenesis, and interferon gamma (IFN-γ) plays an important role in antitumor immune surveillance. We evaluated the clinical significance of ex vivo production of IFN-γ in patients with lung adenocarcinoma.

PATIENTS AND METHODS

We reviewed the medical records of 109 treatment-naive patients with lung adenocarcinoma who had undergone IFN-γ releasing assay. Differences in the IFN-γ level in nil and mitogen tubes were defined as ex vivo IFN-γ production. Correlation analysis was performed to evaluate the correlation between ex vivo IFN-γ production, cancer staging, and Eastern Cooperative Oncology Group performance status. The optimal cutoff values of low and high ex vivo IFN-γ production were estimated using receiver operator characteristic curve analysis. Cox proportional hazard analyses were used to evaluate the prognostic factors of 1-year overall patient survival.

RESULTS

Ex vivo IFN-γ production correlated with N stage, M stage, cancer staging, and Eastern Cooperative Oncology Group performance status. Low ex vivo IFN-γ production (ex vivo IFN-γ production ≤ 7.79 IU/mL) was independently associated with 1-year overall survival (odds ratio = 3.289; 95% confidence interval, 1.573-6.872; P = .002). Additionally, low ex vivo IFN-γ production was an independent predictor of 1-year overall survival in patients with stage IV cancer (odds ratio = 3.156; 95% confidence interval, 1.473-6.760; P = .003).

CONCLUSION

Ex vivo IFN-γ production before treatment might be a useful biomarker for predicting prognosis in patients with lung adenocarcinoma.

NK Cell-Based Immunotherapy in Cancer Metastasis

Metastasis represents the leading cause of cancer-related death mainly owing to the limited efficacy of current anticancer therapies on advanced malignancies. Although immunotherapy is rendering promising results in the treatment of cancer, many adverse events and factors hampering therapeutic efficacy, especially in solid tumors and metastases, still need to be solved. Moreover, immunotherapeutic strategies have mainly focused on modulating the activity of T cells, while Natural Killer (NK) cells have only recently been taken into consideration. NK cells represent an attractive target for cancer immunotherapy owing to their innate capacity to eliminate malignant tumors in a non-Major Histocompatibility Complex (MHC) and non-tumor antigen-restricted manner. In this review, we analyze the mechanisms and efficacy of NK cells in the control of metastasis and we detail the immunosubversive strategies developed by metastatic cells to evade NK cell-mediated immunosurveillance. We also share current and cutting-edge clinical approaches aimed at unleashing the full anti-metastatic potential of NK cells, including the adoptive transfer of NK cells, boosting of NK cell activity, redirecting NK cell activity against metastatic cells and the release of evasion mechanisms dampening NK cell immunosurveillance.

Physical Inactivity and Unhealthy Metabolic Status Are Associated with Decreased Natural Killer Cell Activity

PURPOSE

Several studies have reported relationships among physical activity, healthy metabolic status, and increased natural killer (NK) cell activity. However, large-scale data thereon are lacking. Thus, the present study aimed to assess NK cell activity according to physical activity and metabolic status.

MATERIALS AND METHODS

A cross-sectional study was performed on 12014 asymptomatic examinees. Using a patented stimulatory cytokine, NK cell activity was quantitated by the amount of interferon-γ secreted into the plasma by NK cells. Physical activity levels were assessed using the validated Korean version of the International Physical Activity Questionnaire Short Form.

RESULTS

The physically inactive group showed lower NK cell activity than the minimally active group (median, 1461 vs. 1592 pg/mL, p<0.001) and health-enhancing physically active group (median, 1461 vs. 1712 pg/mL, p=0.001). Compared to women with a body mass index (BMI) of 18.5-27.5 kg/m², those with a BMI <18.5 kg/m² had significantly lower NK cell activity (1356 vs. 1024 g/mL, p<0.001), and those with a BMI ≥27.5 kg/m² tended to have lower NK cell activity (1356 vs. 1119 g/mL, p=0.070). Subjects with high hemoglobin A1c levels and low high-density lipoprotein cholesterol levels, as well as men with high blood pressure and women with high triglyceride levels, exhibited lower NK cell activity. Moreover, physical inactivity and metabolic abnormalities were independently associated with low NK cell activity, even after adjusting for confounders.

CONCLUSION

Physical inactivity and metabolic abnormalities are associated with reduced NK cell activity. Immune systems may become altered depending on physical activity and metabolic status.