The first component of the kinin-forming system in human and rabbit plasma. Its relationship to clotting factor XII (Hageman Factor)

Complement, Kinins, and Hereditary Angioedema: Mechanisms of Plasma Instability when C1 Inhibitor is Absent

Plasma of patients with types I and II hereditary angioedema is unstable if incubated in a plastic (i.e., inert) vessel at 37 °C manifested by progressively increasing formation of bradykinin. There is also a persistent low level of C4 in 95 % of patients even when they are symptomatic. These phenomena are due to the properties of the C1r subcomponent of C1, factor XII, and the bimolecular complex of prekallikrein with high molecular weight kininogen (HK). Purified C1r auto-activates in physiologic buffers, activates C1s, which in turn depletes C4. This occurs when C1 inhibitor is deficient. The complex of prekallikrein-HK acquires an inducible active site not present in prekallikrein which in Tris-type buffers cleaves HK stoichiometrically to release bradykinin, or in phosphate buffer auto-activates to generate kallikrein and bradykinin. Thus immunologic depletion of C1 inhibitor from factor XII-deficient plasma (phosphate is the natural buffer) auto-activates on incubation to release bradykinin. Normal C1 inhibitor prevents this from occurring. During attacks of angioedema, if factor XII auto-activates on surfaces, the initial factor XIIa formed converts prekallikrein to kallikrein, and kallikrein cleaves HK to release bradykinin. Kallikrein also rapidly activates most remaining factor XII to factor XIIa. Additional cleavages convert factor XIIa to factor XIIf and factor XIIf activates C1r enzymatically so that C4 levels approach zero, and C2 is depleted. There is also a possibility that kallikrein is generated first as a result of activation of the prekallikrein-HK complex by heat shock protein 90 released from endothelial cells, followed by kallikrein activation of factor XII.

The Lectin Pathway of Complement and Biocompatibility

In modern health technologies the use of biomaterials in the form of stents, haemodialysis tubes, artificial implants, bypass circuits etc. is rapidly expanding. The exposure of synthetic, foreign surfaces to the blood and tissue of the host, calls for strict biocompatibility in respect to contact activation, the coagulation system and the complement system. The complement system is an important part of the initial immune response and consists of fluid phase molecules in the blood stream. Three different activation pathways can initiate the complement system, the lectin, the classical and the alternative pathway, all converging in an amplification loop of the cascade system and downstream reactions. Thus, when exposed to foreign substances complement components will be activated and lead to a powerful inflammatory response. Biosurface induced complement activation is a recognised issue that has been broadly documented. However, the specific role of lectin pathway and the pattern recognition molecules initiating the pathway has only been transiently investigated. Here we review the current data on the field.

Ficolin-2 reveals different analytical and biological properties dependent on different sample handling procedures

Ficolin-2 (L-ficolin) is a germ line encoded pattern recognition molecule circulating in the blood, and functions as a recognition molecule in the lectin complement pathway. However, consistent and reliable measurements of Ficolin-2 concentration and activity have been difficult to achieve. After recurrent observations of deviations in Ficolin-2 properties between different blood sample procedures, we decided to investigate this closer. Blood samples from ten healthy donors were collected in various serum and plasma tubes and Ficolin-2 properties were evaluated by different ELISA setups. We found that serum prepared from tubes containing the clot activator silica used as a standard technique in many routine laboratories held a significantly lower concentration of Ficolin-2 as compared to the other sample types. Furthermore, Ficolin-2 binding and complement activation potential in this type of serum was impaired when using an acetylated compound as matrix. On the other hand, Ficolin-2 in serum made without clot activator and in plasma irrespective of additive used, had the same concentration and was capable of initiating the lectin pathway measured as C4 and C3 deposition on the ligand. No Ficolin-2 mediated formation of the terminal complement complex was observed under the applied assay conditions. In conclusion, our results show that Ficolin-2 is a promiscuous molecule and that care should be taken during sampling, handling and matrix chosen for measurement of Ficolin-2 levels and activity.

Enhancement of B cell and monocyte populations in rats exposed to chlorpheniramine

Chlorpheniramine is an anti-histamine agent on IgE-mediated inflammation. In order to investigate the immunomodulatory effects of chlorpheniramine, we assessed the changes of peripheral mononuclear cell populations and other general clinical parameters, including hematology and clinical chemistry, following chlorpheniramine administration in rats. Since prednisolone is commonly co-prescribed with anti-histamine in many hypersensitive reactions, we also examined the changes to compare the results after the prednisolone administration. Chlorpheniramine (50, 100 and 200 μg/kg) and prednisolone (1, 2 and 4 mg/kg) were intramuscularly administered to female Sprague-Dawley (SD) rats 3 times, at intervals of 1 week. Except the clinical signs, such as stiffness and abnormal gait due to the local toxicity at injection sites, no other significant changes in body weights, urinalysis, and macroscopic examination were noted in the animals given chlorpheniramine. On the other hand, white blood cells, especially B cells and monocytes, showed a dose-dependent increase in the chlorpheniramine-treated animals; whereas, the numbers of both B and T cells (helper T and cytotoxic T, NKT cells) were decreased in the prednisolone-treated animals. Taken together, these results suggest that chloropheniramine administration enhances white blood cells in the peripheral blood, mostly due to increases of the B cells and monocytes, but no T cells and NK cells.

Immunkomplex-Krankheiten bei Mensch und Tieren

Zusammenfassung

Summary

Acquired factor XII Deficiency in a patient with nephrotic syndrome

A patient with nephrotic syndrome and an acquired factor XII deficiency associated with a factor XII-like procoagulant activity in the urine was investigated. The urinary protein with procoagulant activity was isolated and comparative investigations revealed similar properties to plasma factor XII. It is suggested that the acquired coagulation defect may result from an insufficient biosynthetic capacity to compensate for the loss of factor XII in the urine.

Update on pathogenic mechanisms of systemic necrotizing vasculitis

Systemic necrotizing vasculitis is rare but can have serious sequelae. Despite recent advances in cellular and molecular immunology and genetics, the causes of vasculitic syndromes remain largely undefined. Although mechanisms of blood vessel damage in systemic necrotizing vasculitis are complex, recent studies have provided significant insights.

A swine model of horse serum-induced coronary vasculitis: an implication for Kawasaki disease

An attempt was made to induce immune complex vasculitis by horse serum (HS) infusions in piglets, hoping to produce experimental coronary artery lesions that mimic Kawasaki disease. A total of 21 purebred male piglets of 1.5, 2.5, and 3 mo were divided into HS (n = 14) and control, normal saline (NS; n = 7) groups. In seven piglets, 5 mL/kg of HS was infused, then repeated with 10 mL/kg 10 d later. In another seven piglets, 10 mL/kg of HS was infused three times at 5-d intervals. In three piglets in the control group, 5 and 10 mL/kg of NS was infused at 10-d intervals. In another four piglets of the control group, 10 mL/kg of NS was infused three times at 5-d intervals. Two-dimensional echocardiographic examinations for visualization and measurement of the coronary arteries were done before and after infusions at 4- to 5-d interval. Hematology examination showed that white blood cells and platelets decreased, then increased. The animals were killed at 14-60 d after the first infusion of HS or NS, for histopathologic and immunohistochemical studies. All HS groups developed skin rashes and echocardiographic evidence of coronary artery dilation and histopathologic changes of vasculitis. None in the NS group developed vasculitis. The main changes of the coronary vasculitis were intimal proliferation, smooth muscle cell necrosis, and vacuolization changes. Those that received three HS infusions developed more skin rashes than those that received two infusions. It is concluded that piglets may serve as an experimental model for immune complex vasculitis involving the coronary arteries with skin rashes mimicking Kawasaki disease.

Studies on factor XII in porcine plasma: purification and its conversion to activated form by porcine plasma kallikrein

When porcine plasma was subjected to four steps of ion-exchange column chromatographies, factor XII (F. XII) was separated into two fractions, F. XII-1 and F.XII-2, and about 8.5 mg of F. XII-1 and 2.3 mg of F. XII-2 were obtained from 675 ml of the plasma. The purified proteins were found to give a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The molecular masses of F. XII-1 and XII-2 were estimated to be about 84 kDa by SDS-PAGE, and consisted of a single polypeptide chain. However, F. XII-1 converted to active form after removing Polybrene, but F. XII-2 was not activated. Activation of F. XII-2 took place on incubation with porcine plasma kallikrein, and the activation rate was increased only in the presence of negatively charged surfaces, such as sulfatide. When the preparation was incubated with sulfatide, spontaneous activation was not observed on the condition that we used. Activation of porcine F. XII-2 by porcine plasma kallikrein was found to involve the cleavage of the peptide bond on the disulfide-bridged polypeptide chain, and further fragmentation of activated form was observed during prolonged incubation time.

Role of platelets in progressive glomerular diseases

There is increasing evidence that platelets are involved in the pathogenesis of glomerulonephritis. Intraglomerular platelets or their degradation products are observed in biopsies from patients with lupus nephritis, mesangioproliferative, membranous or IgA nephropathy. Moreover shortened platelet survival in patients with various glomerular diseases has also been described. In models of experimental glomerulonephritis, platelets may participate in glomerular injury, together with other mediators, by complex mechanisms. As extensively documented, platelets release within the glomerulus vasoactive, chemotactic and mitogenic substance that interact with a number of soluble mediators generated by renal resident or inflammatory cells and contribute to amplify glomerular injury. Thus platelet-activating factor and other platelet secretory products, polycationic macromolecules, platelet factor 4 and beta-thromboglobulin, alter glomerular permeability to proteins and enhance immune-mediated glomerular injury. Platelet-derived factors, like platelet-derived growth factor (PDGF) and transforming growth factor beta (TGF beta) mediate renal disease progression in experimental and human glomerulonephritis via their chemotactic activity for infiltrating leucocytes and their effect of promoting extracellular matrix synthesis by resident renal cells. In these settings increased renal expression of PDGF and TGF beta has correlated with clinical features. Specific PDGF and TGF beta inhibitors ameliorated experimental glomerular disease. A wide variety of therapies to inhibit platelet function have been employed over the years, however the results of clinical studies are controversial and do not allow conclusions to be drawn about the efficacy of anti-platelet agents in progressive renal disease. Identification of specific platelet inhibitors or interventions specific for platelet secretory products and their target cells will be crucial for understanding the exact role of platelets and their products in glomerular disease.

Livedo vasculitis: vasculitis or thrombotic vasculopathy?

Elevated fibrinopeptide A levels, suggestive of a thrombogenic state, were observed in six patients with livedo vasculitis. Serological studies demonstrated normal complement levels, and circulating immune complexes were not identified by standard assays. Morphological studies showed no evidence of immune complex deposition or a neutrophilic vascular reaction. These results support classification of this disorder as a thrombogenic vasculopathy rather than as a small vessel vasculitis. Further investigations into the thrombotic abnormalities underlying this entity are warranted.

Anti-IgE autoantibodies in systemic lupus erythematosus. Prevalence and biologic activity

IgG and IgM autoantibodies directed against IgE were determined in 95 serum samples from 67 patients with systemic lupus erythematosus, by an enzyme-linked immunosorbent assay. IgM anti-IgE autoantibodies were found in 18 patients (27%) and IgG anti-IgE autoantibodies were detected in 23 patients (34%). The specificity of the immunoassay was confirmed by the ability to inhibit binding with IgE myeloma, but not other immunoglobulin isotypes and the demonstration that the reactivity was directed to the Fc epsilon fragment of IgE. The IgG fraction of certain sera with anti-IgE activity was capable of inducing histamine release from control basophils and cutaneous mast cells. Clinical associations with the presence of anti-IgE activity were sought by retrospective chart analysis of 61 patients. Significant correlation was found with articular involvement, lymphadenopathy, and anti-DNA antibodies (P less than 0.05). Anti-IgE autoantibodies are observed in a significant number of patients with systemic lupus erythematosus and may contribute to the pathogenesis of the vascular and articular lesions characteristic of this disease.

Renal cell carcinoma and vasculitis: report of two cases

A 63-year-old caucasian male with systemic leukocytoclastic vasculitis involving the skin, lungs, and gastrointestinal tract was found to have a renal cell carcinoma at autopsy. A 77-year-old-woman with a history of hypertension was felt to have temporal arteritis that was confirmed by biopsy. The autopsy revealed a renal cell carcinoma in association with widespread giant cell arteritis. The possible association of renal cell carcinoma with vasculitis and an assessment of the possible clinical usefulness are presented and cases of vasculitis with renal neoplasms are briefly reviewed.

Ultrastructure of the Arthus Phenomenon in muscle

Specific blood-tissue barrier alterations were observed in a 2-year-old boy with a myopathic lesion in his muscle. Close by, degenerative changes were present in muscle fibers, three types of vascular abnormalities, i.e. increased vascular permeability, neutrophil aggregation, and damage of endothelium with thrombi formation, suggest that a process of vasculitis took place in the muscle of this patient. On the basis of current information it is not entirely clear whether this Arthus-like reaction observed in the primarily affected muscle represents a widespread vascular bed defect or whether it is the consequence of an additional secondary symptom possibly dependent upon muscle necrosis.

Factors influencing immune complex localisation

In systemic immune complex (IC) diseases such as SLE and rheumatoid vasculitis, IC accumulate in a number of tissues, either after deposition from the circulation or from in situ formation. The tissue localisation of IC depends on a delicate balance between the production of IC and the ability of the mononuclear phagocytic system (MPS) to remove them from blood. At times IC are cleared inefficiently, persist in the circulation and subsequently localise in tissues. This review evaluates the role of local tissue factors - anatomical, physiological, physical and immunological - in this process. We report on our studies examining the significance of C3b and IgG Fc receptors in tissues subject to IC deposition. No evidence for such receptors was found with the exception of a C3b receptor in human glomeruli. Our negative findings may be due to methodological difficulties in the identification of in situ receptors. Alternatively, immune receptors may not be present at these extra-glomerular sites and would therefore be unlikely to participate in IC localisation.

Influence of augmented Hageman factor (Factor XII) titers on the cryoactivation of plasma prorenin in women using oral contraceptive agents

Prolonged cold storage of plasma may induce the conversion of plasma prorenin (inactive renin) to renin. This phenomenon is exaggerated in oral contraceptive (OC) users; the titer of Hageman factor (HF, Factor XII) in OC users is higher than in nonusers. The present study relates these observations. The increment in plasma renin activity (PRA) during cold storage, as measured by generation of angiotensin I, correlated strongly with the initial plasma titer of HF. Increasing the HF titer of nonusers to that observed in OC users by addition of purified HF increased cold-induced PRA at least twofold, while reducing the plasma HF titer of OC users correspondingly decreased cold-induced PRA. Thus, in OC users, the enhanced conversion of plasma prorenin to renin during cold storage reflects the elevated plasma titer of HF.

The role of hypertension in the vascular disease and myocardial infarcts associated with murine systemic lupus erythematosus

The several kinds of mice that spontaneously develop acute systemic lupus erythematosus (SLE)--BXSB males, MRL/l males and females, and (NZB X W)F1 females--have a 15-20% incidence of degenerative vascular disease (DVD) and myocardial infarcts (MI) in which the affected coronaries contain deposits of immunoreactants, presumably in the form of immune complexes. Among the F1 hybrid crosses of SLE mice, only the (NZW X BXSB)F1, (W X B)F1 male has a significantly higher incidence of DVD/MI (80%). Search for possible causes of this high incidence of myocardial infarcts revealed several unique features of this mouse: hypertension, thrombocytosis, and early onset of circulating immune complexes and glomerulonephritis. Our attempts to prevent this DVD/MI focused on: reduction of hypertension, prevention of thrombosis, and immunosuppression. Immunosuppression by Cytoxan resulted in almost complete prevention of both the SLE disease and DVD/MI. Administration of bretylium, an antihypertensive and anti-arrhythmic agent, resulted in reduction of blood pressure and the severities of glomerulonephritis, DVD, and MI; it also slightly reduced the levels of circulating immune complexes and leukocytosis. Of the 4 antithrombotic agents used, only aspirin showed some reduction in the incidence of DVD/MI and delay of glomerulonephritis-associated mortality.

Neurological complications of vasculitis

The vasculitides are a group of disorders that include the polyarteritis nodosa group of systemic necrotizing vasculitides, hypersensitivity vasculitis, Wegener's granulomatosis, lymphomatoid granulomatosis, giant cell arteritis, Behçet's disease, and isolated angiitis of the central nervous system. Classification is based on clinical, angiographic, and histological features. The frequency and distribution of neurological involvement vary with the underlying disorder and may provide the initial symptoms. Polyarteritis nodosa and Wegener's granulomatosis may affect both the central and peripheral nervous systems, whereas isolated angiitis of the central nervous system and Behçet's disease affect the central nervous system alone. Neurological dysfunction occurs in 80% of patients with polyarteritis nodosa and fewer than 10% of patients with hypersensitivity vasculitis. The mechanism of neurological dysfunction in the vasculitides is tissue ischemia. The clinical effects of ischemia vary, and symptoms may be transient or prolonged. Mononeuritis multiplex, polyneuropathy, and stroke are frequent complications, but encephalopathies, cranial neuropathies, and brachial plexopathies are seen as well. The occurrence of symptoms late in the course of a disease suggests ischemia resulting from healed, scarred vessels as well as from those that are acutely inflamed; this is the case in Takayasu's arteritis and possibly also in polyarteritis nodosa. Treatment is based on identifying and removing the sensitizing agent when possible. Wegener's granulomatosis requires therapy with cyclophosphamide; temporal arteritis, with corticosteroids. In other vasculitides a balance must be reached between the progression of the disease and the side effects of immunosuppression.

Endocardial lesions in acute serum sickness in the rabbit. A scanning electron microscopic study

Endocardial lesions in acute serum sickness in rabbits were studied with the aid of scanning electron microscopy (SEM). Prominent inflammation developed most often in the ventricular (pocket) side of the mitral valve and was confined to a hollowed area formed between valvular ridges. The early lesion consisted of swelling of endothelial cells with monocytic attachments. Subsequently, frequent endothelial perforations occurred, through which a number of monocytes emigrated into the subendothelial space. Focal or diffuse endothelial desquamation then followed. SEM revealed that the denuded basement membrane also had many perforations enabling monocytic emigration into the deeper valve layer. The accumulated monocytes and proliferating mesenchymal cells produced a granulomatous focus in the valvular tissue in which some monocytes were observed to convert to Anitschkow cells. Infiltration by polymorphs was minimal. Deposition of fibrin occurred in the more severe valvulitic lesions, but no verrucous vegetation formation was observed. The inflammatory process regressed rapidly, leaving focal areas of fibrosis. A possible pathogenesis is discussed in connection with the pathophysiologic conditions of the mitral valve pocket.

Platelets as target cells in rheumatoid arthritis and systemic lupus erythematosus: a platelet specific immunoglobulin inducing the release reaction

Sera from patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) were assessed for in vitro platelet activation as measured by serotonin release; 24% (30) of 124 tested RA sera and 51% (35) of 69 SLE sera induced a significant 3H serotonin release. Investigation of 17 synovial fluid samples from RA patients revealed significant release in 82%. Concomitant testing for lymphocytotoxic antibodies and immune complexes did not show any correlation to platelet activation. Upon gel filtration the release-inducing activity of positive sera was localized in the region of 160 000 Daltons. Further characterization by ion exchange chromatography, immune electrophoresis, chromatographic and SDS PAGE molecular weight determinations, as well as analytical ultracentrifugation all confirmed the IgG nature of the release-inducing protein. Negative blocking experiments performed by preincubation of platelets with Fc-IgG fragments prior to challenge with a release-inducing serum excluded the participation of Fc receptors in the reaction. It was concluded that the release was caused by a platelet reactive IgG antibody. This antibody may also cause release of platelet mediators in vivo and may thus contribute to the pathogenesis of the generalized vasculopathy in both diseases.

Guinea pig Hageman factor as a vascular permeability enhancement factor

Hageman factor was purified from guinea pig plasma by successive column chromatography. The guinea pig Hageman factor appeared homogeneous as a single-chain protein on polyacrylamide gels in the presence of sodium dodecyl sulfate (SDS) and beta-mercaptoethanol. The apparent molecular weight was 76,000 daltons by SDS--polyacrylamide gel electrophoresis and 105,000 daltons by gel filtration with a Sephadex G-150 column. Amino acid composition of the guinea pig Hageman factor was similar to that reported for human, bovine, and rabbit Hageman factors. The purified guinea pig Hageman factor, as well as guinea pig plasma, showed strong clotting time correction activity in Hageman-factor--deficient human plasma. The activity could be blocked by the IgG fraction of antiserums against guinea pig Hageman factor raised in rabbits or a goat. The concentration of Hageman factor in guinea pig plasma was determined to be 120 microgram/ml by quantitative radial immunodiffusion assay. The 28,000-dalton active form of Hageman factor (beta-HFa) was prepared from guinea pig Hageman factor by treatment with plasma kallikrein. beta-HFa caused an increase in vascular permeability when injected into guinea pig skin at concentrations as low as 3 x 10(-10) M (0.8 ng). Native, or zymogen Hageman factor did not cause an increase in permeability at concentrations of up to 2 x 10(-7) M. The increased permeability induced by beta-HFa was short lasting, with about a 50% decrease in activity apparent within 6 minutes after intradermal injection. The permeability enhancement activity of beta-HFa was inhibited by pretreatment of beta-HFa with diisopropylfluorophosphate. It may be concluded that active Hageman factor in the interstitial space of guinea pigs acts as a vascular permeability factor of far greater potency than bradykinin.

Pathopysiological aspects of immune complex diseases. Part II. Phagocytosis, exocytosis, and pathogenic depositions

Elimination of IC by the phagocytic system occurs mainly by macrophages and contrarotates to the pathogenic effect. Decisive to prevent systemic IC disease is the capacity of the phagocytic system. In the case of its saturation, the danger of the occurrence of IC disease is greatly enhanced. Conclusive evidence seems to exist that IC of extremely small or extremely high lattice structure (precipitates) are less pathogenic than soluble IC of medium network. Small IC in extreme antigen and antibody excess or precipitates exhibit a reduced complement activating potency. Small IC in extreme antigen or antibody excess hardly interact in vitro with membrane receptors and do not induce IC disease when injected or formed in vivo. Highly lattices IC, especially precipitates, are eliminated extremely quickly from the circulation, mainly by macrophages and there deposition in the kidney is significantly reduced. Thus, lack of quality of the antibody to precipitate the antigen and a reduced capacity and effectivity of the phagocytic system to eliminate the IC may be extremely important in the generation of IC diseases. Facing the overwhelming and partly even inconsistant data of this topic, one may doubt whether IC diseases may be regarded to be a defined and coherent disease. Too many variables and questions exist concerning the nature of the antigen, especially in tumor and autoimmune diseases, concerning the quality of the antibody and the characteristics of the pathogenic IC and concerning localization and the elimination process. Nevertheless, common pathophysiological pathways of IC diseases may be recognized.

Isolation and characterization of bovine plasma prekallikrein (Fletcher factor)

Prekallikrein (Fletcher factor) has been purified from bovine plasma approximately 25 000-fold with an overall yield of 14%. Purification steps included ammonium sulfate fractionation and column chromatography on heparin-agarose, DEAE-Sephadex, CM-Sephadex, benzamidine-agarose, and arginine methyl ester-agarose. The purified protein was homogeneous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino-terminal sequence analysis. Bovine plasma prekallikrein is a glycoprotein with a molecular weight of 82 000 as determined by sedimentation equilibrium centrifugation. It contains 12.9% carbohydrate, including 6.2% hexose, 4.5% N-acetylglucosamine, and 2.2% N-acetylneuraminic acid. Prekallikrein is a single polypeptide chain with an amino-terminal sequence of Gly-Cys-Leu-Thr-Gln-Leu-Tyr-His-Asn-Ile-Phe-Phe-Arg-Gly-Gly. This sequence is homologous to the amino-terminal sequence of human factor XI (plasma thromboplastin antecedent). Both prekallikrein and kallikrein require kaolin to correct Fletcher factor deficient plasma. Kallikrein, however, has a specific activity 3.5 times greater than prekallikrein. Prekallikrein does not correct plasma deficient in factor XII (Hageman factor), factor XI, or high molecular weight kininogen (Fitzgerald factor).

The effect of puromycin on subepithelial deposits induced by antibodies directed against tubular antigens: a quantitative study

The mechanism of the GN induced by the intravenous injection of antibodies directed against renal tubular epithelial antigens (RTE) was studied by the use of antibody specifically purified by affinity chromatography. With this reagent RTE antigens could be demonstrated on frozen sections of glomeruli as well as on glomerular cells in culture. The antibodies were radiolabelled, and using paired label techniques glomerular binding could be measured in vivo. In normal rats, approximately 4% of the antibody injected was specifically bound in the glomeruli. Binding was not detectable on proximal tubular brush borders. In rats treated with 100 mg/kg of aminonucleoside of puromycin, a substance known to induce alterations of glomerular epithelial cells, it could be shown that glomerular binding was selectively decreased. These observations indicate that immune deposits in passive Heyman nephitis are formed mainly in situ and that local alteration of the glomerulus can markedly influence deposit formation.

Prekallikrein activator and kallikrein in acetone- and kaolin-activated rat plasma

Activation of plasminogen-free rat citrated plasma (RCPL-P) with acetone/kaolin yielded BAEe-esterase activities of 0.6--0.8 U/ml. Gel filtration demonstrated one single peak of BAEe-esterase activity (mol. wt. approximately 135000) with a kininogenase-esterase ratio (3.3) close to that known for human plasma kallikrein (2.7). Similarly activated rat citrated plasma (RCPL) revealed on gel filtration an additional esterase peak (mol. wt, approximately 47,000) with a low kininogenase-esterase ratio (0.3), and should accordingly not be used for a BAEe-esterase assay of rat plasma kallikrein. Acetone activation of RCPL-P and of RCPL yielded prekallikrein activator (PKA) activities which were about doubled by treatment with kaolin to 1.9--2.1 and 3.5--4.2 PKA-U/ml respectively. Gel filtration of acetone-activated RCPL-P or RCPL revealed two peaks of PKA activity, mol. wt. approximately 110,000 corresponding to activated factor XII (XIIa), and mol. wt. approximately 33,000 corresponding to XII fragments (XIIf). Kaolin-treatment of acetone-activated RCPL-P, but not of RCPL, caused an extensive fragmentation of XIIa to the 4--6 times more active XIIf. The lower yield of PKA-activity in acetone/kaolin-activated RCPL-P, as compared with activated RCPL, seems to be due to the absence of a factor of significance for the activation of factor XII, which is not plasmin, plasma kallikrein, or high molecular weight kininogen.

The fibrinolysin system in otitis media with effusion

Middle ear effusions can cause the fibrinolytic dissolution of human fibrin clots. The data presented herein indicate that the highest level of fibrinolytic activity and general proteolytic activity is found in the serous effusions. The mucoid effusions show the lowest levels of fibrinolytic activity. The significance of the fibrinolytic activity in middle ear fluids is not fully understood. Plasmin, the active protease of the fibrinolysin system, is capable of activating a number of proteolytic systems, including the intrinsic coagulation system, the vasoactive peptide system, and the complement system. All the inflammatory mediator systems can promote increased vascular permeability, tissue edema, and leukocytic migration. The relation of these systems to inflammation in the middle ear may have a profound influence on the possible conversion of a simple middle ear effusion into chronic otitis media.

The role of serotonin in Masugi nephritis in rabbits

In 12 rabbits with induced experimental Masugi nephritis and in 6 control rabbits the level of 5-HT in whole blood and 5-HIAA excretion in urine/24 h were studied. In all animals of the experimental group a significant increase of 5-HT and 5-HIAA was found, which was strictly correlated in time with two-phase immunological reaction occurring in Masugi nephritis. Moreover, the electorn microscope examinations showed a distinct thickening of glomerular basement membrane on the 8th day of experiment, i.e., at the time of maximum 5-HT increase in the blood, which according to the literature, can be interpreted as having been caused, if not exclusively, so at least among others, by direct action of endogenous 5-HT.

Experimental glomerular lesions induced by chronic immune complex formation. I. Formation and elimination of the immune complex (relationship between the immune status and the glomerular changes)

Chronic immune complex formation was induced in rabbits by daily administration of 12.5 g bovine serum. In good antibody producer animals immediate immune complex production and elimination from the circulation were demonstrable. This was followed within a few minutes by the appearance of free 125I in fairly large amounts in blood, as a sign of immediate phagocytosis and disintegration of the 125I-labelled immune complexes. Phagocytic activity decreased in the host animal during chronic heteroprotein administration in every case. The earliest glomerular changes were those of exudative glomerulonephritis, the extent of which depended on the antibody productivity of the animal. Persistent immunocomplexaemia induced by administration of the antigen over 60 and 100 days, respectively, resulted in mesangioproliferative glomerulonephritis in 7, in membranoproliferative glomerulonephritis in 3, and in membraneous glomerulonephritis in 1 out of 11 laboratory animals.

Acute asthma compared with exacerbations of chronic bronchitis: changes in complement

Complement levels were measured on admission and at 1 and 7 days following admission in twenty patients with acute severe asthma and ten patients with an acute exacerbation of chronic bronchitis. Although no evidence of hypocomplementaemia was found in any patient, there was a mean fall within the normal range of the individual complement components, C4, C3 and factor B in both groups. The mean fall occurred earlier in the bronchitics than in the asthmatics and this may be related to infection or the administration of corticosteroids. There was a significant fall in C3 (P greater than 0.05) in the bronchitics compared with the asthmatics at 24 hr. From our study, however, we could find no evidence of excessive utilization of complement in acute asthma.

Amidolytic properties of single-chain activated Hageman factor

Activation of Hageman factor (Factor XII) upon exposure to negatively charged agents has been attributed to proteolytic cleavage of this molecule. To examine this question, purified Hageman factor was exposed to Sephadex gels to which ellagic acid had been adsorbed. Such Hageman factor, separated from the gels and studied in the fluid phase, was amidolytic. Nonetheless, no cleavage of Hageman factor treated in this way could be demonstrated by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Thus, activation of Hageman factor by negatively charged agents was not necessarily accompanied by molecular scission.