Catecholamines induce alterations of distribution and activity of human natural killer (NK) cells

Catecholamines have been suggested to be responsible for altered cellular immunity after stress. This study was performed to determine the effects of adrenaline and noradrenaline on lymphocyte subpopulations and NK cell functions. Subjects were given a subcutaneous injection of either NaCl, adrenaline (5 µg/kg), or noradrenaline (10 µg/kg). Catecholamine concentrations, subsets of peripheral blood lymphocytes, NK activity, and antibody-dependent cellular cytotoxicity (ADCC) were analyzed before (baseline) and 5, 15, 30, 60, and 120 min after injection. There were no differences between groups in the distribution of CD2⁺ and CD8⁺ lymphocytes over time. However, CD3⁺ and CD4⁺ T cells decreased significantly 5 to 60 min after injection of adrenaline. In contrast, NK cell numbers (CD16⁺, CD56⁺) increased significantly 5 min after injection of adrenaline and noradrenaline, reached the highest values 15 to 30 min postinjection, and subsequently declined to baseline values 60 (noradrenaline) and 120 (adrenaline) min, respectively, after injection. Similar alterations for NK activity and ADCC were observed after administration of both catecholamines. These data suggest that both sympatheticadrenal hormones are similarly potent modulators of natural immunity and provide further evidence that catecholamines might be responsible for the observed alterations in immune functions after phases of acute stress.     

Effect of diazepam on endocrine and cardiovascular responses to head-up tilt in humans

Effects of the GABAergic drug diazepam (0.15 mg kg^-1, i.v.) on cardiovascular and endocrine responses to 50± head-up tilt were evaluated in seven men. During the initial phase of tilt (normotensive phase), increases in heart rate (HR) and total peripheral resistance (TPR) and decreases in cardiac output were unaffected by diazepam. Also the associated increase in plasma noradrenaline did not change, while response in plasma ACTH was diminished and in plasma cortisol abolished by diazepam (F(1, 10) = 6.45; P < 0.03). After 42 ± 4 min of sustained tilt with saline (control) and 47 ± 6 min (n.s.) after diazepam, presyncopal symptoms appeared (hypotensive phase) associated with decreases in HR, MAP, and TPR (P < 0.01). This episode induced a 2–3-fold increase in plasma ACTH, β-endorphin, prolactin, cortisol (< 0.01), and a moderate increase in plasma adrenaline (P < 0.05). Diazepam did not significantly change cardiovascular and endocrine responses to the hypotensive phase of tilt. Results indicate that diazepam attenuates the cortisol part of pituitary-adrenal responses to moderate, but not to severe, central hypovolaemia in humans with no effect on cardiovascular tolerance.     

Immunological Effects of a Hyperinsulinaemic Euglycaemic Insulin Clamp in Healthy Males

The purpose of this study was to determine the in-vivo and in-vitro effects of insulin, at physiological and supraphysiological concentrations, on the human immune system. Ten healthy young men went through a sequential two-step hyperinsulinaemic euglycaemic clamp. Plasma insulin concentrations were increased from baseline (9.0 μU/ml) to 49.1 μU/ml after 1 h of insulin infusion (step I) and to 1281 μU/ml (step II) after 2 h of infusion. As control experiments infusions of isotonic saline were performed. The unstimulated natural killer (NK) cell activity among blood mononuclear cells (BMNC) increased in response to supraphysiological plasma insulin levels (baseline versus step II: 20.6 ± 11.3 versus 27.8 ± 14.4%). The percentages of the CD16⁺ NK cells did not change, indicating an enhanced cytotoxic capability per individual NK cell. Insulin also slightly increased the activity of NK cells in vitro. A decline at step II in the concentrations of monocytes (0.29 ± 0.09 versus 0.12 ± 0.03 × 10⁹/L), lymphocytes (1.57 ± 0.46 versus 1.22 ± 0.25 × 10⁹/L), and CD16⁺ (24.2 ± 17.5 versus 16.7 ± 11.2 × 10⁷/L), CD14⁺ (20.9 ± 10.8 versus 8.6 ± 3.9 × 10⁷/L), HLA-DR⁺ (37.2 ± 22.1 versus 19.2 ± 10.7 × 10⁷/L) and CD45RO⁺ (91.6 ± 33.4 versus 61.7 ± 6.4 × 10⁷/L) cells as well as in the percentages of CD14⁺ cells (11.2 ± 4.7 versus 6.4 ± 2.3%) and CD14⁺/HLA-DR⁺ monocytes (9.7 ± 3.9 versus 4.8 ± 2.8%) were observed. No changes were found at step I. Hyperinsulinaemia did not change the percentages of the CD3⁺, CD4⁺, CD8⁺, CD19⁺, CD56⁺, CD11a⁺, CD45RO⁺ and CD45RA⁺ cells, the numbers of circulating immunoglobulin (Ig)G-, IgA- and IgM- secreting cells, or the proliferative responses of BMNC to phytohaemagglutinin, purified derivative of tuberculin or interleukin (IL)-2. Hyperinsulinaemia did not change the in-vitro sensibility to insulin. In conclusion, supraphysiological insulin levels increased the activity of the individual NK cells, but decreased the numbers of NK cells, lymphocytes and activated monocytes. The findings are presumably of minor clinical relevance but may indicate an insulin-induced immune activation.     

Moesin: A novel receptor on NK lymphocytes binds to TOMM40 on K562 leukemia cells initiating cytolysis

Natural killer lymphocytes (NK cells) are the first line of defense (innate immunity) against viral infections and leukemia since they do not require activation to deliver a lethal hit to infected/aberrant cells. In contrast, T lymphocytes require stimulation by a foreign/neo – antigen, which may take days before they are active against the pathogen (adaptive immunity). A number of receptors on activated NK cells that kill the prototypical leukemia target cell line, K562, have been identified. To date, the receptor(s) by which freshly isolated unstimulated NK cells (naïve, nNK) kill K562 has not been fully elucidated. We provide peptide sequence and immune-blot data from ligand pull down experiments that moesin, a protein that typically links the inner leaf of the plasma membrane to the cytoskeleton, additionally, in NK cells, localizes to the cell surface where it may bind to its ligand, TOMM40 (aka Haymaker, HYMKR), on leukemia cells thereby initiating their destruction. Flow cytometry experiments with a mouse monoclonal antibody (Mab) to a moesin peptide (554 to 565) were performed. Moesin was detected on the surface of CD3^–, CD16⁺ nNK cells but was not detected on the surface of freshly isolated unstimulated CD3⁺, CD16^– T cells or CD19⁺, CD16^– B cells from healthy subjects. Moesin, is therefore another marker that distinguishes unstimulated CD3^–, CD16⁺ NK cells from other non-activated lymphocytes. The anti –moesin peptide Mab was highly effective (>95% inhibition) in blocking target cell cytolysis by CD16⁺ lymphocytes demonstrating that moesin–HYMKR interaction appears to be necessary for most of the observed cell death of K562 caused by unstimulated NK cells.     

Gonadotropin Releasing Hormone (GnRH) Agonist Induces Down-Regulation of the CD3+CD25+ Lymphocyte Subpopulation in Peripheral Blood

PROBLEM : To test whether GnRH agonist could alter in vivo human immune cells and whether the alteration is related to the success of pregnancy in an in vitro fertilization-embryo transfer (IVF-ET) program. METHODS : Thirty-six infertile patients were enrolled under the long protocol of GnRH agonist (buserelin acetate) and superovulation with gonadotropin from our IVF-ET program. Peripheral B cells, NK cells, CD4⁺ and CD8⁺ T cells, and the expression of CD69, CD25, HLA-DR, and CD71 antigens on the T cells were serially examined by dual-color flow cytometry. RESULTS : B cells, NK cells, CD8⁺ T cells, and CD71⁺ T lymphocyte subpopulations were not changed throughout the whole course of treatment. CD4⁺ T cell and CD25⁺ T cell sub-populations were significantly down-regulated when the GnRH agonist was used for approximately 2 wk. CD3⁺CD69⁺, CD3⁺CD25⁺, and CD3⁺DR⁺ lymphocyte subpopulations were increased at 7 days (during implantation) and at 14 days after embryo transfer in pregnant patients, but not in patients who failed to get pregnant. CONCLUSIONS : The GnRH agonist had a transiently immunosuppressive effect on CD4⁺ and CD25⁺ T cells, but CD69⁺, CD25⁺, and HLA-DR⁺ T cells were activated during and after successful implantation.     

1140919448CD200-dependent suppression of human NK activity by IVIG requires CD200 receptor type 2

Problem: IVIG prepared from plasma of stored human blood can be efficacious in improving pregnancy success in a selected subgroup of patients but RCTs using an IVIG showing inferior suppression of NK activity in vitro have been negative (J Assist Reprod Genet 2006). A significant component of NK suppression by IVIG appears to be due to CD200 released into plasma from PBL during storage at 4C. CD200 receptors (CD200R) are expressed at the fetomaternal interface prior to onset of abortion; CD200R1 mediates direct effects on gamma‐delta T cell development and suppresses alpha‐beta T cell responses in vitro, whereas CD200R2 alters DC so as to facilitate development of alpha‐beta Treg cells. Which receptor(s) mediate NK cell suppression? Methods: Purified human PBL or the CD56⁺ NK cell subset of PBL were used to lyse 51Cr‐labeled K562 cells in vitro. Different IVIG preparations were tested for suppressive ability, and suppression was blocked by either anti‐huCD200 mAb or rabbit anti‐huCD200R1 or R2 antibodies. Results: CD200‐dependent IVIG NK suppressive potency differed among IVIG types (Gammagard>Gamunex>>Gamimmune). CD200‐dependent suppression was blocked by anti‐CD200R antibody able to react with the type 2 receptor. K562 cells did not express receptor, and purified CD56⁺ NK cells were suppressed effectively without the need for non‐NK cells. Conclusions: IVIG may directly express NK cell activity via CD200 binding to CD200R2.     

Catecholamines,lymphocyte subsets,and cyclic adenosine monophosphate production in mononuclear cells and CD4+ cells in response to submaximal resistance exercise

We examined the effect of 30 min of submaximal resistance exercise on free and sulphoconjugated plasma catecholamine concentrations determined by high performance (-pressure) liquid chromatography separation, the distribution of circulating lymphocytes quantified by flow cytometry, and isoproterenol induced cyclic adenosine monophosphate (cAMP) production in mononuclear cells (MNL) and CD4⁺ cells. Venous blood samples were taken before, immediately after and 45 min after exercise. Resistance exercise increased free plasma adrenaline (A) and noradrenaline (NA) concentrations, whereas sulphoconjugated catecholamine concentrations remained unchanged. Exercise induced leucocytosis and lymphocytosis was predominantly manifested by an increase in the number of total lymphocytes, monocytes, CD3⁺, CD8⁺ cells and CD3^– CD16/CD56^– cells. Redistribution resulted in a decrease in the CD4^–: CD8⁺ ratio. The total number and distribution of lymphocytes returned to baseline after 45-min rest. An exercise-induced increase in the number of CD3^– CD16/CD56⁺ cells was significantly correlated with the increase in plasma NA (r = 0.66;P = 0.035), indicating a NA dependent process of redistribution. The cAMP-production in MNL was significantly elevated after resistance exercise, when cells were stimulated with 1 mol·1^–1 isoproterenol [pre-exercise 16.5 (SD 3.3); postexercise 21.6 (SD 9.8); 45 min postexercise 10.7 (SD 2.8)]. The cAMP production in CD4⁺ cells was not affected by exercise. Therefore, it is discussed whether redistribution is responsible for the exercise induced increase in cAMP production in MNL.     

GROα in the Fetomaternal and Amniotic Fluid Compartments During Pregnancy and Parturition

PROBLEM: The use of monoclonal antibodies for CD45RA and CD45RO antigens is important in defining maturational and functional stages on lymphocytes. METHOD: To characterize distribution of two isoforms of CD45 antigen CD45RA and CD45RO on CD3⁺, CD4⁺, CD8⁺ and CD56⁺ lymphocyte subsets from first trimester human decidua, two-color flow cytometry were used. RESULTS: In decidua, there were much higher levels of CD45RO^a+ and much lower levels of CD45RA⁺ cells among CD3⁺, CD4⁺, and CD8⁺ cells as compared with peripheral blood samples of the same pregnant women. Only ?40% of CD56⁺ cells in decidua expressed CD45RA. Unlike peripheral blood, ?30% of decidual natural killer (NK) cells weakly stained with anti-CD45RO antibodies. Double-negative CD45RA^? CD45RO^? NK cells were also present in decidua. CONCLUSIONS: The significantly raised percentage of intradecidual T cells expressing CD45RO suggest decidual accumulation of antigen-committed memory cells. The patterns of CD45 isoforms expression on decidual CD56⁺ cells are consistent with hypothesis that uterine CD56⁺ lymphocytes are terminally differentiated cells of NK lineage. PROBLEM: GROα/MGSA is a new member of the chemokine superfamily CXC(α) and is produced by a variety of cells including macrophages, fibroblasts, epithelial, and endothelial cells, and keratinocytes. This chemokine has chemoattractant activity and may participate in neutrophil recruitment and activation during the course of intrauterine infection. This study was conducted to investigate the effect of labor and microbial invasion of the amniotic cavity (MIAC) on amniotic fluid, fetal, and maternal plasma GROα concentrations. METHOD: A cross-sectional study was designed using parameters that included gestational age, results of amniotic fluid (AF) cultures, and labor status at the time of amniocentesis. Fluid was retrieved by transabdominal amniocentesis. MIAC was defined as a positive amniotic fluid culture for bacteria. Umbilical cord blood was retrieved at the time of delivery. Amniotic fluid, maternal and fetal plasma GROα concentrations were measured with a sensitive and specific ELISA (Quantikine, R&D Systems, Minneapolis, MN). RESULTS: 1) GROα was detectable in amniotic fluid, umbilical cord, and maternal plasma samples; 2) GROα concentrations in amniotic fluid increased with advancing gestational age; 3) Both term and preterm gestations with MIAC were associated with higher amniotic fluid GROα concentrations than those with sterile amniotic fluid, independent of the labor status (term, MIAC, labor: median 2.7 ng/ml, range 1.4–12.7 vs. term, no MIAC, labor: median 2.1 ng/ml, range 0.7-3.4, vs term, no MIAC, no labor: median 1.9 ng/ml, range 1.8-4.2; P <0.005; preterm: MIAC median 5 ng/ml, range 0.6–47.9 vs. no MIAC: median 2.3 ng/ml, range 0.5–10; P <0.008); 4) A strong correlation was found between umbilical cord plasma GROα concentrations and neonatal neutrophil count, and between GROα concentrations and white blood cell count in the amniotic fluid (r = 0.67, P < 0.0005 and r ? 0.38, P < 0.001, respectively). CONCLUSION: GROα is a physiologic constituent of amniotic fluid and cord blood. Amniotic fluid GROα concentrations increase with gestational age. Intrauterine infection both preterm and at term is associated with an increase in GROα concentrations of amniotic fluid, suggesting that GROα may play an important role in recruitment of neutrophils into the amniotic cavity.     

A population of CD62Llow NK1.1− CD4+ T cells that resembles NK1.1+ CD4+ T cells

In MHC class II−/− C57BL/6 (II−/−) mouse spleen, a small population of CD4⁺ T cells is present of which NK1.1⁺ CD4⁺ (NK) T cells comprise 40 to 45 %. We report here that many of the NK1.1⁻ CD4⁺ T cells derived from II−/− mice are also NK T cells. They produce large amounts of IL-4 in response to anti-CD3 ligation and do so without any requirement for the presence of IL-4 in the priming culture, a property characteristic of NK T cells. Their IFN-γ production is large and is enhanced by IL-12. In addition, II−/− NK1.1⁻ CD4⁺ T cells produce IL-4 as a result of culture with L cells expressing murine CD1 (L-CD1). We report that CD49b, a component of integrin VLA-2, is expressed on the majority of both NK1.1⁺ and NK1.1⁻ NK T cells. NK1.1⁻ NK T cells also exist in wild-type C57BL/6 mice. Evidence supporting this is that Vβ8 usage by CD62L^low NK1.1⁻ CD4⁺ T cells was ∼ 5 % higher than that by CD62L^high CD4⁺ T cells in wild-type mice in keeping with the estimated proportion of NK1.1⁻ NK T cells in the CD62L^low population. CD62L^low CD4⁺ T cells from β2-m−/− mice, which lack NK T cells, showed no increase in Vβ8 usage. When activated by anti-CD3 or L-CD1, CD62L^low NK1.1⁻ CD4⁺ T cells from conventional but not β2-m−/− and CD1−/− mice produce IL-4 in a manner indistinguishable from II−/− NK1.1⁻ CD4⁺ T cells. NK1.1⁻ NK T cells in normal mouse spleens are approximately as numerous as NK1.1⁺ NK T cells.     

Differential mobilization of leucocyte and lymphocyte subpopulations into the circulation during endurance exercise

Summary A total of 14 healthy subjects [means (SD): 27.6 (3.8) years; body mass 77.8 (6.6) kg; height 183 (6) cm] performed endurance exercise to exhaustion at 100% of the individual anaerobic threshold (Th_an) on a cycle ergometer (mean workload 207 (55) W; lactate concentrations 3.4 (1.2) mmol · l^–1; duration 83.8 (22.2) min, including 5 min at 50% of individual Th_an). Leucocyte subpopulations were measured by flow cytometry and catecholamines by radioimmunological methods. Blood samples were taken before and several times during exercise. Values were corrected for plasma volume changes and analysed using ANOVA for repeated measures. During the first 10 min of exercise, of all cell subpopulations the natural killer cells (CD3^–CD16/CD56+) increased the most (229%). Also CD3^÷CD16/CD56+ (84%), CD8^÷CD45RO^– (69%) cells, eosinophils (36%) and monocytes (62%) increased rapidly during thattime.CD3⁺, CD3⁺HLA-DR⁺, CD4⁺CD45RO⁺, CD4⁺CD45RO^–, CD8⁺CD45RO^÷ and CD19⁺ cells either did not increase or increased only slightly during exercise. Adrenaline and noradrenaline increased nearly linearly by 36% and 77% respectively at 10 min exercise. The increase of natural killer cells and heart rates between rest and 10 min of exercise correlated significantly (r=0.576,P=0.031). We conclude that natural killer cells, cytotoxic, non-MHC-restricted T-cells, monocytes and eosinophils are mobilized rapidly during the first minutes of endurance exercise. Both catecholamines and increased blood flow are likely to contribute this effect.     

Increased natural killer cell subsets with inhibitory cytokines and inhibitory surface receptors in patients with recurrent miscarriage and decreased or normal subsets in kidney transplant recipients late post‐transplant

Patients with recurrent miscarriage (RM) show up‐regulated cytotoxic natural killer (NK) cells that are suspected to play a causal role in abortion. In the present study, we investigated counter‐regulating inhibitory mechanisms and compared the results in RM patients with those of healthy controls (HC), patients with end‐stage renal disease (ESRD) and kidney transplant recipients late post‐transplant (TX). NK, NK T and T cell subsets were analysed in the peripheral blood of 31 RM, 14 female ESRD and nine female TX patients as well as 21 female HC using eight‐colour fluorescence flow cytometry. Compared with HC, RM patients showed significantly higher absolute numbers of CD56⁺ NK cells co‐expressing the phenotype interferon (IFN)‐γR⁺, IL‐4⁺, transforming growth factor (TGF)‐β⁺, IL‐4⁺ human leucocyte antigen D‐related (HLA‐DR)⁺, TGF‐β⁺HLA‐DR⁺, IL‐4⁺TGF‐β⁺, IL‐4⁺TGF‐β^–, IFN‐γ⁺ and/or IL‐10^–IFN‐γ⁺ (all P ≤ 0·01), more IL‐17⁺CD56^bright (P = 0·028) NK cells and more CD56^dimCD16⁺ NK cells co‐expressing IFN‐γR, IFN‐γ, IL‐4 and/or TGF‐β (all P ≤ 0·01). When the same cell subsets were analysed in ESRD or TX patients, cytokine‐producing NK cell subsets were not significantly different from those of HC. RM patients showed significantly higher absolute numbers of CD158a⁺, CD158b⁺, CD158a^–CD158e⁺ (all P < 0·05), NKG2D⁺NKG2A⁺, NKG2D ⁺NKG2A^–, NKG2D⁺ and/or NKG2A⁺ (all P ≤ 0·01) CD56⁺ NK cells and higher CD158a⁺, CD158b⁺ (all P < 0·05), NKG2D⁺ and/or NKG2A⁺ (all P < 0·01) CD56^dim+CD16⁺ NK cells than HC. In contrast, ESRD patients had normal and TX recipients had lower CD158a⁺ and NKG2D⁺NKG2A^–CD56⁺ NK cells and lower CD158a⁺CD56^dim+CD16⁺ NK cells (all P < 0·05) than HC. RM patients have abnormally high circulating NK cells expressing inhibitory cytokines and inhibitory surface receptors which might contribute to the pathogenesis of RM.     

Glatiramer acetate attenuates the pro‐migratory profile of adhesion molecules on various immune cell subsets in multiple sclerosis

An altered expression pattern of adhesion molecules (AM) on the surface of immune cells is a premise for their extravasation into the central nervous system (CNS) and the formation of acute brain lesions in multiple sclerosis (MS). We evaluated the impact of glatiramer acetate (GA) on cell‐bound and soluble AM in the peripheral blood of patients with relapsing–remitting MS (RRMS). Fifteen patients treated de novo with GA were studied on four occasions over a period of 12 months. Surface levels of intracellular cell adhesion molecule (ICAM)‐1, ICAM‐3, lymphocyte function‐associated antigen (LFA)‐1 and very late activation antigen (VLA)‐4 were assessed in T cells (CD3⁺CD8⁺, CD3⁺CD4⁺), B cells, natural killer (NK) cells, natural killer T cells (NK T) and monocytes by five‐colour flow cytometry. Soluble E‐selectin, ICAM‐1, ICAM‐3, platelet endothelial cell adhesion molecule (PECAM)‐1, P‐selectin and vascular cell adhesion molecule (VCAM)‐1 were determined with a fluorescent bead‐based immunoassay. The pro‐migratory pattern in RRMS was verified by comparison with healthy controls and was characterized by up‐regulation of LFA‐1 (CD3⁺CD4⁺ T cells, B cells), VLA‐4 (CD3⁺CD8⁺ T cells, NK cells), ICAM‐1 (B cells) and ICAM‐3 (NK cells). Effects of GA treatment were most pronounced after 6 months and included attenuated levels of LFA‐1 (CD3⁺CD4⁺) and VLA‐4 (CD3⁺CD4⁺, CD3⁺CD8⁺, NK, NK T, monocytes). Further effects included lowering of ICAM‐1 and ICAM‐3 levels in almost all immune cell subsets. Soluble AM levels in RRMS did not differ from healthy controls and remained unaltered after GA treatment. The deregulated pro‐migratory expression profile of cell‐bound AM is altered by GA treatment. While this alteration may contribute to the beneficial action of the drug, the protracted development and unselective changes indicate more secondary immune regulatory phenomena related to these effects.     

CD3−NK1.1+ cells aid in the early induction of a Th1 response to an attaching and effacing enteric pathogen

Extracellular attaching and effacing (A/E) pathogens including pathogenic Escherichia coli colonize the host gut causing diarrhea and inflammation. Although much is known regarding the pathogenesis of A/E bacteria, there remains an incomplete understanding of host immune responses to these microbes. NK cells are an important source of IFN‐γ and are essential for early innate responses to viral pathogens; however, their role during extracellular bacterial infections is still largely unexplored. We studied the host response to the murine A/E pathogen Citrobacter rodentium to investigate NK‐cell function during infection. NK1.1⁺ cell depletions and analysis of colonic intestinal inflammation following Citrobacter infection demonstrated that CD3^?NK1.1⁺ cells play an important role in the initial clearance of C. rodentium, as evidenced by higher bacterial load, intestinal pathology, and crypt hyperplasia at the peak of inflammation in depleted mice. Loss of CD3^?NK1.1⁺ cells resulted in lower colonic IFN‐γ, TNF‐α, and IL‐12, and a delay in homing of IFN‐γ⁺CD4⁺ T cells to the gut. Loss of this response resulted in lower anti‐C. rodentium IgG in NK1.1‐depleted mice. These data establish that CD3^?NK1.1⁺ cells are critical for inducing an early Th1 response involved in clearance of a pathogen that is restricted to the gastrointestinal tract.     

HLA-Cw7 Zygosity Affects the Size of a Subset of CD158b+ Natural Killer Cells

Individuals with certain HLA class I genotypes are highly susceptible to disease after viral infection. Natural killer (NK) cells kill virus-infected cells through a mechanism involving HLA class I receptors. These facts may be connected if an individual's HLA genotype regulates the number and function of NK cells. We have observed that subjects homozygous for the HLA-B/C region of conserved major histocompatibility complex (MHC) extended haplotypes have lower NK cell activity and a significantly lower frequency of CD16⁺CD56⁺ NK cells than heterozygotes. The proportion of CD16^–CD56⁺ NK cells was unaffected by zygosity for the HLA-B/C region. We show here that the frequency of CD16⁺CD158b⁺, but not CD16^–CD158b⁺ NK cells, was significantly lower (p <0.026) in homozygotes for HLA-Cw7 (NK1 ligand) haplotypes than in heterozygotes. The frequencies of CD16⁺CD158a⁺ and CD16^–CD158a⁺ and CD16^–CD158a⁺ or CD16⁺NKB1⁺ and CD16^–NKB1⁺ NK cells were not different in these donor groups. These findings suggest that the proportion of NK cells coexpressing CD16 and CD158b, but not CD158a nor NKB1, is influenced by zygosity for the HLA-Cw7 (NK1 ligand) haplotype. Since NK cells are involved in protection from virus infection, a reduced size of a ligand-specific NK subset in individuals homozygous for some HLA-B/C haplotypes may help explain their increased susceptibility to virus-induced diseases.     

Phenotypical and functional profiles of natural killer cells exhibiting matrix metalloproteinase-mediated CD16 cleavage after anti-HIV antibody-dependent activation

Natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity (ADCC) has been linked to protection from HIV infection and slower progression towards AIDS. However, antibody-dependent activation of NK cells results in phenotypical alterations similar to those observed on NK cells from individuals with progressive HIV infection. Activation of NK cells induces matrix metalloproteinase (MMP)-mediated cleavage of cell surface CD16. In the present study we assessed the phenotype and functional profile of NK cells exhibiting post-activation MMP-mediated CD16 cleavage. We found that NK cells achieving the highest levels of activation during stimulation exhibit the most profound decreases in CD16 expression. Further, we observed that educated KIR3DL1⁺ NK cells from human leucocyte antigen (HLA)-Bw4-carrying donors exhibit larger decreases in CD16 expression post-activation than the KIR3DL1⁻ NK cell subset containing cells educated via other inhibitory receptor/ligand combinations and non-educated NK cells. Lastly, we assessed the ex-vivo expression of CD16 on educated KIR3DL1⁺ NK cells and the KIR3DL1⁻ NK cell subset from HLA-Bw4-carrying HIV-uninfected and HIV-infected donors. Suggestive of in-vivo activation of KIR3DL1⁺ NK cells during HIV infection, CD16 expression was higher on KIR3DL1⁺ than KIR3DL1⁻ NK cells in uninfected donors but similar on both subsets in HIV-infected donors. These results are discussed in the context of how they may assist with understanding HIV disease progression and the design of immunotherapies that utilize antibody-dependent NK cell responses.     

Differential recruitment and activation of natural killer cell sub‐populations by Mycobacterium bovis‐infected dendritic cells

Through complex interplay with APCs, subsets of NK cells play an important role in shaping adaptive immune responses. Bovine tuberculosis, caused by Mycobacterium bovis, is increasing in incidence and detailed knowledge of host–pathogen interactions in the natural host is essential to facilitate disease control. We investigated the interactions of NK‐cell sub‐populations and M. bovis‐infected DCs to determine early innate mechanisms in the response to infection. A sub‐population of NK cells (NKp46⁺CD2^?) selectively expressing lymphoid homing and inflammatory chemokine receptors were induced to migrate towards M. bovis‐infected DCs. This migration was associated with increased expression of chemokines CCL3, 4, 5, 20 and CXCL8 by M. bovis‐infected DCs. Activation of NKp46⁺CD2^? NK cells and secretion of IFN‐γ was observed, a response reliant on localised IL‐12 release and direct cellular interaction. In a reciprocal manner, NKp46⁺CD2^? cells induced an increase in the intensity of cell surface MHC class II expression on DCs. In contrast, NKp46⁺CD2⁺ NK cells were unable to secrete IFN‐γ and did not reciprocally affect DCs. This study provides novel evidence to demonstrate distinct effector responses between bovine NK‐cell subsets during mycobacterial infection.     

Exercise-induced alterations in natural killer cell number and function

To study the effects of exercise on natural killer (NK) cell number and activity (NKCA) healthy male (n = 32) and female (n = 32) subjects were randomly assigned to an exercise or control condition. Exercise involved a continuous incremental protocol consisting of cycling for three periods of 6 min at work rates corresponding to 55%, 70% and 85% peak oxygen uptake ( ). Blood samples were drawn at baseline, at 6 min, 12 min and 18 min during exercise, and at 2 h following completion of exercise. Relative to both baseline and control conditions, exercise resulted in an increase in the number of circulating lymphocytes. The proportion of T cells (CD3⁺) and B cells (CD19 ⁺) significantly decreased, and NK cells (CD3^–CD16⁺CD56⁺) increased throughout exercise. NKCA increased (P < 0.001) during the initial 6 min of exercise with no further changes observed, despite increases (P < 0.001) in the number and proportion of circulating NK cells during exercise at 70% and 85% . Plasma epinephrine and norepinephrine increased (P < 0.001) above baseline at 12 min and 18 min. The changes in NK cell number and function were independent of gender. The results indicate that short-duration low-intensity exercise can significantly increase NK cell number and activity. However, alterations in NK cell number are not accompanied by changes of a similar magnitude in NKCA.     

Decrease in the Frequency of Circulating CD56+CD161+ NK Cells in Human Visceral Leishmaniasis

Background: Natural Killer (NK) cell plays an important role in the innate immune system and is known to produce IFN-γ at an early stage of infection that is essential to eliminate intracellular infection like Leishmania spp. It is already established that Leishmania parasite inhibits the activity of NK cells, avoiding the encounter with the early innate immune response. This, in turn, favors establishment and further dissemination of the infection. Methods: In the present study, we have tried to measure the frequency of different phenotypic subsets of NK cells among visceral leishmaniasis (VL) patients. Results: We have phenotyped three distinct three distinct subsets (CD56^–CD161⁺, CD56⁺CD161^–, and CD56⁺CD161⁺) of NK (CD3^–) cell using their specific markers CD161 and CD56. Conclusion: Interestingly, we observed selective loss of CD56⁺CD161⁺ subset of circulating NK (CD3^–) cells. Importantly, the other subsets (i.e., CD56^?CD161⁺ and CD56⁺CD161^–) of circulating NK cells remain unaffected as compared with healthy subjects.