Circulating Natural Killer Cells Research Articles

Temporal, Quantitative and Functional Characteristics of Single-KIR Positive Alloreactive NK Cell Recovery Account for Impaired Graft Versus Leukemia Activity after Haploidentical HSCT.

Haploidentical Hematopoietic Stem Cell Transplantation (haplo-HSCT) is a promising therapeutic option for patients lacking a fully compatible donor. Due to extensive T cell depletion, Natural Killer (NK) cell activity represents the only immunological protection against disease relapse for the first months after haplo-HSCT. Clinical studies have associated donor-recipient incompatibility for Human Leukocyte Antigen (HLA) ligands of Killer Immunoglobulin-like Receptors (KIR), with a marked anti-leukemic activity. Alloreactive donor NK cells carrying a single KIR whose ligand is missing in the recipient mediate a potent graft vs. leukemia effect, resulting in reduced incidence of relapse and increased Overall Survival (OS). These exciting results have recently been challenged by conflicting clinical and biological data from different groups. In the present study, we have characterized reconstitution of NK cells, in particular of alloreactive single-KIR+ NK cells, in 58 patients who received CD34+ selected haplo-HSCT for high-risk hematologic malignancies. One month after haplo-HSCT CD56bright/CD56dim NK cell subsets were subverted in their proportions and phenotypic features, accounting for enrichment in maturation intermediates. We show that CD25 and CD117 deregulation by CD56bright, and NKG2A and CD62L by CD56dim, are intrinsic to NK cell physiologic differentiation and support a sequential CD56bright-to-CD56dim NK cell maturation. Consistently, the in vitro functional potential of these maturation intermediates against leukemic blasts was heavily impaired, both in terms of cytotoxicity and of cytokine release. Full mature receptor repertoire reconstitution took at least three months. Alloreactive single-KIR+ NK cells had highly variable frequency ranging from less than 1% to more than 30% of NK cells circulating at 90–120 days after transplantation, independently from predicted NK alloreactivity. Importantly, out of three patients with predicted NK alloreactivity, none had a relative expansion of alloreactive single-KIR+ cells, accounting for less than 1% of circulating NK cells in two of them. As demonstrated by flow cytometric analysis of NK cell CD107a mobilization in response to the HLA class I negative target 721.221, single-KIR+ NK cells at three months after haplo-HSCT showed a not yet fully developed functional reactivity, which was recovered to donor-levels only at later time-points. In line with these observations, clinical outcome of haplo-HSCT was not affected in any way by the presence of donor NK alloreactivity. The incidence of relapse was virtually identical in patients transplanted from alloreactive or non-alloreactive donors. Taken together, our data shed new light onto the kinetics of NK cell differentiation in vivo and suggest that NK alloreactivity could be best exploited by the use of mature donor single-KIR+ selected alloreactive NK cells.

Peripheral blood natural killer cell count is associated with clinical outcome in patients with aaIPI 2–3 diffuse large B-cell lymphoma

Background: Lymphocytopenia is a prognostic factor in Hodgkin's disease. In diffuse large B-cell lymphoma (DLBCL), data are much less established, in spite of numerous reports on immune system–lymphoma interactions. This study addresses the prognostic value of blood lymphocyte subsets at diagnosis in DLBCL.Patients and methods: Absolute values of blood lymphocyte subsets and monocytes were prospectively determined by flow cytometry in 140 patients with 2 or 3 adverse age-adjusted International Prognostic Index (aaIPI) factors included in a Groupe d'Etude des Lymphomes de l'Adulte protocol (LNH98B3). Absolute cell counts at diagnosis and aaIPI were evaluated with regard to clinical outcome.Results: Low median cell counts of 337, 211, and 104/μl were evidenced for the CD4+, CD8+ T, and natural killer (NK) cells, respectively. In univariate analysis, only NK cell count [odds ratio (OR) = 1.81 (1.27, 2.57), P = 0.001] and aaIPI [OR = 2.29 (0.95, 5.45), P = 0.06] were associated with induction treatment response. Low NK cell count [Hazard ratio (HR) = 1.27 (1.06, 1.52), P = 0.01] and aaIPI 3 [HR = 1.95 (1.20, 3.16), P = 0.01] were also associated with a shorter event free survival (EFS). In multivariate analysis, NK cell count was associated with response [OR = 1.77 (1.24, 2.54), P = 0.002] and EFS [HR = 1.25 (1.04, 1.50) P = 0.02] independently of aaIPI.Conclusions: This study shows an association between circulating NK cell number and clinical outcome in DLBCL, possibly important in the context of the broadening use of rituximab, a likely NK-dependant therapy.

Clinical and immunologic evaluation of women with multiple sclerosis during and after pregnancy

Multiple sclerosis (MS) is a disabling autoimmune disease of the central nervous system, typically affecting women of childbearing years. Although the disease course of MS is highly unpredictable, disease activity is almost invariably halted during pregnancy. After delivery, however, the relapse rate increases. Despite early recognition of this pattern of disease activity, its explanation remains a mystery. The aim of this study was to elucidate the underlying mechanisms responsible for the amelioration of MS during pregnancy and for its reactivation after delivery. This Finnish prospective study included clinical and immunologic follow-up of patients with MS during pregnancy and 6 months into the postpartum period. Groups of patients with MS who were not pregnant, along with pregnant and nonpregnant healthy women, served as controls. Laboratory investigations included subtype analysis of T, B, and natural killer (NK) cells during and after pregnancy, using immunofluorescence staining and fluorescence-activated cell sorting analysis The clinical and immunologic follow-up data from 42 pregnant patients with MS indicated that the percentage of circulating NK cells decreases during the last trimester of pregnancy and increases again soon after the delivery. This correlates with disease activity as measured by annualized relapse rate. Early postpartum treatment with interferon-0 was effective in preventing relapses, and good response to postpartum treatment coincided with a reduction in the circulating NK cell levels. Our findings have implications for the treatment and follow-up of pregnant women with MS. To prevent postpartum relapses, disease-modifying treatment should be initiated as early as possible.

Killers aid a pregnancy

From a mother's perspective, a fetus is a bag full of foreign antigens—invaders against which an immune system might be expected to protect. But, according to Jacob Hanna, Ofer Mandelboim (Hebrew University, Jerusalem, Israel), and colleagues, certain immune cells actually help fetal cells to invade the uterus and ensure an adequate blood supply. Their success is essential to avoid the often fatal condition of preeclampsia. All this cellular action takes place in the decidua, the outer lining of the uterus during pregnancy. Up to 40% of the cells in this tissue are maternal natural killer (NK) cells—but specifically the NK cells rich in CD56. Unlike the majority of circulating NK cells, these dNK cells are good at excreting proinflammatory cytokines and bad at killing infected cells. The Israeli group found that dNK cells produce chemokines that can attract embryonic cells called trophoblasts. These trophoblasts form the placenta, in part by invading the decidua and tapping into the underlying blood vessels. Blood vessel growth and remodelling appears to be further aided by the VEGF now found to be secreted by dNK cells. If this invasion is insufficient, the result is preeclampsia: blood vessels that do not fully penetrate the myometrium result in high blood pressure in the mother and fetus, which can only be relieved by delivering the fetus. In a recent genetic study, preeclampsia risk was greatest for parental gene combinations that inhibited dNK cell activation. Thus, when fetal cells are looking for a foothold, a pacifist subset of killer cells is the critical collaborator. Reference: Hanna, J., et al. 2006. Nat. Med. doi:.10.1038/nm1452 [PubMed] [Cross Ref]

NK cells and human pregnancy – an inflammatory view

For several years, reproductive immunology has been dominated by the 'Th1/Th2' hypothesis, in which the fetus avoids maternal T-cell rejection through a bias towards T-helper (Th)2 cytokine production. The discovery that normal pregnancy is a controlled state of inflammation, at an early stage at the implantation site and also later systemically, has challenged this concept, as has the finding that the predominant immune interactions in the decidua are between the placental trophoblast and maternal natural killer (NK) cells instead of T cells. Here, we extend this concept to the interaction between the trophoblast and NK cells in the maternal circulation. We suggest novel ways in which the trophoblast might stimulate the maternal systemic inflammatory response, and how dysfunctional NK-cell activation could result in the maternal syndrome of pre-eclampsia.

Changes In The Proportions Of CD56 dim And CD56bright Natural Killer Cells During And After Acute Exercise

Our previous research has shown changes in the relative proportions of natural killer (NK) cell subsets with high and low cytotoxic activities during incremental exercise. Such changes suggest a potential differential mobilization of NK cell subsets during and after acute exercise. PURPOSE: To determine the relative proportions of CD3-CD16brigthCD56dim (CD56dim) and CD3−CD16dim/−CD56bright(CD56bright) NK cells, as a percentage of total lymphocyte counts, during and after moderate exercise (intensities between AT and OBLA). METHODS: Six male students (age: 20.2±0.7 yrs, VO2max: 59.1±2.6 ml•kg-1•min−1) exercised on a cycle ergometer for 30 min at 120% of their individual ventilatory thresholds (69.7±0.1 %VO2max). Blood samples were taken at rest, at the end of exercise, and 5, 30, 60, 90, and 120 min post-exercise. The phenotypes of circulating NK cells were determined by flow cytometry. Possible effects were analyzed using a one-factor ANOVA, and applying Bonferroni's post hoc test for multiple comparisons. RESULTS: The proportion of CD56dim NK cells, expressed as a percentage of total lymphocyte counts, increased significantly (p < 0.001) during exercise, but dropped below the resting level at 60 min post-exercise (p < 0.001). In contrast, the percentage of CD56bright NK cells tended to increase at 30 min post-exercise, but remained statistically unchanged throughout the experiments. CONCLUSIONS: These results suggest that an acute bout of exercise induces a differential the mobilization of CD56dim and CD56bright NK cell subsets.

Cytolytic function and survival of natural killer cells are severely altered in myelodysplastic syndromes

Natural Killer (NK) cells are critical in host defense against malignant transformation and are potent antileukemic cytotoxic effectors. In the present study, we investigated the peripheral NK function in patients with myelodysplastic syndromes (MDS). We demonstrated that the peripheral NK cell population was quantitatively normal in MDS patients. Furthermore, NK cells displayed an expression of the activating natural cytotoxicity receptors (NCR) NKp46 and NKp30 as well as NKG2D similar to that observed in donors, but exert a highly decreased constitutive cytolytic activity compared to resting normal NK cells. Although activation with IL-2 resulted in the upregulation of NKp46 expression by MDS-NK cells, their cytolytic function remained deeply altered as compared to activated donor NK cells. In addition, MDS NK cells did not proliferate in vitro, and displayed an increased rate of apoptosis in response to IL-2 stimulation although the spontaneous apoptosis was not significantly increased. Interestingly, a proportion of peripheral MDS-NK cells were derived from the MDS clone as the cytogenetic anomaly found in bone marrow karyotype was also detected in 20-50% of circulating NK cells. In conclusion, NK cells' cytolytic function and proliferative capacities in response to activation by cytokines are profoundly altered in MDS.

Decreased NK cell frequency in chronic hepatitis C does not affect ex vivo cytolytic killing

Prior studies have suggested that natural killer (NK) cell function might be impaired in chronic hepatitis C virus (HCV) infection. Circulating NK cell frequency and cytolytic activity were examined freshly ex vivo in HCV-infected and uninfected subjects. Surprisingly, the intrinsic cytolytic activity of peripheral blood NK-enriched cells was similar between HCV-infected and uninfected groups (P = .91). Although the percentage of circulating CD3- CD16/56+ NK cells was 30% lower in HCV-infected compared with uninfected subjects (P = .02) paralleled by a decrease of CD56(dim) cytolytic NK cells (P = .02), overall K562 cytolysis by unfractionated peripheral blood mononuclear cells was not affected (P = .29). Analysis of the relationships between NK cytolytic activity and other clinical information revealed an inverse association with liver fibrosis stage (P = .035). In conclusion, NK cell cytolytic function does not appear to be impaired in chronic hepatitis C, but higher levels of NK cell cytolysis are associated with less liver fibrosis.

Increased Airway Granzyme b and Perforin in Current and Ex-Smoking COPD Subjects

Increased bronchial epithelial cell apoptosis and CD8+ T-cell numbers in the blood and airways have been reported in COPD. These cells can induce apoptosis via the granzyme-b/perforin-mediated pathway. We hypothesized that increased levels of granzyme-b/perforin would be detected in COPD, contributing to apoptosis and tissue damage. Intracellular granzyme-b/perforin were measured in blood-derived T-cells and natural killer (NK) cells from COPD subjects (30 current and 30 ex-smokers), 20 asymptomatic current-smokers and 30 never-smokers, and bronchoalveolar lavage (BAL)-derived T-cells from a cohort of these subjects using flow cytometry. Soluble granzyme-b was determined by ELISA. In blood, there was an increased percentage of T-cells expressing intracellular granzyme-b/perforin for both COPD groups but not asymptomatic smokers (versus never-smokers). Soluble granzyme-b was undetectable. In BAL, soluble granzyme-b levels and the percentage of T-cells expressing intracellular granzyme-b/perforin were increased in both COPD groups and asymptomatic smokers. There was a significant correlation between granzyme-b expression in BAL and apoptosis of bronchial epithelial cells. Most circulating NK cells expressed granzyme-b/perforin, with the median fluorescence intensity of staining increased in both COPD groups and asymptomatic smokers. Granzyme-mediated apoptosis may thus be one mechanism of lung injury in COPD. The changes that persist despite smoking cessation in COPD likely reflect pathophysiological changes in COPD as opposed to the effects of smoking per se.

Changes In The Proportion Of Cd56dim And Cd56bright Natural Killer Cells During Incremental Exercise

Our previous research has shown changes in the proportions of natural killer (NK) cell subsets with different cy to toxic ities during one month of intensive training. These changes could partly explain an observed decrease in lytic units per NK cell at the end of training. There has been no report on changes in NK cell subset proportions during an acute bout of exercise. Researcher indicated that the increase in NK cell cytolytic activity following vigorous exercise was less than that expected from the associated increase in NK cell counts. PURPOSE We investigated the cell counts and the relative proportions of CD3-CD16brightCD56dim (CD56dim) and CD3-CD16dim/-CD56bright (CD56bright) NK cells during an incremental exercise to test the hypothesis that high-intensity exercise induces an increase in the proportion of low cytotoxic NK cells in the peripheral blood. METHODS Nine male students exercised on a cycle ergometer for 5 min at 50, 90, 120 and 140% ventilatory threshold (VT)-VO. Blood samples were taken at rest and at the end of each exercise-intensity stage. The phenotypes of circulating NK cells were determined by flow cytometry. RESULTS Both CD56dim (cells with high cytotoxicity, p<0.001) and CD56bright (cells with low cytotoxicity, p<0.02) cell counts increased exponentially as exercise intensity increased. Total NK cell cytolytic activity followed a corresponding pattern (p<0.001). The proportion of CD56dim NK cell expressed as a percentage of total lymphocyte counts increased significantly (p<0.001). In contrast, the percentage of CD56bright NK cells remained unchanged throughout the experiments. CONCLUSIONS These results suggest that a bout of high-intensity exercise did not induce an increase in the proportion of the CD56bright NK cell subset with low cytolytic activities. Supported by Meiji Life Insurance Company.

Does prolonged cycling of moderate intensity affect immune cell function?

Background: Prolonged exercise may induce temporary immunosuppression with a presumed increased susceptibility for infection. However, there are only few data on immune cell function after prolonged cycling at moderate intensities...

Compartmentalization of human natural killer cells

Human natural killer (NK) cells are bone marrow-derived cells that are found in the bloodstream, but can extravasate into various tissue sites upon inflammation. NK cells that migrate toward inflamed sites must be activated prior to their extravasation. However, the factors responsible for NK cell compartmentalization are not clearly defined. Resting human NK cells (CD16 − and CD16 +) express constitutive chemokine receptors, as well as receptors that have both constitutive and inflammatory functions. Upon activation, NK cells up-regulate the expression of the inflammatory chemokine receptors which facilitate their distribution into inflammatory sites. However, chemokines are not expected to play any role in maintaining resting NK cells in the blood circulation. In contrast, members of the lysolipids which are abundant in the bloodstream may be the major factors responsible for maintaining resting NK cells in the bloodstream, and also for facilitating their extravasation into inflamed tissues. Both resting and activated NK cells express receptors for various lysolipids. Hence, chemoattractants which include chemokines and lysolipids have important roles in determining the compartmentalization of NK cells where resting NK cells are found in the blood circulation, and activated NK cells extravasate into inflamed sites.

Interleukin-6 (IL-6) expression and natural killer (NK) cell dysfunction and anergy in heart failure

Immune dysfunction has been postulated to play a role in the pathophysiology of chronic heart failure. We examined the relation between interleukin-6 (IL-6) production and natural killer (NK) cell dysfunction in patients with chronic heart failure. Sera and peripheral blood mononuclear cells (PBMCs) were collected from 82 patients with advanced heart failure. Levels of circulating NK cells and T cells were determined by flow cytometry. NK cell function was measured by standard cytotoxicity assays. IL-6 in supernatants of PBMC cultured in vitro was quantitated by an enzyme-linked immunosorbent assay. The levels of circulating NK cells were lower in patients with heart failure than in normal controls (p = 0.0037). NK cells from patients with heart failure also exhibited impaired cytolytic functions in the absence of stimuli and in response to IL-2 and IL-12 (p <0.0001 for all conditions). PBMCs from patients with heart failure produced higher levels of IL-6 in response to a T-cell stimulus than did PBMCs from healthy controls (p = 0.0012). The level of IL-6 produced by unstimulated PBMCs in patients with heart failure correlated with NK cell cytolytic impairment (p = 0.0012). These results demonstrated that PBMCs are a source of IL-6 in patients with heart failure. Production of IL-6 by PBMCs correlated with NK cell anergy to other cytokines that use signal transduction pathways that may be regulated by IL-6. These results support a model of cytokine-induced anergy in conditions that result in high systemic levels of IL-6.

Natural killer cell lytic activity and CD56(dim) and CD56(bright) cell distributions during and after intensive training.

The purpose of this study was to examine the impact of intensive training for competitive sports on natural killer (NK) cell lytic activity and subset distribution. Eight female college-level volleyball players undertook 1 mo of heavy preseason training. Volleyball drills were performed 5 h/day, 6 days/wk. Morning resting blood samples were collected before training (Pre), on the 10th day of training (During), 1 day before the end of training (End), and 1 wk after intensive training had ceased (Post). CD3(-)CD16(bright)CD56(dim) (CD56(dim) NK), CD3(-)CD16(dim/-)CD56(bright) NK (CD56(bright) NK), and CD3(+)CD16(-)CD56(dim) (CD56(dim) T) cells in peripheral blood were determined by flow cytometry. The circulating count of CD56(dim) NK cells (the predominant population, with a high cytotoxicity) did not change, nor did the counts for other leukocyte subsets. However, counts for CD56(bright) NK and CD56(dim) T cells (subsets with a lower cytotoxicity) increased significantly (P < 0.01) in response to the heavy training. Overall NK cell cytotoxicity decreased from Pre to End (P = 0.002), with a return to initial values at Post. Lytic units per NK cell followed a similar pattern (P = 0.008). Circulating levels of interleukin-6, interferon-gamma, and tumor necrosis factor-alpha remained unchanged. These results suggest that heavy training can decrease total NK cell cytotoxicity as well as lytic units per NK cell. Such effects may reflect in part an increase in the proportion of circulating NK cells with a low cytotoxicity.

Suppression of natural killer cell activity and promotion of tumor metastasis by ketamine, thiopental, and halothane, but not by propofol: mediating mechanisms and prophylactic measures.

Postoperative immunosuppression is partly ascribed to anesthesia and has been suggested to compromise patients' resistance to infection and tumor metastasis. We compared the effects of various anesthetics on natural killer (NK) cell activity and on resistance to experimental metastasis, and studied mediating mechanisms and prophylactic measures. Fischer 344 rats served as controls or were anesthetized for 1 h with ketamine, thiopental, halothane, or propofol. Anesthetized rats were either maintained in normothermia or left to spontaneously reach 33 degrees C-35 degrees C. Rats were then injected IV with MADB106 tumor cells, and 24 h later lung tumor retention was assessed, or 3 wk later, lung metastases were counted. Additionally, the number and activity of circulating NK cells were assessed after anesthesia. All anesthetics, except propofol, significantly reduced NK activity and increased MADB106 lung tumor retention or lung metastases. Hypothermia had no significant effects. Ketamine increased metastasis most potently, and this effect was markedly reduced in rats pretreated with a beta-adrenergic antagonist (nadolol) or with chronic small doses of an immunostimulator (polyriboinosinic:polyribocytidylic acid). Overall, the marked variation in the NK-suppressive effects of anesthetics seems to underlie their differential promotion of MADB106 metastasis. Prophylactic measures may include perioperative immunostimulation and the use of beta-blockers. This study in a rat model of pulmonary metastasis demonstrates that some anesthetics, but not others, increase susceptibility to tumor metastasis, apparently by suppressing natural killer cell activity. Ketamine was most deleterious, and its effects were prevented by peripheral blockade of beta-adrenoceptors combined with low levels of immunostimulation.

Circulating natural killer cells in psoriasis.

Psoriasis is an immunologically mediated, probably autoimmune, disease in which T-helper type 1 cytokines play an important role. Established autoimmune diseases, with similar mechanistic characteristics to psoriasis, include multiple sclerosis, rheumatoid arthritis, type 1 diabetes mellitus and systemic lupus erythematosus. Natural killer (NK) and natural killer-T (NK-T) cells are considered key to the pathogenesis of these conditions, which are characterized by reduced numbers of NK cells in peripheral blood. NK and NK-T cells have been implicated in the pathogenesis of psoriasis and are present in plaques of psoriasis. To investigate whether levels of NK and NK-T cells are reduced in the peripheral blood of patients with psoriasis. Fourteen patients with untreated psoriasis, mean +/- SD age 46 +/- 13 years, and 13 healthy volunteers, mean +/- SD age 34 +/- 9 years, were venesected and peripheral blood mononuclear cells isolated, labelled with a panel of antibodies to T-cells and NK cells including CD3, CD56, CD57, CD16, CD94, CD158a, CD69 and cutaneous lymphocyte-associated antigen (CLA) and analysed using triple-colour flow cytometry. There were significantly fewer cells expressing the NK-cell markers CD16 (P < 0.001), CD56 (P < 0.003), CD94 (P < 0.001) and CD158a (P < 0.02) in patients with psoriasis compared with normal controls. However, circulating numbers of NK-T cells (CD3+ CD56+ CD57+), T-cells (CD3+), activated lymphocytes (CD69+) or CLA+ cells were not significantly different between patients with psoriasis and controls. Circulating NK cells are reduced in psoriasis. This finding is similar to those in established autoimmune diseases such as rheumatoid arthritis. This observation provides some evidence that psoriasis may be an autoimmune disease in which NK cells play a role.

Expansion of natural killer cells in patients with head and neck cancer: detection of "noninhibitory" (activating) killer Ig-like receptors on circulating natural killer cells.

In a group of patients with head and neck cancers (H&NC), the expansion of the population of CD3-,CD16+ natural killer (NK) cells in the peripheral blood was studied. Cytofluorimetric analysis of the expression of killer Ig-like receptors (KIR, namely p58.1, p58.2, p58.3, p70, and p140) and CD94-NKG2a was performed. Cytolytic activities were studied using 51Cr release assay. T and NK cell cloning was performed using limiting dilution culture conditions. Cytokine production was analyzed using commercial enzyme immunoassays. Phenotypic analysis showed that the expanded populations were heterogeneous. Even in the presence of a large number of circulating NK cells, "nonspecific" cytolytic capacities were heavily reduced, whereas cytolytic capacity related to T cells was virtually normal. Unlike NK cell clones derived from healthy donors, most NK cells derived from H&NC patients expressed surface "activating" NK cell receptors (KAR) for HLA, detected by use of a redirected cytolytic assay. Analysis of the CD4+ subpopulation at the clonal level demonstrated that they had a severe proliferative defect. These experimental data indicated that H&NC patients have a polyclonal expansion of functionally deficient NK cells expressing KAR. In addition, the proliferative capacity of patients' "helper" cells was strongly inhibited, thus accounting for a severe impairment of cytolytic activity of the expanded NK cells.

Influence of beta-adrenoceptor antagonists on hemorrhage-induced cellular immune suppression.

Hemorrhagic shock is associated with increasing catecholamine plasma concentrations. Plasma catecholamines are known to affect cellular immune functions. We therefore, investigated the effect of endogenously released catecholamines on lymphocyte distribution (CD4+ lymphocytes, CD8+ lymphocytes, and natural killer (NK) cells), splenocyte apoptosis (Annexin V binding), tumor necrosis factor-alpha (TNF-alpha), and interleukin 10 (IL-10) release during a volume-controlled hemorrhagic shock in mice. Mice received either saline (HEM), the non-selective beta-adrenoceptor antagonist propranolol (PROP; 2 mg/kg i.p.), or the beta1-adrenoceptor antagonist metoprolol (MET; 2 mg/kg i.p.) before induction of hemorrhage. Mice were sacrificed to obtain the spleen and whole blood 1 h after hemorrhage, 1 h after fluid resuscitation, and 24 h after hemorrhage. Flow cytometric analysis revealed an increase in circulating NK cells in the HEM group. This effect was completely abolished by pretreatment with propranolol or metoprolol. Furthermore, administration of either beta-adrenoceptor antagonist led to a decrease of circulating CD8+ lymphocyte numbers. Monitoring of splenocyte apoptosis by determination of Annexin V binding revealed an increase in splenocyte apoptosis 24 h after hemorrhage in the HEM group but not in the animals pretreated with propranolol or metoprolol. Induction of hemorrhage did not affect TNF-alpha or IL-10 plasma concentrations in either experimental group. We conclude that plasma catecholamines affect cellular immunity in the early phase of trauma via a beta-adrenergic pathway.

HIV/host interactions: new lessons from the Red Queen's country.

HIV/host interactions: new lessons from the Red Queen's country.

Natural killer cell enumeration and function in HIV-infected and high-risk uninfected adolescents.

This is the first report of natural killer cell enumeration and function in HIV-infected and high-risk uninfected adolescents. We examined the association of demographic characteristics of this cohort with three outcomes: CD16+ cell absolute count, lytic units per peripheral blood mononuclear cell (PBMC), and lytic units per natural killer (NK) cell. We also examined the association of CD4, CD38, and antiretroviral therapy (ART) use with these outcomes in the subset of HIV-infected adolescents. Adolescents participating in an on-going longitudinal study (the REACH study) were sampled for CD16+ cell count and NK function. This cross-sectional analysis was performed on 412 subjects with NK cell data available. HIV-positive males had higher numbers of CD3-/CD16+/CD56+ NK cells than HIV-positive females. However, for the HIV-negative subjects, we did not observe a gender-related effect for absolute NK cell numbers. Gender, however, was a significant covariate for the analysis, using lytic units per PBMC as the unit of measurement, with males showing higher values than females. Age was not a predictive covariate for any of the three assessments of NK cell number and function examined. Our observations concerning the HIV-positive individuals indicate that reduced CD4+ T cell counts were associated with decreased circulating CD3-/CD16+/CD56+ NK cells. We also observed an association between elevation of CD8+/CD38+/DR+ lymphocytes and lower NK lytic units per PBMC. The results of our multivariate models indicate that there is a reduced number of NK cells and reduced lytic units per PBMC in patients receiving single or multidrug antiretroviral therapy. There are changes in circulating NK cell number and function in HIV-infected adolescents, in comparison with high-risk HIV-negative adolescents. The data suggest that these changes may occur early in the course of HIV disease but that quantitative changes continue to occur with advancing depletion of the CD4+ T cell pool.