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T W Klein

Publications and source records attributed to T W Klein.

At least 73 records · Page 4Linked to original sources
PubMed1994

delta 9-Tetrahydrocannabinol enhances the secretion of interleukin 1 from endotoxin-stimulated macrophages.

Interleukin (IL) 1 is a pleiotropic cytokine and an important mediator of various physiological responses including the acute phase response, inflammation, lymphocyte function and certain central nervous system responses. Because delta 9-tetrahydrocannabinol (THC) treatment also has been reported to affect these physiological responses, we tested the drug effect on IL1 production and secretion. Addition of THC to endotoxin (ETX)-treated murine, resident peritoneal macrophage cultures increased, in a dose-dependent manner, supernatant IL1 activity over ETX only treatment. Treatment with THC alone had no effect. Enzyme-linked immunosorbent assay studies and specific antibody neutralization studies demonstrated both IL1 alpha and IL1 beta were increased by drug treatment. The steady-state levels of cellular IL1 alpha and IL1 beta mRNAs, determined by Northern blotting and reverse transcription-polymerase chain reaction, were unchanged, suggesting the possibility THC was not increasing IL1 production. To examine this possibility further, ETX-activated macrophages, pulsed-labeled with 35S-methionine, were chased for 2, 4 and 6 hr in the presence of THC and the levels of the various IL1 bioforms determined by immunoprecipitation. These results showed THC treatment had no effect on the level of ETX-induced intracellular promature IL1 alpha and IL1 beta proteins; however, a THC-induced increase and prolongation of release of promature IL1 alpha and mature IL1 beta were observed. The immunoprecipitation results were confirmed by studies examining supernatant bioactivity. These results suggest THC augments the ETX-induced processing of IL1 beta and release of IL1 alpha rather than increasing the cellular production of IL1 protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Cocaine suppresses proliferation of phytohemagglutinin-activated human peripheral blood T-cells.

Cocaine has been reported to modulate the immune system of experimental animals. Also, we observed that the drug suppresses the phytohemagglutinin (PHA)-induced proliferation of human peripheral blood mononuclear cells (PBMCs) but at concentrations extremely high relative to those seen in the blood of drug abusers. This suggested that cocaine had a relatively weak effect when tested under conditions of optimum proliferation. We, therefore, decided to examine the effect of lower concentrations of cocaine on suboptimum PHA-induced proliferation. At 0.09-12 microM, cocaine had no effect on the proliferation of PBMC in response to 0.2 micrograms/ml PHA. However, depleting the population of B-cells and monocytes resulted in a drug-induced suppression of the residual T-cells. Maximum suppression by cocaine was observed at 3 microM with both higher and lower concentrations of the drug causing less suppression. Suppression of proliferation was not influenced by either the age or sex of the peripheral blood lymphocytes (PBL) donors. The suppression of T-cell-enriched PBLs induced by cocaine could be eliminated by increasing the dose of the mitogen but was enhanced by preincubating the cells with the drug for 24 h. Also, the drug suppressed cytosolic free calcium mobilization in Fura 2/AM loaded enriched T-cell populations. These results show that cocaine moderately but consistently suppresses PHA-induced proliferation of T-cells from random blood donors at drug concentrations observed in drug abusers. The suppression is only evident under conditions of suboptimum proliferation and is accompanied by a corresponding decrease in the mobilization of cytosolic free calcium. It is suggested that the weak suppressive effect of cocaine is reversed by either helper factors produced by accessory cells or increasing concentrations of mitogen. These factors when present possibly overcome a drug-induced reduction in calcium mobilization and lymphocyte activation.

Adult↗
PubMed1993

delta-9-Tetrahydrocannabinol (THC) decreases the number of high and intermediate affinity IL-2 receptors of the IL-2 dependent cell line NKB61A2.

Treatment of the cloned NK-cell line (NKB61A2) with the major psychoactive marijuana component, delta-9-tetrahydrocannabinol (THC), for 24 h suppressed IL-2-induced proliferation of these cells in the cytokine concentration range of 0.25-10 pM suggesting that the drug inhibits the functional activity of the high affinity IL-2R. The proliferation inhibitory effect of THC was accompanied by a decrease in the number of high and intermediate affinity IL-2 binding sites as measured by equilibrium binding studies. However, the expression of Tac protein on the surface of these cells was increased as determined by flow cytometry analysis. THC was also shown to decrease proliferation and the number of IL-2 binding sites of cells previously pulsed with IL-2 and then treated with the drug in the absence of IL-2. These results suggest that THC inhibits IL-2-induced proliferation by modulating the expression of high affinity IL-2 receptors (alpha/beta) required for cell activation and also suppresses the ongoing process of functional receptor expression and clonal expansion of cells previously activated by IL-2. Because the number of intermediate binding sites is decreased following drug treatment along with an increase in the expression of Tac protein (alpha chain), the lowering of high affinity sites possibly results from a drug-induced depression of beta chain expression.

Animals↗
PubMed1993

Granulocyte colony-stimulating factor potentiates anti-Candida albicans growth inhibitory activity of polymorphonuclear cells.

Granulocyte colony-stimulating factor (G-CSF) stimulates a subset of granulocyte colony forming cells and when administered to neutropenic individuals results in recovery of blood neutrophil numbers to normal levels. Therefore, G-CSF may be a useful therapeutic agent for infections in immunocompromised hosts. However, to date there has been only limited information that G-CSF activates the antimicrobial activity of neutrophils. In the present study, we found that recombinant G-CSF promotes the anti-Candida albicans activity of normal human blood polymorphonuclear (PMN) cells in vitro using both a 3H-glucose uptake procedure and a Candida colony counting assay. As little as 0.1 ng/ml G-CSF induced significant anti-Candida activity in the PMN cultures. G-CSF treatment also enhanced superoxide anion production by the PMNs in response to f-MLP as determined by the superoxide dismutase inhibitable cytochrome C reduction method. Such results show that G-CSF can promote the antimicrobial activity of peripheral blood PMNs against C. albicans.

Candida albicans↗
PubMed1993

Antibody-mediated enhancement of Legionella pneumophila-induced interleukin 1 activity.

The ability of antibody specific for Legionella pneumophila to enhance the induction of interleukin 1 (IL-1) production by murine peritoneal, splenic, and pulmonary macrophages in response to the bacterium was examined. Two preparations of L. pneumophila were utilized, a formalin-killed whole-cell preparation and viable bacteria. We measured both secreted (sIL-1) and cell membrane-associated (mIL-1) activities after incubation of the macrophages with the bacterial preparations in the presence or absence of the antibody. Both bacterial preparations induced sIL-1 and mIL-1 activities in each of the macrophage populations tested. These activities were generally enhanced by pretreating the bacteria with antibody, with the greatest enhancing activity observed for the formalin-killed preparations at lower doses of bacteria.

Animals↗
PubMed1993

Legionella pneumophila growth restriction in permissive macrophages cocultured with nonpermissive lipopolysaccharide-activated macrophages.

Macrophages can be activated by lipopolysaccharides (LPS) from gram-negative bacteria to evince a number of biological activities, including increased resistance to intracellular infection by opportunistic bacteria. In the present study, intraperitoneal injection of LPS into A/J mice activated peritoneal macrophages so that they resisted subsequent in vitro infection with Legionella pneumophila. Coculture of these macrophages with those from nontreated A/J mice converted the entire population of cells from permissive to nonpermissive. This effect did not appear to be mediated by soluble factors released from the LPS-treated macrophages, since the levels of interleukins-1 and -6 and tumor necrosis factor alpha produced by the macrophages were not found to be markedly elevated at the time when the macrophages from the LPS-treated mice were most effective in converting normal macrophages to nonpermissiveness. Furthermore, macrophages from mice injected intraperitoneally with either interferon or tumor necrosis factor alpha did not evince nonpermissiveness and also did not have the ability to convert normal spleen cells to nonpermissiveness. Polymyxin B, a known inactivator of LPS activity, did not inhibit the macrophages from the LPS-treated mice from inducing this resistance. It seemed unlikely that free LPS released from the macrophages mediated this effect. The results of this study thus showed that macrophages activated by LPS in vivo can evince nonpermissiveness for Legionella growth in vitro and also can induce macrophages from normal, permissive mice to become nonpermissive for Legionella growth in vitro.

Animals↗
PubMed1993

Legionella pneumophila induced tumor necrosis factor production in permissive versus nonpermissive macrophages.

The ability of an opportunistic intracellular bacterial pathogen, Legionella pneumophila, to induce tumor necrosis factor (TNF) in macrophages from susceptible A/J or resistant BDF1 and BALB/c mice was determined. Cultures of peritoneal elicited macrophages from these mouse strains produced TNF in response to the Legionella. The TNF levels produced by the macrophages stimulated with either heat-killed Legionella vaccine or lipopolysaccharide were similar and dose dependent, although the amount of TNF produced by macrophages from permissive A/J mice was 2- to 4-fold higher than that produced by macrophages from the nonpermissive mice. Similar differences in TNF levels occurred when macrophages from either permissive or non-permissive mice were infected with viable Legionella. The TNF levels produced by the A/J mouse macrophages increased as a function of time after infection, with a peak of activity on Day 1 or 2, depending upon the initial concentration of the bacteria. Infection of the A/J mouse macrophages with avirulent Legionella resulted in induced levels comparable to those induced by a virulent strain. Although it is widely believed that TNF production by mouse macrophages is related to resistance to infections, the results of this study did not show a relationship between TNF production by macrophages in vitro and resistance versus susceptibility of the macrophage donor mouse strain to Legionella infection.

Animals↗
PubMed1993

Differential effects of ethanol on permissive versus nonpermissive macrophages infected with Legionella pneumophila.

The effect of ethanol treatment was studied in terms of effect on permissive versus nonpermissive macrophages for growth of Legionella pneumophila, which is an intracellular bacterium causing pneumonia in immunocompromised patients. It was found that ethanol treatment of permissive macrophages from L. pneumophila-susceptible A/J mice evinced a decrease in replication of the bacteria compared with nontreated infected macrophages. Whereas there was more than a 100-fold increase in Legionella growth over a 48-hr culture period in infected A/J mouse macrophages, treatment of the macrophages with 0.5% ethanol depressed the ability of the macrophages to be infected by Legionella approximately 45%. A lower concentration of ethanol had a lesser effect but still resulted in inhibition of the ability of the cells to replicate Legionella. In contrast to ethanol-induced inhibition of the A/J mouse macrophages to replicate Legionella, macrophages from Legionella-resistant BALB/c mice, which only minimally replicated Legionella (i.e., only a 2-fold increase or less over a 48-hr replicated Legionella (i.e., only a 2-fold increase or less over a 48-hr period), treatment with ethanol resulted in their greater replication of the Legionella. This effect was most marked with the 1.0% concentration of ethanol after 7 days of pretreatment, while the 0.5% and 0.1% concentrations of alcohol caused less enhancement of bacterial growth in the cells, but these concentrations still had a significant enhancement effect. Thus, ethanol had differing effects on growth of the opportunistic intracellular bacterium Legionella in macrophages from permissive versus nonpermissive mice. Studies on the mechanisms involved are in progress.

Animals↗
PubMed1993

Delta 9-tetrahydrocannabinol injection induces cytokine-mediated mortality of mice infected with Legionella pneumophila.

Delta 9-Tetrahydrocannabinol (THC) injection modulates immune cell function, but the significance of this in altering host resistance to infection is not understood. In addition, exposure to THC and other drugs of abuse during infection is associated with an acute mortality syndrome. We examined the effect of THC injection on the survival of mice infected with Legionella pneumophila (Lp). Mice given two injections of THC (8 mg/kg)-one 24 hr before and the second 24 hr after a sublethal Lp infection-experienced acute collapse and death. The drug injection after infection caused death; deaths occurred within 30 min after the injection, and neither one nor two drug injections before infection resulted in death. The THC-induced mortality resembled cytokine-mediated shock in both kinetics and symptoms; therefore, sera from drug-treated animals were measured for the acute-phase cytokines tumor necrosis factor (TNF) and interleukin 6 (IL6). The level of each cytokine was significantly elevated by THC treatment, suggesting a role in the observed mortality. To directly test this role, mice were administered a single injection of either anti-TNF alpha, anti-IL6, or a mixture of anti-IL1 alpha and -IL1 beta antibodies 1 hr before the second THC injection. Results showed that each antibody treatment protected the mice, with anti-IL6 being the most effective. Fluctuations in blood granulocytes levels also supported a role of acute-phase cytokines in THC-induced mortality. These results show that THC injection increases the blood levels of acute-phase cytokines in infected animal and that these elevated levels, at least in part, account for the mortality induced by THC injection.

Acute-Phase Proteins↗
PubMed1993

Stress and infections.

Neurotransmitters and neuroendocrine hormones can modify the functioning of immune cells and conversely cytokines produced by immune cells can alter brain homeostasis. This connection is further manifested by experimental studies showing a relationship between stress and resistance to infection. Human subjects with a high stress index were shown to be more susceptible to infection with common cold viruses. Furthermore, a diversity of experimental animal paradigms show that laboratory stressors such as forced exercise, avoidance learning, restraint, isolation, and cold exposure make animals more susceptible to primary infection with a variety of viruses and bacteria. The cellular and molecular basis for the observed modulation of host resistance is not fully understood but involves altered functioning of both T lymphocytes and cells of the hypothalamic-pituitary adrenal axis. Also involved is the altered production of cytokines and hormones produced by the immune system and brain.

Animals↗
PubMed1992

Differing macrophage and lymphocyte roles in resistance to Legionella pneumophila infection.

Similar to guinea pig macrophages and human monocytes, macrophages from the peritoneal cavity of thioglycolate pretreated A/J mice are permissive for growth of Legionella pneumophila. In contrast, macrophages from BDF1 mice are not permissive for L. pneumophila. Lymphocytes from A/J and BDF1 mice proliferated in response to Legionella Ag but guinea pig lymphocytes did not. Also, splenocyte cultures from A/J mice treated with either Con A or Legionella vaccine produced supernatants which induced A/J macrophages to restrict Legionella growth, but guinea pig splenocyte culture supernatants obtained after stimulation with L. pneumophila vaccine did not induce Legionella growth restriction activity by guinea pig macrophages. Murine rIFN-gamma but not rIFN-alpha markedly inhibited growth of Legionella in A/J mouse macrophages and monoclonal anti-IFN-gamma antibody neutralized the anti-Legionella activity of culture supernatants from A/J mouse splenocytes responding to Legionella Ag. From these data, IFN-gamma appears to be an important factor in anti-Legionella activity of Ag-activated mouse splenocyte culture supernatants. Cyclosporin A, when given to either A/J or BDF1 mice, reduced the proliferation responses of splenocytes to T cell mitogens and also decreased the IFN production of A/J spleen cells to Legionella Ag. In addition, drug treatment decreased the resistance of A/J mice to Legionella infection as shown by an increase in the number of viable bacteria in the liver. However, injection of drug treated mice with lymphokine-rich splenocyte culture supernatant reconstituted the resistance of these animals. These results suggest an important role for lymphocyte activation and lymphokine production in the resistance of A/J mice to Legionella infection. The greater resistance of BDF1 mice, however, may result from nonpermissive macrophages and responsive lymphocytes. In the case of guinea pigs, susceptibility to Legionella infections may result from both the permissive nature of the macrophages and the relatively unresponsive nature of the lymphocytes in these animals.

Animals↗
PubMed1992

Delta 9-tetrahydrocannabinol suppresses concanavalin A induced increase in cytoplasmic free calcium in mouse thymocytes.

It has been shown that delta-9-tetrahydrocannabinol (THC) suppresses thymocyte, lymph node, and splenic lymphocyte proliferation in response to a mitogenic stimulus. It has also been reported that increases occur in the cytosolic free calcium concentration (Ca2+) in mitogen treated lymphocytes. In an attempt to understand a portion of the molecular basis of the THC induced suppression of lymphocyte proliferation, we have examined the effects of THC on the Concanavalin A (Con A) induced cytosolic free Ca2+ mobilization in mouse thymocytes measured by fluorescent Ca2+ probes and spectrofluorometry. The results show that a 10 minute pretreatment with THC suppresses the normal rise in intracellular free Ca2+ in response to Con A. A THC concentration of 4 micrograms/ml (13 microM) was suppressive and the drug vehicle, DMSO, had no effect. In addition, we found that THC pretreatment did not inhibit the binding of FITC labeled Con A to the thymocytes suggesting that the drug did not interfere with lectin binding to the cell surface. To further define the nature of the Ca2+ response affected by THC, mouse thymocytes containing fura-2 were exposed to Con A either in the presence or absence of Ca(2+)-containing medium. It was observed that THC abrogated both intracellular release (measured in Ca(2+)-free medium) as well as extracellular Ca2+ influx. These results suggest that a portion of the proliferation defect in THC treated lymphocytes may be related to a drug induced inhibition of Ca2+ mobilization that normally occurs following mitogen treatment.

Aminoquinolines↗