Studies on the mechanism of human natural killer cell-mediated cytolysis. I. Modulation by dexamethasone and arachidonic acid

Enhancing Effect of Electromagnetic Exposure on Calciumionophore (A23187), but Not IL-1, Induced Txa2 Release by Human Neutrophils

The exposure of human polymorphonuclears to an extremely low frequency (3 Hz) electromagnetic field for 1 hour had an enhancing effect on thromboxane A2 release stimulated by A23187 calcium ionophore. On the contrary, IL-1 stimulation of TxA2 production was not affected by an electromagnetic field, suggesting that interleukin-1 influence on thromboxane synthesis is not due to a calcium ionophore-like action.

The cellular mechanisms of the antiemetic action of dexamethasone and related glucocorticoids against vomiting

Glucocorticoids, used primarily as anti-allergic and anti-inflammatory drugs, are also effective, alone or combined with other antiemetics, for preventing nausea and vomiting. Dexamethasone, one of the glucocorticoids, has been suggested as a first-line drug for preventing low-level emetogenic chemotherapy- and radiotherapy-induced nausea and vomiting, and in patients with only one or two risks for postoperative nausea and vomiting (PONV). Dexamethasone combined with 5-HT3 or tachykinin NK1 antagonists is also suggested for higher-level emetogenic chemotherapy and radiotherapy and for patients at high risk for PONV. Glucocorticoids may act via the following mechanisms: (1) anti-inflammatory effect; (2) direct central action at the solitary tract nucleus, (3) interaction with the neurotransmitter serotonin, and receptor proteins tachykinin NK1 and NK2, alpha-adrenaline, etc.; (4) maintaining the normal physiological functions of organs and systems; (5) regulation of the hypothalamic-pituitary-adrenal axis; and (6) reducing pain and the concomitant use of opioids, which in turn reduces opioid-related nausea and vomiting.

[Could anaesthesia, analgesia and sympathetic modulation affect neoplasic recurrence after surgery? A systematic review centred over the modulation of natural killer cells activity]

OBJECTIVE

The Natural Killer cells (NK) are an important part of non-specific cellular-mediated and antitumoral immunity. The goal of this review is to recapitulate data published over NK activity during the perioperative period and the influence of anaesthesia, analgesia and modulation of sympathetic system.

DATA SOURCES

Pubmed/Medline database.

STUDY SELECTION AND DATA EXTRACTION

Keywords-based selection, without limit of date: fundamental studies, randomized controlled trials and non-randomized comparative studies.

DATA SYNTHESIS

In human as in animal studies, an important correlation exists between NK activity and prognosis linked to the development of metastasis. The great depression of this cytotoxicity during the perioperative period could be able to compromise host defenses. The influence of anaesthetics and analgesics is important. The effects of the opioids, the agonists and the antagonists of the sympathetic nervous system, the prostaglandins, the NSAIDs, the ketamine, the hypnotics and the locoregional anaesthesia are systematically reviewed. The limits of experimental model presented are covered.

CONCLUSION

The effects of anaesthetic/analgesic drugs and techniques, the consequences of sympathomodulation on NK activity are numerous and sometimes opposite. It is important for the anaesthesiologist to keep in mind that the long term consequences of his techniques on the patients' outcome must be clarified.

Distinct leucocyte redistribution after glucocorticoid treatment among difficult-to-treat asthmatic patients

Difficult-to-treat asthma (DTA) represents a heterogeneous subgroup of asthma. Up to now, the lack of specific diagnosis not only complicates appropriate specification and control of asthma, but also makes targeted research difficult. The aim of this study is to categorize this heterogeneous group of DTA patients (n=27; referring to the GINA guidelines) based on the distinct leucocyte redistribution (LR) after glucocorticoid (GC) treatment. Furthermore, the effect of adjuvant therapies was investigated for its impact on LR. The frequency of CD3+, CD4+, CD8+, CD14+, CD19+ and NK cells was analysed in peripheral blood before and 3 h after systemic GC treatment, along with the markers of activation HLA-DR and CD25. Within 3 h of GC administration, a significant average decrease of 16% in CD3+CD4+ (P < or = 0.001) and a 12% increase in NK-cell frequency (P < or = 0.001) clearly distinguished two groups of patients: LR-responsive and LR-unresponsive patients. The CD3+CD8+ T-cell number and activation marker remained unchanged. Patients who received adjuvant therapy, such as methotrexate or interferon-alpha, because of poor clinical response to GC showed an LR similar to that showed by responsive patients. DTA patients comprise at least two immunologically distinct groups: patients showing an immediate decrease in CD3+CD4+ T cells and an increase in NK cells following GC administration and patients lacking an immediate change. Analysis of LR not only may allow the identification of immunologic steroid resistance, but also may be of value for immunologic determination of effective steroid doses.

Immunostimulation by clarithromycin in healthy volunteers and chronic bronchitis patients

The immune response to infecting pathogens may be either enhanced or depressed by therapeutic antimicrobial agents. Some macrolides have been shown to enhance aspects of the immune response. This study evaluates the effects of clarithromycin, a new broad-spectrum macrolide antibiotic, on leukocyte function in both healthy volunteers (single 500 mg dose) and chronic bronchitis patients (500 mg b.i.d.) by testing blood samples collected at baseline and at 2, 4, 8 and 12 hours after clarithromycin administration. Clarithromycin did not affect leukocyte chemotaxis but did significantly increase (P < 0.01) phagocytosis (both frequency and index), intracellular killing and natural killer activity, in healthy volunteers. In patients, clarithromycin enhanced phagocytosis frequency, index and intracellular killing. Clarithromycin appears to enhance the human immune response; the mechanism, pharmacodynamics, and clinical significance of this enhancement remain unknown.

Surgical stress impairs natural killer cell programming of tumor for lysis in patients with sarcomas and other solid tumors

BACKGROUND

Natural killer (NK) cells may provide a first line of defense against the metastatic implantation of circulating tumor emboli. Because tumor emboli are discharged systemically in patients undergoing solid tumor resection, it is important to determine the nature of surgical-stress impairment of perioperative NK cell cytotoxic function.

METHODS

The authors studied 85 patients undergoing surgical resection of solid tumors, most of whom had an abrupt and marked decrease in NK cell cytotoxicity that was detectable within 18 hours of surgical resection.

RESULTS

This impairment was not caused by rapidly emerging suppressor cells (measured in autologous effector cell mixing studies) or decreased NK cell frequency in the peripheral blood (assessed phenotypically and morphologically). Instead, surgical stress exerted a direct "toxic" effect on NK cells that could be localized to a specific phase of the NK cell tumor lysis cycle. Tumor binding and the first round of tumor lysis were intact postoperatively (measured in single-cell assays). However, postbinding programming for lysis was decreased sharply after surgery (assessed by calcium pulse assays). In addition, the kinetics of lysis and the rate of lytic programming were slower after surgery (assayed in target saturation kinetic chromium-51 release tests).

CONCLUSIONS

These latter defects probably were related to the programming for lysis deficiency because postprogramming NK cell maximal recycling capacity was not affected by surgical stress.

Qualitative defects in natural killer cell function in ia osteopetrotic rats

Recent studies have provided evidence that cells of the immune system and their associated cytokines function in the regulation of bone turnover. The incisors absent (ia) osteopetrotic rat represents a model in which a defect in the immune system and bone resorption can be studied. Osteopetrosis in the ia rat is characterized by a generalized excess accumulation of bone as a result of reduced bone resorption by defective osteoclasts that lack a ruffled border and the ability to exocytose their osteolytic enzymes. Previous attempts to identify associated defects in the ia immune system have proven unsuccessful; ia rats demonstrate normal delayed hypersensitivity, mitogenic activity, and macrophage function. Inasmuch as the skeletal manifestations of the ia mutation may be the result of a defect in exocytosis, related defects may be evident in immune cells utilizing exocytosis of granules or enzymes for their cytolytic function. Natural killer (NK) cells function by such a mechanism. Therefore, these studies were undertaken to evaluate the natural immune system in ia rats. NK activity assessed by 51Cr release assays was significantly reduced in ia animals compared to normal littermates. Mononuclear cells isolated from the peripheral blood of ia rats revealed a significantly greater percentage of large granular lymphocytes than normal littermates. Comparison of NK cell phenotypes using two phenotypic parameters for NK cells (OX8+, OX19- cells and 3.2.3+ cells) revealed that the mononuclear isolates of spleen and peripheral blood of mutant animals had significantly greater percentages of OX8+, OX19- and 3.2.3+ cells than normal controls.(ABSTRACT TRUNCATED AT 250 WORDS)

A study on the blunted natural killer cell activity in severely depressed patients

Recently, some investigators have established a blunted natural killer cell activity (NKCA) in severely depressed patients. In order to replicate these findings NKC cytotoxicity assays--on fresh cell suspensions in human plasma and fetal calf serum--were performed in healthy controls and depressed inpatients. Instead of the commonly used 51Cr-release assay we have used a fluorescent NKC cytotoxicity assay, which allows a greater sensitivity. We observed a significantly blunted NKCA in melancholic patients as compared with healthy controls and minor depressives, whilst simple major depressives exhibited an intermediate position. NKC cytotoxicity assays in fetal calf serum were significantly and negatively correlated with the severity of illness. We were unable to establish any relationship between NKCA and measures of hypothalamic-pituitary-adrenal-axis function, such as baseline, postdexamethasone plasma cortisol and 24 hr urinary cortisol secretion. In addition, we did not find any effects of dexamethasone administration (1 mg orally) on NKCA.

Restraint stress-induced elevations in plasma corticosterone and beta-endorphin are not accompanied by alterations in immune function

A variety of stressors activate the hypothalamic-pituitary-adrenal (HPA) axis, thereby resulting in elevated levels of circulating ACTH, beta-endorphin and corticosterone. Since these hormones have been shown previously to alter measures of immune function, we determined whether presentation of a stressor which activates the HPA axis produces a concomitant alteration in immune function. Restraint stress resulted in significantly elevated levels of corticosterone and beta-endorphin without affecting either proliferative or cytolytic activities of lymphocytes. At concentrations similar to those achieved during stress, in vivo, corticosterone exhibited a dose- and time-dependent reduction in both lymphocyte proliferation as well as natural killer cytotoxicity, in vitro. beta-Endorphin, on the other hand, was without direct or modulatory effects. These results indicate that restraint stress-induced activation of the HPA axis occurs without accompanying alterations in immune function.

Modulation of eicosanoid production and cell-mediated cytotoxicity by dietary alpha-linolenic acid in BALB/c mice

The effects of dietary alpha-linolenic acid (18:3n-3) on fatty acid composition, eicosanoid production, and cell-mediated cytotoxic activity of immune cells before and after challenge with virus or poly I-C from BALB/c mice were studied. Weanling BALB/c mice were fed purified diets containing either 10%-by-weight corn oil or linseed oil providing a ratio of 18:3n-3 to 18:2n-6 of 1/32 or 2/1, respectively, for 6-10 weeks. Fatty acid analysis of splenocyte phospholipids showed an appreciable increase in the percentage of n-3, and a decrease in n-6, fatty acids in splenocytes from mice fed the linseed oil diet. Splenocyte prostaglandin E and peritoneal exudate cell leukotriene C production was significantly lower in the linseed oil-fed mice. In general, cell-mediated cytotoxic activity was similar for immune cells from linseed oil and corn oil-fed mice. However, 6 days after the viral challenge, splenocyte cell-mediated cytotoxic activity was significantly higher in linseed oil mice. This higher activity was associated with nonspecific cytotoxicity rather than that of viral-specific cytotoxic T-lymphocytes. Cell yields from the spleen and peritoneum were frequently significantly higher in linseed oil mice. Interactions between dietary 18:3n-3, eicosanoid production, and immune cell proliferation and/or migration are discussed. In summary, feeding mice a diet rich in 18:3n-3 elevates immune cell n-3 fatty acid content, reduces eicosanoid synthesis and, to a limited extent, enhances the cell-mediated cytotoxic response to a viral challenge.

Restoration of anti-interleukin-1 depressed natural killer activity by human recombinant interferon alpha or gamma, human recombinant interleukin-2 and indomethacin

The lymphokines interleukin-2 and interferon alpha or gamma are synthesized and secreted by activated mononuclear cells (MC) and play a critical role in the proliferative expansion of T-lymphocyte effector cells during the immune response. The pretreatment of human peripheral blood mononuclear cells (PBMC) with antibody IgG against human interleukin-1 (IL-1) from normal rabbit serum, inhibited their natural killer (NK) activity against both myeloid (K562) and lymphoid (MOLT-4) cell lines. Percent specific lysis of tumor cells decreased by increasing the antibody anti-IL-1 dose in an almost linear fashion. When the effector cells were pretreated with human recombinant interleukin-2, human interferon alpha or gamma and indomethacin alone or in combination, the inhibitory effect of antibody against human IL-1 was almost totally reversed.

Cell-mediated cytotoxicity by natural killer and killer cells, lipid peroxidation and glutathione

In the course of spontaneous cell-mediated cytotoxicity (SCMC) and antibody-dependent cell-mediated cytotoxicity (ADCC) with human peripheral lymphocytes as effector cells, no lipid peroxidation occurred as measured by the production of ethane and thiobarbituric acid-reactive material. Furthermore, impairment of major cellular defense systems of target cells (K562 cells for SCMC, Chang liver cells for ADCC), by decreasing their glutathione content, had no effect on either lipid peroxidation or the cytotoxic response. These findings indicate that peroxidative damage is not a mechanism of NK and K cell-mediated cytotoxicity.

Two natural killer-cell subpopulations distinguished by heat sensitivity

We examined the effect of heat on natural killer-cell activity and found that two different natural killer-cell subpopulations can be distinguished by their heat sensitivity; one subpopulation loses natural killer-cell activity at 41 degrees C, and the other is not affected. In a single-cell assay, the ability of natural killer cells to conjugate to K 562 cells was not affected by incubation at 41 degrees C, but the killer activity of natural killer cells after conjugating to K 562 cells was reduced at 41 degrees C. Therefore it is likely that the difference in heat sensitivity between the two subpopulations is due to postbinding cytolytic events. Tetracaine, which influences cytolytic events, was used to examine whether or not the two natural killer-cell subpopulations can be distinguished by tetracaine sensitivity. However, it was found that tetracaine inhibits natural killer-cell activity equally for both of these natural killer-cell subpopulations.

The effect of acute exercise on natural killer-cell activity of trained and sedentary human subjects

The effect of acute exercise on natural killer (NK) activity and on the distribution of phenotypic characteristics of peripheral blood lymphocytes was examined. Trained and sedentary individuals underwent a standard progressive exercise test on a cycle ergometer using an incremental work load of 15 W (90 kpm), increased every minute. Each subject was encouraged to exercise to exhaustion, and total ventilation and mixed expired O2 and CO2 were measured every 30 sec. All subjects reached the "anaerobic" threshold as judged by the deflection of ventilation at a work load near VO2max. NK activity against K562 reached maximum levels immediately after exercise, dropped to a low point 120 min later, then slowly came back to preexercise levels within 20 hr. No significant differences were observed between the trained and the sedentary groups. Furthermore, immediately after exercise the proportion of OKT-3+ and OKT-4+ cells was reduced by 29.8 +/- 3.6 and 33.6 +/- 5.4%, respectively; the percentage Leu-7+ and Leu-11a+ cells was increased by 53.9 +/- 1.7 and 57.3 +/- 2.9%, respectively. The percentage OKT-8+ cells was not significantly altered. When the percentage binding of effector to target cells was examined, it was highest at 0 min post-exercise (19 +/- 6.2%) and lowest at 120 min postexercise (7 +/- 3.9%), but the absolute number of NK cells remained unchanged. The source of serum used in the lytic assay had no effect on the NK activity, as fetal calf serum and autologous sera drawn at different time intervals during exercise gave similar results.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanism of action of phorbol myristate acetate on human natural killer cell activity

We have investigated the kinetics of inhibition and regeneration of human natural killer (NK) cell-mediated lysis of K562, a human erythroleukemia cell line, by the potent tumor-promoting agent phorbol-12-myristate-13-acetate (PMA). It is shown that PMA inhibits NK cell-mediated cytotoxicity (CMC) in a dose-dependent manner whether the compound is present throughout the 4-hr cytotoxic assay or the effector cells (EC) are pretreated with PMA. Pretreatment of the target cells (TC) with PMA produced a different profile of NK activity suggesting that PMA inhibition of NK-CMC is primarily due to the inactivation of EC. PMA-induced inhibition of NK-CMC does not affect TC binding and is not circumvented by compounds that enhance intracellular levels of cyclic guanosine monophosphate (cGMP) or calcium. Furthermore, and contrary to a recent report, PMA-induced inhibition of NK-CMC is independent of monocytes. Finally, kinetic studies revealed that PMA-induced inhibition of NK-CMC occurs rapidly and is fully reversible provided that "regenerated EC" are thoroughly washed, prior to the cytotoxic assay, to rid the cell suspension of residual PMA. The potential implications of these results to the currently accepted theory of TC destruction by NK cells, the stimulus-secretion model, are discussed.