High Natural Killer Cell Activity Research Articles

Influence of Laparoscopic Surgery on Cellular Immunity in Colorectal Cancer: A Systematic Review and Meta-Analysis

Colorectal cancer (CRC) is the third most common cancer worldwide. The main treatment options are laparoscopic (LS) and open surgery (OS), which might differ in their impact on the cellular immunity so indispensable for anti-infectious and antitumor defense. MEDLINE, Embase, Web of Science (SCI-EXPANDED), the Cochrane Library, Google Scholar, ClinicalTrials.gov, and ICTRP (WHO) were systematically searched for randomized controlled trials (RCTs) comparing cellular immunity in CRC patients of any stage between minimally invasive and open surgical resections. A random effects-weighted inverse variance meta-analysis was performed for cell counts of natural killer (NK) cells, white blood cells (WBCs), lymphocytes, CD4+ T cells, and the CD4+/CD8+ ratio. The RoB2 tool was used to assess the risk of bias. The meta-analysis was prospectively registered in PROSPERO (CRD42021264324). A total of 14 trials including 974 participants were assessed. The LS groups showed more favorable outcomes in eight trials, with lower inflammation and less immunosuppression as indicated by higher innate and adaptive cell counts, higher NK cell activity, and higher HLA-DR expression rates compared to OS, with only one study reporting lower WBCs after OS. The meta-analysis yielded significantly higher NK cell counts at postoperative day (POD)4 (weighted mean difference (WMD) 30.80 cells/µL [19.68; 41.92], p < 0.00001) and POD6–8 (WMD 45.08 cells/µL [35.95; 54.21], p < 0.00001). Although further research is required, LS is possibly associated with less suppression of cellular immunity and lower inflammation, indicating better preservation of cellular immunity.

A new natural killer cell-specific gene signature predicting recurrence in colorectal cancer patients.

The protective role of Natural Killer (NK) cell tumour immunosurveillance has long been recognised in colorectal cancer (CRC). However, as most patients show limited intra-tumoral NK cell infiltration, improving our ability to identify those with high NK cell activity might aid in dissecting the molecular features which underlie NK cell sensitivity. Here, a novel CRC-specific NK cell gene signature that infers NK cell load in primary tissue samples was derived and validated in multiple patient CRC cohorts. In contrast with other NK cell gene signatures that have several overlapping genes across different immune cell types, our NK cell signature has been extensively refined to be specific for CRC-infiltrating NK cells. The specificity of the signature is substantiated in tumour-infiltrating NK cells from primary CRC tumours at the single cell level, and the signature includes genes representative of NK cells of different maturation states, activation status and anatomical origin. Our signature also accurately discriminates murine NK cells, demonstrating the applicability of this geneset when mining datasets generated from preclinical studies. Differential gene expression analysis revealed tumour-intrinsic features associated with NK cell inclusion versus exclusion in CRC patients, with those tumours with predicted high NK activity showing strong evidence of enhanced chemotactic and cytotoxic transcriptional programs. Furthermore, survival modelling indicated that NK signature expression is associated with improved survival outcomes in CRC patients. Thus, scoring CRC samples with this refined NK cell signature might aid in identifying patients with high NK cell activity who could be prime candidates for NK cell directed immunotherapies.

Natural killer cell activity level in colorectal cancer screening in an average risk population.

Increased natural killer cell activity (NKCA) is linked to reduced risk of colorectal cancer (CRC). Several prior studies have investigated the association of NKCA and the incidence of CRC in high-risk subjects. The aim of our study was to investigate NKCA sensitivity in diagnosing advanced neoplasia (AN) and CRC in an average risk population. NKCA was assessed by an enzyme-linked immunosorbent assay (ELISA) blood test in average risk subjects with a range of 25-2500 pg/ml set for ELISA. NKCA higher than 200 pg/ml was defined as negative. The performance of NKCA was evaluated using measures such as sensitivity, specificity, negative and positive predictive values (NPV, PPV), clinical utility index, etc. In addition, odds ratios for developing CRC using logistic regression models were calculated. NKCA was evaluated in 354 average risk individuals (mean age: 58.5 years; 36.2% male). The diagnostic accuracy of NKCA for CRC and AN was 75.5% and 72.3% respectively, with 96.4% NPV. The NKCA test demonstrated a good negative clinical utility index for CRC and AN (0.664 and 0.741, respectively). Individuals with low NKCA had 6.84 times higher odds of having CRC (95% CI: 2.31-20.27; p < 0.001). NKCA was higher in men vs. women (548.5 pg/ml vs. 500.0 pg/ml) and lower in smokers (412 pg/ml vs. 544 pg/ml), non-exercisers (413 pg/ml vs. 653.5 pg/ml), alcohol users (389 pg/ml vs. 476 pg/ml), and native Kazakhs and other Asian ethnic groups (446 pg/ml vs. 514 pg/ml). A high NKCA level has potential ability to rule out CRC and AN in an average risk population.

Prognostic value of natural killer cell activity for patients with HER2 + advanced gastric cancer treated with first-line fluoropyrimidine-platinum doublet plus trastuzumab.

We aimed to evaluate the prognostic value of natural killer (NK) cell activity for patients with HER2 + advanced gastric cancer (AGC) treated with first-line fluoropyrimidine-platinum doublet plus trastuzumab. Forty-one patients with HER2 + AGC who received fluoropyrimidine-platinum doublet plus trastuzumab as first-line treatment were prospectively enrolled. NK cell activity was evaluated using the NK Vue®. The median age was 63.5years, and 31 patients (75.6%) were male. Patients with low baseline NK cell activity (≤ median, n = 21) were associated worse progression-free survival (PFS) and overall survival (OS) compared with patients with high baseline NK cell activity (> median, n = 20) with a median PFS of 4.21 vs. 9.53months (P < 0.001), and median OS of 8.15months vs. 17.82months (P = 0.025), respectively. In the multivariate analysis, low baseline NK cell activity was independently associated with poor PFS (HR 4.35, P = 0.007). NK cell activity recovered to a normal range in nine patients (47.4%) with a low baseline NK cell activity (n = 19) after two cycles of treatment. The median PFS and OS among patients with recovered NK cell activity were significantly better than that among patients with persistently low NK cell activity (PFS, P = 0.038; OS, P = 0.003). Our results demonstrated the prognostic value of baseline NK cell activity for patients with HER2 + AGC treated with fluoropyrimidine-platinum doublet plus trastuzumab. The association between treatment outcomes and dynamic changes in NK cell activity suggests that NK cell treatment may improve treatment outcomes, especially for patients with low baseline NK cell activity.

3 Cases of Cancer Patients Whose Natural Killer Cell Activity Improved with Traditional Korean Medicine Treatment: A Case Series

Objectives: High natural killer cell activity (NKA) is associated with a clinically favorable status in patients with cancer. This study explores whether traditional Korean medicine (TKM) improves NKA in patients with cancer.Methods: We report three clinical cases involving patients with cancer who underwent NKA tests while they received TKM treatment, including acupuncture, moxibustion, wild ginseng pharmacopuncture, and Korean herbal medicines. We analyzed the treatment process and NKA test results of each patient.Results: The NKA of all three patients presented with an increasing tendency during the treatment process. Patient 1, who had been diagnosed with breast cancer, received inpatient treatment 3 times between September 16, 2017 and February 27, 2019. The NKA increased from 7.2 pg/mL to 571.7 pg/mL. Patient 2, who had thyroid cancer, was hospitalized 4 times between July 23, 2019 and August 27, 2020. The NKA improved from 317.4 pg/mL to 2000 pg/mL. Patient 3, who had liver cancer, received inpatient treatment 4 times between May 27, 2016 and January 10, 2017. The NKA increased from 22.2 pg/mL to 459.5 pg/mL. The chief complaints of these patients also were alleviated.Conclusions: TKM may be an effective treatment for accelerating NKA. Further research is needed to establish evidence that TKM stimulates NKA.

Abstract P24: Evidenced-based natural therapies and immune-enhancing strategies to control, prevent, and treat co-morbidities COVID-19 and cancer

Abstract The purpose of this research is to provide evidence-based natural therapies and foods that will enhance the immune system to fight the virus SARS CoV-2 and cancer. Minority populations that include Black African Americans and Hispanics are experiencing higher mortality rates due to both socioeconomic and lifestyle factors in the US and globally. Successful lessons learned from controlling previous 1918 pandemic flu will be discussed. Hypotheses: We hypothesize that targeting lifestyle factors such as diet, exercise, and hydrothermal therapy that enhance the immune system can effectively control and reduce the risk to COVID-19 disease and cancer simultaneously. The target cells for the SARS CoV-2 virus contain the ACE2 and TMPRSS2 receptors which serve as portals of entry. They are expressed throughout the body including the nose, lungs, heart, bladder, pancreas, kidneys and brain found on the epithelial and vascular tissue cells of these organs. Covid-19 affects multiple organs in the body and disrupts the innate immune system, especially the natural killer cells, monocytes, and neutrophils. Studies have shown that countries where BCG was used have less than 10% of COVID-19 cases and countries that do not use the BCG vaccine such as the US and Italy had high cases. It was also seen that people who had higher natural killer cell activity had 100% survival rates. Enhancing the innate immune system through natural therapies has shown to enhance immune cells to fight COVID-19 as well as cancer and destroy it. Methodology: Our research is exploratory and is based on recently published literature on COVID-19 diseases. The following databases were searched: CINAHL, Web of Science, PubMed, EBSCOHost, Google Scholar, Academic Search Complete, AccessMedicine, MedlinePlus, Nutrition Care Manuel, JSTOR and Publons. Results: During the Spanish flu pandemic death rates of those who received the best medical care was 6.7% compared with those who received hydrotherapy at 1.34%. Hydrotherapy will increase the body temperature and stimulate the activity of the immune cells, which can kill the viruses. Increasing the body temperature to 39.5 degrees centigrade was shown to kill the virus. Following the hot water bath with cold treatment was shown to be even more effective. Many foods have been found to enhance the immune system and to fight the flu virus. Foods such as blueberries, garlic, and probiotics were shown to improve natural killer activity. Vitamin C, Vitamin D, Zinc, and selenium play a role in immunity. Foods rich in antioxidants such as kale, blueberries, red bell peppers, and all citrus fruits also help enhance the immune system. During the 1918 flu pandemic that received hydrotherapy and other natural remedies, out of the 120 students and staff exposed, there were 90 patients, none very sick, and there were no deaths. Natural remedies used in the Spanish flu pandemic and should be instituted to help enhance immunity and lessen the deadly impact of COVID-19 cancer patients. Citation Format: Padma P. T. Uppala, Sherri Isaak, Brian Wong, Kimberly Ferreira, Carlos Garberoglio, John Kelly. Evidenced-based natural therapies and immune-enhancing strategies to control, prevent, and treat co-morbidities COVID-19 and cancer [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2021 Feb 3-5. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(6_Suppl):Abstract nr P24.

Efficacy of natural killer cell activity as a biomarker for predicting immunotherapy response in non-small cell lung cancer.

BackgroundThe establishment of biomarkers that can be used to predict the response to immunotherapy for malignancy is extremely important. In particular, noninvasive analysis of immune cells from peripheral blood before treatment has gained increased attention, and natural killer (NK) cell activity has been shown to be related to treatment response. Here, we aimed to confirm the relationship between the response to immunotherapy and NK cell activity.MethodsIn this prospective observational study, patients with advanced NSCLC who were scheduled for immunotherapy from October 2018 to December 2019 were enrolled. Baseline NK cell activity was compared according to the best clinical response to immunotherapy.ResultsA total of 54 patients with advanced NSCLC were enrolled, and 34 patients were analyzed. The baseline NK cell activity was significantly higher in the non‐PD group than in the PD group (P = 0.002). At the cutoff level of ≥1200 pg/mL, baseline NK cell activity yielded a sensitivity of 80% and a specificity of 68.4% in predicting the response to immunotherapy (AUC = 0.8, P < 0.003). The median progression‐free survival (PFS) was significantly better in the high NK group (P = 0.003), and correlation between baseline NK cell activity and PFS was also confirmed (r = 0.517, P = 0.002).ConclusionsBaseline NK cell activity was related to the response to immunotherapy and the PFS. We suggest that NK cell activity from peripheral blood before immunotherapy is a noninvasive, simple, and novel way to predicting the treatment response in patients with NSCLC.Key pointsSignificant findings of the study The response to immunotherapy was significantly better in patients with high baseline NK cell activity, and there was a significant correlation between baseline NK cell activity and PFS. What this study adds This study demonstrates the efficacy of baseline NK cell activity from peripheral blood as a biomarker for predicting immunotherapy response.

Clinical factors associated with pregnancy outcome in women with recurrent pregnancy loss

The aim of this prospective cohort study was to evaluate clinical factors associated with pregnancy outcomes in women with recurrent pregnancy loss (RPL). Women with a history of two or more pregnancy losses underwent workups for clinical factors of RPL and their pregnancies were followed-up with informed consent. Two hundred eleven (81.5%) of 259 women with RPL became pregnant. The multivariable analyses demonstrated that age (p < .01, OR 0.9, 95%CI 0.97–0.83), uterine abnormality (p < .05, OR 0.3, 95%CI 0.11–0.8), and protein C (PC) deficiency (p < .01, OR 0.14, 95%CI 0.03–0.6) were independent factors for becoming pregnancy in women with RPL. The number of previous pregnancy loss (p < .01, OR 0.57, 95%CI 0.43–0.75) and natural killer (NK) cell activity ≥33% (p < .01, OR 0.31, 95%CI 0.13–0.73) were independent factors for live birth in the subsequent pregnancy. Advanced age, the presence of uterine abnormality, and PC deficiency were risk factors for reduced pregnancy rate in women with RPL. Increased number of previous pregnancy loss and high NK cell activity were risk factors for miscarriage in the subsequent pregnancy. These results involve important information and are helpful for clinical practitioners.

Association Between Natural Killer Cell Activity and Colorectal Cancer in High-Risk Subjects Undergoing Colonoscopy

Low activity of natural killer (NK) cells has been associated with increased risk of cancer and has been reported in patients with colorectal cancer (CRC). Activity of NK cells can be measured in a small volume of whole blood by a commercially available test. We investigated whether this test could be used to identify patients with CRC, using findings from colonoscopy as a reference standard. We performed an open-label, prospective, cross-sectional study of 872 high-risk subjects (more than 40 years old) screened for CRC by colonoscopy at a university hospital in Montreal, Canada from October 2014 through January 2016. Blood samples were collected on the day of colonoscopy, prior to the procedure. The test involves stimulation of whole blood with cytokine that induces NK cells to secrete interferon gamma (IFNG), which is quantified by an ELISA. Tissue samples were taken from lesions during the colonoscopy and analyzed histologically; subjects were classified as having no evidence of disease, adenomatous polyps of less than 10 mm, of 10 mm or more, or CRC. We used the non-parametric Mann-Whitney test to compare NK cell activity between subjects with no evidence of CRC and subjects found to have CRC. Receiver operating characteristic curve analysis was used to assess the ability of the test to identify individuals with CRC. The primary objective was to determine the difference in NK cell activity between subjects with vs without CRC. The secondary objective was the test performance, based on receiver operating characteristic analysis, and cut-off value that most accurately identified individuals with CRC. We found a significant difference in NK cell activity between the 23 subjects with CRC (based on pathology analysis) and the 849 subjects without CRC: subjects found to have CRC by colonoscopy had a median level of 86.0 pg IFNG/mL (inter-quartile range, 43.3-151.0 pg IFNG/mL), whereas subjects without CRC had a median level of 298.1 pg IFNG/mL (inter-quartile range, 100.4-920.2 pg IFNG/mL) (P= .0002). The cut-off value that most accurately identified subjects with CRC was 181 pg/mL. The NK cell activity test identified subjects with CRC with 87.0% sensitivity, 60.8% specificity, a positive predictive value of 5.7%, and a negative predictive value of 99.4%. The odds ratio for detection of CRC in subjects with low NK cell activity vs subjects with higher NK cell activity was 10.3 (95% CI, 3.03-34.9). Using colonoscopy as the reference standard, a test for NK cell activity in whole blood samples identified patients with CRC with 87.0% sensitivity and a negative predictive value of 99.4%. Subjects with low NK cell activity had a 10-fold higher risk of CRC compared with subjects with high NK cell activity. This test might be used in clinical practice to assess patients for risk of CRC. Clinicaltrials.gov number: NCT02291198.

Vitamin D2 from UVB light exposed mushrooms modulates immune response to LPS in rats

Poor vitamin D (vitD) status is linked to increased risk of infectious diseases, thus there is need for vitD-rich foods. UVB-exposed mushrooms synthesize vitD₂ but knowledge of bioavailability and function in immune response is lacking. One hundred rats were fed one of five diets--control, 20 IU vitD₃/day; no vitD₃/day; 5% unexposed mushroom, 2.4 IU vitD₂/day; 2.5% UVB mushroom, 300 IU vitD₂/day; and 5% UVB mushroom, 600 IU vitD₂/day--for 10 wk and challenged with either saline or the endotoxin LPS. Blood and tissues were collected at 3 h postchallenge. Plasma 25-hydroxyvitamin D (25OHD) levels from UVB-exposed mushroom fed rats were significantly elevated and associated with higher natural killer cell activity and reduced plasma inflammatory response to LPS compared to control diet fed rats. Microarray evaluation of rat spleens for changes in inflammatory gene expression showed significant upregulation of proinflammatory genes after LPS compared to saline controls in all groups. However, compared to control rats, upregulation of the proinflammatory genes was markedly reduced in the groups fed vitD₂-enriched mushrooms. Rats fed UVB-exposed mushrooms had significantly higher plasma total 25OHD levels that were associated with increased innate immune response and anti-inflammatory effects.

Stress conditioning in mice: Alterations in immunity and tumor growth

The neuroendocrine and autonomic nervous systems are known regulators of brain–immune interaction. However, the functional significance of this interaction under stress is not fully understood. We investigated the effect of a stress paradigm by applying electric foot shock followed by three reminders, on behavior, immune parameters, and lymphoma tumor growth. Male C3H mice were divided into two groups: Group 1—exposed to electric foot shock followed by three reminders, and Group 2—untreated (controls). Sets of mice underwent the elevated plus maze, staircase, and hot plate tests. After foot shock, natural killer (NK) cell activity, and lymphocyte proliferation were measured. In addition, sets of mice were either vaccinated twice with B-cell lymphoma 38C-13 immunoglobulin for determination of anti-idiotype (Id) antibodies in sera, or inoculated with tumor cells and monitored for tumor development and survival time. Mice exposed to electric foot shock followed by the three reminders had higher NK cell activity, levels of anti-Id antibodies, and a higher proliferation rate of splenocytes in response to mitogens, than the control mice. The exposed mice also showed attenuated tumor growth. Thus, the stress paradigm inhibited tumor development and lead to some immune changes that were not accompanied by behavioral changes.

Critical role of natural killer cells in the rejection of human hepatocytes after xenotransplantation into immunodeficient mice

The severe combined immunodeficiency/albumin linked-urokinase type plasminogen activator (SCID/Alb-uPA) human liver chimeric mouse model has added a new dimension to studies of liver based human diseases and has important potential for study of human hepatic drug metabolism. However, it remains unclear if natural killer (NK) cell in SCID/Alb-uPA mice has an important negative impact on engraftment and expansion of human hepatocytes after transplantation. Here, we explore the role of mouse NK cells in the rejection of transplanted human hepatocytes in SCID/Alb-uPA mice. We assessed NK cell activity in vivo, using (125)I-iodo-2'-deoxyuridine incorporation assay. Low serum human alpha-1 antitrypsin (hAAT, <10 microg/ml) recipients, representing graft failure, showed resistance to engraftment of MHC class I knockout marrow (indicating high NK cell activity), while NK cell-depleted low hAAT recipients and high hAAT (>100 microg/ml) recipients accepted MHC class I knockout marrow, indicating a correlation between low NK cell activity, in vivo, and high level human hepatocyte engraftment. We also showed that higher level engraftment of human hepatocytes was achieved in both NK cell-depleted SCID/Alb-uPA mice and Rag2(-/-)gammac(-/-)/Alb-uPA (T,B and NK cell deficient) mice compared with untreated SCID/Alb-uPA mice. These results support a critical role for mouse NK cells in the rejection of human hepatocytes xenotransplanted to immunodeficient mice.

Opposite impact of NKG2D genotype by lifestyle exposure to risk of aerodigestive tract cancer among Japanese

It was reported that there are 2 haplotypes in natural killer complex (NKC) region. One of them could be divided by NKG2D polymorphism into 2 haplotype alleles (high and low natural killer (NK) cell activity) and were associated with overall cancer risks. However, its impact on a specific cancer is unclear. Therefore, by a case-control study, we analyzed the association between NKG2D genotype and aerodigestive tract cancer risk. Subjects were 502 aerodigestive tract cancer patients (276 with head and neck, 226 with esophageal) and 1,004 sex-age matched noncancer controls. Exposures to 2 lifestyle factors, smoking and drinking, were evaluated by a self-administered questionnaire. The genotype of NKG2D was determined by the TaqMan method, and its impact was assessed by multivariable logistic regression models. Association strength was measured by the odds ratio (OR) and its confidence intervals (CI). An overall analysis revealed no statistically significant association between NKG2D genotype and the risk of aerodigestive tract cancer. However, we found protective effects of G allele among never smokers (OR 0.35; 95% CI 0.15-0.84) and never drinkers (0.42; 0.19-0.94). In contrary, increased risks were observed for G allele among heavy smokers (5.92; 3.23-10.85) and heavy drinkers (4.13; 2.29-7.47). Interactions between NKG2D genotype and lifestyle exposure were statistically significant (interaction p = 0.001 for smoking, 0.005 for drinking). The same trends were observed in both sexes, and in head and neck cancer and esophageal cancer independently. These results suggest an opposite impact of NKG2D genotype by lifestyle exposure to the risk of aerodigestive tract cancer among a Japanese population.

Decreased risk of colorectal cancer with the high natural killer cell activity NKG2D genotype in Japanese

NKG2D is an immune receptor on natural killer (NK) and other cells active in the immune system. It recognizes ligands expressed on mainly transformed cells and plays a role in their elimination through the so-called 'cancer immune surveillance'. It was reported that there are two haplotypes of NKG2D, HNK1 (high NK activity) and LNK1 (low NK activity). Harboring the HNK1 is reported to reduce the overall cancer risk. To elucidate its impact on colorectal cancer (CRC), we conducted the present case-control study. The subjects were 379 CRC patients and 1137 sex-age-matched non-cancer controls. Data on lifestyle factors including diet were obtained by self-administered questionnaire. The NKG2D genotypes (rs1049174: G-C, LNK1/LNK1:CC; LNK1/HNK1:CG and HNK1/HNK1:GG) were assessed by the TaqMan method. Associations were then assessed by multivariate logistic regression models, considering potential confounders. The measure of association was the odds ratio (OR) and its confidence intervals (CIs). We found a reduced risk of CRC with the NKG2D HNK1. Adjusted ORs were 0.77 for LNK1/HNK1 (95% CI: 0.60-0.99) and 0.48 for HNK1/HNK1 (0.32-0.72) relative to LNK1/LNK1. The same association was consistently observed with stratified analyses across all confounders except regular exercise and body mass index (BMI). Thus, the impact of harboring HNK1 was more evident among those with BMI >/= 25 and those exercising regularly, suggesting possible interactions between NKG2D genotype and these factors. We found that the HNK1 genotype, associated with high NK cell activity, might be an independent protective factor for CRC among the Japanese population. This possibility warrants further analysis.

Induction of an Antitumoral Immune Response by Wild-Type Adeno-Associated Virus Type 2 in an In Vivo Model of Pancreatic Carcinoma

We analyzed the immunologic impact of adeno-associated virus type 2 (AAV-2), a small single-stranded parvovirus with tumorsuppressive properties, on DSL6A pancreatic carcinoma in syngeneic rats. Established tumors of animals treated with AAV-2 or mock infected were resected (Ro), and DSL6A cells were rechallenged on the different site. Eleven (92%) of 12 mock-infected animals but only 3 (25%) of 12 AAV-2-treated animals redeveloped tumors. Adeno-associated virus type 2 infection provoked systemic raises in monocytes and neutrophils numbers and in levels of the proinflammatory monocyte chemoattractant protein 1 and interleukin 10. Adeno-associated virus type 2-treated tumors were infiltrated with monocytes, macrophages, natural killer cells, CD4+ T cells, and especially CD8+ T cells. In cytotoxicity assays, AAV-2-infected DSL6A tumor cells were recognized by lymphocytes from AAV-2-treated animals and from controls. Yet, uninfected DSL6A cells were exclusively killed by lymphocytes from AAV-2-treated animals. Additionally, those lymphocytes displayed high natural killer cell activity but failed to attack unrelated tumor targets. Taken together, these results suggest that the antiviral response toward AAV-2 cross-activates the immune system toward simultaneously present tumor disease. This and the known potential to significantly reduce toxic side effects of chemotherapy make nonpathogenic viruses such as AAV-2 as "1-agent combination therapy" to an interesting treatment option of residual tumor disease.

Enhanced natural-killer cell and erythropoietic activities in VEGF-A–overexpressing mice delay F-MuLV–induced erythroleukemia

AbstractWe have previously reported that VEGF-A, in combination with MCP-5, contributes to leukemia progression within the splenic microenvironment of mice infected with F-MuLV. To study the influence of constitutively elevated VEGF-A levels on the progression of erythroleukemia, mice heterozygous for a VEGF-A “hypermorphic” allele (Vegfhi/+) were inoculated with F-MuLV. Unexpectedly, a significant delay in erythroleukemia was observed in Vegfhi/+ mice when compared with wild-type controls. These results suggested an altered physiologic response arising from elevated VEGF-A levels that decelerated erythroleukemic progression. Characterization of hematopoiesis in Vegfhi/+ spleens showed a higher natural killer cell activity, elevated B cells, and a decrease in T-cell number. Furthermore, higher erythroid progenitors (ie, CD34+, CD36+, and Ter119+ cells) were evident in the bone marrow, spleen, and peripheral blood of Vegfhi/+ mice. The CFU-E levels were significantly elevated in Vegfhi/+ bone marrow cultures, and this elevation was blocked by a neutralizing antibody to VEGF-A receptor (VEGFR-2). Moreover, erythroleukemic mice were treated with recombinant erythropoietin and, similar to diseased Vegfhi/+ mice, showed a delay in disease progression. We propose that a compensatory erythropoietic response combined with increased natural killer (NK) cell activity account for the extended survival of erythroleukemic, Vegfhi/+ mice.

Alloimmune and Autoimmune Background in Recurrent Pregnancy Loss – Successful Immunotherapy by Intravenous Immunoglobulin

Immunotherapies [leukocyte immunization, intravenous immunoglobulin (IVIG)] introduced to treat women with recurrent spontaneous abortions (RSA) have still controversial results in most clinical trials. A selection of these patients would be advantageous for higher efficacy. A complex immunological panel assay was offered to patients with reproductive failure without any other known cause. We focused here on the cellular immunological parameters. High cytotoxic T lymphocyte precursor frequency and cell-mediated cytotoxic activity and a rather high natural killer cell activity were found in alloimmune RSA patients. Thirty-two patients were investigated by immunological assays and in 78% of the women an alloimmune background could be defined. The efficacy of IVIG treatment was 96% in this group. The novel cellular immunological assays proved to be favourable for the indication of RSA patients and showed the usefulness of this selection process for effective immunotherapy.

Cytotoxic activity of lymphocytes isolated from mouse liver involved into tumor process

We studied cytotoxic activity and immunophenotype of mononuclear cells isolated from the liver of mice after implantation of ovarian cancer cells into the liver parenchyma. The isolated cells exhibited higher natural killer cell activity and possessed higher cytotoxic potential against autologous tumor cells compared to spleen lymphocytes. The ratio of CD3+ lymphocytes and natural killer cells was high in the liver with tumor metastases. Lymphoid cells were practically absent in the liver of intact animals. Natural killer cells and T cells from liver tumor tissue play an important role in antitumor immunity and can be used for local and regional adjuvant immunotherapy of liver metastases.

Preconception Peripheral Natural Killer Cell Activity as a Predictor of Pregnancy Outcome in Patients with Unexplained Infertility

Preconception high peripheral natural killer (NK) cell activity in women with recurrent spontaneous abortion can predict subsequent miscarriages. We have examined prospectively, for the first time, the pregnancy rate in patients with unexplained infertility by measuring the peripheral NK activity. We tested the peripheral NK activity of 94 infertile women who despite treatment were unable to conceive for 6 or more months (mean; 2.4 years). Peripheral NK activity was measured by a chromium-51 release cytotoxicity assay. Women were followed for 2 years and assessed. In 77 patients who were followed for 2 years, 28 had conceived but 49 did not. The peripheral NK activity of the group that became pregnant (mean +/- S.D.; 34.5 +/- 13.8%) was significantly lower than that of non-conception group (42.3 +/- 13.3%, P = 0.017). Our finding suggests that elevated peripheral NK activity in patients with unexplained infertility is a risk factor for attaining pregnancy success.

Reduced splenic natural killer cell activity in rats with a hyperreactive dopaminergic system

Interactions between the nervous system and the immune system have been recognized as important regulatory processes in determining the activity of the immune response. We have previously shown that rats, which differ in the reactivity of the dopaminergic system (APO-SUS and APO-UNSUS rats), also differ in experimental metastasis formation and in susceptibility to autoimmunity. APO-SUS rats have a high response to administration of apomorphine and can be characterized as hyperdopaminergic, whereas their APO-UNSUS counterparts show low susceptibility to apomorphine and have a hypodopaminergic phenotype. In this study we investigated whether the decreased experimental metastasis formation of APO-SUS rats compared to APO-UNSUS rats is associated with higher natural killer cell activity in APO-SUS rats. Surprisingly, splenic NK cell activity of hyperdopaminergic APO-SUS female as well as male rats is significantly lower than NK cell activity of their hypodopaminergic APO-UNSUS counterparts. The reduced splenic NK activity of female APO-SUS rats is associated with lower percentages of NK cells in the spleen cell population. In contrast, male APO-SUS and APO-UNSUS rats show similar numbers of NK cells in the spleen. There was no difference in plasma dopamine levels between APO-SUS and APO-UNSUS rats and i.p. treatment of rats with the dopaminergic agonist quinpirole did not alter NK cell activity. In conclusion, our data demonstrate that differences in the reactivity of the dopaminergic system are associated with differences in splenic NK cell activity. Moreover, our data demonstrate that in this model lower splenic NK cell activity is not related to increased experimental lung metastasis formation.