A model for the quantitative study of Arthus (immunologic) hypersensitivity in rats

Methods for Testing Immunological Factors

Hypersensitivity reactions can be elicited by various factors: either immunologically induced, i.e., allergic reactions to natural or synthetic compounds mediated by IgE, or non-immunologically induced, i.e., activation of mediator release from cells through direct contact, without the induction of, or the mediation through immune responses. Mediators responsible for hypersensitivity reactions are released from mast cells. An important preformed mediator of allergic reactions found in these cells is histamine. Specific allergens or the calcium ionophore 48/80 induce release of histamine from mast cells. The histamine concentration can be determined with the o-phthalaldehyde reaction.

Diagnosis of Mesobuthus eupeus envenomation by skin test: reverse passive Arthus reaction

While being stung by two large families of scorpions, Buthidae and Scorpionidae have different symptoms and complications, a similar maintenance treatment usually considers as the scorpion species could not be identified easily. Therefore, this study was an attempt to develop an immunologic response for designing a skin sensitivity test that can be used to determine the poisoning. The sensitivity and the specificity of RPA reaction for detecting experimental envenomated mice were evaluated. The inflammatory response for detection of envenomation was obtained by the injection of a solution containing complement, polyelectrolytes and purified monovalent antibodies. As the result, 84.44% sensitivity and 100% specificity recorded 15 min after challenge. Macroscopic findings were also confirmed histologically. No cross-reactions were observed with other species of scorpions and snake venoms. Designed Skin test induced obvious inflammatory reaction without any histological lesions. Besides adding the complement components and polyelectrolyte to the monovalent antibody leads to an increased susceptibility of inflammatory cells in this reaction, resulting in forming a visible inflammation in a short time. According to satisfactory specificity and sensitivity and visible results in about 15 min, non-harmful and cost benefity of reverse passive Arthus test can be used for diagnosis of scorpion envenomation.

Heme oxygenase isoform expression in cellular and antibody-mediated models of acute inflammation in the rat

Heme oxygenase (HO) is the rate-limiting enzyme in the catabolism of heme to biliverdin, carbon monoxide (CO), and free iron. The enzyme exists as a constitutive isoform (HO-2) and an inducible isoform (HO-1), which is also a stress protein (HSP32). HO-1 has previously been shown to be associated with the resolution phase of a non-immune model of acute inflammation. In addition, elevation of the enzyme was markedly anti-inflammatory. In the present study, these observations have been extended to two pleural models of immune-driven inflammation in the rat, an immediate type III hypersensitivity (Arthus) reaction and a delayed type IV hypersensitivity reaction. Whilst these models have differing inflammatory mechanisms and time courses, they both showed HO activity to be maximal during the resolution phase. This activity was associated with increases in exudate bilirubin (a breakdown product of biliverdin) and increased expression of HO-1. Immunocytochemical analysis of inflammatory cell smears from the two models showed that HO-1 and HO-2 expression was restricted to mononuclear cells in the type IV hypersensitivity reaction, but included the polymorphonuclear cell population in the type III hypersensitivity reaction. Thus, irrespective of the pathogenesis of the lesion, evidence is accumulating to suggest that HO-1 has a universal role in the resolution of inflammation.

Characterization of phospholipase A2 activity in rat RPAR-induced pleurisy

At 10 min, 2 h and 4 h after induction of a reverse passive Arthus reaction (RPAR) in the pleural cavity of rats, pleural exudate was collected and analyzed in vitro for phospholipase A2 (PLA2) acyl hydrolytic activity. Inasmuch as exudate PLA2 was inhibited by addition of EDTA, the acyl hydrolytic activity appeared calcium-dependent. However, addition of exogenous calcium to the exudate had only a minor effect on the activity. Maximum hydrolysis in all exudates was observed over a pH range of 6-9 with a neutral optimum. The 4 h exudate PLA2 activity was almost fully inhibited by para-bromophenacyl bromide (pBPB), whereas the acyl hydrolytic activity in the 10 min and 2 h exudates was reduced by 44% and 46%, respectively, by 200 microM pBPB. Although the PLA2 in the 4 h exudate displayed an increased sensitivity to high exogenous calcium concentrations and to pBPB inactivation, the basic properties of the exudate PLA2 at the three time points appeared similar.

Phospholipase A2 acyl-hydrolytic activity in rat RPAR-induced pleurisy

Endogenous phospholipase A2 (PLA2) specific activity (SA) (% hydrolysis/min/mg protein) in the rat pleural cavity, measured as the acyl-hydrolysis of [3H]-arachidonic acid E. coli substrate, was quantitated after induction of a reverse passive Arthus reaction (RPAR). PLA2 SA, derived when the rate of hydrolysis was linear (1-5 min), was 1.9, 1.4, 3.8 and 4.1% h/min/mg at 10 min, 2 h, 4 h and 24 h, respectively, after induction of the RPAR. This time course appeared to correlate with the influx of mononuclear inflammatory cells, although the effect of plasma leakage on changes in exudate PLA2 SA could not be determined. Oral administration of antiinflammatory drugs significantly inhibited pleural fluid exudation and inflammatory cell influx to varying degrees. However, whereas these drugs additionally reduced total exudate protein and PLA2, they had no effect on the concentration of either parameter, implying that pleural PLA2 may be passively linked to fluid and cell movement.

Comparison of several new 5-lipoxygenase inhibitors in a rat Arthus pleurisy model

The 5-lipoxygenase inhibitors WY-50,295 tromethamine, A-64,077, L-663,536 and ICI-207,968 were compared in a reverse passive Arthus reaction-induced pleurisy model of eicosanoid biosynthesis in the rat. When a 1 h pretreatment schedule was employed, all four inhibitors equivalently blocked leukotriene B4 (LTB4) production with ED50 values of 2.0-2.9 mg/kg p.o. Conversely, WY-50,295 tromethamine (225 mg/kg p.o.) and L-663,536 (100 mg/kg p.o.) did not significantly alter thromboxane B2 (TxB2) levels, whereas A-64,077 (50 mg/kg p.o.) and ICI-207,968 (100 mg/kg p.o.) significantly reduced TxB2 by 50 and 72%, respectively. When 3 and 18 h pretreatment schedules were employed, WY-50,295 tromethamine demonstrated a longer duration of action than the other 5-lipoxygenase inhibitors with ED50 values of 1.7 and 6.3 mg/kg p.o., respectively. At doses of 50 and 100 mg/kg p.o., all drugs tested significantly inhibited inflammatory cell influx by 15-27%, albeit in a non-dose-related manner. However, only A-64,077 significantly lowered fluid extravasation by 35%, presumably due to inhibition of cyclooxygenase product formation. These results demonstrate that in this rat reverse passive Arthus pleurisy model, WY-50,295 tromethamine potently and selectively inhibits 5-lipoxygenase in vivo, and possesses a longer duration of action than the other 5-lipoxygenase inhibitors employed.

Inhibitory effect of methyl 7-butyl-4,5,6,7-tetrahydro-3-methylamino-4,6-dioxo-5-propyl-2H-pyrazol o[3, 4-d]pyrimidine-2-carboxylate (AA-2379) on type III allergic (Arthus) reaction

Methyl 7-butyl-4,5,6,7-tetrahydro-3-methylamino-4,6-dioxo-5-propyl-2H- pyrazolo[3,4-d]pyrimidine-2-carboxylate (AA-2379), a non-steroidal, non-acidic agent, markedly inhibits type III allergic (Arthus) reaction; the ID50 values of AA-2379 in the rat reversed passive Arthus pleurisy, the rat active Arthus pleurisy, and the reversed passive Arthus reaction in rat skin were 5-10 mg/kg, p.o., and 30 mg/kg of AA-2379 inhibited the active Arthus reaction in rabbit skin by about 50%. Dexamethasone, but not acidic non-steroidal anti-inflammatory drugs and aminopyrine, inhibited the Arthus reaction. The vascular permeability in the reversed passive Arthus pleurisy is enhanced biphasically in the early response mediated by physiologically active amines, prostaglandins, and leukotrienes, and in the late response mediated by complements and polymorphonuclear leukocytes (PMNs). AA-2379 inhibited the late response more potently than the early one. Furthermore, when given after the early response was reduced, AA-2379 obviously inhibited the late response. Rat zymosan-induced paw edema and mouse zymosan-activated serum-induced peritonitis, mediated by complements, were dose-dependently inhibited by AA-2379; the ID50 values were 11.4 and 10.2 mg/kg, p.o., respectively. The results suggest that AA-2379 differs from non-steroidal anti-inflammatory agents in strongly inhibiting the late response of the Arthus reaction, which associated with PMNs.

Leukotriene B4 production and pharmacologic regulation of reverse passive Arthus pleurisy: importance of antigen dose

Immunoreactive leukotriene B4 (iLTB4), detected in the pleural cavity following induction of a reverse passive Arthus reaction (RPAR), was inhibited by the mixed lipoxygenase-cyclooxygenase inhibitors, phenidone and BW 755C, but not by cyclooxygenase inhibitors or by chlorpheniramine or methysergide. Both iLTB4 production and the subsequent pleural inflammation were dependent upon the dose of BSA antigen employed to elicit the RPAR pleurisy. However, inasmuch as BW 755C and phenidone were not distinguished from the cyclooxygenase inhibitors in their effects on fluid accumulation and cellular infiltration in RPAR pleurisy, it is doubtful that LTB4 plays a functional role in this inflammation model.

Acute synovitis induced by preformed immune complexes

The morphology of acute immune complex (IC) elicited synovitis in rabbit knee joints was studied, as well as IC-induced leukocyte activation in vivo and in vitro. Acute synovitis was induced by intra-articular injection of in vitro preformed, complement activating bovine serum albumin (BSA)-anti-BSA IC. Within 30 min, migration of polymorphonuclear granulocytes (PMNGs) was observed. Scanning electron microscopy showed that adhering, apparently activated leukocytes were attached to the synovial lining, often forming clusters. Phagocytosis of IC was evident, as immunoglobulins were detected within the leukocyte cytoplasm by the direct immunofluorescence technique. At the peak accumulation of PMNGs, focal erosions of the synovial lining were observed. Later, monocytes and macrophages appeared and degenerated PMNGs were found, sometimes within the cytoplasm of large macrophages. Chemiluminescence experiments showed a maximum in vitro activation of leukocytes by complement activating IC formed near optimal precipitation proportions and in slight antigen excess, whereas IC in large antigen excess gave a smaller and later response.

Immunological concepts and the eye: a review of the classical and ocular arthus reactions

Inflammatory processes can involve any tissue in the eye. Despite advances in therapy, the sequelae of inflammation continue to be a major cause of visual impairment. Knowledge of disease pathogenesis in clinical ocular inflammations remains imprecise, and defined models are crucial in developing this understanding and evolving rational approaches to treatment. This review analyzes the contributions that studies of the classical and Arthus ocular Arthus-type reactions have made as to how the eye functions as an immunological entity. The anticipated development of therapeutic agents that may modulate immune processes with remarkable specificity, gives a new impetus to such experimental studies.

Modification of neutrophil chemotactic responsiveness during various inflammatory reactions

Various inflammatory reactions have been induced in order to examine the chemotactic response of polymorphonuclear leucocytes (PMN) collected under various experimental conditions. Cells were harvested from the pleural cavity of rats after the induction of three acute non specific inflammatory reactions and two immune reactions. The results obtained with two techniques of chemotactic assessment (agarose assay and Boyden chamber technique) demonstrated a variation of chemotactic response depending on the cell source and the chemoattractants used. Using agarose assay, we distinguished locomotor reactivity of PMN harvested after immune inflammatory reactions from that of PMN harvested after non immune inflammatory reactions. Chemokinetic and chemotactic responses to various chemoattractants were inhibited in the first case and not affected in the second. Using the Boyden chamber technique, inhibition of random or oriented migration of PMN harvested after immune inflammatory reactions after the injection of a non antigenic irritant such as calcium pyrophosphate crystals (CaPP) was also observed.

Comparison of anti-inflammatory compounds in the carrageenan induced paw edema model and the reversed passive Arthus model utilizing the same animal

In order to better define antiinflammatory activity in new agents, a test was devised utilizing both carrageenan induced paw edema and the reversed passive Arthus reaction in the same animal. The model of carrageenan induced rat paw edema is a standard laboratory assay used to predict classical "aspirin-like" antiinflammatory molecules. The reversed passive cutaneous Arthus reaction involves precipitating antigen-antibody complexes, complement and infiltrating polymorphonuclear leukocytes (PMN's) and can be used to identify agents that affect one or more of these factors specifically. Antiinflammatory compounds were given orally one hour prior to the administration of carrageenan and goat anti-rat serum. Comparisons were made between several non-steroidal compounds and the steroid hydrocortisone. All of the compounds tested gave good carrageenan activity, but only hydrocortisone produced significant Arthus lesion inhibition in this assay.

Ex vivo effects of nonsteroidal antiinflammatory drugs on arachidonic acid metabolism in neutrophils from a reverse passive Arthus reaction

Rat neutrophils isolated from 4-h reverse passive Arthus reaction (RPAR) pleural exudates actively metabolize arachidonic acid via cyclooxygenase and lipoxygenase. Utilizing this system, the effect of oral doses of nonsteroidal antiinflammatory drugs on the ability of these cells to produce HHT, 5-HETE, and LTB from exogenously added arachidonic acid has been investigated. In vitro and ex vivo, indomethacin and timegadine inhibit cyclooxygenase activity in rat pleural neutrophils. In vitro, timegadine is a lipoxygenase as well as a cyclooxygenase inhibitor. This dual inhibition is confirmed by the observation that ex vivo timegadine inhibits the production of lipoxygenase as well as cyclooxygenase metabolites. While indomethacin, a cyclooxygenase inhibitor, primarily inhibits edema formation, the inhibition of both pathways of arachidonic acid metabolism by timegadine is reflected in the drug's ability to reduce cellular influx as well as edema formation in the RPAR pleural cavity inflammatory reaction.

In vivo effects of indomethacin and flurbiprofen on the locomotion of neutrophils elicited by immune and non-immune inflammation in the rat

The in vivo effects of indomethacin (3 mg/kg) and flurbiprofen (1.5 mg/kg) were investigated on the development of three different pleural inflammations in the rat and on in vitro locomotion of elicited neutrophils (PMN). Indomethacin and flurbiprofen similarly reduced the development of non-immune pleurisy induced by decomplemented isologous rat serum (DIRS) to a similar degree but had no effect in the delayed hypersensitivity reaction (DHR) model. Flurbiprofen was less effective than indomethacin in the immediate hypersensitivity reaction (IHR) model. PMN elicited by the two immune reactions (IHR and DHR) displayed lower random and directed locomotion than DIRS-elicited PMN. Neither drug interfered with DIRS-elicited PMN locomotion. They inhibited both random migration and directed locomotion of unwashed PMN (i.e. suspended in their original exudate) elicited by IHR or DHR and stimulated by the peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) or isologous rat serum (IRS). Locomotion of washed IHR-elicited PMN stimulated with IRS was also inhibited by the two drugs. The data suggest that these drugs could impair PMN movement at inflammatory sites.

Expression of macrophage functions in hybrids of a myeloma cell line with inflammatory macrophages: evidence for negative control mechanisms in the expression of macrophage functions

Mouse inflammatory macrophages from C57BL/6N mice were fused with BALB/c mouse-derived myeloma cells (the CANS series). The hybrids in the early period after cell fusion (8 weeks) showed no macrophage functions (chemotaxis, EA and EAC rosette-forming abilities, phagocytosis or lysozyme production). EA rosette-forming ability was observed when these hybrids were treated with trypsin, whereas other macrophage functions were not. After prolonged culture, the hybrids (12 clones of 13 randomly selected) showed all the macrophage functions along with chromosome loss. Myeloma cell functions (kappa light chain production) were found in the young hybrids soon after cell fusion but were absent in the aged hybrids. These results indicated that reexpression of macrophage properties, except for EA rosette-forming abilities, takes place after the loss of chromosomes or genes repressing the expression of macrophage functions.

Lotifazole (F 1686), a non-steroidal anti-inflammatory agent with an unusual pharmacological spectrum

Lotifazole (F 1686) - 4-phenyl-2-(2',2',2-trichloroethoxycarboxamido) thiazole - has a range of anti-inflammatory activities in animals that differs from the activities of classic non-steroidal drugs. It reduces carrageenin-induced oedema in rats, UV-induced erythema in guinea pigs, and Arthus pleurisies in rats only at high doses. It does not affect Freund's-adjuvant polyarthritis, and it only slightly affects passive skin anaphylaxis in rats and anaphylactic shock in guinea pigs. Lotifazole does not greatly inhibit prostaglandin synthesis. However, at low doses and after various conditions of treatment, F 1686 reduces PPD- and Bordetella- pertussis-induced delayed-hypersensitivity pleurisy in guinea pigs and rats, respectively, and contact hypersensitivity reactions to picryl chloride and oxazolone in mice. Its action on the two models of delayed-hypersensitivity pleurisy is reflected in a decrease of the pleural exudate and of the number of mononuclear cells in the focus of inflammation. At active doses, Lotifazole does not cause changes in the differential leukocyte count in normal animals. It appears, furthermore, to be a T-lymphocyte stimulant.

Differential effects of anti-inflammatory drugs on lipoxygenase and cyclo-oxygenase activities of neutrophils from a reverse passive Arthus reaction

Rat neutrophils isolated from four-hour reverse passive Arthus reaction pleural exudates actively metabolize arachidonic acid. Production of 11-hydroxy- and 15-hydroxy-icosatetraenoic acid and 12-hydroxy-heptadecatrienoic acid is inhibited by indomethacin, benoxaprofen, BW 755C, piroxicam, ibuprofen, timegadine, and naproxen, suggesting that production of these arachidonic acid metabolites occurs at similar enzymic active sites. In addition, in the presence of the calcium inophore A23187 or the non-ionic detergent, BRIJ 56, rat neutrophils also produce the lipoxygenase products 5-hydroxy-icosatetraenoic acid and leukotriene B. The production of these metabolites is calcium dependent. Moreover, the calcium ionophore A23187 and BRIJ 56 synergistically act to augment the metabolism of exogenously added arachidonic acid via lipoxygenase. The formation of these metabolites is inhibited by BW 755C, benoxaprofen and timegadine but not by other non-steroidal anti-inflammatory drugs tested. In fact, at doses which inhibit cyclo-oxygenase activity, indomethacin, naproxen, and ibuprofen stimulate arachidonic acid metabolism via lipoxygenase.

Effects of various substances on two types of inflammatory reaction in animals

The effects of 16 substances, including non-steroidal anti-inflammatory agents, a corticoid, phenols, immunomodulators and gold salts, were studied using two types of acute inflammatory reaction, a non-specific reaction (carrageenan-induced oedema) and an immune reaction (reversed passive Arthus reaction in the rat or active Arthus reaction in the mouse). Results revealed that the active Arthus model appears to be more selective than the passive reversed Arthus model, which is itself less sensitive than the carrageenan model. The active Arthus reaction might be useful for secondary screening of molecules that act on mechanisms modulating the intervention of complement and the various functions of polymorphonuclear leucocytes, and the passive Arthus reaction appears to be more suitable for preliminary screening. The activities of the different substances studied are discussed in terms of their modes of action and toxicity.

A model of Arthus pleurisy: modulation by various pharmacologic and therapeutic agents

A reversed passive Arthus reaction was elicited in the rat pleural cavity. The kinetics of this inflammatory response indicate that exudate volume (cells and fluid) reaches a maximum level approximately 2 to 4 hr postantibody challenge. The neutrophil is the major cellular constituent of the pleural exudate during the first 12 hr of this reaction, reaching peak values at 4 hr; whereas, the monocyte predominates between 15 and 24 hr. Lymphocytes, eosinophils, and mast cells were also identified in the pleural exudates. The serotonin antagonists, cyproheptadine and methylsergide, and the antihistamine, chlorpheniramine, demonstrated marginal activity in the Arthus pleurisy model. The histamine antagonist, metiamide, was inactive. The nonsteroidal anti-inflammatory agents, flurbiprofen, ibuprofen, indomethacin, and benoxaprofen caused a modest suppression of exudate volume (18-32%) and cell accumulation (28-34%). The fluid and cellular components of the Arthus reaction were significantly inhibited by dexamethasone, triamcinolone, paramethasone, and prednisolone. The oral gold preparation, auranofin, had a pronounced effect on exudate volume; whereas, other antirheumatic agents such as D-penicillamine, azathioprine, and chloroquine had no effect on the Arthus pleurisy reaction. The immunomodulator, levamisole, suppressed exudate volume, but had no effect on cell accumulation in the pleural cavity.

Comparison of the effect of phenylbutazone, desonide and cyclophosphamide on four types of experimental pleurisy

The action of phenylbutazone, a non-steroid anti-inflammatory drug, desonide, a corticosteroid, and cyclophosphamide, an immunosuppressant agent, was studied on four types of experimental pleurisy: carrageenan-pleurisy in rats; passive reversed Arthus pleurisy in rats; Bordetella pertussis-delayed hypersensitivity pleurisy in rats and PPD (purified protein derivative)--delayed hypersensitivity pleurisy in guinea-pigs. For each compound, the action on the exudate and on the number of the different categories of leucocytes in the inflammation focus was evaluated. In carrageenan-inflammation, phenylbutazone reduced the oedema and the number of neutrophils and macrophages. Its favourable effect on exudative events in Arthus--and B. pertussis--reactions was not accompanied by high modifications at the cellular level. With the exception of PPD-pleurisy, desonide reduced the three other reactions. Its action related to the exudate and the various leucocyte types, except in the Arthus reaction in which only the number of neutrophils was decreased. The effect of cyclophosphamide was mainly in B. pertussis pleurisy in which it resulted in a decrease of oedema and a reduction in the number of mononuclears. For each compound, correlations between the effect on exudative and cellular phenomena are discussed.

Studies on cell motility in inflammation. I. The chemotactic activity of experimental, immunological and non-immunological, inflammatory exudates

The accumulation of leucocytes at the site of inflammation may be brought about by chemotaxis or proliferation in the extravascular tissues. The present paper focuses on the chemotactic properties of different types of experimental inflammatory pleural exudates, using a modified Boyden chamber. The time-course of carrageenan-induced exudate chemotactic activity for polymorphs was maximal at 4 h, thereafter diminishing towards 24 and 48 h. Chemotactic activity for mononuclear cells remained unchanged throughout the 4--48 h time-course. Heating the exudates to 56 degrees C for 1 h partially reduced chemotactic activity. These results correlate well with the migration of polymorph and mononuclear cells into the pleural cavity during carrageenan-induced pleurisy. The potency of polymorph and mononuclear cell chemotactic activity of different exudates was of the following order: carrageenan greater than calcium pyrophosphate greater than reverse passive Arthus greater than dextran. The results are discussed in order to elucidate the differences between the underlying mechanisms responsible for leucocyte accumulation in different types of inflammatory reaction.

The Arthus reaction in rats, a possible test for anti-inflammatory and antiheumatic drugs

The Arthus reaction is an immunologically induced inflammatory response characterized by immune complex deposition, complement fixation, polymorphonuclear leukocyte infiltration and tissue damage. Many of these same pathological tissue alterations are found in the lesions of rheumatoid arthritis (RA). The similarities between the reversed passive Arthus reaction (RPAR) and RA led us to investigate the usefulness of the RPAR in the search for new antirheumatic agents. The RPAR was elicited in the skin of rats using chicken ovalbumin and the IgG fraction of rabbit anti-ovalbumin. Paramethasone, hydrocortisone, indomethacin, pirprofen, sulfinpyrazone, thalidomide and theophylline all gave significant inhibition of the RPAR. Ibuprofen, naproxen, cyprohepatadine and cromolyn sodium were inactive, while phenylbutazone and ASA exhibited a dose-dependent effect. The data show that the Arthus reaction, which is the result of the complex interaction of many factors, can be affected either generally or selectively at different time intervals by various therapeutic agents. The RPAR in rats may prove useful in detecting new therapeutic agents for the treatment of RA.

Cyclic adenosine 3', 5'-monophosphate and the mechanism of action of three common anti-inflammatory drugs

1 The effects of indomethacin, dexamethasone and colchicine on cyclic adenosine 3', 5'-monophosphate (cyclic AMP) concentration in leucocytes during a crystal-induced pleurisy in rats were studied. 2 Each of the drugs significantly increased leucocyte cyclic AMP content within 3 h of the injection of crystals. 3 By 6 h, leucocyte cyclic AMP levels returning toward control levels and could not be sustained at the higher level by an additional administration of the respective anti-inflammatory drug.

Protease inhibitors reduce the reverse passive Arthus reaction

Trasylol, ovomucoid, tranexamic acid and soybean inhibitor decrease the vascular permeability as measured by extravasation of 131I-albumin when injected with the antibody at induction of a reverse passive Arthus reaction in the rat skin. Trasylol given systemically also had a suppressive effect, similar to phenylbutazone. When the reaction was induced in the pleural cavity, both Trasylol and tranexamic acid reduced the influx of leucocytes.

Cyclic AMP and the mechanism of leucocyte lysosomal enzyme release during an immediate hypersensitivity reaction in vivo

The pleural cavity of rats was used to study the effect of altering leucocyte cyclic AMP content on the release of B-glucuronidase activity during an immediate hypersensitivity reaction. The effect on intravenous colchicine was also studied. Despite an increase of 135 to 235% in leucocyte cyclic AMP content no decrease in B-glucuronidase release was observed. Similarly, colchicine had no effect on enzyme release. It was concluded that the cyclic nucleotides and leucocyte microtubules may have no significant role to play in the release of lysosomal enzymes during acute inflammation in vivo.

The value of multifactorial screening for anti-inflammatory activity as shown by coumarin

Different types of acute inflammatory pleural reactions have been used as a means of detecting the anti-inflammatory potential of a particular drug coumarin. The latter had some type of activity in all the reactions. However, whereas coumarin inhibited leucocyte accumulation induced by dextran it had no effect on the volume of fluid exudate. Conversely, coumarin reduced the volume of exudate in the Arthus reaction whereas the cellular infiltrate remained unaltered. Leucocytes from dextran-induced exudate (predominantly polymorphs) removed from animals pretreated with coumarin showed marked inhibition of migration in vitro. This correlated well with the suppression by coumarin of the dextran-induced leucocyte response in vivo. Coumarin administered in vivo was also shown to stimulate phagocytosis of latex by mouse peritoneal macrophages in vitro. These findings are discussed with respect to the evaluation of anti-inflammatory drug activity and to the mode of action of coumarin.

Cyclic adenosine 3',5'-monophosphate and leucocyte chemotaxis in vivo

1 The effect of local elevation of leucocyte cyclic adenosine 3',5'-monophosphate (cyclic AMP) content on the continued migration of leucocytes to a site of acute inflammation was studied in the pleural cavity of rats. 2 Leucocyte cyclic AMP levels were elevated by injecting with the irritant into the pleural cavity dibutyryl cyclic AMP alone or with theophylline. 3 The treatments both produced a marked reduction in leucocyte migration into a pleural reaction induced by immediate hypersensitivity, but had no effect on cell numbers in pleurisy induced either by pyrophosphate or urate crystals.

Effects of modification of intracellularcyclic AMP levels on the imediate hypersensitivity reaction in vivo

Experiments were performed to study the effects of agents that elevate endogenous cyclic AMP levels on the progression of a reverse passive Arthus reaction in the pleural cavity of rats. Three hours after the onset of the reaction a marked reduction in histamine release was observed which correlated well with increases in cellular cyclic AMP concentration. The results at 6 hr suggested a relationship between cyclic AMP and leucocyte PGE, the latter being reduced dramatically both in the cells and in the fluid exudate by agents that elevate cyclic AMP. It was concluded that cyclic AMP may play an important regulatory role in vivo in the release of inflammatory mediators from leucocytes.