The observation of immune complex formation and deposition in the eyes of living rabbits

Fluorescence microscopy of the conjunctival and episcleral circulations of the rabbit's eye has revealed for the first time the formation and deposition of intravascular and perivascular immune complexes in undisturbed capillaries in vivo. During intravascular immune complex formation, immune aggregates appear abruptly, at a critical antigen/antibody ratio, and embolize to the arterial side of the capillary bed. This is accompanied by a fall in the circulating platelet count. The emboli disperse over the ensuing 120 min. In frozen sections immune aggregates are coarsely granular and intraluminal at the moment they embolize. However, after they disperse, subendothelial granules of antigen can be found. IgG and C3 are associated with both intraluminal and subendothelial antigen. Perivascular immune complex formation is accompanied by an intense inflammatory response, which is absent after the deposition of an intravascular immune precipitate. The mechanism by which immune complexes may accomplish their transition across the capillary endothelium is discussed.

Effects of the new antiallergic drug 11-oxo-11H-pyrido[2,1-b] quinazoline-2-carboxylic acid on type I allergic reactions

Antiallergic effects of the newly synthesized, quinazoline derivative 11-oxo-11H-pyrido[2,1-b]quinazoline-2-carboxylic acid (Sm 857) were investigated. The following results were obtained. 1. Anaphylactic and non-immunologic histamine and slow reacting substance of anaphylaxis (SRS-A) release from guinea pig lung fragments was dose-dependently inhibited by 10(-6)-10(-4) and 10(-7) -10(-4) g/ml of Sm 857, respectively. Similar inhibition of the mediator release by the compound was obtained from the experiments of passively sensitized monkey and human lung fragments by antigen. 2. Seven-day passive cutaneous anaphylaxis of guinea pigs was not inhibited at 1-20 mg/kg (i.v.) of Sm 857, but inhibited at 20-100 mg/kg (p.o.) in some experiments without dose dependency. 3. Cutaneous anaphylaxis and histamine-induced cutaneous reaction in guinea pigs were hardly affected by the treatment of 50 and 100 mg/kg (p.o.) of Sm 857. 4. Passive systemic anaphylaxis in guinea pigs was not inhibited at 50-200 mg/kg (p.o.) of Sm 857. 5. Arthus reaction in rabbits was slightly and dose-dependently enhanced at 50-200 mg/kg given twice p.o. 6. Sm 857 (10(-6)-10(-4) g/ml) exhibited antispasmogenic activity against histamine and leukotriene D4 in isolated human bronchi and guinea pig trachea, however, this activity is attributable to non-specific musculotropic smooth muscle relaxation. From these results it may be concluded that Sm 857 exerts preferential effect on the respiratory system and that it might be useful in allergic asthma.

A specific antagonist of platelet-activating factor suppresses oedema formation in an Arthus reaction but not oedema induced by leukocyte chemoattractants in rabbit skin

The properties of a novel platelet-activating factor (PAF) antagonist, L-652731, on oedema responses in rabbit skin induced by exogenous inflammatory mediators and by mediators generated endogenously in a reversed passive Arthus reaction have been investigated. Oedema responses in the skin were measured by using the local accumulation of i.v. injected 125I-albumin. The antagonist, mixed with mediators before intradermal injection, caused a dose-dependent suppression of oedema responses to PAF. In contrast, responses induced by other directly acting mediators (bradykinin and histamine) and responses induced by PMN leukocyte-dependent mediators (C5a des Arg, N-formyl-methionyl-leucyl-phenylalanine, and leukotriene B4) were not suppressed. Thus, a secondary release of PAF does not appear to be involved in mediating the actions of these agents. In a reversed passive Arthus reaction, intradermal injection of L-652731 together with antibody resulted in a significant inhibition of the oedema formation measured for 2 hr after i.v. antigen challenge. In contrast, oedema responses induced by intradermal injection of preformed immune complexes were not affected by the antagonist. These results suggest that the endogenous production of PAF, in close proximity to microvascular endothelial cells, appears to be an important step in the development of an Arthus reaction. The cellular source of PAF is unknown, but one possibility is the PMN leukocyte, which releases PAF during phagocytosis of immune complexes.

Scanning electron microscopy of antigen induced arthritic joints. I. Inflammatory cell interactions at synovial-meniscal surfaces during the Arthus response

Scanning electron microscopy has been used to study experimental antigen induced arthritis, providing a unique perspective of the early inflammatory events. An initial aggregation of acute inflammatory cells was noted at the synovial-meniscal junction with maximal numbers observed between 12 and 24 h post challenge. Variations in cell surface ruffling, which may represent different phases of activation, were observed throughout the Arthus response. By 48 h post challenge the meniscal and synovial surfaces were covered by a mat of fibrin and degraded cell remnants.

Models for evaluating the anti-inflammatory effects of inhibitors of arachidonic acid metabolism

Inhibitors of arachidonic acid metabolism were characterized by their ability to modulate slow reacting substance (SRS) and prostaglandin E2 (PGE2) release from stimulated mouse peritoneal macrophages in-vitro. Differential effects of cyclo-oxygenase (CO) and lipoxygenase (LO) enzyme inhibitors and compounds which inhibit both enzymes were demonstrated using several animal models of inflammation. Carrageenan-impregnated sponges implanted subcutaneously in rats and immune-complexes injected intraperitoneally in mice produced inflammatory responses characterized respectively by polymorphonuclear (PMN) cell infiltration and by increased vascular permeability. Dual CO/LO inhibitors (eg. BW 755c and timegadine) were capable of suppressing both parameters and reduced SRS and PGE2 formation in-vivo. In contrast, selective CO inhibitors (e.g. indomethacin, naproxen and R-830) were less active against permeability, and potentiated SRS release. Although selective CO inhibitors reduced PMN migration, this occurred at doses which exceeded those required for inhibition of PGE2. Compounds possessing LO inhibitory activity suppressed the cellular component of an Arthus type reaction in the rat pleural cavity, but were less active than selective CO inhibitors against carrageenan-induced paw oedema in rats.

CGS 12970: a novel, long acting thromboxane synthetase inhibitor

CGS 12970 is a potent selective inhibitor of human platelet thromboxane synthetase in vitro (IC50 = 12 nM). It is four orders of magnitude less potent as an inhibitor of sheep seminal vesicle cyclooxygenase, bovine aorta prostacyclin synthetase and human leucocyte 15-lipoxygenase. The compound inhibited collagen-induced thromboxane B2 production by human platelets in vitro without an effect on the accompanying platelet aggregation induced by collagen, ADP, platelet activating factor, thrombin, arachidonic acid or the prostaglandin mimetic, U 46619. Administration of CGS 12970 to rats inhibited collagen-induced thromboxane B2 production but had no effect on platelet aggregation ex vivo. It also had no effect on platelet aggregation induced by thrombin or on plasma clotting times. A single oral dose of 1 or 3 mg kg-1 to rabbits inhibited thromboxane B2 production in clotting blood ex vivo for 12 or 24 h respectively. CGS 12970 inhibited thromboxane B2 production in vivo induced by intravenous administration of collagen to rats or calcium ionophore to guinea-pigs. In both cases there was a concomitant elevation of immunoreactive 6-keto-prostaglandin F1 alpha but no effect on the induced thrombocytopenia. As with other thromboxane synthetase inhibitors, CGS 12970 prolonged tail bleeding time in the rat. However, CGS 12970 was not as potent as other thromboxane synthetase inhibitors in this test. In addition to these usual effects of thromboxane synthetase inhibitors, CGS 12970 inhibited the thrombocytopenia induced by the Forssman reaction or ADP administration. In these tests the effect of the compound was of short duration. 8 CGS 12970 had no effect on the thrombocytopenia associated with the Arthus reaction which distinguishes it from cyclo-oxygenase inhibitors. It also had no effect on thrombus formation on a cotton thread in an arteriovenous shunt in the rat.

Acquired resistance and expression of a protective humoral immune response in guinea pigs infected with Treponema pallidum Nichols

Resistance to cutaneous syphilitic reinfection in strain 2 and strain 13 guinea pigs developed gradually 3 to 7 months after primary infection and reached maximum levels at 6 to 7 months after the induction of primary cutaneous disease. Associated with this acquired resistance was the occurrence of Arthus reactions and anamnestic-type antibody responses. Passive transfer of immune serum containing high-titered treponemal antibody into normal strain 2 guinea pigs significantly delayed the appearance and markedly diminished the severity and duration of skin lesions that developed after these recipients were challenged with treponemes but did not prevent the dissemination of organisms to the draining lymph nodes. These findings provide direct evidence that syphilitic infection elicits the formation of serum factors that are, at least, partially protective against symptomatic disease.

Acute inflammation induced by immune complexes in the microcirculation

The aims of the studies presented in this publication were to elucidate the morphology and quantitate the kinetics of an inflammatory reaction elicited by immune complexes and to ascertain the role of complement in the reaction. The hallmark of both the direct active (DAA) and reversed passive (RPA) Arthus reactions was the accumulation of immune precipitates and polymorphonuclear leukocytes (PMNs) in and around vessels. Using fluoresceinated antigen as a tracer, immune complexes localized in the lumina and walls of venules and small veins in the DAA and in the wall of vessels and perivascularly in RPA. PMNs accumulated at these same sites, phagocytosed the fluoresceinated complexes and became degranulated. The precise localization of immune complexes was achieved by examining the same tissue sections first by fluorescence microscopy, followed by conventional staining and examination by light microscopy. Marked stasis of the microcirculation was observed, particularly in DAA, in which a few immune complex-containing PMNs were entrapped in a mass of densely packed red blood cells. Some edema was observed in early lesions and definitive separation of collagen fibers was noted in lesions older than 2 hr. Hemorrhage became the dominant characteristic of both types of reactions from 2 hr onward. By administering radiolabeled cells, proteins, and microspheres as a "pulse," given at various times before sacrifice, the quantitation and kinetics of the inflammatory lesions elicited by immune complexes could be elucidated. In RPA all parameters quantitated reached a peak soon after elicitation of the reaction (2-4 hr), which is in keeping with other forms of acute inflammation. In DAA there was some difficulty in assessing the quantitation because of interanimal variations and because of progression of the inflammatory lesions, as the antigen diffused peripherally from the site of its injection. Peak activities occurred in 4- to 8-hr-old lesions. These observations and a comparison of the center and periphery of the lesions, strengthen the contention that the RPA and DAA have common features and features which differ. In common are immunological mechanisms (antigen-antibody interaction and complement activation) and cellular events (polymorphonuclear leukocyte chemotaxis, phagocytosis, and release of lysosomal contents). Different features are the site of immune complex formation and its sequelae. In RPA they form primarily in the wall of venules and small veins and hence have a marked effect on increase in vessel permeability. In the DAA most of the complexes form and the leukocytes accumulate in the lumen of the same vessels.(ABSTRACT TRUNCATED AT 400 WORDS)

Cellular transfer of autoimmune aspermogenic orchiepididymitis (AIAO) by the i.v. route in the guinea pig

In this study, AIAO was adoptively transferred with a high proportion of success to syngeneic recipient guinea pigs. Donors of strains 2 and 13 were sensitized with a series of spermatozoal autoantigens (whole spermatozoa and three autoantigens isolated therefrom: S, P and T). Syngeneic (experimental) and allogeneic (control) recipients were all transferred by strictly i.v. injections of lymphoid cells. The damage observed in testis and epididymis (mainly in the latter) was identical to, but milder than, that seen in active forms of AIAO. The incidence and severity of the disease were dependent on: the type of inducing antigen, S, T, P in order of decreasing efficiency; the length of immunization in donors, with increasingly serious lesions as periods ranged from 1 to 4 weeks; the presence or not of a complementary treatment of recipients with bacterial adjuvant enhancing the disease. Other parameters were less important, such as the strain 2 or 13 specificities, the amount of immunogen or the addition of peritoneal cells to lymph node cells. Skin hypersensitivity was concomitantly transferred to a large majority of isogenic recipients. But the incidence and severity of the disease showed only a partial correlation with Arthus type or delayed type responses to autoantigens. Thus guinea pig AIAO, already known to be transferable by immune sera (mainly anti-P and also anti-T) may also be transferred in physiological conditions by sensitized lymphoid cells (mainly anti-S and also anti-T).

Generation of C5a and prostacyclin (PGI2) in an inflammatory response to zymosan and a reversed passive Arthus-type reaction in the peritoneal cavity of the rabbit

Exudate fluids were removed from the rabbit peritoneal cavity 2 h after the injection of zymosan or the initiation of a reversed passive Arthus-type reaction. Inflammatory oedema was measured using Evans blue dye extravasation and the concentrations of C5a and the PGI2 metabolite, 6-oxo-PGF1 alpha, were measured by radioimmunoassay. High levels of C5a were found in these inflammatory exudates and we suggest that the extravascular generation of C5a is important in the induction of increased microvascular permeability. The presence of PGI2 may have an enhancing effect on plasma protein leakage.

Lipopolysaccharide tolerance inhibits eye inflammation. II. Preliminary studies on the mechanism

The effect of endotoxin tolerance on ocular inflammation was studied in rabbits. Compared with a control group, a passive Arthus reaction in tolerant rabbits was characterized by a sharp decline in the expected increase in vascular permeability and slightly reduced leukocyte extravasation. Aqueous humor withdrawal (paracentesis) and intravitreal injection of prostaglandin E2 were also examined in lipopolysaccharide (LPS)-tolerant rabbits; in both circumstances, ocular protein exudation was decreased. These studies suggest that the prostaglandin system is particularly affected in the ocular responses of LPS-tolerant rabbits, and raise the possibility that other phenomena described in LPS tolerance may have a similar basis.

Immune-mediated migration of neutrophils into the uterine lumen of guinea pigs

Metritis was elicited by intrauterine infusion of tuberculin or killed Campylobacter fetus ssp. venerealis into vaccinated guinea pigs and lipopolysaccharide or immune complexes into normal animals. The local inflammatory response to intrauterine infusion of antigens, lipopolysaccharide, and immune complexes was determined by changes in differential cell counts in the uterine lavage fluid and by histopathological examination of uterine tissue. The percentage of neutrophils was significantly (p less than 0.01) greater in uterine lavage fluid collected at 4 hr after infusion of tuberculin into animals vaccinated locally (intrauterine) with M. tuberculosis than in animals vaccinated parenterally (subcutaneously). In contrast, the local response to infusion with C. fetus ssp. venerealis was approximately the same in animals vaccinated intrauterine and subcutaneously with Campylobacter. The systemic response, measured by the delayed type hypersensitivity cutaneous reaction to intradermal injection of tuberculin, was significantly (p less than 0.01) greater in animals vaccinated subcutaneously than intrauterine. Similarly, the concentration of Campylobacter antibody in the serum of animals vaccinated subcutaneously was significantly (p less than 0.01) greater than in guinea pigs vaccinated intrauterine. The intrauterine infusion of immune complexes, composed of C. fetus ssp. venerealis and corresponding antibody, into the uterus of normal guinea pigs stimulated neutrophil migration into the uterine lumen. Infusion of lipopolysaccharide also stimulated neutrophil migration into the uterine lumen. A correlation between an increased percentage of neutrophils in uterine lavage fluid and infiltration of the uterine epithelium with neutrophils was observed.

Immunologic mechanisms of parenchymal lung injury

The lung, like most other organs, is susceptible to injury by circulating immune complexes, and also by humoral autoantibody and immune lymphocytes which specifically recognize selected lung antigens. In addition, by virtue of its direct communication with the external environment, the lung can also be injured by inhaled environmental agents which trigger inflammatory reactions mediated by immune effector systems. Although major emphasis to date has been placed on the ability of inhaled antigens to first sensitize, then provoke, immunologically specific reactions in the lung, there is increasing evidence to show that these same immune effector systems are also triggered in an immunologically nonspecific fashion by a certain environmental agents (termed "mitogens") which activate leukocytes in a polyclonal fashion. Such agents include certain viruses and other microorganisms, bacterial endotoxin, a wide variety of plant lectins, and certain chemicals, such as the phorbol esters. Although such agents act in an immunologically nonspecific fashion, they are nonetheless quite specific from a chemical viewpoint, and in many cases act by binding to specific receptors on the cell surface. By activating macrophages directly, and by activating much larger percentages of a given lymphocyte population than do specific antigens, they induce correspondingly amplified inflammatory reactions in vivo. Recent studies with animal models indicate that inhaled mitogens are strikingly effective in inducing pulmonary inflammation, whereas inhaled antigens (lacking mitogenic activity) produce little if any parenchymal injury in immunized recipients, unless administered in conjunction with a mitogen. Ongoing studies using such models promise to provide valuable new insight into the biologic properties which govern the pathogenicity of inhaled environmental agents, the mediators they release, and the biochemical basis for variations in individual susceptibility to injury by such agents.

Studies on the antigenicity of glucagon

In order to test the safety of glucagon (GG), the immunogenicity of GG was studied in rabbits and guinea pigs. Any sensitization, as revealed by anaphylactic shock, Arthus reaction, passive cutaneous anaphylaxis (PCA) or radioimmunoassay, was not demonstrated in animals immunized with GG alone. The anti-GG antibodies were detected by PCA and radioimmunoassay in two of the five animals immunized with GG mixed with Freund's complete adjuvant. Anti-GG IgE antibody production in mice was found in one of the ten mice given 570 micrograms and three of the six mice given 1,000 micrograms of GG with aluminum hydroxide gel (Alum), but other doses of GG with Alum produced no IgE antibody. These results indicate that the antigenicity of GG is very weak.

Prostaglandins and the inflammatory response

Prostaglandins not only mediate the classic signs of inflammation but also help to regulate the function of cellular constituents in an inflammatory reaction. Clinical and experimental evidence of the role of prostaglandins as mediators is highlighted.

Antiinflammatory effects of endotoxin. Inhibition of rabbit polymorphonuclear leukocyte responses to complement (C5)-derived peptides in vivo and in vitro

Although capable of provoking a variety of inflammatory effects, endotoxin (bacterial lipopolysaccharide) paradoxically has been reported to be antiinflammatory. The authors have found that single intravenous injections of Escherichia coli endotoxin, 24 hours before challenge, inhibit almost completely the vascular permeability changes and exudation of polymorphonuclear leukocytes induced in rabbit skin by reversed passive Arthus reactions. Whereas intravenous injections of endotoxin also caused modest inhibition of the vascular permeability changes induced in rabbit skin by the synthetic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP), exudation of polymorphonuclear leukocytes was unaffected. Polymorphonuclear leukocytes from rabbits given single injected doses of endotoxin exhibited markedly diminished chemotactic and degranulation responses to complement (C5)-derived peptides in vitro. Responses of these cells to FMLP, however, were normal. These data suggest that selective suppression of polymorphonuclear leukocyte responses to C5-derived peptides accounts, in part, for the antiinflammatory effects of endotoxin.

The delayed-type hypersensitivity response to (4-hydroxy-3-nitrophenyl) acetyl- (NP) coupled proteins is carrier-specific: in vivo and in vitro demonstrations

In vivo and in vitro approaches for measuring DTH to NP and the cross-reactive hapten, NIP, were taken. Mice were immunized subcutaneously with NP-OVA, NP-BGG or NP-CGG in CFA or NP-spleen cells, challenged intradermally with NP or NIP-coupled to a heterologous carrier, and footpad or ear swelling determined 4, 24, and 48 h later. Alternatively, draining LNC were removed and challenged in vitro with either haptenated protein or haptenated, irradiated, syngeneic spleen cells to induce lymphotoxin (LT) production or proliferation. Our results show that although carrier-specific DTH responses are easily elicited both in vivo and in vitro, NP-specific DTH effector cells cannot be evoked by conventional immunization regimens. This failure to induce hapten-specific DTH is not due to suppressor mechanisms. Attempts to induce LT production and T cell proliferation by re-exposure to NP were unsuccessful. Immunization with NP-coupled protein in CFA does elicit an intense Arthus reaction when mice are challenged with the hapten 8 days later. The antibody-mediated nature of this hapten-specific response is indicated by the kinetics of the reaction, which peaks 4 hr after challenge, intensely positive ELISA of circulating anti-NP antibodies, sensitivity to pretreatment with a high dose of cyclophosphamide, and the ability to transfer the reaction to naive recipients with serum. This early response is highly cross-reactive with NIP and is not restricted to mice of the igh-1b allotype.