Localization of platelet antigens in human kidney disease

Low platelet count at diagnosis of anti-neutrophil cytoplasmic antibody-associated vasculitis is correlated with the severity of disease and renal prognosis

Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is an autoimmune disease that involves inflammation of blood vessels. There is increasing evidence that platelets play a crucial role not only in hemostasis but also in inflammation and innate immunity. In this study, we explored the relationship between platelet count, clinical characteristics, and the prognosis of patients with AAV. We divided 187 patients into two groups based on their platelet count. Clinicopathological data and prognostic information were retrospectively gathered from medical records. Univariate and multivariate regression analyses were used to identify risk factors for prognosis, including end-stage renal disease (ESRD) and mortality. The cutoff point for platelet count was set at 264.5 × 109/L, as determined by the receiver operating characteristic (ROC) curve for predicting progression to ESRD in patients with AAV. We observed patients with low platelet count (platelets < 264.5 × 109/L) had lower leukocytes, hemoglobin, complement, acute reactants, and worse renal function (P for eGFR < 0.001). They were also more likely to progress to ESRD or death compared to the high platelet count group (platelets > 264.5 × 109/L) (P < 0.0001, P = 0.0338, respectively). Low platelet count was potentially an independent predictor of poor renal prognosis in the multivariate regression analysis [HR 1.670 (95% CI 1.019-2.515), P = 0.014]. Lower platelet count at diagnosis is associated with more severe clinical characteristics and impaired renal function. Therefore, platelet count may be an accessible prognostic indicator for renal outcomes in patients with AAV.

Prevention of Chronic Glomerular Uremia in Steroid Resistant Glomerulonephritis. A Clinical Trial with a New Antithrombotic Agent

To investigate the possibility of slowing down disease progression 27 patients with primary glomerular diseases unresponsive to steroids and cytotoxic drugs were treated with Defibrotide. This drug is a single stranded DNA fraction which has profibrinolytic and deaggregating properties and can promote the generation and release of prostacyclin from vascular tissue. Before treatment all patients showed proteinuria in excess of 1 g/day and 16 had a nephrotic syndrome (59%); 10 patients had serum creatinine above 1.6 mg/dl (37%) and 6 were hypertensive. After therapy a significant decrease in daily proteinuria was observed, although the reduction exceeded 50% of pre-treatment values in only 16 patients (59%). A progressive decrease in serum creatinine occurred in patients with abnormal renal function; serial measurement of renal plasma flow showed a progressive improvement with an average increase of 6 and 12%, after 1 and 3 months of treatment, respectively.

These observations confirm the view that drugs improving endothelial function and renal hemodynamics can be of value in the treatment of chronic glomerular diseases and can contribute to the maintenance of renal function.

The role of platelets in the pathogenesis of systemic sclerosis

Systemic sclerosis (SSc) is an inflammatory disease of unknown etiology characterized by widespread organ dysfunction due to fibrosis and ischemia. Its nebulous pathogenic background and the consequent absence of an etiological therapy prevent the adoption of satisfying treatment strategies, able to improve patients’ quality of life and survival and stimulate researchers to identify a unifying pathogenic target. Platelets show a unique biological behavior, lying at the crossroads between vascular function, innate and adaptive immunity, and regulation of cell proliferation. Consequently they are also emerging players in the pathogenesis of many inflammatory diseases, including SSc. In the setting of SSc platelets are detectable in a persistent activated state, which is intimately linked to the concomitant presence of an injured endothelium and to the widespread activation of the innate and adaptive immune system. As a consistent circulating source of bioactive compounds platelets contribute to the development of many characteristic phenomena of SSc, such as fibrosis and impaired vascular tone.

Smoking and diabetic nephropathy

Forty-seven patients with insulin-dependent diabetes (IDDM) and diabetic nephropathy and 47 controls with IDDM without diabetic nephropathy were interviewed about their previous and current smoking habits. The patients in the two groups were matched according to sex, age, age at onset, and duration of diabetes. All patients in the nephropathy group had proteinuria and decreased glomerular filtration. None in the control group had ever had proteinuria as tested by dip stick. The total amount of smoking until date of interview was estimated for each individual and presented as an index. The patients with nephropathy had a significantly higher smoking index than the controls. In the nephropathy group there were also more numerous current smokers, more heavy smokers and fewer individuals who had never smoked than in the control group. The link between diabetic renal microangiopathy and smoking may be through mechanisms such as increased platelet aggregation, accentuated tissue hypoxia and hemodynamic or metabolic effects of repeated noradrenaline release.

Human platelets stimulate mesangial cells to produce monocyte chemoattractant protein-1 via the CD40/CD40 ligand pathway and may amplify glomerular injury

Platelets are thought to play an important role in the initiation and the progression of a variety of glomerulonephritides. This study examined whether platelets induce production of monocyte chemoattractant protein-1 (MCP-1), a chemokine involved in leukocyte recruitment and glomerular injury, by cultured human mesangial cells (MC). To this end, platelets isolated from normal human donors were cocultured with MC at various ratios. MCP-1 synthesis was evaluated by quantitative real-time PCR and enzyme-linked immunosorbent assay. Platelets at 1:100 ratio (MC to platelets) induced an approximately 20-fold increase in mesangial MCP-1 mRNA and protein expression through an obligatory cell-to-cell contact-dependent mechanism. Importantly, blockade of the CD40/CD40 ligand (CD40L) pathway with neutralizing antibodies decreased MCP-1 production by approximately 60%. It was confirmed that CD40 was functionally expressed on MC. Gel-shift assays and inhibitors of phosphorylation were used to demonstrate that activation of p38 mitogen-activated protein kinase, protein tyrosine kinases, and nuclear factor-kappa B activation were essential for MCP-1 production. These data indicate that platelet/MC contact stimulates the production of MCP-1 and may contribute to glomerular inflammatory responses by recruiting leukocytes from the peripheral blood.

Role of endothelial cells in the development of glomerular lesions of mesangiocapillary glomerulonephritis

The histological and ultrastructural changes of mesangiocapillary glomerulonephritis (MCGN) are not unique to this entity: splitting of basement membrane (BM) is seen in a number of conditions with an altered coagulation pattern. The distribution of endothelial cells in the glomerular capillaries in five cases of MCGN was studied by light and electron microscopy and immunocytochemistry; endothelial cells were stained with peroxidase or FITC-conjugated antibodies against Factor VIII-related antigen or CD34 antigen and observed with conventional light/immunofluorescence microscopy and confocal laser scanning microscopy for three-dimensional reconstruction. Electron microscopy was performed with colloidal gold labelling. Endothelial cells were shown to be present within the duplicated basement membranes of capillaries and continuity was demonstrated with endothelial cells lining the capillary lumina. These results suggest that endothelial cells as well as mesangial cells can participate in the formation of the characteristic double contour of capillary walls in MCGN, especially in the early stages. There are some similarities to the changes seen in larger arteries as a consequence of thrombotic disease.

Platelet involvement in experimental immune complex-mediated glomerulonephritis in the nonhuman primate

Abundant glomerular platelet deposition is a hallmark of certain animal models of immune complex (IC)-mediated glomerulonephritis (GN). By contrast, conspicuous platelet deposition is uncommon in the IC-GN seen in humans. This could result from intrinsic differences between human and animal platelets, which are known to be present. To assess whether abundant glomerular platelet deposition can occur in humans with IC-GN, the present studies were undertaken in nonhuman primates (cynomolgus monkeys, CYN), with active experimental IC-GN induced by 12 weeks of daily intravenous infusion of bovine gamma globulin (BGG). CYN are appropriate for these studies because, like humans, CYN platelets do not express the C3b receptor but do express receptors for the Fc region of IgG (FcR gamma II). Furthermore, in this model of IC-GN, which is indistinguishable from IC-GN seen in humans, it is possible to time the biopsy to coincide with a period of peak activity of the GN. The present studies proceeded as follows: ten CYN were studied before and after intravenous infusion of BGG sufficient to achieve conditions near antigen/antibody equivalence for circulating precipitating antibody to BGG. The infusion of BGG, which was given over 10 minutes, resulted in an acute reduction in circulating platelets (mean 43% +/- 5 SE, P < 0.001). However, renal biopsies performed before and five minutes after the acute reduction in circulating platelets showed that relatively few of the platelets removed from the circulation lodged in glomeruli (platelets/glomerular cross section: 0.2 +/- 0.06 before BGG vs. 0.88 +/- 0.31 after BGG, P = 0.035). In five of the CYN studied under the above protocol, autologous platelets were labeled with 111In and reinfused into the CYN just prior to the BGG infusion. These studies confirmed the paucity of platelet deposition in kidney but showed major uptake of the 111In-labeled platelets by liver and spleen (mean +/- SE 111In CPM/mg of tissue: kidney cortex 18 +/- 8, liver 132 +/- 42, and spleen 808 +/- 127, P = 0.038, comparing kidney to liver or spleen by paired t-test). Thus, the platelets removed from the circulation were taken up at the sites which are also the principal sites of IC uptake (liver and spleen), and over the time interval that coincides with the period of maximum uptake of IC by liver and spleen, after BGG infusion. In vitro studies, discussed herein, showed that BGG anti-BGG IC bind to CYN platelets via FcR gamma II.(ABSTRACT TRUNCATED AT 400 WORDS)

Detection of activated platelets in urinary sediments by immunofluorescence using monoclonal antibody to human platelet GMP-140 in patients with IgA nephropathy

The presence of activated platelets in the urinary sediments was studied by indirect immunofluorescence using monoclonal antigranular membrane protein (GMP)-140 antibody. GMP-140 is generally expressed on the activated-platelets and -vascular endothelial cells. The purpose of the present study was to determine if the presence of activated platelets in the urinary sediments is correlated with glomerular injuries in patients with IgA nephropathy. Fourteen patients with IgA nephropathy and 11 patients with diffuse mesangial proliferative glomerulonephritis without glomerular IgA deposition (PGN) were examined. The number of activated platelets in the urinary sediments was markedly increased in patients in the advanced stage of IgA nephropathy. The ratio of activated platelets to total platelets in the urinary sediments was also increased in such patients. It appears that the detection of activated platelets in the urinary sediments is useful in determining the degree of histological changes in IgA nephropathy.

Inhibition of active oxygen generation by dipyridamole in human polymorphonuclear leukocytes

The effect of dipyridamole on active oxygen generation by human polymorphonuclear leukocytes (PMN) was investigated. Dipyridamole inhibited the production of oxidative metabolites from human PMN stimulated by opsonized zymosan and formyl-methionyl-leucyl-phenylalanine dose and time dependently. To determine whether dipyridamole directly inhibits the production of oxygen metabolites by human PMN, human PMN were preincubated with dipyridamole washed prior to stimulation. Dipyridamole was found to directly inhibit human PMN from generated active oxygen metabolites at therapeutic concentrations. Dipyridamole may possibly be a potential scavenger of active oxygen metabolites since it inhibited active oxygen metabolite production from human PMN very rapidly. Dipyridamole was also found to directly affect the scavenging of active oxygen metabolites generated by opsonized zymosan-stimulated human PMN at therapeutic concentrations. This action of dipyridamole was also noted to be exerted against hydroxyl radicals and superoxide anions produced biochemically by an electron spin resonance spectrometer. It thus follows that dipyridamole may inhibit human PMN active oxygen metabolite generation and affect directly the scavenging of active oxygen metabolites at therapeutic concentrations.

Intraglomerular platelet aggregation and experimental glomerulonephritis

Oxygen free radical production inhibits ADPase-mediated antithrombotic action. Different forms of experimental glomerulonephritis (GN) are characterized by early glomerular influx of inflammatory cells and thrombus formation. The causal relationship of these inflammatory events is obscure. Previous studies have shown that glomerular ADPase in the rat kidney may function as a potent antithrombotic principle, whereas this enzyme is highly sensitive for oxygen free radicals. To study whether O2- producing inflammatory cells are able to induce intraglomerular thrombosis via impairment of ADPase, we investigated influx of inflammatory cells in relation to glomerular ADPase activity and platelet aggregation in three models of GN. In two of these models (anti-Thy1 and anti-GBM GN) influx of neutrophils and thrombus formation occurs, whereas in anti-FX1A nephritis this aspect of the inflammatory phase is not present. The results show a relationship between influx of oxygen free radical-producing cells, reduction of glomerular ADPase activity and increased platelet aggregation. Moreover, it is shown that impairment of glomerular ADPase and increased platelet aggregation in anti-Thy1 and anti-GBM GN could be reduced by treatment with superoxide dismutase and catalase. The demonstration that activated neutrophils perfused ex vivo in the rat kidney can directly affect glomerular ADPase and antithrombotic potential in an O2- dependent manner, further supports the proposed sequence of events; oxygen free radicals produced by activated neutrophils reduce glomerular ADPase activity, leading to facilitation of thrombus formation.

Control of rat glomerular epithelial cell growth in vitro

The interaction of cultured rat GEC1 with several growth factors was explored in order to obtain a better understanding of in vivo factors which might stimulate GEC proliferation. GEC proliferated in response to EGF but not IGF-1, MSA or PDGF. Specific, saturable receptors for EGF were detected in saturation and competition binding studies utilizing 125I-EGF with an approximate Kd of 1.7 nM and 86,000 binding sites per cell. TGF-beta inhibited GEC growth in a time and dose dependent manner with a brief early exposure resulting in prolonged growth inhibition which was not reversible by EGF. Exposure to TGF-beta sufficient to maximally inhibit growth had no effect on EGF binding to GEC. More prolonged exposure to TGF-beta, however, did result in an increase in the apparent number of EGF receptors on GEC but no change in Kd. These studies suggest that EGF and TGF-beta released by inflammatory cells or platelets during the course of glomerular injury may play a role in modulating glomerular cell proliferation.

Ovine mesangiocapillary glomerulonephritis type I and crescent formation

Morphologic examination of four Finnish Landrace mixed-breed lambs, 27 to 35 days of age, affected with mesangiocapillary glomerulonephritis type 1, demonstrated a progressive glomerulonephritis. By 27 days of age, three lambs had crescents in 58 to 93% of glomeruli. These three lambs were also uremic. The accelerated rate of crescent formation was attributed to infiltrating polymorphonuclear leukocytes and monocytes, the result of discontinuities (gaps) in the glomerular basement membrane, and to the loss of the integrity of Bowman's capsule. In the three lambs, platelets were identified adjacent to the endothelium or denuded glomerular basement membrane. Two distinctly different types of crescents were noted, apparently dependent on the integrity of Bowman's capsule. One type resulted from the influx of inflammatory cells and dissociation of parietal epithelial cells from Bowman's capsule. The other type was more extensive and contained collagen and was associated with damage to Bowman's capsule resulting in cellular infiltration from the interstitium and sclerosis. Based on morphologic similarities, ovine mesangiocapillary glomerulonephritis is a suitable model for studying the pathogenesis and treatment of mesangiocapillary glomerulonephritis type 1 in human beings.

Transforming growth factor-beta. Murine glomerular receptors and responses of isolated glomerular cells

Proliferation of resident glomerular cells and the accumulation of mesangial matrix are histologic abnormalities which are observed in the course of many progressive glomerular diseases. We explored the potential regulatory effects of transforming growth factor-beta (TGF-beta) on these processes. We found that cultured mouse glomerular endothelial, mesangial, and epithelial cells as well as isolated intact rat glomeruli possess high-affinity receptors for TGF-beta. We also found that, although TGF-beta consistently inhibited the proliferation of glomerular endothelial and epithelial cells, it acted as a bifunctional regulator of mesangial cell proliferation. TGF-beta significantly increased the production of collagen and fibronectin by glomerular mesangial cells whereas only fibronectin production was augmented in glomerular epithelial cells. The presence of TGF-beta receptors on intact glomeruli and on each glomerular cell type and the demonstrated responsiveness of these cells to TGF-beta combine to suggest that potentially important interactions may occur between resident glomerular cells and TGF-beta in vivo.

Platelets mediate neutrophil-dependent immune complex nephritis in the rat

Neutrophils and platelets are frequently present in glomeruli in immune glomerulonephritis (GN). No role for the platelet in acute neutrophil-mediated renal injury has been defined. We investigated a neutrophil-mediated model of subendothelial immune complex GN in the rat. Rats were platelet-depleted (mean platelet less than 10,000/microliter) with goat anti-platelet IgG before induction of GN by the renal artery perfusion of concanavalin A followed by anti-concanavalin A IgG. Platelet-depletion resulted in a significant reduction in albuminuria (7 +/- 2 vs. 55 +/- 10 mg/24 h) and fractional albumin excretion (0.045 +/- 0.01 vs. 0.410 +/- 0.09) compared with controls. The decrease in albuminuria was not due to differences in blood or glomerular neutrophil counts, complement, renal function, or glomerular antibody binding. Platelet-depleted rats had equivalent subendothelial deposits and glomerular endothelial cell injury but had minimal platelet infiltrates and fibrin deposition compared with controls. These studies demonstrate a role for platelets in mediating acute neutrophil-induced glomerular injury and proteinuria in this model of GN.

Increased platelet thromboxane synthesis in renal glomerular diseases

Washed platelets were prepared from healthy children and adults, and patients with renal glomerular diseases, and incubated with [1-14C] arachidonate to measure the generation capacities of thromboxane (Tx) A2 and 12-hydroxyeicosatetraenoate (12-HETE). Tx generation capacity of platelets was significantly higher in patients with chronic glomerulonephritis, purpura nephritis and lupus nephritis than in healthy control subjects. There was no significant increase in minimal change nephrotic syndrome. 12-HETE showed a decreasing tendency in the glomerular diseases, which was restored to normal level by in vitro addition of indomethacin. Such increased Tx generation capacity of platelets may cause abnormal enhancement of platelet functions and conceivably constitute an aggravating factor of glomerular and microvascular damage in the affected kidney.

Glomerular deposition of cross-linked fibrin in human kidney diseases

The immunofluorescent localization of cross-linked fibrin (XFb) in kidneys from 87 patients with renal diseases was evaluated using a monoclonal antibody that discriminates XFb from fibrinogen and its derivatives. Glomerular deposition of XFb, along the endothelial surface and in the mesangium, was frequently observed in patients with IgA nephropathy, Henoch-Schönlein purpura nephritis (HSPN), lupus nephritis, and hemolytic uremic syndrome (HUS), which was confirmed by immunoelectron microscopy. Dual-label immunofluorescent studies showed that XFb was deposited in limited areas among the sites reactive with anti-fibrinogen antibodies; XFb was not present in the crescents, Bowman's capsule or interstitium. The localization of XFb was generally discordant with that of the platelet membrane antigen and von Willebrand factor (factor VIII-related) antigen. Subendothelial co-deposition of XFb and immunoglobulins (IgA with or without IgG) occasionally accompanying C3 was found in the glomeruli of some of the patients with IgA nephropathy and HSPN. The distribution of XFb observed by immunoelectron microscopy was similar to that of electron dense deposits. The glomerular population of monocytes/macrophages in patients with XFb deposition was similar to that of those without deposition. Urinary XFb derivatives were detected by the latex agglutination test in three of the 16 patients with glomerular XFb deposition, and in two of the 18 patients without it. These data indicate that the coagulation system is activated in the kidney of patients with IgA nephropathy, HSPN, lupus nephritis and HUS, and support the concept that glomerular fibrin deposition is associated with endothelial/subendothelial and mesangial injury. The activation of the coagulation system in IgA nephropathy and HSPN seems to be mediated by immune complexes rather than monocytes/macrophages. Determination of urinary XFb derivatives is not helpful for assessing glomerular XFb deposition.

Platelet cationic proteins are present in glomeruli of lupus nephritis patients

Synthetic polycations have been shown to bind and neutralize glomerular polyanions (GPA), thereby increasing the permeability of the glomerular capillary wall (GCW). In the present study it is demonstrated that human platelet-derived cationic proteins (HuPlt CP), which are able to increase cutaneous vascular permeability, bind in vitro to the GCW following incubation of normal human kidney sections with purified HuPlt CP or with washed human platelets stimulated with thrombin, immune complexes (IC) and platelet-activating factor (PAF), or stimulated with a suspension of washed human platelets and polymorphonuclear leukocytes in the presence of phagocytable substrate. The antiserum used in immunofluorescence test to detect the binding of HuPlt CP was specific for two different molecular types of HuPlt CP, both with an isoelectric point (pI) of 10.5. Glomerular deposits of HuPlt CP were also detectable by immunofluorescence microscopy in renal glomeruli present in tissue obtained by biopsy from patients with systemic lupus erythematosus (SLE), a disease in which platelets have been implicated as mediator of glomerular injury. These data indicate that when activated platelets release HuPlt CP in vivo, these proteins bind to glomerular structures. The binding of HuPlt CP to GCW appears to be ionic in nature since heparin, a polyanion, prevents this binding in vitro. In addition, heparin, as well as a high molarity buffer, removed deposits of HuPlt CP bound in vitro to normal GCW or bound in vivo to glomeruli of patients with SLE. The binding of HuPlt CP to GCW is associated with loss of colloidal iron staining, a qualitative technique that demonstrates primarily epithelial cell surface anionic sialoglycoproteins. In experiments of in vitro binding of purified HuPlt CP to section of normal kidney treatment with heparin completely restores the normal pattern of colloidal iron staining suggesting ionic neutralization of GPA. In contrast, heparin is only partially effective in restoring colloidal iron staining in normal kidney sections treated with platelets directly stimulated with IC or PAF or in kidney sections of patients with SLE. These observations indicate that under these conditions the ionic interaction of HuPlt CP with GCW is only partially responsible for the loss of colloidal iron staining. The results of the present study suggest that biologically active polycationic mediators released from stimulated platelets localize in GCW and participate in the induction of glomerular injury.

Decreased plasma fibronectin levels in children with hemolytic-uremic syndrome

Fibronectin is a normal plasma glycoprotein thought to have an important role in platelet aggregation and clot formation. Because of the participation of the coagulation system in hemolytic-uremic syndrome, the present study sought to determine if fibronectin plays a role in the pathogenesis of this disease. With this purpose in mind, plasma fibronectin levels were measured in 17 children with the clinical diagnosis of hemolytic-uremic syndrome and in 22 age-matched control subjects. Fibronectin levels were significantly depressed in 13 of 17 (76 percent) patients with hemolytic-uremic syndrome during the acute phase of their illness. The levels did not correlate with age, sex, serum creatinine level, platelet count, or hemoglobin concentration. Serial plasma samples were available in eight of these patients: fibronectin remained depressed from two to 10 days and then returned toward the normal range concomitant with increasing platelet counts and improvement in renal function. During remission, fibronectin levels were normal in all nine patients tested. To try to determine if fibronectin is deposited in the kidney during hemolytic-uremic syndrome, kidney biopsy specimens from six patients with hemolytic-uremic syndrome were examined by immunofluorescence for the presence of fibronectin, fibrinogen, and platelet antigens. Extensive deposition of all three antigens was demonstrated along the glomerular capillary wall in all biopsy specimens. In conclusion, plasma fibronectin levels are decreased during the acute phases of hemolytic-uremic syndrome in the majority of patients. Kidney biopsy findings suggest that fibronectin is intimately involved in the activation of the coagulation system in this disease and that decreased plasma fibronectin levels in hemolytic-uremic syndrome may be due, at least in part, to accelerated consumption of the protein at the sites of injury.

Binding of platelet factor four (PF 4) to glomerular polyanion

Synthetic polycations have been shown to bind to glomerular polyanion (GPA) and increase glomerular permeability. Here, we show that human platelet factor 4 (PF 4), a platelet secretory protein, binds to GPA. The following methods were used to assess PF 4 binding to GPA: (1) Sections of human and rat renal cortex were incubated with PF 4 or PF 4 was injected intravenously into rats followed by immunofluorescence techniques; (2) 125I-PF 4 was added to isolated glomerular basement membrane (GBM) suspensions and binding assessed isotopically; (3) PF 4 was perfused through rat kidneys ex vivo followed by immunoperoxidase methods for electron microscopy (EM). In vitro and in vivo, PF 4 bound to the mesangium and linearly to capillary walls. Isotopic studies showed dose-dependent saturable binding of PF 4 to GBM which was reversed by heparin. By EM, PF 4 binding sites were resolved in the GBM, particularly in the laminae rarae as punctate densities similar in distribution to anionic sites revealed by cationic dyes. Also, endothelial and epithelial cell surfaces stained. An ionic interaction between PF 4 and GPA was indicated by elimination of staining by washing PF 4-treated sections with buffer containing 1.0 and 3.0 M NaCl or with heparin. Pretreatment of rats with polyethyleneimine (a synthetic polycation) blocked PF 4 binding. Heparin administration in vivo removed previously bound PF 4. By virtue of its affinity for GPA and behavior like a polycation, PF 4 may alter glomerular permeability and play a role in glomerular disease.

Prospective trial of warfarin and dipyridamole in patients with membranoproliferative glomerulonephritis

A prospective trial of warfarin and dipyridamole was performed in patients with membranoproliferative glomerulonephritis. Eighteen completed either a control or treatment year, and 13 completed both a control and treatment year. To obviate the bias of excluding control patients who had renal failure after one year, both an unpaired and a paired analysis were performed. The unpaired analysis compared 10 patients followed for an initial control year with eight patients receiving treatment first. Renal function remained stable over the year in the treated group, but worsened in the control group. Slopes of regression lines for reciprocal serum creatinine values were significantly different between groups (p less than 0.025). Urine protein excretion also decreased in the treated group. Four of 10 control patients had a two-fold increase in serum creatinine levels, but no treatment patient did. In the paired crossover analysis, significant differences in renal function were detected between control and treatment years in six patients whose renal function significantly changed over one of the years. In every instance, there was better preservation of renal function in the treatment year. Urinary protein also decreased significantly over the treatment year compared with the control year. Bleeding was the most frequent complication. These data suggest that warfarin and dipyridamole have a beneficial effect on renal function in membranoproliferative glomerulonephritis.