Effect of cyclic AMP on release of lysosomal enzymes from phagocytes

Differential phagocytic expression of IC-21 macrophages and their scavenging receptors during inflammatory induction by oxysterol: A microscopic approach

Phagocytosis by macrophages dates back to a long history in science, this present study deals with new approaches that have been analyzed and standardized towards the interesting aspects of primary and secondary macrophages. The distinct morphological differences in primary and secondary phagocytic cells were observed and the phagocytic response of secondary macrophages under the influence of 7-ketocholesterol and lipopolysaccharide was analyzed. The primary peritoneal and secondary IC-21 cells unveiled explicit differences in nuclear numbers shapes and sizes of the granules present within the cytoplasmic region. Further, potent inducers 7KCh and LPS influenced an effective activation of IC-21 macrophages and resulted in ROS generation, irregulated protein expressions of CD86, CD68, and CD206 with enhanced phagocytic responses towards goat, cow, and human RBC targets with significant phagocytic rate and index were observed. Moreover, a remarkable observation of target specificity and aggregations with IC-21 phagocytic macrophages revealed the notion that specific membrane receptors and secretory molecules (lysosomes) are primarily involved in their phagocytic mechanism. RESEARCH HIGHLIGHTS: IC-21 macrophages are peritoneal origin from mice but the primary peritoneal macrophages and cell line show distinct differences. IC-21 macrophages express target-specific phagocytosis. Phagocytosis in IC-21 macrophages is regulated by CD markers (68, 86, and 206).

Enzymatic Changes in Alveolar Macrophages of Rats Exposed to Lead and Nickel by Inhalation

In previous inhalation studies, rats exposed to aerosol concentrations of lead oxide (Pb2O3), 150 μg/m3; lead chloride (PbCl2), 100 μg/m3; nickel oxide (NiO), 120 μg/m3; and nickel chloride (NiCl2), 109 μg/m3; significant changes were observed in the lungs and alveolar macrophages. In this study the hydroiytic enzymes, acetylesterase, acid and alkaline phos-phatases, lysozyme, and beta-glucuronidase, in alveolar macrophages and lung washout fluid from rats subjected to the inhalation of the lead and nickel aerosols were examined. Washed alveolar macrophages from animals exposed to lead and nickel aerosols were found to contain reduced quantities of the various hydrolytic enzymes (except for acetylesterase) when compared with those from control rats. On the other hand, a significant increase in enzymatic activity was noted in lung washout fluid from exposed animals. The functional efficiency of macrophages, relative enzyme changes, and the mechanism of action of metals are discussed. It is important to note that the changes observed in these studies were from animals exposed to metallic concentrations near their Threshold Limit Values.

[The therapy of pain in rheumatic joint-and spine diseases.]

The therapy of pain caused by rheumatic diseases above all must take into consideration the cause of the pain. In rheumatoid arthritis, especially in the early stages, inflammation is the primary cause of the pain. The pain decreases the inflammation subsides following the administration of non-steroidal anti-inflammatory drugs (NSAIDs), or corticosteroids, if necessary. The so-called disease modifying anti-rheumatic drugs do not influence the inflammation or consequently, the pain directly, but rather through mechanisms before the local joint process some of which are not exactly known. In later stages of the progressive joint degeneration the NSAIDs only have a limited effect regarding the inhibition of inflammation. In osteoarthrosis, in which the pain is caused by a secondary inflammation and increasingly by capsular, muscular and tendon involvement, the pain is only treated by NSAIDs in active inflammatory stages; otherwise, the treatment is physical activity and medication. In degenerative and static disorders of the spine the pain is caused predominantly by muscular bracing. Therefore, physical and especially gymnastic therapy play a major role. Whether muscle relaxants have an effect on muscle bracing is doubtful. If there is pressure on the ligaments and, in cases of vertebral dislocation with overstraining of the vertebral joints, therapy with local injections is indicated. The pain in osteoporosis is also predominantly muscular and must be treated accordingly. Above all, high doses of calcium and calcitonin are effective analgesics. Moreover, fluoride also acts as an analgesic once the osteoporosis has stabilized. In most cases fibromyalgia, which is mostly of a psychosomatic nature, cannot be influenced by medical therapy. Instead repeated attempts at treatment help to make the affliction chronic with neurotic fixation. Also, as a rule, myotonolytic and tranquilizing substances are not effective.

Tissue distribution and levels of natural and induced serum lysozyme immunoreactive molecules in a freshwater snail

Lysozyme immunoreactive molecules (irLm) in Planorbarius corneus was demonstrated by an immunocytochemical method in oocytes, the kidney, spreading phagocytic hemocytes (SH), digestive phagocytic cells, and epithelial cells of the stomach and intestine. Three hr after the injection of a variety of bacteria or substances (S. aureus, E. coli, E. coli LPS, latex particles, PBS) a statistically significant increase in irLm serum level was detected by the microELISA method. Twenty-four hr later, this increase was detected only in specimens which had been injected with bacteria. A similar response was observed 14 days later, following a second injection of the above-mentioned substances in the same snails. The results suggest that: 1) irLm appears to be an inducible molecule responding non-specifically to foreign challenge; 2) no anamnestic response is observed for irLm; 3) a relationship exists between irLm and phagocytosis; indeed, irLm have chemotactic activity towards SH; 4) serum irLm probably originates from different sources; in fact, they are released from SH and the kidney. The increase in the serum irLm level is responsible, at least in part, for the lytic attack and death of bacteria, but it is probably also involved in unspecific inflammatory reactions.

Mammalian G proteins and their cell type specific functions

Heterotrimeric G proteins are key players in transmembrane signaling by coupling a huge variety of receptors to channel proteins, enzymes, and other effector molecules. Multiple subforms of G proteins together with receptors, effectors, and various regulatory proteins represent the components of a highly versatile signal transduction system. G protein-mediated signaling is employed by virtually all cells in the mammalian organism and is centrally involved in diverse physiological functions such as perception of sensory information, modulation of synaptic transmission, hormone release and actions, regulation of cell contraction and migration, or cell growth and differentiation. In this review, some of the functions of heterotrimeric G proteins in defined cells and tissues are described.

Cyclooxygenase-2 expression in lipopolysaccharide-stimulated human monocytes is modulated by cyclic AMP, prostaglandin E(2), and nonsteroidal anti-inflammatory drugs

Using human blood monocytes (for determination of cyclooxygenase-2 (COX-2) mRNA by RT-PCR) and human whole blood (for prostanoid determination), the present study investigates the influence of the second messenger cAMP on lipopolysaccharide (LPS)-induced COX-2 expression with particular emphasis on the role of prostaglandin E(2) (PGE(2)) in this process. Elevation of intracellular cAMP with a cell-permeable cAMP analogue (dibutyryl cAMP), an adenylyl cyclase activator (cholera toxin), or a phosphodiesterase inhibitor (3-isobutyl-1-methylxanthine) substantially enhanced LPS-induced PGE(2) formation and COX-2 mRNA expression, but did not modify COX-2 enzyme activity. Moreover, up-regulation of LPS-induced COX-2 expression was caused by PGE(2), butaprost (selective agonist of the adenylyl cyclase-coupled EP(2) receptor) and 11-deoxy PGE(1) (EP(2)/EP(4) agonist), whereas sulprostone (EP(3)/EP(1) agonist) left COX-2 expression unaltered. Abrogation of LPS-induced PGE(2) synthesis with the selective COX-2 inhibitor NS-398 caused a decrease in COX-2 mRNA levels that was restored by exogenous PGE(2) and mimicked by S(+)-flurbiprofen and ketoprofen. Overall, these results indicate a modulatory role of cAMP in the regulation of COX-2 expression. PGE(2), a cAMP-elevating final product of the COX-2 pathway, may autoregulate COX-2 expression in human monocytes via a positive feedback mechanism.

Influence of synthetic peptide corresponding to the ACTH-like sequence of human immunoglobulin G1 on activity of murine thymocytes and peritoneal macrophages

The purpose of the present study was to investigate properties and mechanism of action of the synthetic adrenocorticotropin (ACTH)-like peptide VKKPGSSVKV, corresponding to the sequence 11-20 of the variable part of human immunoglobulin G1 (IgG1) heavy chain. The ACTH-like peptide was shown to act as an immunosuppressive agent in vitro: it inhibits the blast transformation of mouse thymocytes and reduces the spontaneous motility of mouse peritoneal macrophages as well as their bactericidal activity against Salmonella typhimurium 415 virulent strain bacteria. High affinity receptors for the ACTH-like peptide were found on thymocytes and macrophages and shown to be at the same time the receptors for ACTH. The kinetic characteristics of the ACTH-like peptide and 125I-labeled ACTH (13-24) (ACTH 'address segment') specific binding to the receptors were determined. It was found that the ACTH-like peptide binding to the receptors on target cells is accompanied by an increase in both adenylate cyclase activity and intracellular cAMP content.

Intracellular measurement of prostaglandin E2: effect of anti-inflammatory drugs on cyclooxygenase activity and prostanoid expression

Cyclooxygenase (COX) converts arachidonic acid to prostaglandin (PG) H2, which is further metabolized to various prostaglandins, prostacyclin and thromboxane A2. COX exists in at least two different isoforms. COX-1 is constitutively expressed, whereas COX-2 is induced by proinflammatory stimuli. Prostaglandin E2 is a major metabolite of COX activation. In order to compare the activity of target ligands and COX inhibitors on PGE2 synthesis and release, the responsiveness of several cell lines to the calcium ionophore A23187, bacterial lipopolysaccharide (LPS), nonsteroidal anti-inflammatory drugs (NSAIDs), and the glucocorticoid, dexamethasone, were investigated. For intracellular measurements, the culture supernatant was aspirated, and the cells were thoroughly washed and lysed with dodecyltrimethylammonium bromide. Intracellular and secreted PGE2 were measured with an enzyme immunoassay. A23187 and LPS increased intracellular PGE2 in a dose-dependent manner. Kinetic experiments with A23187-stimulated mouse 3T3 fibroblast cells revealed a distinct biphasic response in COX activity. In the presence of NSAIDs or dexamethasone, there was a dose-dependent inhibition in intracellular PGE2 with A23187-stimulated 3T3 cells. Inhibitory studies demonstrated an apparent increased sensitivity of COX activity to the action of inhibitors when measuring intracellular PGE2 compared with using cell culture supernatants. Indeed, intracellular PGE2 levels were comprehensively reduced in the presence of low concentrations of inhibitor. The utilization of cell culture lysates and, in particular, measurement of intracellular PGE2 should prove useful for identifying new COX inhibitors.

Association and release of prostaglandin E1 from liposomes

PGE1-lipid interactions were studied in several liposome systems. Data from both circular dichroic (CD) measurements and differential scanning calorimetry (DSC) indicated that PGE1 in the protonated form seeks the less polar environment of the lipid bilayer. CD measurements made on PGE1 in solution showed that the wavelength of maximum absorbance red shifted approximately 8 nm with decreasing solvent polarity. The CD spectrum of liposomal PGE1 prepared in pH 4.5 but not pH 7.2 buffer was also red shifted. There was no red shift in the CD spectrum of PGE1 detected at pH 4.5 in the absence of phospholipid. DSC measurements on DSPC bilayers prepared with 5 mol% PGE1 at pH 4.5 but not pH 7.2 revealed an almost complete loss of the pre-transition as well as broadening of the main phase transition. The amount of 3H-PGE1 initially associated with EPC, POPC or DSPC liposomes was determined using size exclusion filters and centrifugation. This amount was found to be dependent on the pH of the buffer (pH 4.5 >> pH 7.2) and fluidity of the bilayer (EPC = POPC > DSPC), but independent of the lamellarity of the liposome. In all cases, addition of cholesterol reduced the amount of PGE1 associated with the liposome. The time-dependent release of PGE1 from the liposomes was determined by rapidly diluting the sample 100-fold into pH 7.2 buffer. Lipid saturation was a key factor influencing this release. Gel-phase liposomes of DSPC showed a rapid initial release (t(1/2) < 2 min) of PGE1, corresponding to the amount in the outer monolayer, followed by a very slow, almost negligible release of the remaining PGE1. A rapid initial release also occurred in fluid-phase membranes, followed by a more gradual release of the remaining PGE1 over several hours. This release rate could be slowed by increasing the lamellarity of these liposomes, or adding cholesterol to decrease the fluidity of the membrane.

Bruceine B, a potent inhibitor of leukocyte-endothelial cell adhesion

Leukocyte adhesion to vascular endothelial cells is an essential step in the development of inflammatory diseases. We have searched for inhibitors of leukocyte-endothelial cell adhesion that could be used as anti-inflammatory drugs and found that bruceine B (0.2 microgram/ml; 0.44 microM) inhibited human neutrophil or T cell adhesion to tumor necrosis factor-alpha (TNF) stimulated human umbilical vein endothelial cells (HUVEC). The inhibition of neutrophil adhesion to TNF-stimulated HUVEC by bruceine B was not derived from cytotoxic effects, as determined by measurement of the level of lactate dehydrogenase (LDH) activity in conditioned medium. The effect of bruceine B on neutrophil adhesion to HUVEC was not seen when the neutrophils were preincubated with bruceine B. However, inhibitory effects were evident when the HUVEC were preincubated with bruceine B. Bruceine B also inhibited neutrophil adhesion to lipopolysaccharide-stimulated HUVEC and T cell adhesion to TNF-stimulated HUVEC. These findings suggest that bruceine B may have anti-inflammatory activity.

Endogenously opsonized particles divert prostanoid action from lethal to protective in models of experimental endotoxemia

We report that, in rats, the lethal consequences of high-dose endotoxin challenge are exacerbated by the intravascular administration of prostaglandin E1 but attenuated by the intravascular administration of endocytosable particles. This protection is mediated by opsonins. Nonopsonizable particles were unable to provide protection unless first pseudoopsonized with antibody directed against the CR3 (CD11b/CD18) phagocyte receptor. We show that endogenously opsonized particles can act in concert with prostaglandin E1 (putatively by elevation of neutrophil intracellular cAMP and the resultant downregulation of CR3) to completely rescue animals from the lethal late-stage sequelae of experimental endotoxemia. These data illustrate that the interaction of particles with cellular receptors can transform the overall systemic response to prostaglandin E1 from pro- to antiinflammatory. This suggests a role for multiple receptor engagement events in defining the systemic prostaglandin response and offers a rationale for developing new therapeutic modalities in the treatment of sepsis and other inflammatory diseases.

Morphology and distribution of ecto-5'-nucleotidase-positive cells in the rat choroid plexus

The aim of this report was to find out whether adenosine can be produced locally in the choroid plexus of rats. Therefore we investigated the distribution of the enzyme ecto-5'-nucleotidase which hydrolyzes extracellular adenosine monophosphate to adenosine and phosphate. Enzyme activity histochemistry and immunohistochemistry demonstrated that ecto-5'-nucleotidase is present in the stroma but not in the epithelium. The positive cells in the stroma were identified as fibroblasts by their localization and by their shape. Double-labelling immunohistochemistry actually showed that ecto-5'-nucleotidase was absent from MHC class II-positive cells and from vessel walls. These data indicate that adenosine may be produced in the choroid plexus, and specifically in the interstitium. From there, adenosine would have direct access to nerves, immune cells, the epithelium and microvessels. Because adenosine has been reported to modulate blood supply and the rate of production of cerebrospinal fluid, a local control mechanism involving adenosine might operate in the choroid plexus in a similar way to that described in other tissues. Effects of adenosine on nerves and immune cells are discussed. The exclusive presence of ecto-5'-nucleotidase in the fibroblasts that are in contact with choroid plexus epithelium suggests that the expression of the enzyme is controlled by factors produced by epithelial cells, for instance by extracellular nucleotides.

Misoprostol: new frontiers; benefits beyond the gastrointestinal tract

Recent findings suggest that the protective role that misoprostol exerts in the gastrointestinal tract against nonsteroidal anti-inflammatory drug (NSAID) damage may be extended to a variety of other tissues and other noxious stimuli including those mediated by molecules such as interleukin 1 (IL-1), tumor necrosis factor (TNF), and endotoxin. The protective effects of misoprostol outside the gastrointestinal tract may involve prevention of triggering activities that would otherwise initiate a sequence of tissue damaging events. If this capacity of misoprostol to maintain homeostasis in a variety of settings is recognized, a cohesive pattern of action emerges. Numerous studies have shown that misoprostol is likely to act as a regulator within various cascades of immunological regulatory events. The in vitro and in vivo experimental data described in this paper suggest that the events which trigger episodes of pain and inflammation may be controllable by the administration of misoprostol. Mitigation of adverse effects of certain NSAIDs on renal function and cartilage metabolism has also been observed. Demonstration of this latter phenomenon in the clinical setting will greatly benefit the patient if it is shown to modify the arthritis disease process. The therapeutic applications of misoprostol beyond the gastrointestinal tract appear to be among the most interesting of therapeutic advances offered by any class of compound in the next decade. Because of the inflammatory and pain processes associated with arthritis disease progression, particular emphasis and confirmation through further clinical study should be placed on the potential effect of misoprostol on chondroprotection and synergy with NSAIDs.

Effect of platelet-activating factor on tumor necrosis factor-induced superoxide generation from human neutrophils. Possible involvement of G proteins

The effect of platelet-activating factor (PAF) and of two specific PAF antagonists on tumor necrosis factor (TNF) induced superoxide production by human polymorphonuclear neutrophils (PMN) was examined. PAF alone (0.1 pM to 0.1 nM) failed to evoke superoxide production; however, when PAF was added for 10 min to cells upon prior incubation with 10 ng/mL TNF for 50 min, superoxide production was significantly enhanced as compared to that induced by TNF alone. Maximum amplification (+30%) was obtained with 10 pM PAF; however, the effect was completely abolished by two structurally unrelated PAF antagonists, BN 52021 and BN 52111. The antagonists also decreased by 25% the superoxide production elicited solely by TNF, implicating the involvement of endogenous PAF in this process. Pretreatment of the PMN with either pertussis or cholera toxin attenuated the PAF amplified superoxide production in TNF stimulated cells, suggesting that G proteins sensitive to these toxins may be involved in the mechanisms controlling amplification.

Theophylline therapy inhibits neutrophil and mononuclear cell chemotaxis from chronic asthmatic children

1. Theophylline is commonly used to relieve symptoms of chronic asthma. Since neutrophil and mononuclear cell activation are associated with late phase asthmatic reactions, effects of theophylline on these cells may be of importance. 2. In the present investigation we compared neutrophil and mononuclear cell chemotaxis from chronic asthmatic children during and after theophylline therapy. 3. Thirty patients were recruited for the study. Each patient received theophylline orally for 10 days. The theophylline dose was 20 mg kg-1 day-1 given in four divided doses. On the tenth day, blood was collected into heparinized (100 u ml-1) and siliconized tubes 2 h after the last theophylline dose for chemotactic assays, cAMP and theophylline plasma determinations. When clinical conditions allowed, theophylline was discontinued for 7 days and the chemotactic assays, cAMP and theophylline plasma concentrations repeated. Serum complement and IgE levels were also determined. 4. Theophylline therapy clearly inhibited both spontaneous and stimulated neutrophil and mononuclear cell chemotaxis. Twenty-seven patients had therapeutic plasma concentrations of theophylline (5-20 micrograms ml-1). Discontinuation of theophylline therapy caused a significant decrease in plasma cAMP levels (44 and 31 pmol ml-1 respectively during and after treatment, n = 30, P less than 0.001). 5. The inhibition of neutrophil and mononuclear cell migration by theophylline therapy in chronic asthmatic children may be beneficial for the control of the inflammatory response observed in these patients.

Induction of leukotriene production before antigen challenge enhances antibody affinity in genetically selected mice

Mice genetically selected for their incapacity to produce high-affinity antibody to protein antigens in adjuvant (nonmaturing (NM) mice) were treated with indomethacin, an inhibitor of the cyclooxygenase pathway of arachidonic acid metabolism. Pretreatment with indomethacin significantly enhanced the affinity of antibodies produced 21 days after immunization with human serum albumin (HSA). Blockage of the cyclooxygenase pathway in this way was shown to induce the production of leukotrienes via the lipoxygenase pathway. The production of leukotrienes may well be responsible for the enhanced antibody affinity, since blockage of the lipoxygenase pathway in addition to the cyclooxygenase pathway reversed the effect. In an attempt to elucidate the mechanisms involved, IL-1 production and Ia expression by macrophages were examined. Ia expression by peritoneal cells from untreated NM mice was significantly lower than that by their high-affinity-producing counterparts 3 days after immunization. Indomethacin pretreatment raised inducible Ia antigen levels on macrophages of NM mice to those seen on cells from untreated high-affinity mice. Indomethacin treatment alone induced the production of IL-1 by macrophages in NM mice. However, 3 days after immunization and the withdrawal of indomethacin in NM mice, IL-1 production was significantly lower than the response of NM mice given antigen alone, suggestive of the induction of a feedback mechanism. Thus indomethacin pretreatment results in a cascade of events in macrophages which produce a decrease in IL-1 production and an increase in inducible Ia expression 3 days after antigen challenge.

Fc-receptor-mediated phagocytosis: abnormalities associated with diabetes mellitus

The family of Fc receptors (FcR) for IgG play pivotal roles in affector, effector, and regulatory functions of cells of the immune system. Thus, changes in expression and activation of FcRs may contribute to a variety of disease manifestations that are the consequence of abnormalities in immune system function. Patients with diabetes mellitus are often plagued with recurrent bacterial and mycotic infections, as well as large and small vessel injury which may in part be immune mediated and which lead to organ dysfunction. Hormone-mediated changes in immune system function have been postulated to contribute to a variety of the complications experienced by patients with diabetes mellitus. It is the purpose of this review to summarize current knowledge regarding abnormalities in immune system function in diabetes mellitus with special emphasis on classical hormonal modulation of Fc receptor-mediated phagocytosis.

Is the origin of atopy linked to deficient conversion of omega-6-fatty acids to prostaglandin E1?

Our hypothesis on the origin of atopy links alterations in omega-6-fatty acid metabolism in atopic persons (i.e., reduced formation of delta-6-desaturase products) to deficient T cell differentiation and function. We suggest that a relative deficiency in dihomo-gamma-linolenic acid-derived prostaglandin E1 is the major etiologic factor for diminished T cell maturation postpartum. Its precursors, gamma-linolenic acid and dihomo-gamma-linolenic acid, are physiologically provided in colostrum and mature breast milk of healthy mothers. Depressed cell-mediated immunity and uncontrolled B-cell response with increased IgE synthesis are explained as prostaglandin E1-dependent defects of T cell differentiation caused by insufficient supply of prostaglandin E1 precursors during early infancy. Thus, in our opinion atopy is a metabolic disorder and the associated immunologic disturbances are epiphenomena.

Prostaglandin E2 production is enhanced in mice genetically selected to produce high affinity antibody responses

Spleen cells from mice selectively bred to produce high affinity antibody responses to protein antigens (HI) had reduced responses to both T and B cell mitogens when compared to those from mice selectively bred to produce low affinity (LO) responses. The reduced response by spleen cells from HI mice was partially reversed by the addition of indomethacin in vitro. Spleen adherent cells from HI mice had increased production of prostaglandin E2 when compared to those from LO mice. In addition, spleen adherent cells from mice which fail to show affinity maturation not only produced lower amounts of PGE2 than those from HI mice but also a decreased proportion of spleen cells adhered to plastic in these mice. To test the possibility that the increased PGE2 production in HI mice was responsible for the production of high affinity antibodies, indomethacin was administered in vivo and resulted in a significant reduction in antibody affinity. The possibility that PGE2 production may control the balance between the TH1 and TH2 cells of Mosmann and Coffman is discussed.

Effects of theophylline on human natural killer cells

Theophylline has been shown previously to inhibit a number of cellular immune functions of granulocytes and T-lymphocytes. In the present report, we demonstrate that theophylline, in a dose-dependent fashion, suppresses human natural killer (NK) cell activity in vitro. To determine if theophylline produces quantitative or qualitative alterations in NK cells in vivo we quantitated peripheral blood NK cells with three monoclonal antibodies and FACS analysis and measured NK cytolytic activity in eight normal volunteers who took theophylline for eight days. No change was noted in the number of cytolytic activity of NK cells over the eight days of monitoring. We conclude that theophylline does not alter NK cells in vivo when given in therapeutic doses.

Comparative studies on the effects of erythromycin A and azithromycin upon extracellular release of lysosomal enzymes in inflammatory processes

In the present studies the in vivo and in vitro effects of erythromycin A and azithromycin, a new type of macrolide (Fig. 2.), were investigated upon extracellular release of lysosomal enzymes, beta-glucuronidase (beta-Gluc) and beta-N-acetylglucosaminidase (beta-Glm) by using two experimental model systems: in vivo-adjuvant-induced arthritis in rats and in vitro- human polymorphonuclear leucocytes (PMNL) exposed to bovine serum albumin/anti-bovine serum albumin (BSA/anti-BSA), immune complex. Administrations of erythromycin A or azithromycin at doses of 5, 10 and 15 mg/kg into rats one day prior and 2, 4, 6, 8 and 10 days after a single subplantar injection of Freund's complete adjuvant significantly (p less than 0.01) inhibited extracellular release of lysosomal enzymes tested in the synovial fluid of injected left hind paw. These effects were dose-dependent. Further, erythromycin A and azithromycin at concentrations of 10(-7) M, 10(-6) M and 10(-5) M significantly (p less than 0.01) reduced excocytosis of both lysosomal enzymes, beta-Gluc and beta-Glm from human PMNL initiated by BSA/anti-BSA in a dose-related fashion. However, azithromycin was by far more effective (p less than 0.01) in decreasing extracellular release of beta-Gluc and beta-Glm either in the in vivo or in vitro experiments in comparison with erythromycin A. Appropriate control experiments excluded the possibilities that erythromycin A or azithromycin interfered with activities of lysosomal enzymes or with test reagents. Also, in no instances was there enhanced release of a cytoplasmic enzyme LDH.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of oxygen radical release from murine peritoneal macrophages by pharmacologic doses of PGE2

The ability of pharmacologic doses of PGE2 to alter the release of superoxide (O2-) and hydrogen peroxide (H2O2) from elicited peritoneal macrophages (M theta) was studied. Twice-daily administration of 200 or 100 micrograms of PGE2 to mice during accumulation of peritoneal M theta resulted in a significant reduction in M theta recovery and in the triggered release of H2O2, but not O2-. Cultivation of elicited M theta from normal mice with concentrations of PGE2 in excess of 10(-7) M for 24-48 h resulted in a significant reduction in the triggered release of H2O2, but not O2-. Cultivation for shorter periods of time or with lower concentrations of PGE2 failed to alter H2O2 release. This effect of PGE2 was reproduced by the phosphodiesterase inhibitor theophylline. The ability of PGE2 to inhibit H2O2 release in the presence of normal production of O2- was not prevented by the addition of superoxide dismutase. Cultivation of peritoneal M theta with 10(-5) M PGE2 for 48 h failed to increase intracellular catalase, although increased H2O2 scavenger activity was demonstrated. The inhibition of extracellular release of H2O2, but not O2-, by pharmacologic doses of PGE2 may be one mechanism for the anti-inflammatory action of this compound.

In vivo exocytosis of lysosomes by the endothelium of the venous sinuses of bone marrow and liver: visualization at normal and low body temperature

We have visualized the exocytosis of lysosomes into the peripheral circulation by the phagocytic endothelia of the venous sinuses of liver and bone marrow of rats. Perfusion fixation at normal body temperature produced images of the earliest stages of lysosomal exocytosis. After fixation at low body temperatures (7-12 degrees C), advanced stages of this process became evident, showing extrusion of lysosomes and their contents into the circulation. It is postulated that this form of exocytosis has escaped structural detection because of its rapidity and relative infrequency as compared to merocrine secretory exocytosis, and that fixation at low body temperatures arrests or slows down these exocytic events in sufficient measure for ultrastructural visualization. The possibility that this lysosomal exocytosis contributes to the presence of lysosomal enzymes detected in the peripheral blood should be considered. In addition, it is likely that lysosomal degradation products may be discharged by exocytosis into the circulation.

Effect of sodium thiomalate on immune complex-induced release of lysosomal enzymes from human polymorphonuclear leucocytes

The extracellular release of beta-glucuronidase and beta-N-acetylglucosaminidase from normal human polymorphonuclear leucocytes initiated with bovine serum albumin/anti-bovine serum albumin immune complex (15 micrograms/ml) was significantly inhibited (p less than 0.01) by pretreatment with increasing concentrations (10(-8) M, 10(-7) M, 10(-6) M and 10(-5) M) of sodium thiomalate in a time- and dose-related fashion. Also, beta-glucuronidase and beta-N-acetylglucosaminidase exhibited similar responses to the effects of bovine serum albumin/anti-bovine serum albumin or sodium thiomalate. In contrast, neither bovine serum albumin/anti-bovine serum albumin nor sodium thiomalate provoked appreciable leakage of the cytoplasmic enzyme, lactate dehydrogenase. This indicates that cell integrity remains intact under the experimental conditions described.

Prior exposure of macrophages to a low temperature enhances their cyclic AMP responses due to microtubule disruption

Prior exposure of intact macrophages to a low temperature (4 degrees C) resulted in tremendous increases in their cAMP-generating responses to prostaglandin (PG) E1, epinephrine, adenosine, forskolin, and cholera toxin. The extent of the enhancement was dependent on the site of stimulation by these agents. The effect of cold exposure was (a) completely reversed by reexposure of the cold-treated cells to 37 degrees C; (b) mimicked by antimicrotubule agents, colchicine and vinblastine; (c) not further increased by colchicine or vinblastine treatment; and (d) efficiently antagonized by D2O and taxol, microtubule stabilizers. These results demonstrated that enhancement of cAMP generation by cold exposure was mediated through microtubule disruption. The effects of cold exposure and microtubule-disrupting agents on hormone-induced refractoriness was also studied. Macrophages stimulated at 37 degrees C by PGE1 became refractory to the subsequent stimulation by PGE1, regardless of whether the cells had been, or were subsequently, exposed to 4 or 37 degrees C. In contrast, cells stimulated by PGE1 in the presence of colchicine, or cells pretreated with PGE1 at 4 degrees C, responded to PGE1 rechallenge normally. The results suggested that disassembly of microtubules provides a condition unfavorable for development of receptor refractoriness, but never favors recovery therefrom.

Peripheral blood lymphocyte numbers, lymphocyte proliferative responses in vitro, and serum immunoglobulins in regular hemapheresis donors

Selected tests of lymphoid function were used to screen a population of volunteer hemapheresis donors. Testing included: 1) absolute lymphocyte numbers, and percentage of T-cell, B-cell, and mononuclear phagocytes, 2) serum immunoglobulins, and, 3) in vitro proliferative responses to lectin mitogens (phytohemagglutinin, concanavalin A, and pokeweed mitogen), soluble antigens (staphylococcal filtrate, candida, and streptococcal varidase), and cell-bound alloantigens (mixed lymphocyte culture). A control population of first-time plateletpheresis donors was examined similarly. Regular donors manifested a small but statistically significant decrease in absolute lymphocyte counts (p less than 0.02), and IgM (p less than 0.02) compared to controls. Leukapheresis donors also manifested significant decreases in percentage of T cells (p less than 0.02). These findings are qualitatively similar to changes reported following intensive lymphocytapheresis and indicate the need for conservative policies regarding donation frequency in hemapheresis programs.

Cyclic nucleotides and their relationship to complement-component-C2 synthesis by human monocytes

The time courses of changes in cyclic nucleotide levels in monocytes have been studied. Histamine and prostaglandin E2 (PGE2) produced a rapid rise in cyclic AMP (peak 15 min) levels, which returned to normal within 4h, whereas cholera toxin, NaF and phosphodiesterase inhibitors produced slow sustained rises lasting over 24h. With the exception of isobutylmethylxanthine (10 mumol X 1(-1), none of these reagents altered cyclic GMP levels. alpha 1-Adrenergic and nicotinic cholinergic receptor-ligand interactions and imidazole produced rapid and relatively short-lived falls in cyclic AMP, and rises in cyclic GMP. In contrast, prostaglandin synthetase inhibitors produced delayed but more sustained falls in cyclic AMP but no rises in cyclic GMP. Agents that increased cyclic AMP decreased complement-component-C2 production, and those that decreased cyclic AMP increased C2 production. Agents that increased cyclic GMP alone (ascorbate, nitroprusside and prostaglandin F2 alpha) did not affect C2 production. Antigen-antibody complexes that stimulate C2 synthesis produced falls in cyclic AMP and rises in cyclic GMP similar to those produced by adrenergic and cholinergic ligands. Serum-treated complexes and anaphylatoxins, which inhibited C2 production, were associated with changes in cyclic AMP similar to those produced by histamine and PGE2. These data suggest that there are two transmembrane signals involved in the regulation of C2 production by monocytes. The inhibitory signal is adenylyl cyclase activation. The stimulatory signal is not so obvious, but may be Ca2+ influx, since the time courses of changes in cyclic nucleotides produced by agents that stimulate C2 synthesis are identical, and alpha 1-adrenergic agonists cause the formation of Ca2+ channels.

Synthesis of prostanoids and cyclic nucleotides by phagocytosing rat Kupffer cells

Rat Kupffer cells in monolayer culture were allowed to phagocytose unopsonized zymosan granules. They responded with a strongly stimulated synthesis and release of prostanoids, mainly the immunologically determined prostaglandins PGE2 and PGF2 alpha. The same response could be obtained by treatment with the calcium ionophore A23187. The effects of the ionophore and the zymosan particles were of the same magnitude but not additive. The rapid uptake of Ca2+ after contact with phagocytosable material recently described by us [(1983) Eur. J. Biochem. 131, 539-543] appears to mediate the enhanced prostaglandin synthesis. That response was suppressed not only by indomethacin but also by trifluoperazine which does not inhibit Ca2+ entry in the Kupffer cells. Similar effects by R24571 and 4-bromophenacyl bromide support the participation of calcium-calmodulin and of phospholipase A2. The calcium channel blocker Verapamil did not influence the zymosan-provoked production of prostaglandin PGE2 nor were any indications obtained for a feedback inhibition by PGE1 or PGE2. Contact with zymosan resulted in a rapid but transient rise of the intracellular levels of cAMP and cGMP: 10 nM indomethacin completely blocked the increase of both cyclic nucleotides while trifluoperazine elicited different responses in the cAMP and cGMP levels. The stimulated release of prostaglandin E2 was inhibited in a dose-dependent manner by nordihydroguaiaretic acid, an inhibitor of 5-lipoxygenase and by FPL 55712, known as a receptor antagonist for some leukotrienes. This suggests a regulatory role for its metabolites on prostaglandin synthesis.

Identification of receptor regulatory proteins, membrane glycoproteins, and functional characteristics of adenylate cyclase in vesicles derived from the human neutrophil

Human neutrophils were disrupted by brief sonication under conditions which preserve the hormone sensitivity of adenylate cyclase and yield minimal granule lysis. Fractions enriched in adenylate cyclase were analysed for hormonal and guanine nucleotide regulation of the enzyme as well as structural proteins. Adenylate cyclase was activated by PGE1 and isoproterenol in a GTP-dependent fashion, while f-met-leu-phe and C5a gave no stimulation. Cholera toxin treatment, which specifically modifies cyclase-related GTP-binding proteins, caused a dose-dependent enhancement of GTP activation, in which GTP alone activated maximally and PGE1 was without further effect. The following proteins were detected in the cyclase-containing vesicles: a 42 K mol. wt protein labeled selectively by cholera toxin; protein subunits observed in SDS gels at 214, 165, 105 and 47 K, of which the 47 K band was the most prominent and comigrated with actin; prominent lectin-binding activities at 165 K (concanavalin A and wheat germ agglutinin) as well as at 100 K (wheat germ agglutinin); and a set of proteins and lectin-binding activities in fractions containing beta-glucuronidase activity distinct from adenylate cyclase containing vesicles. The identification of receptor-controlled cyclase, GTP-binding regulatory proteins, cytoskeletal elements and unique lectin-binding activities in a single vesicle preparation should contribute to an understanding of receptor-mediated control of neutrophil function.

Induction of zymosan-air-pouch inflammation in rats and its characterization with reference to the effects of anticomplementary and anti-inflammatory agents

Induction of an experimental inflammation of the air-pouch type with the aid of zymosan (known to activate the alternative pathway of the complement system) was carried out in an attempt to induce a reproducible inflammatory model suitable for quantitative studies. Rats were injected subcutaneously with 8 ml of air on the dorsal surface to make an air-pouch, followed 24h later by 4 ml of 1.6% (w/v) zymosan suspension. This induced inflammatory responses. Treatment with zymosan suspension provoked exudation of fluid, accumulation of polymorphnuclear leukocytes (PMN) in the pouch and the development of granulation tissue as a wall of the pouch. Approximately half of the PMN in the pouch formed a characteristic layer of aggregated cells sticking onto the inner surface of the pouch wall. They were counted after being completely disaggregated by means of incubation with trypsin. In preliminary experiments with potential anti-inflammatory drugs, local application of a novel anti-complementary agent, K-76COONa, inhibited leukocyte accumulation in the pouch, whereas the potent anti-inflammatory agent, dexamethasone, was ineffective. By contrast, exudation of the pouch fluid was effectively inhibited by dexamethasone but not by K-76COONa.