Inhibition of superantigen-induced T cell proliferation and monocyte IL-1 beta, TNF-alpha, and IL-6 production by acute ethanol treatment

Alcohol use has been shown to decrease monocyte antigen presentation capacity and inflammatory cytokine production, thereby increasing susceptibility to infections. Here, we demonstrate that in vitro acute treatment of normal monocytes with pharmacological doses of ethanol can decrease superantigen [Staphylococcus enterotoxins B (SEB) and A (SEA)]-induced T cell proliferation. Furthermore, ethanol treatment (25-100 mM) significantly inhibited SEA- or SEB-induced production of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and IL-6 in monocytes. Ethanol-induced down-regulation of monocyte TNF-alpha, IL-1 beta, and IL-6 occurred at both the protein and mRNA levels. Additional data suggest that ethanol can decrease IL-1 beta mRNA stability. Furthermore, experiments using cycloheximide indicate that de novo protein synthesis is required for the inhibitory effect of ethanol on SEB-induced IL-1 beta mRNA production. Finally, ethanol treatment decreased HLA-DR expression in monocytes, suggesting that ethanol treatment can compromise monocyte stimulation by down-regulating the SEB-binding capacity of monocytes. These results suggest that acute ethanol treatment can interfere with monocyte activation by SEB at multiple steps. Consequently, decreased superantigen-induced polyclonal T cell activation and inflammatory monokine production would contribute to an impaired immune response to bacterial challenge with superantigens after acute alcohol intake.

Functional expression of an epitope-tagged G protein-coupled K+ channel (GIRK1)

An epitope-tagged form of an inwardly rectifying and G protein-coupled K+ channel (GIRK1-cp) was expressed at high levels in transfected mammalian cells. Immunoblot analysis of transfected human embryonic kidney cells (HEK293) and mouse insulinoma cells (beta TC3) revealed several GIRK1-cp polypeptides, including the major 59-kDa band, corresponding to the predicted mass of the GIRK1 polypeptide plus the epitope tag. Immunohistochemical staining using two anti-tag antibodies showed abundant immunoreactive material, which was predominantly concentrated in the perinuclear area in both transfected cell types. While functional GIRK1-cp message was present in poly(A)+ RNA prepared from HEK293 cells expressing GIRK1-cp protein, appropriate K+ currents could not be detected. In contrast, whole cell recordings made directly from transfected beta TC3 cells expressing GIRK1-cp revealed inwardly rectifying, pertussis toxin-sensitive currents activated by norepinephrine and galanin. Single channel recordings in excised patches of beta TC3 cells expressing GIRK1-cp showed rectifying K+ currents when activated by 50 microM guanosine 5'-O-(thiotriphosphate), with a slope conductance of 39.1 +/- 1.0 picosiemens. This is the first report of stable heterologous expression of a functional G protein-coupled K+ channel in mammalian cells. The activity of an epitope-tagged channel in insulinoma cells demonstrates the utility of this system for further biochemical and biophysical analyses of G protein-K+ channel interactions.

Membrane depolarization prevents cell invasion by Bordetella pertussis adenylate cyclase toxin

Adenylate cyclase toxin from Bordetella pertussis is a 177-kDa calmodulin-activated enzyme that has the ability to enter eukaryotic cells and convert endogenous ATP into cAMP. Little is known, however, about the mechanism of cell entry. We now demonstrate that intoxication of cardiac myocytes by adenylate cyclase toxin is driven and controlled by the electrical potential across the plasma membrane. The steepness of the voltage dependence of intoxication is comparable with that previously observed for the activation of K+ and Na+ channels of excitable membranes. The voltage-sensitive process is downstream from toxin binding to the cell surface and appears to correspond to the translocation of the catalytic domain across the membrane.

Anesthetics reduce the magnitude of the membrane dipole potential. Measurements in lipid vesicles using voltage-sensitive spin probes

Lipid membranes possess a large internal dipole potential that greatly exceeds the magnitude of typical transmembrane or surface potentials. The volatile general anesthetics, halothane, isoflurane and enflurane were tested by the use of positively and negatively charged hydrophobic ion spin labels in lipid bilayer vesicles for their ability to modulate the membrane dipole potential. These anesthetics decreased the binding of negatively charged hydrophobic ion spin probes based on trinitrophenol, but increased the binding of positively charged hydrophobic ion probes based on triphenylalkylphosphoniums. They also enhanced the transit rates for both hydrophobic anions and cations; however, translocation rates were enhanced to a greater extent for the cation probes compared to the anion probes. The changes in binding constant for cations versus anions could be accurately accounted for using a simple model for the free energy profile for hydrophobic ions across membranes, and indicate that these anesthetics decrease the membrane dipole potential. From a fit of the experimental data to this model, anesthetics could promote a decrease in the dipole potential in two ways. First, anesthetics appear to modify the effective dipole moment in the membrane interface and may accomplish this by orienting their molecular dipole antiparallel to the intrinsic dipoles at the interface. Second, they modify the membrane dielectric constant, leading to a decrease in the field across the interface. At equivalent membrane concentrations, isoflurane, enflurane, and halothane produced similar changes in the dipole potential and decreased the dipole potential as much as 65 mV at a membrane mole fraction of 0.20.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiocirculatory effects of acutely increased intracranial pressure and subsequent brain death

Hemodynamic instability and functional impairment of the donor heart are currently reported problems in organ transplantation. Actual shortage of potential donor hearts continues to raise controversial discussion about adequate donor management with regard to graft quality. In an experimental open chest model, physiopathologic effects of acutely induced, irreversible intracranial hypertension (AIIHT) were investigated in situ with respect to hemodynamics, cardiac pump and muscle function, and hormonal parameters. Acutely induced irreversible intracranial hypertension was induced by rapid inflation of a subdural balloon catheter in 10 anesthetized dogs, four animals serving as controls. The observation period in both groups was 300 min. Cardiocirculatory stability was maintained by continuous crystalloid volume substitution without the use of inotropic or pressor agents. After AIIHT, three characteristic hemodynamic response phases have been observed: 1) The "acute hyperdynamic phase" lasting up to 15 min with marked increases of heart rate (HR), left ventricular pressure (LVP), cardiac output (CO) and myocardial contractility indices, 2) At the end of the "early restabilization phase", (60 min), these parameters returned close to control levels, except HR (+50%) and systemic vascular resistance (SVR) (-40%), 3) During the "late restabilization phase", filling pressures, LVP and CO remained within control limits at low SVR, contractility indices showed a decreasing tendency. All assessed plasmatic hormones (Catecholamines, triiodothyronine (T3), thyroxine (T4), adrenocorticotropic hormone (ACTH), cortisol and anti-diuretic hormone (ADH) showed a continuous fall to levels significantly below control over the phases of restabilization. Acutely induced irreversible intracranial hypertension leads to multifactorial hemodynamic and hormonal changes. At low SVR, cardiac pump function was preserved exclusively by continuous volume substitution, while myocardial contractility indicated a slight decrease. From this observed hemodynamic and functional state within the donor organism, no reliable prediction on graft functional capacity can be made.

Acute ethanol consumption synergizes with trauma to increase monocyte tumor necrosis factor alpha production late postinjury

The hypothesis that acute ethanol uptake plus trauma can synergize to increase immunosuppression was tested. We found that, unlike non-alcohol-exposed patients, patients with acute alcohol use prior to trauma have a transient decrease in monocyte tumor necrosis factor alpha (TNF alpha) production during the very early postinjury (0-3 days) period. However, TNF alpha production by these alcohol-exposed patients' monocytes (M0) became hyperelevated late postinjury (> 9 days). Consequently, these massively elevated M0 TNF alpha levels can contribute to posttrauma immunosuppression after acute alcohol use. We also demonstrate that normal monocyte activation with the superantigen, Staphylococcus enterotoxin B (SEB), results in a preferential induction of cell-associated M0 TNF alpha production, described as characteristic of immunosuppressed trauma patients. Acute in vitro ethanol treatment down-regulated the elevated TNF alpha production by trauma patients' M0 after either SEB, muramyl-dipeptide (MDP), interferon-gamma plus MDP, or lipopolysaccharide (LPS) stimulation. Both SEB- and LPS-induced TNF alpha mRNA induction was inhibited by acute alcohol treatment in normal M0, indicating that ethanol can regulate cytokine gene expression. An additional immunosuppressive effect of acute ethanol's stimulation was suggested by its induction of elevated transforming growth factor beta production in trauma patients' activated M0.

Distinct protein forms are produced from alternatively spliced bicistronic glutamic acid decarboxylase mRNAs during development

It has been shown that the enzyme glutamic acid decarboxylase (GAD; EC 4.1.1.15), which catalyzes the conversion of L-glutamate to gamma-aminobutyric acid in the central nervous system of vertebrates, can be first detected in rodents at late embryonic stages. In contrast, we have found that the gene coding for the 67-kDa form of GAD is already transcriptionally active at embryonic day E10.5 in the mouse. In addition to the 3.5-kb adult-type mRNA, we have detected two 2-kb embryonic messages that contain alternatively spliced exons of 80 (I-80) and 86 (I-86) bp, respectively. The overlapping stop-start codon TGATG, found in the embryonic exons, converts the monocistronic adult-type transcript into a bicistronic one, coding for a 25-kDa leader peptide and a 44-kDa enzymatically active truncated GAD. A second stop codon at the 3' end of the 86-bp exon abolishes the expression of truncated GAD. The products of the two embryonic mRNAs were identified in a rabbit reticulocyte in vitro translation system, COS cells, and mouse embryos. The two GAD embryonic forms represent distinct functional domains and display characteristic developmental patterns, consistent with a possible role in the formation of the gamma-aminobutyric acid-ergic inhibitory synapses.

Differential effects of pertussis toxin on the muscarinic regulation of Ca2+ and K+ currents in frog cardiac myocytes

The ability of acetylcholine (ACh) to inhibit beta-agonist stimulated calcium current was compared to its ability to activate the inwardly rectifying potassium current IK(ACh) in frog atrial myocytes. As suggested by previous studies, ACh inhibited the calcium current at concentrations (EC50 = 8 nM) significantly lower than those required for the activation of IK(ACh) (EC50 = 101 nM). The pharmacological profiles of the two responses suggest that despite the differences in agonist sensitivity, both are mediated by the same (m2) type of muscarinic receptors. Intracellular application of GDP beta S, an inhibitor of G protein function, completely abolished both responses, implying that both actions of ACh are coupled to effectors by G proteins. In contrast, intracellular application of pertussis toxin (PTX) shifted to higher concentrations (EC50 = 170 nM) but did not abolish inhibition of the calcium current by ACh even though the block of the IK(ACh) response was complete. Increasingly large PTX concentrations and/or prolonged PTX treatments revealed a limiting, PTX-resistant inhibitory component that appears to be mediated by a PTX-insensitive G protein distinct from that mediating IK(ACh). For the PTX-sensitive components, the different agonist dependencies of IK(ACh) activation and calcium current inhibition may imply that different G proteins mediate each response although alternate possibilities involving the same G protein either functionally sequestered and/or differentially affected by interactions with effectors, can not be ruled out.

Adenylate cyclase toxin from Bordetella pertussis produces ion conductance across artificial lipid bilayers in a calcium- and polarity-dependent manner

Adenylate cyclase toxin (AC toxin) from Bordetella pertussis enters target cells to produce supraphysiologic levels of cAMP and, by a cAMP-independent process, is hemolytic. In the present study, we show for the first time that this toxin also produces ion-permeable, cation-selective pores in phospholipid bilayers. The resulting membrane conductance is absolutely calcium-dependent, as are the intoxication and hemolytic activities. It is strongly affected by the polarity and magnitude of the membrane potential and enhanced by the presence of negatively charged phospholipid. AC toxins from two mutants, BPDE386 and BPD377, which are defective in toxin activity, produce little or no conductance. Finally, evaluation of the current-voltage relationships and the concentration dependence of pore formation and of hemolysis reveal a greater than 3rd power dependence, suggesting that a multimer of AC toxin, probably consisting of three or more holotoxin molecules, is involved in pore formation.

The L-selectin (Leu8) molecule is associated with the TcR/CD3 receptor; fluorescence energy transfer measurements on live cells

Several accessory molecules were shown to play important roles in T cell functions and be in close proximity to the T cell receptor (TcR/CD3). The L-selectin molecule (Leu8, LAM1-1, LECAM1) also plays an important role in lymphocyte homing and proliferation. We were interested in determining the proximity of this molecule to the TcR/CD3 complex on live peripheral human T cells. Using a fluorescence energy transfer method, designed to study individual cells, we could show that L-selectin is within 170 A of the TcR/CD3 complex. Monoclonal antibody directed against the LAM1-1 (Leu8) epitope of the L-selectin molecule suppressed the mitogenic activity of antibodies specific for various CD3 epitopes in vitro. Intracellular Ca2+ mobilization obtained with wt31 followed by cross-linking antibody or with anti-CD3 was not influenced by anti-Leu8 antibody. Also antibody directed against the LAM1-1 epitope did not influence the binding of the mitogenic antibodies, as shown by fluorescence-based flow cytometry. Therefore, we suggest that binding of TcR/CD3 bound mitogenic antibodies to accessory cell Fc receptors may be hindered by antibodies bound to the close proximity L-selectin molecules.

Regulatory potential of ethanol and retinoic acid on human monocyte functions

Retinoic acid (RA), a metabolic product of vitamin A, has been shown to affect a variety of immune functions, including monocytes. Monocyte functions and mediator production are also modulated by ethanol exposure. This study demonstrates that therapeutic doses of RA (0.1-10 microM) significantly increase transforming growth factor-beta (TGF beta) production both in THP-1, human myelomonocytic cells, and in human peripheral blood monocytes. We have previously reported TGF beta induction by ethanol in human M theta. Combination of RA stimulation with acute in vitro ethanol treatment, however, resulted in significantly lower M theta TGF beta production than TGF beta levels induced by RA alone (p < 0.003). Down-regulation of M theta TGF beta production by ethanol was tested at the concentration range of 25-150 mM and occurred both at high and low RA concentrations (10-0.1 microM). In contrast to its inhibitory effect on RA-induced M theta TGF beta production, ethanol augmented TGF beta production induced by muramyl dipeptide (20 micrograms/ml), suggesting that ethanol can either up- or down-regulate M theta TGF beta production, depending on the costimulatory factors. RA also induced a moderate increase in M theta tumor necrosis factor-alpha (TNF alpha) production, which was down-regulated by ethanol both at the level of secreted and cell-associated TNF alpha. In addition to regulation of cytokine production, both RA and ethanol decreased expression of CD4 on THP-1 cells. The degree of inhibition of CD4 expression by RA was more significant than by ethanol, but RA-induced decrease in CD4 expression was not significantly affected by the combined stimulation with ethanol.(ABSTRACT TRUNCATED AT 250 WORDS)

Dibutyryl-cAMP modulation of receptor expression and antigen presentation capacity in monocyte subpopulations

Monocyte phenotype heterogeneity is often associated with functional differences between the distinguished Mphi subpopulations. We have previously demonstrated that the Mphi subpopulation separated and stimulated by rosetting Mphi via the Type I Fc gamma R (CD64) are poor antigen presenting cells but can be induced to greater production of TNF alpha, IL-6 and PGE2 than the Fc gamma RI- Mphi population. Here we demonstrate that the Fc gamma RI- Mphi represent the major antigen presenting Mphi population and that APC capacity of the FcRI- Mphi can be further increased by elevating intracellular cAMP levels. Treatment of the Fc gamma RI+ Mphi with db cAMP decreases both their expression of CD64 and their capacity to produce TNF alpha to the levels typical of Fc gamma RI- Mphi. Db cAMP treatment of the Fc gamma RI+ Mphi subpopulation, however, cannot augment the antigen presenting capacity of this low APC Mphi subpopulation to the level of that of the Fc gamma RI- Mphi. Basal expression of the Mo3 activation marker was comparable in the FcRI+/FcRI- Mphi subpopulations, but the FcRI+ Mphi were induced by db cAMP treatment to increase their Mo3 expression to higher levels than the FcRI- Mphi. These results suggest that although elevated intracellular cAMP levels can modulate some Fc gamma RI+ Mphi functions to more closely parallel those of the Fc gamma RI- Mphi, this treatment cannot increase the efficiency of the Fc gamma RI+ Mphi subpopulation as an antigen presenting cell.

Selective inhibition of antigen-specific T lymphocyte proliferation by acute ethanol exposure: the role of impaired monocyte antigen presentation capacity and mediator production

Ethanol consumption is associated with impaired immunity. Our data demonstrate that even a single dose of a biologically relevant concentration (25-150 mM) of ethanol can down-regulate antigen-specific T lymphocyte proliferation. In contrast, ethanol augmented mitogen-induced T cell proliferation, suggesting that its inhibitory effect on antigen-specific T cell proliferation was due to its effects on monocytes (m phi s) rather than on T cells. The immunodepressive effects of ethanol on m phi antigen-presenting cell (APC) capacity were manifested whether alcohol treatment was limited to the antigen uptake-processing period only or was present during the entire period of antigen presentation. These inhibitory effects of ethanol were also evident on both the high-antigen-presenting, Fc gamma RI-negative (-31 +/- 17%), and low-antigen-presenting, Fc gamma RI-positive (-42 +/- 15%) m phi subpopulations. Further analysis demonstrated that ethanol inhibits the production of interleukin-1 beta (IL-1 beta) and induces transforming growth factor beta (TGF-beta) and prostaglandin E2 (PGE2), monocyte-derived mediators that can affect T cell proliferation. Ethanol resulted in a dose-dependent down-regulation of secreted and cell-associated IL-1 beta protein as well as IL-1 beta mRNA levels induced by adherence or bacterial stimulation. The causal relationship between decreased m phi IL-1 beta production, elevated TGF-beta levels, and the decreased m phi APC capacity was further substantiated when exogenous IL-1 beta protein or anti-TGF-beta neutralizing antibody prevented the down-regulatory effect of ethanol on antigen-specific T cell proliferation. Utilizing a cyclooxygenase inhibitor, we also demonstrated that the ethanol-induced decrease in m phi APCs is not mediated by enhanced PGE2 production.

The effect of ion channel blockers, immunosuppressive agents, and other drugs on the activity of the multi-drug transporter

The MDRI protein is an energy-dependent transport protein responsible for the multi-drug resistance seen in many tumors. A variety of drugs have been shown to inhibit the function of this pump, including compounds known to block various ion channels. The mouse lymphoma cell line L5178Y has been transduced with the human mdrI gene. Using this cell line, we have tested a number of compounds to determine whether there is a correlation between the ability to block a specific type of ion channel, or shift membrane potential, and the ability to act as an MDR-reversing agent using the fluorescent substrates Rhodamine 123 and daunorubicin as test compounds. Our results show no apparent correlation between the ability to block a specific ion channel and reversal of MDR transport ability. We have found active MDR inhibitors in compounds that affect K+, Na+, Ca++, H+, but not Cl- channels. Our data suggest that Cl- channel activity may be distinct from MDR activity. Several immunosuppressive compounds and analogs were also tested and found to be active reversing agents. Measurements suggest a significant difference in resting membrane potential between the L5178YvMDR line and the L5178Y parental cell line used in these experiments. No correlation was found between the ability of drugs to alter membrane potential and to inhibit MDR transport activity. Our results suggest that MDR transport function may be independent of the physiological movement of ions and show that a wide variety of compounds can inhibit MDR transport.

Characterization of adenylate cyclase toxin from a mutant of Bordetella pertussis defective in the activator gene, cyaC

Bordetella pertussis adenylate cyclase (AC) toxin has the abilities to 1) enter target cells where it catalyzes cyclic AMP production and 2) lyse sheep erythrocytes, and these abilities require post-translational modification by the product of an accessory gene cyaC (Barry, E. M., Weiss, A. A., Ehrmann, E. E., Gray, M. C., Hewlett, E. L., and Goodwin, M. St. M. (1991) J. Bacteriol. 173, 720-726). In the present study, AC toxin has been purified from an organism with a mutation in cyaC, BPDE386, and evaluated for its physical and functional properties in order to determine the basis for its lack of toxin and hemolytic activities. AC toxin from BPDE386 is indistinguishable from wild-type toxin in enzymatic activity, migration on SDS-polyacrylamide gel electrophoresis, ability to bind calcium, and calcium-dependent conformational change. Although unable to elicit cAMP accumulation, AC toxin from BPDE386 exhibits binding to the surface of Jurkat cells which is comparable to that of wild-type toxin. This target cell interaction is qualitatively different, however, in that 99% of the mutant toxin remains sensitive to trypsin, whereas approximately 20% of cell-associated wild-type toxin enters a trypsin-resistant compartment. To evaluate the ability of this mutant AC toxin to function at its intracellular site of action, the cAMP-stimulated L-type calcium current in frog atrial myocytes was used. Extracellular addition of wild-type toxin results in cAMP-dependent events that include activation of calcium channels and enhancement of calcium current. In contrast, there is no response to externally applied toxin from BPDE386. When injected into the cell interior, however, the AC toxin from BPDE386 is able to produce increases in the calcium current comparable to those observed with wild-type toxin. Although AC toxin from BPDE386 is unaffected in its enzymatic activity, calcium binding, and calcium-dependent conformational change, the mutation in cyaC does result in a toxin which is able to bind to target cells but unable to elicit cAMP accumulation. In that AC toxin from BPDE386 is able to function normally when injected artificially to an intracellular site, we conclude that the disruption of cyaC produces a defect in insertion and transmembrane delivery of the catalytic domain.

Agonist-independent effects of muscarinic antagonists on Ca2+ and K+ currents in frog and rat cardiac cells

1. The whole-cell patch clamp and intracellular perfusion techniques were used for studying the effects of atropine and other muscarinic acetylcholine receptor (mAChR) antagonists on the L-type calcium currents (ICa) in frog and rat ventricular myocytes, and on the mAChR-activated K+ current (IK(ACh)) in frog atrial myocytes. 2. In frog ventricular myocytes, atropine (0.1 nM to 1 microM) reversed the inhibitory effect of acetylcholine (ACh, 1 nM) on ICa previously stimulated by isoprenaline (Iso, 2 microM), a beta-adrenergic agonist. However, in the concomitant presence of Iso, ACh and atropine, ICa was > 50% larger than in Iso alone. 3. The effects of atropine were then examined in the absence of mAChR agonists. After a preliminary stimulation of ICa with Iso (0.1 or 2 microM), atropine induced a dose-dependent stimulation of ICa. EC50 (i.e. the concentration of atropine at which the response was 50% of the maximum) and Emax (i.e. maximal stimulation of ICa expressed as percentage increase in ICa with respect to the level in Iso alone) were respectively 0.6 nM and 35%. The stimulatory effect of atropine on ICa was not voltage dependent. 4. Atropine (1 microM) had no effect on frog ICa (i) under basal conditions, (ii) upon stimulation of ICa by the dihydropyridine agonist (-)-Bay K 8644 (1 microM), or (iii) when ICa had been previously stimulated by intracellular perfusion with cyclic AMP (3 microM). However, atropine increased ICa after a stimulation by forskolin (0.3 microM). Therefore, an increased adenylyl cyclase activity was required for atropine to produce its stimulatory effect on ICa. 5. The order of potency of mAChR antagonists to reverse the inhibitory effect of ACh on Iso elevated ICa in frog ventricle was atropine > AF-DX 116 >> pirenzepine. In the absence of ACh, mAChR antagonists produced their stimulatory effect on Iso elevated ICa with the same order of potency. 6. Intracellular substitution of Gpp(NH)p (5'-guanylylimidiphosphate) for GTP (420 microM) induced a strong inhibition of frog ICa in the presence of Iso (2 microM). This effect was attributed earlier to the spontaneous and irreversible activation of the GTP-binding regulatory protein (G protein), Gi, responsible for adenylyl cyclase inhibition. Atropine (1 microM) slowed down by a factor of 2 the rate of ICa inhibition induced by Gpp(NH)p. 7. In frog atrial myocytes, intracellular perfusion with 1 mM Gpp(NH)p induces spontaneous activation of IK(ACh). This effect was attributed earlier to the spontaneous and irreversible activation of the G protein, GK.(ABSTRACT TRUNCATED AT 400 WORDS)

Down-regulation of tumor necrosis factor alpha activity by acute ethanol treatment in human peripheral blood monocytes

As the most commonly used drug that can modulate both metabolic and immune pathways, ethanol is evaluated in this report as a regulator of tumor necrosis factor alpha (TNF alpha) production in human peripheral blood monocytes (M phi) in combination with a variety of stimuli. While acute ethanol treatment did not induce TNF alpha in M phi, it was a potent down-regulator of M phi TNF alpha production whether induced by the combination of interferon-gamma plus muramyl dipeptide (MDP) (P < 0.001), lipopolysaccharide (LPS) alone (P < 0.01), or interferon-gamma plus LPS. Down-regulation of M phi TNF alpha by ethanol was dose dependent and statistically significant in the biologically relevant, 25-150 mM, ethanol concentration range. We also demonstrate that these ethanol concentrations did not affect M phi viability. TNF alpha down-regulation by ethanol was most effective when ethanol was administered 4 hr prior to MDP stimulation; however, it was also effective--though to a lesser extent--if it was added at the time of MDP stimulation. Furthermore, ethanol also down-regulated TNF alpha production of the in vivo preactivated M phi of trauma patients, which produce hyperelevated levels of TNF alpha. We have previously shown that the majority of posttrauma elevated M phi TNF alpha is produced by the M phi subpopulation expressing high-affinity type I Fc gamma receptors (Fc gamma RI). When the Fc gamma RI cross-linking-stimulated M phi subpopulation was treated with acute ethanol, TNF alpha production was suppressed again both in in vivo preactivated M phi of trauma patients and in M phi of normal controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of transforming growth factor-beta and prostaglandin E2 production by ethanol in human monocytes

To test our hypothesis that monocytes (M phi) and their mediators are major contributors to ethanol-related immunodepression, the modulating capacity of acute ethanol treatment was assessed on the production of transforming growth factor-beta (TGF beta) and prostaglandin E2 (PGE2) by human peripheral blood M phi. We demonstrate that acute in vitro treatment of adherent M phi with either 50 or 150 mM ethanol induced a significant increase in the production of TGF beta (P < 0.045 and P < 0.001, respectively). Furthermore, M phi pretreatment with both 50 and 150 mM ethanol augmented TGF beta production in response to subsequent stimulation with the synthetic bacterial analog, muramyl dipeptide (MDP) (P < 0.05 and P < 0.001, respectively). Ethanol also increased TGF beta production in interferon gamma (IFN gamma-activated M phi in response to MDP stimulus (P < 0.05). M phi TGF beta levels, however, were always lower in IFN gamma-activated than in non-IFN gamma-activated M phi after the same stimulation with ethanol plus MDP, suggesting that M phi preactivation by IFN gamma can partially counteract the TGF beta inducing potential of ethanol. Similar to its TGF beta-inducing potential, ethanol (150 mM) had the capacity to induce PGE2 production in adherent human M phi (P < 0.045). However, ethanol failed to augment M phi PGE2 production induced by the PGE2 secretagogue, MDP. TGF beta induction by ethanol was unaffected by the presence of cyclooxygenase inhibitor, suggesting that ethanol-induced M phi TGF beta production does not require M phi PGE2 production. These results indicate that ethanol is a potent inducer for inhibitory M phi mediators, TGF beta and PGE2, and also has the capacity to augment M phi TGF beta production in response to subsequent stimulation. Thus, ethanol-induced elevation of M phi TGF beta and PGE2 production might contribute to decreased T cell proliferation and abnormal M phi functions after alcohol exposure, resulting in a depressed immune response.

A voltage-gated calcium channel is linked to the antigen receptor in Jurkat T lymphocytes

Activation of T lymphocytes results in an increase in intracellular Ca2+ due in large part to influx of extracellular Ca2+. Using the patch clamp technique, an inward current in Jurkat T lymphocytes was observed upon depolarization from a holding potential of -90 mV but not from -60 mV. This whole-cell current was insensitive to tetrodotoxin, carried by Ba2+, and blocked by Ni2+. Occupancy of the T lymphocyte antigen receptor increased the current's magnitude. These data suggest that antigen receptor-induced Ca2+ entry in T lymphocytes may be mediated by a voltage-regulated Ca channel.