Major histocompatibility complex class II expression by intrinsic renal cells is required for crescentic glomerulonephritis.

The requirement for major histocompatibility complex class II (MHC II) to initiate immune renal injury was studied in a murine model of CD4(+) T cell-dependent crescentic glomerulonephritis (GN). C57BL/6 (MHC II+/+) mice developed crescentic GN with glomerular CD4(+) T cell infiltration and renal injury, in response to a nephritogenic antigen (sheep globulin) planted on their glomerular basement membrane. MHC II-deficient C57BL/6 mice (MHC II-/-) did not develop crescentic GN, CD4(+) T cell infiltration, or injury, indicating that this form of immune glomerular injury is MHC II dependent. The requirement for MHC II expression by intrinsic renal cells was studied in chimeric mice, which expressed MHC II on bone marrow-derived cells and in the thymus, but not in the kidneys. These chimeric mice had normal T and B cell populations and MHC II expression in their spleens and lymph nodes and developed an immune response to systemically and cutaneously administered sheep globulin. However, they did not develop crescentic GN, CD4(+) T cell infiltration, or renal injury in response to the sheep globulin planted in their glomeruli. These studies demonstrate that interaction of CD4(+) T cells with intrinsic renal cells expressing MHC II is required for development of cell-mediated immune renal injury.

Plasminogen and plasminogen activators protect against renal injury in crescentic glomerulonephritis.

The plasminogen/plasmin system has the potential to affect the outcome of inflammatory diseases by regulating accumulation of fibrin and other matrix proteins. In human and experimental crescentic glomerulonephritis (GN), fibrin is an important mediator of glomerular injury and renal impairment. Glomerular deposition of matrix proteins is a feature of progressive disease. To study the role of plasminogen and plasminogen activators in the development of inflammatory glomerular injury, GN was induced in mice in which the genes for these proteins had been disrupted by homologous recombination. Deficiency of plasminogen or combined deficiency of tissue type plasminogen activator (tPA) and urokinase type plasminogen activator (uPA) was associated with severe functional and histological exacerbation of glomerular injury. Deficiency of tPA, the predominant plasminogen activator expressed in glomeruli, also exacerbated disease. uPA deficiency reduced glomerular macrophage infiltration and did not significantly exacerbate disease. uPA receptor deficiency did not effect the expression of GN. These studies demonstrate that plasminogen plays an important role in protecting the glomerulus from acute inflammatory injury and that tPA is the major protective plasminogen activator.

Protease-activated receptor 1 mediates thrombin-dependent, cell-mediated renal inflammation in crescentic glomerulonephritis.

Protease-activated receptor (PAR)-1 is a cellular receptor for thrombin that is activated after proteolytic cleavage. The contribution of PAR-1 to inflammatory cell-mediated renal injury was assessed in murine crescentic glomerulonephritis (GN). A pivotal role for thrombin in this model was demonstrated by the capacity of hirudin, a selective thrombin antagonist, to attenuate renal injury. Compared with control treatment, hirudin significantly reduced glomerular crescent formation, T cell and macrophage infiltration, fibrin deposition, and elevated serum creatinine, which are prominent features of GN. PAR-1-deficient (PAR-1(-/-)) mice, which have normal coagulation, also showed significant protection from crescentic GN compared with wild-type mice. The reductions in crescent formation, inflammatory cell infiltration, and serum creatinine were similar in PAR-1(-/-) and hirudin-treated mice, but hirudin afforded significantly greater protection from fibrin deposition. Treatment of wild-type mice with a selective PAR-1-activating peptide (TRAP) augmented histological and functional indices of GN, but TRAP treatment did not alter the severity of GN in PAR(-/-) mice. These results indicate that activation of PAR-1 by thrombin or TRAP amplifies crescentic GN. Thus, in addition to its procoagulant role, thrombin has proinflammatory, PAR-1-dependent effects that augment inflammatory renal injury.

Macrophage-induced glomerular fibrin deposition in experimental glomerulonephritis in the rabbit.

Glomerular fibrin deposition is important in the pathogenesis of renal failure and crescent formation in glomerulonephritis. The mechanisms of glomerular fibrin deposition are unknown. The current studies explored the role of macrophages in this process. Methods were developed for measuring glomerular fibrin deposition and glomerular procoagulant activity in a passive model of the autologous phase of antiglomerular basement membrane antibody-induced glomerulonephritis in rabbits. Significant fibrin deposition was observed to be associated with glomerular macrophage accumulation. Leukocyte ablation with mustine hydrochloride prevented both glomerular macrophage accumulation and fibrin deposition without affecting the coagulation system or the deposition of disease-inducing antibodies and complement. Repletion with mononuclear inflammatory cells produced significant fibrin deposition. To examine the role of tissue injury per se in glomerular fibrin deposition, a macrophage-independent model of glomerular injury (heterologous phase glomerulonephritis) was also studied. Although a similar degree of glomerular injury occurred, there was no significant fibrin deposition. This suggests that macrophages, rather than injury alone, are responsible for fibrin deposition. Lysates of isolated glomeruli containing macrophages demonstrated greatly enhanced procoagulant activity compared with lysates of glomeruli without macrophages. Thus macrophages appear to be directly responsible for glomerular fibrin deposition in antiglomerular basement membrane antibody-induced glomerulonephritis, and this appears to be due to their ability to express procoagulant activity rather than their propensity to cause glomerular injury.

Glomerular macrophages express augmented procoagulant activity in experimental fibrin-related glomerulonephritis in rabbits.

Glomerular fibrin deposition and augmentation of procoagulant activity (PCA) are dependent on glomerular macrophage infiltration in anti-glomerular basement membrane antibody-induced glomerulonephritis (anti-GBM GN) in rabbits. Expression of PCA on the surface of glomerular macrophages and/or augmentation of intrinsic glomerular cell PCA by macrophage cytokines (such as IL 1) are potential mechanisms by which macrophages may augment glomerular PCA. Macrophages were isolated from glomeruli of rabbits developing anti-GBM GN to measure their PCA expression. These macrophages were characterized by morphological and functional criteria. Glomerular macrophages expressed markedly augmented PCA (2.8 +/- 0.7 mU/10(3) cells) compared with blood monocytes (0.05 +/- 0.02 mU/10(3) cells) and alveolar macrophages (0.09 +/- 0.02 mU/10(3) cells) from the same rabbits. Glomerular macrophage PCA was functionally identical to the PCA of whole glomeruli, and was consistent with that of tissue factor. Supernatants from nephritic glomeruli contained IL 1 bioactivity and augmented endothelial cell PCA in vitro. However, these supernatants and purified IL 1 failed to augment the PCA of normal and macrophage-depleted nephritic glomeruli. These studies demonstrate that, in this model of anti-GBM GN, glomerular macrophages contribute directly to the augmented glomerular PCA by their expression of surface membrane PCA, and have the potential to indirectly augment glomerular PCA by their production of cytokines capable of enhancing endothelial cell PCA.

Glomerular procoagulant activity in human proliferative glomerulonephritis.

Mechanisms for initiation of glomerular fibrin deposition were studied using renal tissue obtained from two patients with rapidly progressive, crescentic glomerulonephritis. Histological examination showed extensive glomerular monocyte infiltration and fibrin deposition in both patients. Sonicated cell suspensions of isolated glomeruli from these patients contained markedly augmented levels of procoagulant activity (PCA) compared with the levels found in normal glomeruli. This PCA was characterized as tissue factor by its functional dependence on Factors VII and V, independence of Factors VIII and XII, inhibition by concanavalin A and phospholipase C, and association with cell membranes. Its coagulant activity was also inhibited by a specific monoclonal anti-human tissue factor antibody. Tissue factor could be identified in glomeruli from these two patients by indirect immunofluorescence using this antibody. These studies implicate extrinsic pathway activation via tissue factor in intraglomerular deposition of fibrin in these patients. Activated monocytes, known to be a potent source of procoagulant activity and seen in large numbers within glomeruli from these patients, are a likely source of this tissue factor.

Renal expression of tissue factor pathway inhibitor and evidence for a role in crescentic glomerulonephritis in rabbits.

Tissue factor pathway inhibitor (TFPI) was demonstrated in the kidneys of normal rabbits and in a crescentic model of glomerulonephritis (GN), where fibrin is a key mediator of injury. In normal kidneys, TFPI was expressed in glomeruli, in intrarenal arteries and the interstitial capillary network. Evidence for TFPI synthesis in vivo was provided by in situ demonstration of TFPI mRNA in glomeruli and intrarenal vessels and by biosynthetic labeling of TFPI released from glomeruli in vitro. In fibrin-dependent crescentic GN, glomerular TFPI synthesis and expression was initially decreased (TFPI antigen at 24 h, 7.5 +/- 0.7 ng/10(3) glomeruli; normal, 11.1 +/- 0.9 ng/10(3) glomeruli, P < 0.02) and subsequently returned to normal values. Plasma TFPI levels increased progressively throughout the evolution of disease. In vivo inhibition of TFPI using an anti-TFPI antibody during the development of GN significantly increased glomerular fibrin deposition (GFD) and exacerbated renal impairment. Infusion of recombinant human TFPI significantly reduced development of GFD (fibrin scores, TFPI treated 0.82 +/- 0.11, control 1.49 +/- 0.14, P < 0.01), proteinuria and renal impairment. This data indicates that TFPI is synthesized and expressed in normal glomeruli and is down regulated in the early response to glomerular injury. Endogenous glomerular TFPI and treatment with recombinant TFPI reduces GFD and injury in fibrin dependent GN. TFPI has the potential to be of therapeutic benefit in the management of fibrin dependent human GN.

Cyclosporine treatment reduces early atherosclerosis in the cholesterol-fed rabbit.

While T helper cell infiltration is an early event in the development of atherosclerosis in cholesterol-fed rabbits, their functional contribution to atherogenesis is not clear. To investigate their role, T cell activation was blocked with cyclosporine A (CsA) in New Zealand White (NZW) rabbits fed a 1% cholesterol diet. CsA was administered at a dose of 16 mg/kg body weight, intramuscularly every second day, resulting in circulating whole blood levels of 460 +/- 39 micrograms/l. After 4 weeks on the cholesterol diet, untreated rabbits developed atherosclerotic plaques covering 74.4% +/- 3.5% of their aortic arch, 19.8% +/- 7.8% of their thoracic aorta and 19.8% +/- 6.2% of their abdominal aorta. T cells were observed in plaques of their aortic arches (CD5 positive, 11.1 +/- 7.3 cells/mm2; CD4 positive, 9.9 +/- 4.9 cells/mm2) by immunofluorescence using monoclonal anti-rabbit CD5 and CD4 antibodies. Rabbits treated with CsA developed significantly less extensive plaques after 4 weeks (aortic arch 33.0% +/- 6.2%, P < 0.001; thoracic aorta 6.3% +/- 1.5%, P < 0.05; abdominal aorta 2.7% +/- 0.5%, P < 0.005) than untreated rabbits. No CD4 or CD5 positive cells were observed in their plaques. Treatment with CsA did not affect the weight gain of rabbits or reduce their serum cholesterol levels. Circulating T cell numbers and subsets were unaffected. These studies suggest that inhibition of T cell activation prevents their localisation in plaques and reduces the extent of early lesions, suggesting a role for T cells in the initiation of atherosclerosis.

Procoagulant activity expression by macrophages from atheromatous vascular plaques.

Embolization of thrombi from ulcerated plaques is an important cause of morbidity from atherosclerotic carotid artery disease. Factors controlling thrombus formation on these lesions are not well understood. Macrophages were isolated from atherosclerotic plaques to assess their potential to promote local fibrin deposition. Plaques were collected from 11 patients undergoing carotid endarterectomy and 9 patients undergoing reconstructive procedures for atherosclerotic disease of their distal aorta or femoral arteries. Blood was also collected concurrently to isolate monocytes. Procoagulant activity (PCA) of carotid macrophages (8.6 +/- 4.1 mU/10(6) cells) was significantly higher than that of macrophages from non-carotid lesions (0.35 +/- 0.20 mU/10(6) cells; P less than 0.05) or blood monocytes from either group of patients. The PCA of carotid plaque macrophages from patients with recent emboli was 16.1 +/- 8.4 mU/10(6) cells (n = 5) compared to 2.4 +/- 0.8 mU/10(6) cells (n = 6) for plaque macrophages from assymptomatic carotid endarterectomy patients. Carotid macrophage PCA was factor V and factor VII dependent. Its functional activity was inhibited by an anti-tissue factor antibody, and immunohistochemical studies on tissue sections from carotid plaques showed tissue factor in areas where macrophages were abundant. These studies demonstrate that macrophages within carotid artery plaques have augmented procoagulant activity compared with blood monocytes and macrophages from other atherosclerotic lesions and indicate that carotid plaque macrophages are activated. Augmented macrophage PCA may contribute to thrombus formation on ulcerated plaques.

Interleukin-1 receptor antagonist: characterisation of its gene expression in rabbit tissues and large-scale expression in eucaryotic cells using a baculovirus expression system.

The gene expression of rabbit interleukin-1 receptor antagonist (RbIL-lra) was examined in rabbit tissues. RNA was isolated from heart, lung, kidney, muscle, liver, spleen, brain, and peripheral blood monocytes (PBMs), and RbIL-lra mRNA was identified as a single species by Northern analysis using a RbIL-lra probe. RbIL-lra was abundantly expressed in lung, brain, heart, and liver, expressed at low levels in spleen, and undetectable in kidney and unstimulated PBMs. Expression of large scale recombinant production of RbIL-lra was achieved by subcloning the cDNA into a baculovirus expression vector. Recombination of this vector was completed with the BacPAK6 baculovirus genome. The recombinant virus, containing the RbIL-lra cDNA, was used to infect Spodoptera frugiperda (Sf21) insect cells in a spinner flask system and in monolayers in cell culture flasks. Recombinant rabbit IL-lra (rRbIL-lra) was secreted into the culture medium in this system at very high levels (35 mg/l). The protein was identified by reducing SDS-PAGE electrophoresis, was variably glycosylated and had a molecular weight between 19-25 kDa. It was then purified by size exclusion HPLC on a Du Pont Gf-250 column. The rRbIL-lra was demonstrated to be functionally active by inhibiting recombinant human IL-1 alpha in a mouse thymocyte proliferation assay. 20 ng/ml (6.7 U/ml) of rRbIL-lra inhibited 95% of the activity of 2 ng/ml IL-1 alpha.

Crescentic glomerulonephritis--a manifestation of a nephritogenic Th1 response?

Crescentic glomerulonephritis (GN) is the histopathological correlate of the clinical syndrome of rapidly progressive glomerulonephritis. Glomerular crescent formation complicates proliferative forms of GN and indicates severe disease with a poor renal prognosis. In the past 10 years evidence from experimental models of GN and from human disease has accumulated suggesting that crescentic glomerulonephritis is a manifestation of a delayed type hypersensitivity (DTH)-like response to nephritogenic antigens. The elucidation of T helper 1 (Th1) and Th2 subsets in mice and in humans has led to the hypothesis that crescentic GN is a manifestation of a Th1 predominant DTH mediated immune response. Recent experiments performed mainly in a murine model of crescentic glomerulonephritis have tested this hypothesis. Crescent formation in this model is substantially interleukin (IL)-12 and interferon-gamma (IFN-gamma) dependent. Administration of IL-12, deletion of endogenous IL-4 or IL-10 results in enhanced disease, while administration of exogenous IL-4 and/or IL-10 reduces crescentic injury. These findings, together with the available evidence from human studies (examining the pattern of immune effectors in glomeruli, data on cytokine production by peripheral blood mononuclear cells and case reports of the induction of proliferative and/or crescentic GN by administration of IFN-gamma or IL-2) suggest that human crescentic GN is manifestation of a Th1 mediated DTH-like nephritogenic immune response.

Measurement of anti-DNA antibodies by ELISA: a comparative study with Crithidia and a Farr assay.

One hundred and twenty six sera from 116 patients with systemic lupus erythematosus (SLE) and from 51 control patients were assayed for the presence of anti-DNA antibodies, using a commercial enzyme linked immunosorbent assay (ELISA). Fifty three sera (42%) from SLE patients were positive and a further 13 sera (10%) fell in the 'equivocal' positive range. Three control sera were positive. In a standard 14C DNA Farr assay, 67 sera (53%) from SLE patients were positive. One control serum was weakly positive. There was a good linear correlation between absorption in the ELISA and the 14C DNA binding result (r = 0.73). Results in the ELISA and Farr assays were concordant in 96 of the 126 SLE sera, and 47 of 51 control sera. Sequential sera from a further 6 patients with fluctuating clinical activity of SLE showed similar patterns of change of anti-DNA antibodies in both assays. The ELISA was more sensitive than the Crithidia luciliae immunofluorescence assay which detected 44 positive sera (35%) in the SLE group. These results suggest that this ELISA assay may be a useful alternative to the Crithidia assay or an effective screen prior to testing in the more technically difficult and time consuming Farr assay for the measurement of anti-DNA antibodies.

Glomerulonephritis, Th1 and Th2: what's new?

Glomerulonephritis (GN), the major worldwide cause of chronic renal disease and renal failure, shows a wide spectrum of histological patterns, severity of injury and clinical outcomes that may be related to the nature of the nephritogenic immune response. In the majority of cases, there is evidence of a central role for cognate immunity in the initiation of human GN and contributions of both humoral and cellular effector mechanisms have been demonstrated in both humans and in animal models. T helper cell subsets are known to activate different immune effector mechanisms which influence disease outcomes in infectious and autoimmune diseases and evidence is now accumulating that Th1 and Th2 subsets direct diverging effector pathways that lead to different patterns and severity of glomerular injury in GN. Th1-predominant responses appear to be associated strongly with proliferative and crescentic forms of GN that result in severe renal injury, while Th2 responses are associated with membranous patterns of injury. The challenge remains to understand fully the relevance of T helper cell subset responses to the spectrum of human GN and to apply this new knowledge to the development of more potent and selective therapeutic strategies.

Isolation and characterization of glomerular macrophages in experimental glomerulonephritis.

Adherent cells emigrating from glomeruli of rabbits developing anti-glomerular basement membrane antibody induced glomerulonephritis were isolated and characterized as macrophages. Glomeruli were isolated using a sterile graded sieving technique and cultured in plastic tissue culture flasks. After varying culture times, emigrating adherent cells were harvested by 'cold shock' or trypsin-versene. These cells had the morphological and functional characteristics of macrophages. They were largely mononuclear, esterase-positive, phagocytic cells, which exhibited surface Fc receptors. A mean of 4.8 +/- 2.1 X 10(4) macrophages could be isolated from 2 X 10(4) glomeruli after 1 h in tissue culture. Greater numbers of macrophages could be isolated with further time in culture. After 72 h however, intrinsic glomerular cell contamination occurred. The majority of the cells were viable by fluorescein diacetate hydrolysis, and Trypan Blue exclusion. Further functional studies of these cells may provide some new insights into the cellular basis of macrophage-induced glomerular injury in experimental glomerulonephritis.

Effect of cyclosporin A on antibody-induced experimental glomerulonephritis.

The effect of cyclosporin A (CYA) on the development of active and passive models of rat anti-glomerular basement membrane antibody-induced glomerulonephritis (anti-GBM-GN) was assessed. Active GN was induced by an intravenous injection of sheep anti-rat GBM globulin to preimmunized rats. After 5 days, a diffuse proliferative GN with proteinuria and linear GBM deposition of rat IgG was regularly observed. CYA treatment, commencing prior to preimmunization, significantly attenuated the glomerular lesion, reduced proteinuria, prevented linear deposition of rat IgG and reduced the serum titre of anti-sheep globulin antibody. However, treatment started after the antibody response was established failed to alter antibody production, its glomerular deposition or the outcome of the disease. CYA treatment did not effect passive anti-GBM-GN, occurring 24 h after intravenous administration of sheep anti-rat GBM globulin to unimmunized rats. Thus, CYA is able to block anti-GBM-GN when given prior to induction of disease, by preventing an active antibody response. However, it did not alter GN when the antibody response was well established, or when glomerular injury was passively induced.

The mechanism of action of corticosteroids on glomerular injury in acute serum sickness in rabbits.

Macrophages have recently been identified as the predominant mediators of the glomerular injury in acute serum sickness (AcSS) in rabbits. Corticosteroids have been shown to prevent this lesion, but the mechanism of this effect is unknown. As corticosteroids are potent anti-macrophage agents, the effect of prednisolone treatment (2 mg/kg/day) on glomerular macrophage accumulation and injury was assessed in rabbits developing AcSS. Eleven untreated animals all developed a proliferative endocapillary glomerulonephritis (mean 71.7 +/- 1.9 sem cells per glomerular cross section, c/gcs) with glomerular macrophage accumulation (46.3 +/- 5.7 macrophages per glomerulus, macs/glom) and proteinuria (555 +/- 379 mg/24 h). Eight animals were treated with prednisolone commencing not more than 48 h prior to immune elimination (IE). Glomerular injury was markedly attenuated with significantly less cellular proliferation (49.1 +/- 2.1 c/gcs, P less than .005), fewer macrophages within glomeruli (10.5 +/- 7.7 macs/glom, P less than .005) and minimal proteinuria (19.3 +/- 5.5 mg/24 h, P less than 0.01). Treatment did not alter the amount of circulating BSA-anti-BSA immune complex; its time of IE (11.1 +/- 0.4 days treated, 11.4 +/- 0.4 days untreated) its renal deposition (2.36 +/- 0.64 micrograms BSA/g renal cortex treated, 2.66 +/- 0.52 mg BSA/g renal cortex untreated) or its glomerular localization. These results indicate that prednisolone treatment can effectively reduce the glomerular injury of AcSS. This effect is not dependent on any alteration of immune complex formation or deposition, but involves reduction of macrophage accumulation at the inflammatory site.

The participation of macrophages, glomerular procoagulant activity, and factor VIII in glomerular fibrin deposition. Studies on anti-GBM antibody-induced glomerulonephritis in rabbits.

The temporal relationships of macrophage accumulation, glomerular fibrin deposition, the expression of glomerular procoagulant activity (PCA), and Factor VIII antigen deposition were studied in rabbits in which antiglomerular basement membrane antibody-induced glomerulonephritis (anti-GBM GN) developed. The initiation of injury coincided with the accumulation of glomerular macrophages. Glomerular fibrin, assessed by immunofluorescence and by deposition of 125I-fibrinogen, paralleled the development of glomerular crescents and renal impairment. Macrophage ingress clearly preceded the deposition of 125I-fibrinogen within glomeruli. Augmented levels of PCA were present in glomeruli prior to the initiation of fibrin deposition, and peak levels coincided with the peak glomerular macrophage presence. Factor VIII related antigen was apparent late in the disease and was present mainly at the margins of fibrinous crescents. These data demonstrate that accumulation of glomerular macrophages precedes glomerular fibrin deposition in anti-GBM GN. The augmentation of PCA, coincident with the appearance of glomerular macrophages, suggests a role for macrophage PCA in the initiation of fibrin deposition within the glomerular tuft in this model.

Production of tumor necrosis factor and interleukin-1 by macrophages from human atheromatous plaques.

The production of cytokines by atheromatous plaque macrophages from human endarterectomy tissue was assessed in vitro by short-term cell culture and in situ by immunohistology. Macrophages were isolated from plaques of 14 patients undergoing carotid endarterectomy and 7 patients undergoing reconstructive procedures on atheromatous distal aortic and femoral arteries. Tumor necrosis factor (TNF) and interleukin 1 (IL-1) production by plaque macrophages and blood monocytes isolated concurrently from these patients was assessed. TNF release by macrophages from carotid plaques (0.39 +/- 0.12 ng/10(6) cells/24 hours) was significantly augmented compared to the release by corresponding blood monocytes (0.014 +/- 0.011 ng/10(6) cells/24 hours, P = 0.03), and by macrophages from noncarotid lesions (0.038 +/- 0.036 ng/10(6) cells/24 hours, P < 0.04). Cellular TNF expression by macrophages within carotid plaques was also more prominent than in noncarotid lesions. By contrast, IL-1 production by plaque macrophages from both carotid and noncarotid plaques was not augmented compared to blood monocytes, and only infrequent and low-intensity labeling for IL-1 was present on macrophages within plaques from either group. These results provide functional and immunohistological evidence for increased production of TNF but not IL-1 by activated macrophages, indicating local and selective augmentation of cytokine production within carotid plaques. This suggests that macrophages play an active role in the inflammatory response within atheromatous carotid plaques.

Attenuation of adjuvant arthritis in rats by treatment with oxygen radical scavengers.

The contribution of reactive oxygen species (ROS), in particular hydroxyl radical (OH.), to joint inflammation was examined in rats developing adjuvant arthritis (AA) by treatment with ROS scavengers dimethylthiourea (DMTU) and DMSO. Adjuvant arthritis was induced in Sprague-Dawley (SD) rats by a single intradermal (i.d.) injection of Mycobacterium tuberculosis (MT) in oil on day 0. By day 14, all rats exhibited arthritis in the hindlimbs and the majority had involvement of the forelimbs. A marked inflammatory cell influx (75% neutrophils) was present in the synovial fluid. These cells, in vitro, spontaneously produced OH. (0.96 +/- 0.28 OH. units/h per 10(5) cells). In contrast, spontaneous OH. production by normal circulating leucocytes was absent (0.07 +/- 0.03 OH. units/h per 10(5) cells). Adjuvant-injected rats were treated with DMTU (500, 250 and 100 mg/kg), DMSO (330 and 165 mg/kg) or saline (disease control) once daily on days 8, 9 and 10 and twice daily on days 11, 12 and 13 postadjuvant injection. Both DMTU and DMSO significantly reduced the clinical evidence of arthritis (clinical scores: DMTU [500 mg/kg] = 0, P < 0.0001; DMSO [3.0 mL/kg] = 0.4 +/- 0.3, P < 0.01, compared with disease control = 2.3 +/- 0.3). Synovial fluid cell accumulation was also significantly reduced (DMTU [500 mg+kg] = 0.5 +/- 0.1 x 10(5) cells/four joints, P < 0.0001; DMSO [3.0 mL/kg] 2.75 +/- 1.9 x 10(5) cells/four joints, P < 0.01 compared with disease control = 11.76 +/- 1.7 x 10(5) cells/four joints). Neither treatment inhibited cutaneous delayed type hypersensitivity (DTH) to the disease inducing antigen.(ABSTRACT TRUNCATED AT 250 WORDS)

Fibrinolytic therapy with streptokinase for established experimental glomerulonephritis.

The efficacy of fibrinolytic therapy with streptokinase was assessed in rabbits developing anti-glomerular basement membrane antibody induced glomerulonephritis. Untreated animals developed renal failure (mean creatinine 615 +/- 120 microM/l) and a severe glomerulonephritis with prominent fibrin deposition. Streptokinase treatment of animals with established disease (creatinine 204 +/- 35 microM/l) reduced renal impairment (creatinine 256 +/- 68 microM/l, p less than 0.025) and fibrin deposition. Treatment of more advanced disease (creatinine 416 +/- 68 microM/l) did not preserve renal function (creatinine, 518 +/- 106 microM/l), although glomerular fibrin deposition was reduced. These studies indicate that fibrinolytic therapy with streptokinase reduces glomerular fibrin deposition and, if used early, protects from loss of renal function.