Prolonged Duration of Erythropoiesis-Stimulating Agents' Action Delays Disease Progression in Anti-Thy 1 Antibody-Induced Chronic Glomerulonephritis Rats.

BACKGROUND: Although erythropoiesis-stimulating agents (ESAs) exert renoprotective effects in renal disease models, it has not been revealed whether the prolonged duration of action of ESAs contributes to their renoprotective effects. OBJECTIVE: We examined whether the prolonged duration of ESAs' action contributes to their renoprotective effects by comparing a divided administration of a short-acting ESA, epoetin beta (EPO), or a single administration of a long-acting ESA, epoetin beta pegol (continuous erythropoietin receptor activator; C.E.R.A.), to a single administration of EPO in chronic glomerulonephritis (GN) rats. MATERIALS AND METHODS: Chronic GN was induced by intravenous injection of anti-Thy 1.1 antibody (0.6 mg/kg) into uninephrectomized rats (day 0). Chronic GN rats were intravenously injected once with vehicle (disease control; DC), EPO 5,000 IU/kg (single EPO), or C.E.R.A. 25 µg/kg (single C.E.R.A.) on day 1; or 3 times during the first week with EPO 1,667 IU/kg from day 1 (divided EPO; total 5,000 IU/kg). Hemoglobin (Hb) level and urinary total protein (U-TP) level which are the indexes of hematopoiesis and renoprotective effects, respectively, were measured several times over 8 weeks. RESULTS: Divided EPO and single C.E.R.A. increased Hb levels more greatly than did single EPO. In all chronic GN rats, elevated U-TP levels decreased transiently 2 weeks after chronic GN induction and then flared again. Single EPO significantly suppressed this exacerbation of U-TP levels compared to DC. Divided EPO and single C.E.R.A. each significantly suppressed the exacerbation of U-TP levels compared to single EPO. CONCLUSION: Prolonged duration of ESAs' action contributed significantly to their renoprotective effects.

Renal Contrast-Enhanced Sonography Findings in a Model of Acute Cellular Allograft Rejection.

Noninvasive methods to diagnose and differentiate acute cellular rejection from acute tubular necrosis or acute calcineurin inhibitor toxicity are still missing. Because T lymphocytes play a decisive role in early states of rejection, we investigated the suitability and feasibility of antibody-mediated contrast-enhanced ultrasound by using microbubbles targeted to CD3(+) , CD4(+) , or CD8(+) T cells in different models of renal disease. In an established rat renal transplantation model, CD3-mediated ultrasound allows the detection of acute rejection as early as on postoperative day 2. Ultrasound signal intensities increased with the severity of inflammation. Further, an early response to therapy could be monitored by using contrast-enhanced sonography. Notably, acute tubular necrosis occurring after ischemia-reperfusion injury as well as acute calcineurin inhibitor toxicity could easily be differentiated. Finally, the quantified ultrasound signal correlated significantly with the number of infiltrating T cells obtained by histology and with CD3 mRNA levels, as well as with chemokine CXCL9, CXCL11, and CCL19 mRNA but not with KIM-1 mRNA expression, thereby representing the severity of graft inflammation but not the degree of kidney injury. In summary, we demonstrate that antibody-mediated contrast-enhanced ultrasound targeting T lymphocytes could be a promising tool for an easy and reproducible assessment of acute rejection after renal transplantation.

Effect of mesenchymal stem cells on anti-Thy1,1 induced kidney injury in albino rats.

OBJECTIVE: To evaluate the effect of mesenchymal stem cells (MSCs) in rats with anti-Thy1,1 nephritis. METHODS: Female albino rats were divided into three groups, control group, anti-Thy1,1 group and treatment with i.v. MSCs group. MSCs were derived from bone marrow of male albino rats, Y-chromosome gene was detected by polymerase chain reaction in the kidney. Serum urea and creatinine were estimated for all groups. Kidney of all studied groups was examined histologically and histochemically (total carbohydrates and total proteins). DNA fragmentation and expression of α-SMA were detected. RESULTS: Kidney of animals injected with anti-Thy1,1 showed inflammatory leucocytic infiltration, hypertrophied glomeruli, tubular necrosis and congestion in the renal blood vessels. The kidney tissue also showed reduction of carbohydrates and total proteins together with increase in apoptosis and in expression of α-SMA. Moreover, the levels of urea and creatinine were elevated. Treating animals with MSCs revealed that kidney tissue displayed an improvement in the histological and histochemical changes. Apoptosis and α-SMA expression were decreased, and the levels of urea and creatinine decreased. CONCLUSIONS: The obtained results demonstrated the potential of MSCs to ameliorate the structure and function of the kidney in rats with anti-Thy1,1 nephritis possibly through the release of paracrine growth factor(s).

Contrasting dose-effects of multi-glycoside of Tripterygium wilfordii HOOK. f. on glomerular inflammation and hepatic damage in two types of anti-Thy1.1 glomerulonephritis.

Multi-glycoside, one of the extracted compounds from Tripterygium wilfordii HOOK. f. (GTW), has been shown to be clinically effective in suppressing glomerular inflammation in chronic kidney disease. However, its clinical application is often limited by its cytotoxic actions on the liver. This study was performed to contrast the dose-effects of GTW on glomerular inflammation and hepatic damage in two types of anti-Thy1.1 glomerulonephritis (GN). Rats with acute or chronic anti-Thy1.1 GN were either left untreated (the Vehicle group) or treated with a high or low dose of GTW and sacrificed on day 7 or day 45. GTW was administrated 3 days before or at the same time as the antibody injection and lasted until sacrifice. GTW at high dose ameliorated glomerular macrophage accumulation, mesangial proliferation, proteinuria, and interleukin-2 expression in the acute anti-Thy1.1 GN model, but caused structural and functional lesions in the liver. In contrast, GTW at low dose improved activated macrophage and T lymphocyte infiltration, mesangial injury, proteinuria, and interleukin-2 and interferon-γ expressions without hepatic toxicity in the chronic model of GN induced by anti-Thy1.1 antibody. In conclusion, GTW at low dose not only effectively inhibits glomerular inflammation but also avoids severe injuries to the liver.

Anti-Fya antibodies as the cause of an unfortunate post-transplant course in renal transplant recipient.

BACKGROUND: Duffy glycoprotein, belonging to blood group alloantigens, is also recognized as chemokine-binding protein, therefore the role of Duffy antigen in chemokine distribution has been postulated. Duffy positive phenotype prevalent among Caucasians is associated with antigen expression on erythrocytes and endothelium of several organs including kidney. The role of anti-Duffy antibodies significant in transfusiology may be also important in kidney transplantation. CASE REPORT: The case of renal transplant recipient with Fy (a-b+) phenotype, possessing anti Fya antibodies, with unfortunate post-transplant course complicated with acute cellular and antibody-mediated graft rejections, with the presence of crescentic glomerular lesions, kidney graft insufficiency and recurrent urinary tract infections is presented. The role of anti-Duffy antibodies in acute antibody-mediated rejection is discussed. CONCLUSIONS: Fy(a )antibodies present in renal recipient with Fy(a-b+) phenotype may be the reason for unfavorable transplantation outcome resulting from reaction against Duffy antigen up-regulated on graft tissue during ischemia reperfusion injury and acute rejection episode. In renal transplant recipients with antibody-mediated rejection without antidonor specific antibodies, incompatibility in blood group antigens other than AB0 system could be considered.

Complement activation plays a key role in antibody-induced infusion toxicity in monkeys and rats.

Infusion reactions are a major side effect of the administration of therapeutic Abs and are the result of a complex immune reaction. In this study, we report that substitutions of Fc amino acids in the anti-HLA-DR Ab HD8 reduce its ability to induce infusion reactions in rats and monkeys. We first showed that i.v. administration of IgG1- and IgG2-subclass HD8 Abs induces severe infusion reactions in monkeys. These Abs express strong complement-dependent cytotoxicity (CDC), and in vivo depletion of complement in rats by pretreatment with cobra venom factor abrogated the lethal infusion reactions generated by HD8-IgG1. Thus, the infusion reactions appear to be largely driven by the complement system. To reduce the CDC function of HD8-IgG1, its Fc region was modified by two amino acid substitutions at Pro(331)Ser and Lys(322)Ala. The modified Ab was incapable of expressing CDC in vitro and did not induce severe infusion reactions in rats and monkeys, even at extremely high doses. The modified Ab retained its Ab-dependent cellular cytotoxicity function as well as its antitumor activity in a tumor-bearing mouse model. In summary, complement appears to drive infusion reactions, and modifications that eliminate the CDC activity of an Ab also reduce its ability to induce infusion reactions.

The leukotriene B4 receptor antagonist ONO-4057 inhibits mesangioproliferative changes in anti-Thy-1 nephritis.

OBJECTIVE: ONO-4057 is a specific leukotriene B4 (LTB4) receptor antagonist which inhibits human neutrophil aggregation, chemotaxis and degranulation induced by LTB4. This study was conducted to evaluate the role of LTB4 in glomerulonephritis, and to examine whether ONO-4057 moderated anti-Thy-1 nephritis. METHODS: Experiment 1: Sixty Wistar rats were divided into three groups. Rats of Group A (n = 20) underwent intraperitoneal administration of placebo as a control group, rats of Group B (n = 20) first underwent intraperitoneal administration of 100 mg/kg ONO-4057 and rats of Group C (n = 20) first underwent intraperitoneal administration of 300 mg/kg ONO-4057 daily from day 3 before anti-Thy-1 antibody (OX7) injection to day 14 after OX7 injection, respectively. Experiment 2: Forty rats were divided into two groups. ONO-group (n = 20) was treated with 300 mg/kg BW of ONO-4057 and placebo-group (n = 20) with placebo daily from days 1 to 13 after OX7 injection. Urine and blood samples were collected and the kidneys were extirpated from five rats of each group sacrificed at 3 h, 24 h, day 7 or day 14 after the injection of OX7 in both experiments. Urinary protein excretion, renal function and pathological findings were analysed in each group of both experiments. RESULTS: (1) Glomerular infiltration by polymorphonuclear leucocytes (PMNs) and macrophages at 3 h was less in Groups B and C than in Group A, and matrix scores at day 7 were lower in Groups B and C than in Group A. Injury scores did not differ among the groups. (2) Urinary protein excretion at day 7 was less in Group C than in Group A. (3) Neither pathological findings nor urinary protein excretion differed between ONO-group and placebo-group. CONCLUSION: These results suggest that LTB4 is associated not with the pathogenesis of complement-dependent mesangial cell lysis but with that of mesangial proliferative change in anti-Thy-1 nephritis.

Monoclonal antibody 1-22-3-induced glomerulonephritis in uninephrectomized rats as a model of progressive renal failure.

BACKGROUND: At present, there are few available animal models of progressive renal failure originating from mesangial proliferative glomerulonephritis (GN). In the current study, we examined the usefulness of anti-Thy-1 monoclonal antibody (mAb) 1-22-3-induced GN in uninephrectomized rats as a model of progressive renal failure by analysing the similarities to human disease. METHODS: GN was induced by intravenous injection of mAb 1-22-3 into uninephrectomized male Wistar rats. The natural course of the disease was analysed in this model for 47 weeks. The effect of treatment with the angiotensin-converting enzyme inhibitor, captopril, on renal functional outcome was also examined in this model for 23 weeks, beginning from 1 week after antibody injection. RESULTS: Injection of mAb 1-22-3 induced a persistent proteinuria during the entire study period. Animals showed a progressive decline in renal function and 63% died by week 47. Severe glomerular and tubulointerstitial lesions were consistently observed. Treatment with captopril significantly inhibited increases in proteinuria and blood pressure, and attenuated renal injury. Captopril also retarded the progression of renal failure, and decreased mortality. Finally, the level of proteinuria was significantly correlated with the rate of decline in renal function, and the reduction in proteinuria by captopril was accompanied by a slower progression of renal failure. CONCLUSIONS: The mAb 1-22-3-induced GN in a uninephrectomized rat model simulates the clinical manifestations of human disease, indicating that this model may be useful for studying progressive renal failure and for investigating new therapeutic strategies against renal failure.

Preformed cytotoxic antibodies in potential allograft recipients: recent data.

Presensitization to donor human leukocyte antigen (HLA) remains a major barrier to cell and organ transplantation, thereby contributing to patient mortality. The risks associated with transplantation in the presence of preformed antidonor HLA antibodies range from hyperacute rejection and increased frequency and severity of rejection to no appreciable effect on transplant outcome. Recent evidence has emphasized the importance of immunologic history, anti-HLA antibody class and titer, and differential organ susceptibility to antibody-mediated damage to explain differences in risk for antibody-mediated rejection. Furthermore, in studies of endothelial cells, ligation of class I molecules by subsaturating concentrations of antibodies stimulated expression of cell survival proteins, raising the possibility that, under certain conditions, antibodies promote graft accommodation providing a mechanism for the endothelium to resist immune and inflammatory damage. The discovery of capillary-bound C4d as a robust diagnostic marker for antibody-mediated rejection, coupled with the development of solid-phase assays for the identification of HLA-specific antibodies, has enhanced our ability to detect antibody-mediated rejection and interpret cross-match results. With new diagnostic tools and immunosuppression regimens such as plasmapheresis and intravenous immunoglobulin therapy targeting the humoral immune response, it is time for a concerted effort to reassess the role of alloantibodies in acute and chronic rejection.

Retinoic acid receptor alpha and retinoid X receptor specific agonists reduce renal injury in established chronic glomerulonephritis of the rat.

Retinoids, derivatives of vitamin A, inhibit mesangial cell proliferation, glomerular inflammation, and extracellular matrix deposition in acute anti-Thy1.1 glomerulonephritis (Thy-GN) of the rat. We examined a model, chronic mesangioproliferative Thy-GN (MoAb 1-22-3), which is more akin to human disease. Treatment started on day 23 when Thy-GN had already been established. Nonnephritic control and Thy-GN rats were treated orally for 67 days with vehicle or with two doses of either the retinoic acid receptor alpha-specific agonist AGN 195183 (RARalpha agonist) or the retinoid X receptor specific agonist AGN 194204 (RXR agonist). Doses of either the RARalpha or the RXR agonist significantly reduced albuminuria and normalized blood pressure during the course of treatment. The glomerulosclerosis index, glomerular cell and interstitial cell counts, and area of the interstitial space were significantly lower in nephritic rats treated with the RARalpha agonist or RXR agonist than with vehicle. The RARalpha and RXR agonist significantly reduced the infiltration of the glomerulus by macrophages. The increase in glomerular TGFbeta1 and prepro-ET(1) gene expression in vehicle-treated nephritic rats was significantly attenuated by RARalpha or RXR agonists. Glomerular expression of RXRalpha and RARalpha receptor mRNA was significantly greater in vehicle-treated nephritic rats than in nonnephritic controls. Treatment with RARalpha or RXR agonists tended to normalize retinoid-receptor gene expression. Our data indicate that both RARalpha agonists and RXR agonists reduce renal damage in rats with established chronic glomerulonephritis. Receptor-specific retinoids may provide a novel therapeutic approach for the treatment of chronic glomerulonephritis.

A novel therapeutic approach combining human plasma-derived Factors VIIa and X for haemophiliacs with inhibitors: evidence of a higher thrombin generation rate in vitro and more sustained haemostatic activity in vivo than obtained with Factor VIIa alone.

BACKGROUND AND OBJECTIVES: Therapy with recombinant Factor VIIa (rFVIIa) for haemophiliacs with inhibitors still has some unresolved problems, such as the requirement for frequent infusions of rFVIIa every 2-3 h to sustain haemostatic activity for an extended time-period and that the therapeutic dose of rFVIIa is not always predictable. In the present study, we searched for an effective combination of plasma-derived FVIIa with other blood coagulation factors, and demonstrated that a therapeutic approach combining plasma-derived FVIIa and Factor X (FX) was more useful for treating haemophiliacs with inhibitors than FVIIa alone. MATERIALS AND METHODS: The haemostatic effects of FVIIa and FX were evaluated in vitro and in vivo. In in vitro experiments we assessed the following: the ability to enhance the thrombin generation rate in a reconstituted blood coagulation model without Factor VIII (FVIII) or Factor IX (FIX); the ability to correct the activated partial prothrombin time (APTT) of FVIII-depleted plasma or FIX-depleted plasma; and the ability to correct the clotting time of haemophilia-like whole blood using thromboelastography (TEG). In in vivo experiments, the haemostatic activity of the combination treatment of FVIIa and FX was determined by measuring the bleeding time and TEG using a monkey haemophilia B model produced by the injection of anti-human FIX polyclonal antibodies. The degree of thrombogenicity of the combination was evaluated using the rabbit stasis model. RESULTS: The addition of FX to FVIIa dramatically enhanced the thrombin generation rate in the reconstituted blood coagulation model and corrected the prolonged APTTs of FVIII- and FIX-depleted plasmas to levels achieved by the replacement therapies. In contrast, the addition of prothrombin to FVIIa did not show such enhancing activity. Furthermore, FVIIa-induced whole blood clotting times in the FVIII- and FIX-inhibited states were also shortened by the addition of FX in a concentration-dependent manner. Finally, the co-administration of FVIIa (80 microg/kg) and FX (800 microg/kg) in a monkey haemophilia B model resulted in a more robust and persistent haemostatic effect on the secondary bleeding time and whole-blood clotting time of TEG than that of FVIIa alone. The results of rabbit stasis tests for evaluating the risk of thrombogenicity showed that the combination of FVIIa and FX was less thrombogenic than FEIBA. CONCLUSIONS: The present study demonstrated that the combination of FVIIa and FX appeared to have a higher and more sustainable haemostatic potential than FVIIa alone, and less thrombogenicity than FEIBA. A therapeutic approach combining FVIIa and FX could be a promising and novel approach to compensate for the disadvantages of rFVIIa and FEIBA for haemophiliacs with inhibitors.

Heterogeneity of macrophage activation in anti-Thy-1.1 nephritis.

Macrophages infiltrating glomeruli in telescoped nephrotoxic nephritis are programmed. The purpose of this study was to assess whether macrophages infiltrating glomeruli of rats with passively induced injury become similarly programmed, and to determine whether macrophage commitment is an early event. Glomerular macrophages isolated from rats with resolving and proliferative anti-Thy-1 nephritis were examined for nitric oxide (NO) generation and expression of lysosomal hydrolases. After a single injection of Thy-1 antibody the cells generated large amounts of NO that was attenuated ex vivo by transforming growth factor-beta and other anti-inflammatory cytokines. In contrast macrophages infiltrating glomeruli immediately after a second injection of Thy-1 antibody generated NO spontaneously and were unresponsive to alternative activation. beta-Glucuronidase expression was used as a second independent assay for macrophage activation and the results confirmed the observations made for NO. Furthermore, macrophages infiltrating the glomerulus after the second antibody injection exhibited a striking dichotomy in that 70% of the cells behave as programmed by interferon-gamma and 30% by transforming growth factor-beta. The results show that macrophage commitment occurs very early after monocyte migration and that infiltration itself does not invariably induce macrophage programming. It demonstrates that macrophages infiltrating inflamed glomeruli at the same time do not respond uniformly, but are capable of engaging different activation programs. This emphasizes the critical importance of the underlying disease process for macrophage functional development in an inflamed environment.

Initial management of immune thrombocytopenic purpura in adults: a randomized controlled trial comparing intermittent anti-D with routine care.

We conducted a randomized clinical trial in adults with a new diagnosis of ITP and a platelet count <30000/muL to test the hypothesis that initial intermittent treatment with anti-D may avoid or defer the need for splenectomy when compared to current routine care (glucocorticoid treatment, followed by splenectomy). Splenectomy was to be performed in the anti-D group if patients failed to respond to three consecutive anti-D treatments given within 10 days. The incidences of splenectomy were 14 of 37 (38%) in the routine care group and 14 of 33 (42%) in the anti-D group (absolute risk reduction = 4.6% in favor of the routine care group, 95% CI, -18.4 to 27.6%). However, splenectomy was performed prematurely, not according to the protocol, in 11 of 14 patients in the anti-D group. The median time to splenectomy was 36 days (range, 9-78) in the routine care group and 112 days (range, 19-558) in the anti-D group (P = 0.045 at 100 days after randomization, P = 0.840 at 1 year after randomization, using log-rank analysis). Patients in the anti-D group were treated with prednisone for fewer days (70 days) compared to the routine care group (112 days, P = 0.01). No major bleeding events occurred. In this study, initial treatment of patients with intermittent anti-D initially deferred splenectomy. Whether our aggressive regimen of anti-D could have prevented splenectomy if it had been adhered to in all patients remains uncertain. However, compliance with this anti-D regimen was not feasible for many patients and/or their physicians.

Monoclonal IgG can ameliorate immune thrombocytopenia in a murine model of ITP: an alternative to IVIG.

Intravenous immunoglobulin (IVIG) is used to treat immune thrombocytopenia resulting from a variety of autoimmune and nonautoimmune diseases such as idiopathic thrombocytopenic purpura (ITP), heparin-induced thrombocytopenia, and posttransfusion purpura. IVIG is a limited resource and although considered safe, may nevertheless carry some risk of transferring disease. Its high cost makes monoclonal antibodies, capable of mimicking the clinical effects of IVIG, highly desirable. We show here, using a murine model of ITP, that selected monoclonal antibodies can protect against thrombocytopenia. SCID mice were pretreated with 1 of 21 monoclonal antibodies before induction of thrombocytopenia by antiplatelet antibody. Four antibodies reacted with the CD24 antigen on erythrocytes. Two antibodies were of the IgM class, and although one IgM antibody caused a minimal degree of anemia (P <.05), neither antibody ameliorated immune thrombocytopenia. One of 2 anti-CD24 antibodies of the IgG class ameliorated immune thrombocytopenia and blocked reticuloendothelial system function at the same doses that protected against thrombocytopenia. Some antibodies reactive with other circulating cell types also protected against immune-mediated thrombocytopenia while no antibody without a distinct target antigen in the mice was protective. Protective monoclonal antibodies significantly prevented thrombocytopenia at down to a 1000-fold lower dose (200 microg/kg) as compared with standard IVIG treatment (2 g/kg). It is concluded that monoclonal IgG with specificity for a circulating cellular target antigen may provide an alternative therapeutic approach to treating immune thrombocytopenia.

C-ANCA-positive IgG fraction from patients with Wegener's granulomatosis induces lung vasculitis in rats.

The aim of the present study was to analyse in rats the ability of C-ANCA-positive IgG fraction in triggering inflammatory response on pulmonary tissue. Wistar rats (n = 18) were injected via the the internal jugular vein with 20 mg of total C-ANCA-positive IgG fraction isolated from serum of three different Wegener's granulomatosis patients obtained before therapy. Similarly, control rats were treated with IgG fraction from two rheumatoid arthritis patients (n = 7), IgG from six normal human sera (n = 15) or saline (n = 18), respectively. Animals were sacrificed after 24h of injection for histological analysis of the lungs. Vasculitis and inflammatory infiltrate were consistently absent in rats injected with rheumatoid arthritis IgG or saline and in 14/15 of normal IgG treated animals. In contrast, marked vasculitis was observed in all 18 animals injected with C-ANCA-positive IgG fraction. The histological features were characterized by the presence of a perivascular pleomorphic cellular sheath, particularly around small vessels, endothelial adherence and diapedesis of polymorphonuclear leucocytes and presence of granuloma-like lesions. A dose-response relationship was observed between protein concentration of C-ANCA IgG sample and the intensity of the inflammatory response in the animals. In addition, IgG fraction with undetectable C-ANCA, obtained from one patient in remission after treatment, was not able to reproduce the pulmonary tissue alterations induced by its paired IgG that was positive for C-ANCA taken before therapy. The experimental model described herein may be useful to characterize more effectively the pathogenic mechanism of C-ANCA in Wegener's disease.

Does treatment with intermittent infusions of intravenous anti-D allow a proportion of adults with recently diagnosed immune thrombocytopenic purpura to avoid splenectomy?

This study explored whether repeated infusions of intravenous anti-D could allow adults with recently diagnosed immune thrombocytopenic purpura (ITP) who had failed an initial steroid course to postpone and ultimately avoid splenectomy. Twenty-eight Rh(+), nonsplenectomized adults with ITP diagnosed within 1 to 11 months and platelet counts 30 x 10(9)/L (30 000/microL) or below were enrolled. Anti-D was infused whenever the platelet count decreased to 30 x 10(9)/L (30 000/microL) or below. "Response" was defined as a platelet increase of more than 20 x 10(9)/L (20 000/microL) to more than 30 x 10(9)/L (30 000/microL) within 7 days of treatment. Patients were a median 3.5 months from ITP diagnosis at enrollment and had received a median of 2 previous therapies, including prednisone in 26 of 28 cases. They were followed for a median 26 months. A total of 93% responded to their initial infusion of anti-D, and 68% repeatedly responded with counts maintained above 30 x 10(9)/L (30 000/microL) using anti-D alone. Currently, 12 (43%) of 28 patients have been off all treatment for more than 6 months without undergoing splenectomy, 6 maintaining counts above 100 x 10(9)/L (100 000/microL). Seven continue on treatment, 8 underwent splenectomy, and 1 was lost to follow-up at 10 months. One patient discontinued anti-D because of toxicity. Patients with platelet counts at least 14 x 10(9)/L (14 000/microL) at enrollment were more likely to discontinue treatment (P <.05). Anti-D was an effective maintenance treatment for two thirds of Rh(+), nonsplenectomized adults with ITP who had failed an initial steroid course. Intermittent infusions of intravenous anti-D allowed more than 40% of these adults to avoid splenectomy and to achieve stable platelet counts off all therapy, even after many months of treatment. Platelet count at study entry was the primary predictor of outcome.

Models of renal insufficiency: the anti-thy-1.1 model of acute proliferative glomerulonephritis.

This unit describes the rat anti-Thy-1.1 model of acute proliferative glomerulonephritis for the study of chronic renal insufficiency. A procedure is detailed for the induction of glomerulonephritis in rats as well as measurement of daily urinary excretion of protein, which is a convenient, primary screening tool. The unit also provides methods for assessment of glomerular filtration rate and effective renal plasma flow in anesthetized rats with anti-Thy-1.1-induced renal insufficiency.

Venular thrombosis is the key event in the pathogenesis of antibody-mediated cardiac rejection.

A review of the histopathologic features of serial biopsies and excised grafts of 117 experimental and clinical cardiac allografts and xenografts revealed a common sequence in the development of histopathologic changes in grafts showing antibody-mediated (hyperacute and acute vascular) rejection. Based on these observations, we propose the new concept that thrombosis of cardiac veins and venules is the initial key event in antibody-mediated rejection. This is followed by the development of congestion in the subtended venules and capillaries accompanied by interfascicular and, later, intermyocyte edema. Subsequently, focal or diffuse interstitial hemorrhage affecting the subendocardium, extending sometimes to involve the inner half of the ventricular myocardium, is observed. Antibody-mediated rejection therefore appears to be analogous to incomplete venous infarction of the heart. The observed histopathology (in which venular thrombosis plays a key role) favors a thrombogenic basis for the classical features of antibody-mediated rejection, namely edema, vascular thrombi and interstitial hemorrhage. A key role for venular thrombosis would explain the non-uniform distribution of the changes and may suggest new ways of preventing antibody-mediated xenograft rejection.

Specific B cell tolerance is induced by cyclosporin A plus donor-specific blood transfusion pretreatment: prolonged survival of MHC class I disparate cardiac allografts.

Donor-specific blood transfusion (DST), designed to prolong allograft survival, sensitized recipients of the high-responder PVG-RT1u strain, resulting in accelerated rejection of MHC-class I mismatched (PVG-R8) allografts. Rejection was found to be mediated by anti-MHC class I (Aa) alloantibody. By pretreating recipients 4 wk before grafting with cyclosporin A (CsA) daily (x7), combined with once weekly (x4) DST, rejection was prevented. The investigation explores the mechanism for this induced unresponsiveness. CD4 T cells purified from the thoracic duct of CsA/DST-pretreated RT1u rats induced rejection when transferred to R8 heart-grafted RT1u athymic nude recipients, indicating that CD4 T cells were not tolerized by the pretreatment. To determine whether B cells were affected, nude recipients were pretreated, in the absence of T cells, with CsA/DST (or CsA/third party blood) 4 wk before grafting. The subsequent transfer of normal CD4 T cells induced acute rejection of R8 cardiac allografts in third party- but not DST-pretreated recipients; prolonged allograft survival was reversed by the cotransfer of B cells with the CD4 T cells. Graft survival correlated with reduced production of anti-MHC class I (Aa) cytotoxic alloantibody. The results indicated that the combined pretransplant treatment of CsA and DST induced tolerance in allospecific B cells independently of T cells. The resulting suppression of allospecific cytotoxic Ab correlated with the survival of MHC class I mismatched allografts. The induction of B cell tolerance by CsA has important implications for clinical transplantation.

Mesangiolysis: an update.

Mesangiolysis occurs in many renal diseases, both human and experimental. At least three types of mesangiolysis may be recognized, which differ in their mode of origin and in morphologic features. The first type is severe mesangiolysis with formation of glomerular cysts and subsequent cellular proliferation resembling glomerulonephritis. In the second type, mesangiolysis is associated with extensive widening of the subendothelial space and is thought to follow endothelial injury. The third type is mesangiolysis with lamellated mesangial nodules which is believed to result from relatively mild but persistent or recurrent localized mesangial, and perhaps also endothelial damage, with lysis of mesangial anchor points.