New milestones ahead in complement-targeted therapy

The complement system is a powerful effector arm of innate immunity that typically confers protection from microbial intruders and accumulating debris. In many clinical situations, however, the defensive functions of complement can turn against host cells and induce or exacerbate immune, inflammatory, and degenerative conditions. Although the value of inhibiting complement in a therapeutic context has long been recognized, bringing complement-targeted drugs into clinical use has proved challenging. This important milestone was finally reached a decade ago, yet the clinical availability of complement inhibitors has remained limited. Still, the positive long-term experience with complement drugs and their proven effectiveness in various diseases has reinvigorated interest and confidence in this approach. Indeed, a broad variety of clinical candidates that act at almost any level of the complement activation cascade are currently in clinical development, with several of them being evaluated in phase 2 and phase 3 trials. With antibody-related drugs dominating the panel of clinical candidates, the emergence of novel small-molecule, peptide, protein, and oligonucleotide-based inhibitors offers new options for drug targeting and administration. Whereas all the currently approved and many of the proposed indications for complement-targeted inhibitors belong to the rare disease spectrum, these drugs are increasingly being evaluated for more prevalent conditions. Fortunately, the growing experience from preclinical and clinical use of therapeutic complement inhibitors has enabled a more evidence-based assessment of suitable targets and rewarding indications as well as related technical and safety considerations. This review highlights recent concepts and developments in complement-targeted drug discovery, provides an overview of current and emerging treatment options, and discusses the new milestones ahead on the way to the next generation of clinically available complement therapeutics.

Experimental study of δ-ALA-PDT in the treatment in BXSB lupus-prone mice

Extracorporeal photochemotherapy can correct immune disease and treat many autoimmune diseases. The aim of this study was to investigate the effects of delta-aminolevulinic acid photodynamic therapy (δ-ALA-PDT) on BXSB mouse. The 24-h urine protein, titers of serum antinuclear antibodies, peripheral blood lymphocyte apoptosis and deposition of immune complex in renal glomeruli were determined in BXSB mice after δ-ALA-PDT treatment. Results showed that δ-ALA-PDT treatment could reduce 24-h urine protein, titers of serum antinuclear antibodies, and deposition of immune complex in renal glomeruli. The δ-ALA-PDT treatment could also lead to significant increase in the rate of peripheral blood lymphocytes.

Cryoglobulin/albumin complexes in a patient with severe autoimmune syndrome

We describe the case of a 30-year-old man with a severe autoimmune disease characterized by cryoglobulinaemia, pulmonary hypertension, Raynaud's phenomenon, lymphadenopathy, and glomerulonephritis. Despite initial remission following autologous stem cell transplantation, his disease relapsed and he died from pulmonary hypertension. At presentation the patient had hypergammaglobulinaemia and a number of autoantibodies, including rheumatoid factor (1:10240). The most striking feature was the extremely high level of cryoglobulins. The cryoprecipitate consisted of polyclonal IgM, IgG and albumin. Interestingly, the albumin in the cryoprecipitate was exclusively present in SS-bonded oligomeric forms, and contained an abnormal acidic component as judged by 2D gel electrophoresis. Oxidized albumin was also present in serum, and represented a small but significant fraction. None of the many known albumin variants have so far been associated with a particular disease; thus our results may represent the first description of an altered albumin associated with severe disease.

Activating and inhibitory IgG Fc receptors on human DCs mediate opposing functions

Human monocyte-derived DCs (moDCs) and circulating conventional DCs coexpress activating (CD32a) and inhibitory (CD32b) isoforms of IgG Fcgamma receptor (FcgammaR) II (CD32). The balance between these divergent receptors establishes a threshold of DC activation and enables immune complexes to mediate opposing effects on DC maturation and function. IFN-gamma most potently favors CD32a expression on immature DCs, whereas soluble antiinflammatory concentrations of monomeric IgG have the opposite effect. Ligation of CD32a leads to DC maturation, increased stimulation of allogeneic T cells, and enhanced secretion of inflammatory cytokines, with the exception of IL-12p70. Coligation of CD32b limits activation through CD32a and hence reduces the immunogenicity of moDCs even for a strong stimulus like alloantigen. Targeting CD32b alone does not mature or activate DCs but rather maintains an immature state. Coexpression of activating and inhibitory FcgammaRs by DCs reveals a homeostatic checkpoint for inducing tolerance or immunity by immune complexes. These findings have important implications for understanding the pathophysiology of immune complex diseases and for optimizing the efficacy of therapeutic mAbs. The data also suggest novel strategies for targeting antigens to the activating or inhibitory FcgammaRs on human DCs to generate either antigen-specific immunity or tolerance.

Treatment of refractory antibody mediated autoimmune disorders with an anti-CD20 monoclonal antibody (rituximab)

BACKGROUND

Rituximab, a chimeric monoclonal anti-CD20 antibody, has recently been used for the treatment of refractory antibody mediated autoimmune diseases such as immune mediated thrombocytopenia and haemolytic anaemia.

PATIENTS

Because of its novel mechanism of action, rituximab was used to treat three patients with refractory systemic antibody mediated autoimmune disorders. The first patient, a 71 year old woman with idiopathic type II mixed essential cryoglobulinaemia, had both dermatological and neurological manifestations with marked renal disease attributed to her cryoglobulinaemia. Patient 2, a 73 year old woman with Goodpasture's syndrome, was refractory to conventional treatment (cyclophosphamide, prednisone, plasmapheresis). She had persistent haemoptysis and haematuria and positive antiglomerular basement membrane antibodies. The third patient, a 75 year old man with primary biliary cirrhosis, myelodysplasia, and systemic immune complex vasculitis, had progressive renal insufficiency, a macular erythematous rash, and severe thrombocytopenia.

RESULTS

Treatment with rituximab resolved all clinical and laboratory manifestations in the three patients.

CONCLUSIONS

Rituximab may be an important therapeutic agent for the treatment of patients refractory or intolerant to corticosteroid or cytotoxic treatment, or both.

Immune complex type crescentic glomerulonephritis and ANCA-positivity in a nine-year-old girl

We report a nine-year-old girl who presented with the clinical and laboratory findings of rapidly progressive glomerulonephritis. She was found to be positive for both pANCA and cANCA. However, renal histopathology revealed immune complex type of crescentic glomerulonephritis. Thus, although testing for ANCA is an important tool in the prediction of the subtype of crescentic glomerulonephritis, a renal biopsy is still required to establish the diagnosis.

[Comparison of plasma exchange (PEX) vs. double filtration plasmapheresis (DFPP) with or without steroid administration in a case of MPO-ANCA-positive immune complex type crescentic glomerulonephritis]

The effect of plasmapheresis(PP) monotherapy and PP with corticosteroid administration were evaluated in a male with crescentic glomerulonephritis(CrGN). On the first admission, since he was positive for both anti-neutrophil cytoplasmic myeloperoxydase autoantibody(MPO-ANCA) and circulating immune complex(IC), the treatment was started with PP alone to reduce these autoantibodies immediately. During two months, three series of PP were performed: three sessions of plasma exchange (PEX) with fresh frozen plasma(FFP), two sessions of double filtration plasmapheresis(DFPP), and then, another two sessions of PEX, respectively. ANCA remained suppressed for 4 weeks after the first series of PEX, and increased thereafter. Subsequent DFPP caused a rebound of ANCA titer while the second PEX suppressed ANCA, at least, for 1 week. Though creatinine clearance(Ccr) improved after the first PEX and this level was maintained, ANCA increased again after the second PEX. Therefore the patient was treated with methyl-prednisolone(m-PSL) semipulse therapy followed by mild cocktail therapy including prednisolone(PSL) at 20 mg/day and mizoribine at 100 mg/day. In two weeks, ANCA and IC became negative and Ccr improved further. When PSL was tapered off, the ANCA became positive again. Since ANCA was not suppressed and Ccr declined gradually even after re-administration of oral PSL at 30-40 mg/day, PP was superimposed on steroid therapy with 3 sessions of DFPP and PEX, respectively. Ccr was improved, but ANCA was not sufficiently decreased by DFPP. Subsequent PEX was more efficient than DFPP in reducing the ANCA level. However, m-PSL semipulse was eventually required for complete suppression of ANCA. Thus PP was partially effective, but not sufficient as monotherapy. However it was considered advantageous as an adjunct therapy to reduce the dose of immunosuppressive drugs in CrGN. As to the mode of PP, PEX with FFP appeared to be more effective than DFPP in reducing the plasma ANCA level.

Novel therapeutic approach by culture filtrate of Cryptococcus neoformans var. gattii (CneF) in experimental immune complex glomerulonephritis

The present study was undertaken to determine the therapeutic effect of the culture filtrate of Cryptococcus neoformans var. gattii (CneF) in experimental immune complex glomerulonephritis. Bovine serum albumin (BSA) nephritis was induced in rats by a subcutaneous immunization and daily intravenous administration of BSA. CneF solution at three different doses (36, 54, and 90 mg/kg based on carbohydrate concentration) was administered intraperitoneally at regular 72-h intervals for 4 weeks. Onset of treatment was day 65, and urinary protein was measured at different intervals. Animals were euthanized on day 107. Serum and urine determinants were measured at the time of sacrifice and kidney specimens were examined. Results of this experiment showed that CneF therapy could significantly reduce the urinary protein excretion, blood urea nitrogen (BUN), plasma concentration of triglyceride, and increase the serum HDL cholesterol in treated rats vs. nontreated controls. Moreover, there was significant difference in glomerular changes between treated and nontreated groups. These observations show that the beneficial effect of CneF may be related to decreased number of glomerular leukocytes. Our findings suggest that treatment with CneF as a new antiinflammatory compound can reduce proteinuria, suppress the development of glomerular lesions, and exert lipid-lowering property in a rat model of immune complex glomerulonephritis.

Treatment of autoimmune and extra-hepatic manifestations of HCV infection

Hepatitis C virus (HCV) infects mononuclear cells and may, like other viruses, cause immunological disorders. Immunological abnormalities observed in HCV infections are usually nonspecific (e.g. cryoglobulinemia, immune complex deposits, autoantibodies). There is a clear association between cryoglobulinemia and hepatitis C and cryoglobulinemia related symptoms are usually improved by treatment with interferon alpha, although patients usually relapse after treatment end. The relationships between hepatitis C and other immunological abnormalities are unclear. The association between chronic hepatitis C and anti-smooth muscle or anti-nuclear antibodies does not appear to be significantly different from that in other hepatic disorders, particularly hepatitis B. Conversely, patients with hepatitis C have significantly more often anti-liver kidney microsomal (LKM1) antibodies than patients with other causes of liver diseases. When clinical, histological and biological findings are indicative of HCV infection with chronic hepatitis, interferon alpha or combination therapy with ribavirin are treatments options. Conversely, when clinical context and results of laboratory tests are in favor of an autoimmune disorder or of overlap-syndromes (i.e. both autoimmune and viral hepatitis), interferon should not be given in first intention, since revelation or exacerbation of autoimmune hepatitis have been reported under interferon. An important prevalence of anti-HCV antibodies has also been reported in patients with sialadenitis, lichen planus and thyroiditis. It has been clearly demonstrated that interferon may induce or worsen such immunological diseases, but there are very few studies showing improvement of these manifestations under interferon. In conclusion, interferon may be appropriate in patients with HCV infection and extrahepatic manifestations linked to immune complex deposition, whereas, in other cases, careful assessment of patients with autoimmune processes is necessary before choosing any treatment strategy.

Endothelial targeting and enhanced antiinflammatory effects of complement inhibitors possessing sialyl Lewisx moieties

The complement inhibitor soluble complement receptor type 1 (sCR1) and a truncated form of sCR1, sCR1[desLHR-A], have been generated with expression of the selectin-reactive oligosaccharide moiety, sialyl Lewisx (sLex), as N-linked oligosaccharide adducts. These modified proteins, sCR1sLex and sCR1[desLHR-A]sLex, were assessed in the L-selectin- and P-selectin-dependent rat model of lung injury following systemic activation of complement by cobra venom factor and in the L-selectin-, P-selectin-, and E-selectin-dependent model of lung injury following intrapulmonary deposition of IgG immune complexes. In the cobra venom factor model, sCR1sLex and sCR1[desLHR-A]sLex caused substantially greater reductions in neutrophil accumulation and in albumin extravasation in lung when compared with the non-sLex-decorated forms. In this model, increased lung vascular binding of sCR1sLex and sCR1[desLHR-A]sLex occurred in a P-selectin-dependent manner, in contrast to the absence of any increased binding of sCR1 or sCR1[desLHR-A]. In the IgG immune complex model, sCR1[desLHR-A]sLex possessed greater protective effects relative to sCR1[desLHR-A], based on albumin extravasation and neutrophil accumulation. Enhanced protective effects correlated with greater lung vascular binding of sCR1[desLHR-A]sLex as compared with the non-sLex-decorated form. In TNF-alpha-activated HUVEC, substantial in vitro binding occurred with sCR1[desLHR-A]sLex (but not with sCR1[desLHR-A]). This endothelial cell binding was blocked by anti-E-selectin but not by anti-P-selectin. These data suggest that sLex-decorated complement inhibitors have enhanced antiinflammatory effects and appear to have enhanced ability to localize to the activated vascular endothelium.

Immunologic aspects of renal disease

The kidney can become involved in immune-mediated diseases through 3 mechanisms. It can be the primary target of antibody-mediated injury. Good-pasture syndrome, with antibodies directed at the glomerular basement membrane, is an example of this type. The kidney can be injured by immune complexes that are trapped in the kidney and cause local inflammation. Examples include systemic lupus erythematosus and IgA nephropathies. Finally, the kidney can be injured by immune responses initiated in other organs. In Wegener granulomatosis, inflammation begins in the airway but results in glomerulonephritis. Currently available therapies lack efficacy and specificity. New therapies based on pathophysiology are being developed in animal models.

Regulatory effects of interleukin-6 in immunoglobulin G immune-complex-induced lung injury

Interleukin-6 (IL-6) is a cytokine produced in response to a variety of inflammatory stimuli. Although IL-6 is often observed in increased amounts in acute respiratory distress syndrome, its role in the development of lung injury is unclear. The role of IL-6 was studied in the rat model of lung injury induced by the intra-alveolar deposition of IgG immune complexes. IL-6 induction, as determined by Northern blot analysis and bioactivity, was found as a function of time during the course of development of injury. Recombinant IL-6 instilled intratracheally at commencement of injury led to substantial reductions in lung vascular permeability, neutrophil accumulation, and levels of tumor necrosis factor (TNF)-alpha and macrophage inflammatory protein (MIP)-2 in bronchoalveolar lavage fluids. Conversely, blocking of intrinsic IL-6 by a neutralizing antibody resulted in increases in lung vascular permeability, neutrophil content, and TNF-alpha levels in bronchoalveolar lavage fluids. Rat alveolar macrophages stimulated in vitro with lipopolysaccharide in the presence of IL-6 showed a significant reduction in TNF-alpha expression. Together, these findings suggest that IL-6 acts as an intrinsic regulator of lung inflammatory injury after deposition of IgG immune complexes and that the protective effects of exogenously administered IL-6 may be in part linked to suppressed TNF-alpha production.

[Correction of immune disorders in surgery of duodenal ulcer]

The dynamics of immune status in 124 patients operated on for duodenal ulcer are analysed. The patients were divided into two groups: in the study group (60 patients) regional lymphoimmune stimulation with T-activin was used, in patients of the control group T-activin was not used. The depression of immune system in short term period after surgical intervention was detected. The injection of T-activin into the round ligamentum of the liver influences favourably the course of the disease and promotes correction of immune disorders, thus preventing short-term postoperative complications.

Amelioration of lupus-like autoimmune disease in NZB/WF1 mice after treatment with a blocking monoclonal antibody specific for complement component C5

New Zealand black x New Zealand white (NZB/W) F1 mice spontaneously develop an autoimmune syndrome with notable similarities to human systemic lupus erythematosus. Female NZB/WF1 mice produce high titers of antinuclear antibodies and invariably succumb to severe glomerulonephritis by 12 months of age. Although the development of the immune-complex nephritis is accompanied by abundant local and systemic complement activation, the role of proinflammatory complement components in disease progression has not been established. In this study we have examined the contribution of activated terminal complement proteins to the pathogenesis of the lupus-like autoimmune disease. Female NZB/W F1 mice were treated with a monoclonal antibody (mAb) specific for the C5 component of complement that blocks the cleavage of C5 and thus prevents the generation of the potent proinflammatory factors C5a and C5b-9. Continuous therapy with anti-C5 mAb for 6 months resulted in significant amelioration of the course of glomerulonephritis and in markedly increased survival. These findings demonstrate an important role for the terminal complement cascade in the progression of renal disease in NZB/W F1 mice, and suggest that mAb-mediated C5 inhibition may be a useful approach to the therapy of immune-complex glomerulonephritis in humans.

Cryoglobulinemia in chronic hepatitis C virus infection: prevalence, clinical manifestations, response to interferon treatment and analysis of cryoprecipitates

Chronic hepatitis C virus infection can be associated with mixed cryoglobulinemia and systemic vasculitis. The pathogenesis remains poorly understood. 55 consecutive patients with chronic HCI infection (anti-HCV- and serum HCV RNA-positive) were studies prospectively. Cryoglobulinemia was detected in 28 patients (51%) with a mean cryocrit level of 2.2%. Clinical symptoms of vasculitis were encountered in six patients. Compared to those HCV-infected patients without cryoglobulinemia the following distinctive features were observed in the presence of cryoglobulinemia: increased age (p<0.02), female preponderance (p<0.002), longer-lasting HCV infection (mean of 10.7 vs. 4.7 yrs), higher prevalence of cirrhosis (42.8 vs. 0%), increased serum concentration of IgM and increased rheumatoid factor activity, decreased concentration of serum C4 (each p<0.05). The response to interferon treatment was similar in patients with and without cryoglobulinemia. When cryoprecipitates were analyzed by immunofixation, type II cryoglobulinemia was present in 1/3 and type III in 2/3 of patients. By SDS-PAGE four different proteins were demonstrable in cryoprecipitates each identified by immunoblotting as IgG and IgM heavy or light chains respectively. Cryoprecipitate IgGs were shown to react with HCV structural as well a non-structural proteins in a recombinant immunoblotting assay (RIBA). In contrast, cryoprecipitate IgMs reacted only to the HCV core protein c22-3. HCV RNA was detected in cryoprecipitates without a significant enrichment when compared to the corresponding serum or supernatant HCV RNA content. Given the monoclonality of some cryoprecipitate IgM and their reactivity to HCV core, a cross-reactivity to IgG was postulated. In fact, when performing a computer-assisted search for sequence homology, a motif within the core protein (EGLGWAGWL, conserved in HCV genotypes) was identified homologous to a sequence of IgG heavy chains. Thus, temperature-dependent affinity changes of IgM anti-HCV core (nonapeptide) and ensuing complex formation with IgG via binding to the homologous IgG sequence could be a mechanism of cryoprecipitate formation.

[Skin ulcers in rheumatoid arthritis]

The appearance of severe ulceration of the skin in patients with rheumatoid arthritis is often associated with a tendency to progression of the underlying disease, involvement of internal organs and increased mortality. In the pathogenesis of such ulceration there are multiple causes for their development, persistence and tendency to poor healing. They include localized or generalized immune complex vasculitis, treatment with anti-inflammatory drugs and their side effects following the treatment, arterial and venous insufficiency, and mechanical factors. The management of severe ulceration requires stabilization of the underlying autoimmune disease, e.g. with high doses of glucocorticosteroids or other immunosuppressive drugs or plasmapheresis. Adjuvant treatment of pain with analgesics, improvement of blood perfusion and anti-inflammatory drugs should accompany the topical therapy of ulcers. After suppression of the local inflammatory reaction surgical intervention becomes necessary in most of the patients, and vascularized muscle flaps should be used in preference to meshgrafts or split skin grafts for extensive ulceration in rheumatoid arthritis. A hopeful perspective in the treatment of severe rheumatoid arthritis might be opened up with immunotherapy using monoclonal antibodies.

[Today's apheresis therapy]

Recent apheresis therapy is developing day by day. Now we can say that we do not achieve suitable treatment without an apheresis technology. Acute and chronic renal failure, severe hepatic failure, acute necrotic pancreatitis and MOS are not able to treat without haemodialysis (HD), haemofiltration (HF) and plasma exchange (PE). Immunomodulation for immune complex diseases and removing of pathologic antibodies are controlled by this technique. In the near future, it will play an important role for controlling of xenotransplantation. LDL apheresis for hyperlipidemia is very effective in cleaning the blood, and the prevention of ASO, angina syndrome and coronary disease is discussed. LAK therapy and immune therapy using apheresis technique have been effective for cancer and it will be developed moreover. Lastly, apheresis used to prevent aging is the music of the future.

[Subacute progressive polyneuropathy syndrome in HIV infection. The efficacy of immunosuppressive treatment?]

A subacute advanced severe sensorimotor polyneuropathy developed over 6 months in a 47-year-old patient in stage 5 of an HIV infection (Walter Reed Hospital classification). Clinical examination, cranial computed tomography and spinal nuclear magnetic imaging failed to demonstrate any central nervous system complication. Cerebrospinal fluid showed a lymphocytic pleocytosis of 57/3 cells and total protein raised to 132 mg/dl as sign of an abnormal blood-brain barrier. Circulating immune complex in blood was raised to 30%. Assuming an immune-complex mediated neuropathy treatment with oral steroids was started, initially 150 mg daily. The signs of polyneuropathy regressed almost completely, even after prednisolone was discontinued. The proportion of circulating immune complexes in blood fell within 7 weeks to 10% during this treatment. It is suggested that in HIV-infected patients severe polyneuropathies may develop as part of a humoral immune reaction in which immunosuppressive treatment can be effective. Even in advanced HIV infection high-dosage and prolonged steroid treatment can be undertaken, under strictest indications, and may have impressive results.

The systemic vasculitides

Taken together, the systemic vasculitides constitute a small but significant component in the practice of many primary care physicians. Like most diseases with autoimmune aspects, the vasculitides increase in prevalence with age. Of paramount importance is careful differentiation, to provide early appropriate treatment and to monitor adverse effects.

Intravenous gamma-globulin therapy in systemic lupus erythematosus and immune complex disease

Immune complexes (ICs) are felt to be of primary pathological importance in the mediation of many human glomerular diseases. This is based on the demonstration of Ig and C' in renal cortex tissue of affected individuals. Systemic lupus erythematosus (SLE) is a prototype IC disease where ICs have been demonstrated in target tissues. Moreover, glomerulonephritis (GN) is a common feature of many autoimmune and infectious diseases associated with IC generation. Current therapeutic alternatives are restricted to immunosuppressive agents. Tomino et al. (Clin. Exp. Immunol. 58, 42, 1984) demonstrated that glomerular IC deposits could be solubilized with HGG. Palla et al. (Clin. Nephrol. 26, 314, 1986) treated four membranous nephritis patients with IVGG and had dramatic resolution of proteinuria in three of them. Gaedlicke et al. (Blut 48, 387, 1984) reported improvement in vasculitis in one of two patients treated with IVGG. We have experienced exacerbation of GN with IVGG therapy in two SLE patients. IVGG is useful in treating the common variable immunodeficiency that occurs in some SLE patients and in treating the immunodeficiency associated with florid nephrotic syndrome. IVGG given to one patient with Henoch-Schönlein purpura resulted in the onset of gross hematuria. In sum, IVGG may be useful in treating specific IC renal diseases by solubilization of circulating or in situ ICs but definitive proof is lacking. In other situations, IVGG may exacerbate the glomerulonephritis, possibly through enhanced IC formation. Furthermore, IVGG may induce modulation of immune responses by induction of auto-anti-idiotypic immunity.

Cisplatin-associated hemolytic-uremic syndrome. Successful treatment with a staphylococcal protein A column

Cisplatin-associated hemolytic-uremic syndrome (HUS), an under-reported form of HUS induced by chemotherapy, typically pursues a fulminant and lethal course. We report the cases of two patients with squamous cell carcinoma of the head and neck who developed massive hemolysis, profound thrombocytopenia, and dialysis-dependent renal failure after therapy with cisplatin. Plasma exchange was ineffective in both patients, but plasma perfusion with a staphylococcal protein A column produced a dramatic and permanent response in the second patient. These cases show the importance of considering HUS as a cause of renal failure in such patients who receive cisplatin-based chemotherapy, and support the role of staphylococcal protein A plasma perfusion as treatment for this condition.

[Rapidly progressing glomerulonephritis. Spontaneous course and differential therapy with special reference to the infection-associated form]

Since 1971 we observed 31 patients with histologically proven rapidly progressive (crescentic) glomerulonephritis. At the onset of therapy 16 patients presented with end stage renal failure, the others with impaired renal function. 21 patients received combined immunosuppressive therapy, consisting of prednisone, cyclophosphamide and azathioprine. 8 patients were treated with membrane plasmapheresis, additionally. 10 patients received no specific therapy. After 5 years 13 patients were on hemodialysis, 4 had impaired renal function and 10 patients were dead. Two patients died due to the progression of underlying diseases, the others were lost following infectious diseases. There was no additional positive effect in the group treated with membrane plasma separation compared with patients treated only immunosuppressive. Only in 4 patients without specific therapy normalization of renal function occurred. In these patients RPGN appeared after an infectious disease. We conclude that an infectious disease associated RPGN is an own entity of glomerulonephritis that has a very good prognosis and needs only antibiotic therapy.

In vivo binding of circulating immune complexes by C3b receptors (CR1) of transfused erythrocytes

The effects of packed erythrocyte transfusion with high CR1 activity on circulating immune complex concentrations were studied in 14 transfusion experiments involving 12 patients with immune complex related diseases. Before erythrocyte transfusion circulating immune complex concentrations ranged from 8 to 128 micrograms/ml. After transfusion (2-3 units) immune complex concentrations decreased depending on the levels of CH50 titres in the recipients. In 11 experiments, in which the patients' CH50 titres ranged from 21 to 44, immune complex concentrations decreased by 75-100% within five days. The CH50 titres were also decreased after erythrocyte transfusion but subsequently increased to initial ranges within 6-35 days. In three patients with low CH50 titres (1.0-10.0) decreases in immune complexes were not observed. Direct Coombs' tests for IgG and C3 were performed before and after erythrocyte transfusion to determine potential in vivo binding of circulating immune complexes. Thus in eight of 14 experiments, in which erythrocytes carried no IgG before packed erythrocyte transfusion, seven became Coombs' positive for IgG after the transfusion. In seven of 14 experiments, in which erythrocytes were negative for complement before transfusion, five became positive afterwards. Moreover, in 12 instances slight increases of CR1 activity of patients' erythrocytes were observed within eight days, which improved further within 35 days after erythrocyte transfusion. These studies suggest that transfusion of erythrocytes with high CR1 activity results in the removal of circulating immune complexes and that this process is dependent on complement consumption. These experiments support the hypothesis that erythrocyte-CR1 has a functional role in the removal of circulating immune complexes and may thereby inhibit the deposition of immune complexes within body tissue constituents.

Down regulation of Fc receptors by IVIgG

IVIgG preparations are now widely applied for immune modulatory treatment in various forms of autoimmune and immune complex diseases. Several controlled studies clearly demonstrated the clinical efficacy of this type of treatment; the underlying pathophysiological mechanisms, however, have yet to be elucidated. Among the mechanisms suggested to play a role in this context is the interaction of gamma globulin with Fc gamma receptors (Fc gamma R) expressed in the membrane of immunocompetent cells. Our studies concentrated on these aspects and focused on possible functional consequences of IgG-Fc gamma R interaction. By using the peripheral blood monocyte as a model system for an Fc gamma R-bearing cell, we confirmed previous reports by showing differences in Fc gamma R binding and Fc gamma R modulation induced by IgG in its various forms (monomeric IgG, Polymeric IgG, immune complexes). As biological consequences of Fc gamma R modulation, changes in effector and accessory function of these cells were observed. The results presented in this brief review emphasize especially the difference between ligand-oriented Fc gamma R diffusion (induced by surface-bound IgG) and true long-term down-modulation of Fc gamma R (mediated by fluid-phase IgG polymers) and show that only the down-modulation of Fc gamma R correlated with impaired functions of the affected cell.

Renal transplantation and schistosomiasis mansoni

Eleven patients with schistosomiasis mansoni received a renal transplant. In 5 patients, the schistosomiasis was asymptomatic and had been diagnosed by routine examinations and had no relationship to nephropathy. In 4 patients, the nephropathy was suggestive of being of schistosomal origin. Three of them had symptomatic hepatosplenic schistosomiasis, and histologic studies of original kidneys disclosed chronic glomerulonephritis in 2 and membranous glomerulonephritis in 1 patient. These histologic pictures do not establish definitively the schistosomal origin of nephropathy. The other patient had membranoproliferative glomerulonephritis that recurred in the allograft, but he had intestinal schistosomiasis. This form of the disease is not considered by all as capable of inducing nephropathy. Two patients had the hallmarks of schistosomal nephropathy: hepatosplenic form and membranoproliferative glomerulonephritis. The 1st patient developed nephrotic syndrome 3 years after the transplantation, and an allograft biopsy disclosed membranoproliferative glomerulonephritis. The other patient had an uneventful outcome with good renal function and no proteinuria. An allograft biopsy performed 14 months after the transplant disclosed slight mesangial proliferation with IgM++ and C3++ in the mesangium.

Amelioration of immune complex-mediated glomerulonephritis by synthetic protease inhibitors

Proteases are involved in the pathogenesis of inflammatory diseases by participating in the activation of mediator systems and by producing proteolytic tissue injury. Homeostatic control of inflammation is accomplished in part by physiologic protease inhibitors. The authors investigated the effectiveness of a number of synthetic protease inhibitors in ameliorating the glomerular injury induced by immune complex-mediated glomerulonephritis in mice. Two amidine-type protease inhibitors, bis (5-amidino-2-benzimidazolyl)methane and 1,2-bis (5-amidino-2-benzimidazolyl)ethane, had the greatest effects. They caused a marked reduction in glomerular necrosis (P less than 0.001) but did not affect the amount or site of immune complex localization or leukocyte influx. The inhibition constants of the protease inhibitors against nine purified physiologic proteases were determined. These results were discussed in relation to the effectiveness of the protease inhibitors in reducing glomerular injury. This investigation indicates that the administration of synthetic protease inhibitors can have a beneficial effect on immune-mediated inflammatory injury.

Role of immune complexes in pathogenesis of renal disease

When judged by histological criteria, kidney tissue is practically devoid of immune tissue; as yet a broad spectrum of immunological diseases are targeted at the kidneys, especially at the glomeruli. Glomerular epithelial cells exhibit immune protein receptors and hence could clear immune complexes decorated with complement from the circulation. Alternatively, circulating immune complexes could become trapped in the glomerular filter and start off inflammatory reactions. Anti-glomerular basement membrane antibody reacts with glomeruli and causes glomerulonephritis. The present text is an analysis of the impact of immune complex formation on renal pathology and contains retrospective clinical data of our own hospital obtained on 192 patients undergoing diagnostic renal biopsy.