[THE EFFECT OF OF POLY(ADP-RIBOSE) POLYMERASE INHIBITOR 4-HYDROXY-QUINAZOLINE ON DEATH OF IMMUNE CELLS UNDER IMMUNE COMPLEX-MEDIATED INJURY IN MICE]

The influence of poly(ADP-ribose) polymerase (PARP) in- hibitor 4-hydroxyquinazoline (4-HQ) on the level of DNA damage and on the death of thymic and lymph node cells in mouse model of immune complex injury was investigated to reveal its possible cytoprotective effect. As shown by comet assay, DNA damage index of immune cells was increased 4,0 times in mice with immune complex-mediated pathology induced by a long-term immunization of CBA mice with bovine serum albumin (BSA), P<0,001. The percentage of thymic cells with strong DNA damage was increased to 77% under immunization (compared to 1,5% in control mice) and the percentage of such cells from lymph nodes was increased to 80% (compared to 0% in control), in both cases P< 0,001. Genotoxic stress was reduced by treatment of immunized mice with 4-HQ: the percentage of lymphocytes with strong DNA damage was significantly decreased that promoted increase in the amount of cells having intact DNA. PARP inhibition exerted a strong cytoprotective effect: viability of thymus and lymph node cells was increased mainly due to reduced level of necrosis. So, our results suggest that PARP may be involved in thymic and lymph node cell damage in immune complex mediated pathology and give evidence that inhibition of this enzyme may constitute a perspective target in immune complex diseases prevention and therapy.

Glyco-engineering for the production of recombinant IgA1 with distinct mucin-type O-glycans in plants

IgA nephropathy (IgAN) is a common autoimmune disease that is characterized by formation and deposition of IgA1-containing immune complexes frequently leading to end-stage kidney disease. The IgA1 in these immune complexes carries aberrantly glycosylated O-glycans. In circulating IgA1 these galactose-deficient mucin-type O-glycans are bound by autoantibodies and thus, contribute to immune complex formation and pathogenesis. Even though the disease is associated with the overproduction of aberrant O-glycans on IgA1, specific structure-function-studies of mucin-type O-glycans are limited. Compared to other expression hosts, plants offer the opportunity for de novo synthesis of O-glycans on recombinant glycoproteins as they are lacking the mammalian O-glycosylation pathway. Recently, we demonstrated that Nicotiana benthamiana are suitable for the generation of distinct O-glycans on recombinant IgA1. Here, we expand our engineering repertoire by in planta generation of galactose-deficient and α2,6-sialylated O-glycans which are the prevailing glycans detected on IgA1 from patients with IgAN.

[ANTI-Hsp60 ANTIBODIES IN ARTERIAL HYPERTENTION DIFERENT DEGREE OF SEVERITY]

More than 12.1 million people with hypertension (32.2% of the adult population) were registered in Ukraine according to the official statistics on 1 January 2011. The etiopathogenesis of AH is not fully established. Hsp60 is the molecular chaperon/chaperonin, and it's expression significantly increases in response to different kinds of stress (emotional stress, infections, smoking etc). Elevated blood pressure is a mechanical stress to the endothelium and it can induce expression of heat-shock protein 60 (Hsp60) on the endothelial cell surface. Endothelial cells in the vessel wall can be damaged by (auto) immune reactions to Hsp60 present on the cell surface. Elevation of anti-Hsp60 in the circulation is associated with the presence and severity of coronary heart disease, atherosclerosis development, pathological changes in the small vessels of the brain etc etc. Specificity of the anti-Hsp60 antibodies and their role in the pathogenesis of AH has not been established. The aim of this work was to identify the level of anti-Hsp60 antibodies in the sera of patients with AH. 128 patients with AH were examined. To define level of anti-Hsp60 antibodies the sera 39 patients with AH, including 12 clinically healthy individuals (the family history are included the AH cases)--1 group, 19 patients with stage 2--2 group and 8 patients with stage 3--3 group were examined. The control group included 112 blood donors. Anti-Hsp60 antibodies in sera were determined by ELISA and immunobloting (Western-blotting). Recombinant piotein GroEL Escherihia coli (prokaryotic homologue of human Hsp60) and human Hsp60 were used as antigens. Average of levels of antibodies against GroEL and human Hsp60 in the serum of all groups twice exeeded the value of the control (P < 0.001). Antibodies to prokaryotic Hsp60 were prevailed in patients with AH. The seropositive serum to Hsp60 were detectived in patients, that had the risk of the AH complications by ELISA and immunoblotting. In addition, highly reactive IgG anti-Hsp60 antibodies purified by affinity chromatography from human sera of patients with AH recognized GroEL and human Hsp60 in immunoblotting. Elevated levels of anti-Hsp60 antibody in sera of patients with AH stage 3 correlated with pronounced changes in the target organs such as a massive recurrent hemorrhage into the retina, acute ischemic stroke, cardiosclerosis and angionephrosclerosis. It may indicate the involvement of anti-Hsp60 antibodies in the development of the target organ damage.

Staphylococcal protein A-formulated immune complexes suppress enterotoxin-induced cellular responses in nasal polyps

BACKGROUND

Recent studies have revealed that Staphylococcus aureus and its components participate in the pathogenesis of eosinophilic airway diseases, such as chronic rhinosinusitis with nasal polyps.

OBJECTIVE

We sought to determine whether staphylococcal protein A (SpA) from S aureus regulated cellular responses in nasal polyps, especially when coupled to immunoglobulins in immune complexes (ICs).

METHODS

Dispersed nasal polyp cells (DNPCs) or peripheral blood monocytes were cultured in vitro with SpA in the presence or absence of IgG, and IL-5, IL-13, IFN-γ, IL-17A, and IL-10 levels were measured in the supernatants. The effect of SpA exposure on staphylococcal enterotoxin B-induced cytokine production by DNPCs in the presence and absence of IgG, IgA, and autologous serum was also examined.

RESULTS

Exposure to SpA induced DNPCs to produce significantly higher IL-10, IL-13, and IL-17A levels than DNPCs without SpA, although the magnitude of the IL-17A increase was less than that of IL-10 and IL-13. SpA induced IL-10 production mainly from adherent DNPCs, and this was significantly enhanced in the presence of IgG; similar results were observed in peripheral blood monocytes. IC formation between SpA and IgG (SpA-IgG ICs) was confirmed by using native polyacrylamide gel electrophoresis. SpA-IgG ICs, but not SpA alone, almost completely suppressed staphylococcal enterotoxin B-induced IL-5, IL-13, IFN-γ, and IL-17A production by DNPCs; similar inhibition was observed in DNPCs treated with SpA in the presence of either IgA or autologous serum.

CONCLUSIONS

Our results suggest that SpA can regulate the pathogenesis of enterotoxin-induced inflammation in patients with chronic rhinosinusitis with nasal polyps through coupling to immunoglobulins.

CD55 deposited on synovial collagen fibers protects from immune complex-mediated arthritis

INTRODUCTION

CD55, a glycosylphosphatidylinositol-anchored, complement-regulating protein (decay-accelerating factor), is expressed by fibroblast-like synoviocytes (FLS) with high local abundance in the intimal lining layer. We here explored the basis and consequences of this uncommon presence.

METHODS

Synovial tissue, primary FLS cultures, and three-dimensional FLS micromasses were analyzed. CD55 expression was assessed by quantitative polymerase chain reaction (PCR), in situ hybridization, flow cytometry, and immunohistochemistry. Reticular fibers were visualized by Gomori staining and colocalization of CD55 with extracellular matrix (ECM) proteins by confocal microscopy. Membrane-bound CD55 was released from synovial tissue with phospholipase C. Functional consequences of CD55 expression were studied in the K/BxN serum transfer model of arthritis using mice that in addition to CD55 also lack FcγRIIB (CD32), increasing susceptibility for immune complex-mediated pathology.

RESULTS

Abundant CD55 expression seen in FLS of the intimal lining layer was associated with linearly oriented reticular fibers and was resistant to phospholipase C treatment. Expression of CD55 colocalized with collagen type I and III as well as with complement C3. A comparable distribution of CD55 was established in three-dimensional micromasses after ≥3 weeks of culture together with the ECM. CD55 deficiency did not enhance K/BxN serum-induced arthritis, but further exaggerated disease activity in Fcgr2b (-/-) mice.

CONCLUSIONS

CD55 is produced by FLS and deposited on the local collagen fiber meshwork, where it protects the synovial tissue against immune complex-mediated arthritis.

The Complement—Fixing Activity of Immune Complexes Containing IgG Antibodies of Different Functional Affinities: Effects on Superoxide Production by Rabbit Neutrophils

When neutrophil phagocytes are stimulated by IgG containing immune complexes (IgG-IC), with or without the participation of the complement system, they show a sharp increase in oxygen uptake and begin to release large quantities of superoxide anions (O2-) and hydrogen peroxide (H2O2) into the surrounding medium. The aim of the present investigation was to provide insights into the production and release of O2- by rabbit neutrophils activated with immune complexes (IC) containing IgG antibodies of different functional affinity, opsonized and not opsonized by complement system components. For this purpose, two populations of polyclonal anti-ovalbumin (OVA) IgG antibodies with different functional affinity, 5 x 10(8) M(-1) and 2 x 10(7) M(-1), were prepared. The production of O2- was measured spectrophotometrically by a method using the superoxide dismutase-inhibited reduction of ferricytochrome C to the ferrous form. The activation of complement by different IgG-IC was determined by estimating the total residual haemolytic activity of the alternative and classical pathways in sera treated with different concentrations of anti-OVA IgG/ OVA immune complexes formed at equivalence. The results showed that: 1) antibody functional affinity influenced O2- production and the complement-fixing activity induced by the IC. In general, the higher functional affinity antibodies were more efficient in stimulating the respiratory burst of neutrophils and in activating complement by the classical and alternative pathways than the lower functional affinity antibodies at all IC concentrations tested; 2) complement components incorporated into the immune complex lattice caused an increase in the stimulatory activity of both IgG antibodies to produce O2- (approximately equal to 15% for the IC of IgG with Ka = 5 x 10(8) M(-1) and approximately equal to 7% for the IC of IgG with Ka = 2 x 10(7) M(-1)). This effect was dependent on antibody affinity and concentration; 3) there was a direct relationship between the overall level of complement activation, antibody affinity and superoxide production by neutrophils. Thus, we conclude that antibody affinity influences immune complex lattice formation, modulating its three-dimensional structure and the disposition of Fc fragments interfering with the antibody's biological properties. These results can help understand the precise role of antibody functional affinity in antigen-antibody complex diseases and define the immunochemical characteristics of pathogenic complexes.

Soluble TNF-like cytokine (TL1A) production by immune complexes stimulated monocytes in rheumatoid arthritis

TNF-like cytokine (TL1A) is a newly identified member of the TNF superfamily of ligands that is important for T cell costimulation and Th1 polarization. However, despite increasing information about its functions, very little is known about expression of TL1A in normal or pathological states. In this study, we report that mononuclear phagocytes appear to be a major source of TL1A in rheumatoid arthritis (RA), as revealed by their strong TL1A expression in either synovial fluids or synovial tissue of rheumatoid factor (RF)-seropositive RA patients, but not RF-/RA patients. Accordingly, in vitro experiments revealed that human monocytes express and release significant amounts of soluble TL1A when stimulated with insoluble immune complexes (IC), polyethylene glycol precipitates from the serum of RF+/RA patients, or with insoluble ICs purified from RA synovial fluids. Monocyte-derived soluble TL1A was biologically active as determined by its capacity to induce apoptosis of the human erythroleukemic cell line TF-1, as well as to cooperate with IL-12 and IL-18 in inducing the production of IFN-gamma by CD4(+) T cells. Because RA is a chronic inflammatory disease with autoimmune etiology, in which ICs, autoantibodies (including RF), and various cytokines contribute to its pathology, our data suggest that TL1A could be involved in its pathogenesis and contribute to the severity of RA disease that is typical of RF+/RA patients.

APAAP complex: production and usage in immunocytochemical and immunohistochemical staining

BACKGROUND

The affinity of antibody to antigen, in addition to providing the possibility of measuring the antigen in tissue extracts through methods such as RIA (Radioimmunoassay) and EIA (Enzymimmunoassay) and possibility of isolating and analyzing dispersed cell colonies using flowcytometry, makes it possible to determine the site of antigen in tissues (Immunohistochemistry) or in cells (Immunocytochemistry).

OBJECTIVE

Production of APAAP complexes and comparing them with similar foreign products to determine the site of antigen in tissues or in cells.

METHODS

Secreted antibodies of the two hybridomas (A(1)G(9)G(3) and A(1)G(8)F(7) produced in our laboratory) were concentrated, purified and characterized. Then the monoclonal antibodies were mixed with alkaline phosphatase enzyme (ALP) to use in immunocytochemistry (ICC) and immunohistochemistry (IHC) staining.

RESULTS

Both of the cell colonies had the potentiality of producing anti- alkaline phosphatase monoclonal antibody with high affinity. The complex from mAb and enzyme - for the third phase of APAAP technique - was very effective and its sensitivity was comparable to that of the similar foreign kit.

CONCLUSION

Considering the high affinity of the mAb of the two hybridomas and the stability of the complex resulted from mixing mAb and the enzyme ALP for a long time, it is possible to use the obtained APAAP complex in the immunocyto (or histo) chemistry - as the third phase.

Preeclampsia: the Death of Goliath

In this review, a novel and unifying pathophysiologic mechanism of preeclampsia is presented whereby a minimal excess of placental immune complex production versus removal causes a proinflammatory autoamplification cascade of trophoblast apoptosis/necrosis and oxidative stress, culminating in clinical preeclampsia. This concept immediately leads to a plethora of new and robust therapeutic strategies.

Autoantibody-Induced Formation of Immune Complexes in Normal Human Serum

Intravenous immunoglobulins (IVIg) are concentrated preparations of purified human plasma-derived IgG routinely used in the treatment of many autoimmune diseases. Their precise mechanisms of therapeutic action have remained unclear in most diseases and are attracting much interest due to the rapidly increasing use of this precious plasma-derived product. The presence in IVIg of IgG reactive with various human structures has been known for many years. In this review, we first briefly discuss the formation and role of natural autoreactive human IgG in healthy individuals. A role for IgG autoantibodies in the in vivo immunomodulatory effects of IVIg has been proposed several years ago but the underlying mechanism has remained unclear. Recent work has shown that the large IVIg doses infused in many patients could oversaturate the normal anti-idiotype-dependent inhibition of autoreactive IgG present in the plasma of all healthy individuals since the formation of autoimmune complexes could be observed in normal serum in presence of therapeutic amounts of IVIg. These autoimmune complexes could have potent in vivo immunomodulatory effects by interacting with various IgG and complement receptors. Furthermore the autoreactive IgG can be easily purified from IVIg by affinity chromatography, raising the interesting possibility of further fractionating IVIg into different sub-products for use in the treatment of different diseases. These results indicate that natural autoantibodies have important in vivo roles not only for the protection of the body against infectious agents but also for the efficiency of passive immunotherapy procedures used in the treatment of many diseases.

Mechanisms of immune-deposit formation and the mediation of immune renal injury

The passive trapping of preformed immune complexes is responsible for some forms of glomerulonephritis that are associated with mesangial or subendothelial deposits. The biochemical characteristics of circulating antigens play important roles in determining the biologic activity of immune complexes in these cases. Examples of circulating immune complex diseases include the classic acute and chronic serum sickness models in rabbits, and human lupus nephritis. Immune deposits also form "in situ". In situ immune deposit formation may occur at subepithelial, subendothelial, and mesangial sites. In situ immune-complex formation has been most frequently studied in the Heymann nephritis models of membranous nephropathy with subepithelial immune deposits. While the autoantigenic target in Heymann nephritis has been identified as megalin, the pathogenic antigenic target in human membranous nephropathy had been unknown until the recent identification of neutral endopeptidase as one target. It is likely that there is no universal antigen in human membranous nephropathy. Immune complexes can damage glomerular structures by attracting circulating inflammatory cells or activating resident glomerular cells to release vasoactive substances, cytokines, and activators of coagulation. However, the principal mediator of immune complex-mediated glomerular injury is the complement system, especially C5b-9 membrane attack complex formation. C5b-9 inserts in sublytic quantities into the membranes of glomerular cells, where it produces cell activation, converting normal cells into resident inflammatory effector cells that cause injury. Excessive activation of the complement system is normally prevented by a series of circulating and cell-bound complement regulatory proteins. Genetic deficiencies or mutations of these proteins can lead to the spontaneous development of glomerular disease. The identification of specific antigens in human disease may lead to the development of fundamental therapies. Particularly promising future therapeutic approaches include selective immunosuppression and interference in complement activation and C5b-9-mediated cell injury.

Antigen-specific down-regulation of immunopathological events in an experimental autoimmune kidney disease

Heymann nephritis (HN) is an experimental autoimmune disease of rats characterized by immune-complex (IC) depositions on the epithelial side of the glomerular basement membrane (GBM) and by proteinuria. Several forms of HN have been produced by various investigators, but one thing has been common to all of them, namely their inducement by the development of pathogenic IgG autoantibodies (aabs). The aim of this review is to describe how pathogenic IgG aab production (which initiates and maintains the disease) in slowly progressive HN (SPHN) can be specifically terminated by injections of ICs made up of native rat renal tubular antigens and IgM antibodies directed against them.

Highly immunogenic and protective recombinant vaccine candidate expressed in transgenic plants

Vaccine development has been hampered by difficulties in developing new and safe adjuvants, so alternative technologies that offer new avenues forward are urgently needed. The goal of this study was to express a monoclonal recombinant immune complex in a transgenic plant. A recombinant protein consisting of a tetanus toxin C fragment-specific monoclonal antibody fused with the tetanus toxin C fragment was designed and expressed. Immune complex formation occurred between individual fusion proteins to form immune complex-like aggregates that bound C1q and FcgammaRIIa receptor and could be targeted to antigen-presenting cells. Unlike antigen alone, the recombinant immune fusion complexes were highly immunogenic in mice and did not require coadministration of an adjuvant (when injected subcutaneously). Indeed, these complexes elicited antibody titers that were more than 10,000 times higher than those observed in animals immunized with the antigen alone. Furthermore, animals immunized with only 1 mug of recombinant immune complex without adjuvant were fully protected against lethal challenge. This the first report on the use of a genetic fusion between antigen and antibody to ensure an optimal expression ratio between the two moieties and to obtain fully functional recombinant immune complexes as a new vaccine model.

Visualizing the Onset and Evolution of an Autoantibody Response in Systemic Autoimmunity

The onset of systemic autoimmunity is variable, making it difficult to identify early events. In this study, we show in rheumatoid factor (RF) Ig-transgenic autoimmune-prone mice that the appearance of RF B cells in blood signifies the onset of RF B cell activation in spleen, providing a novel window into the initiation of an autoantibody response. This allowed us to study the early and late phases of spontaneous induction of the B cell autoimmune response. Using this approach we showed that extensive Ab-forming cell generation in spleen, accompanied by somatic hypermutation, occurred despite the lack of an early germinal center response. The onset of the RF response correlated with the levels of IgG2a-containing immune complexes but not total IgG2a. By identifying the time of onset in individual mice, we were able to track progression of disease. We found remissions of RF Ab-forming cell production in some mice, suggesting that at the clonal level, chronic autoantibody responses are dynamic and episodic, much like acute pathogen responses. Surprisingly, there was little accumulation of long-lived plasma cells in bone marrow of mice with long-standing RF responses in spleen. These studies are among the first to define the early events of a spontaneous B cell autoimmune response.

Circulating Immune Complexes Augment Severity of Antibody-Mediated Myasthenia Gravis in Hypogammaglobulinemic RIIIS/J Mice

Experimental autoimmune myasthenia gravis (EAMG) is severe in RIIIS/J mice, despite a significant B cell immunodeficiency and a massive TCR V beta gene deletion. Severity of EAMG in RIIIS/J mice is greater than MHC-identical (H-2(r)) B10.RIII mice, suggesting the influence of non-MHC genes as an EAMG-potentiating factor in this strain. To delineate the role of deleted TCR V beta genes in RIIIS/J mice, we obtained (RIIIS/J x B10.RIII)F(1) (V beta(b/c)) x RIIIS/J (V beta(c)) backcross mice using Mendelian genetic methods and immunized them with acetylcholine receptor. EAMG susceptibility was not elevated in mice with V beta(c) genotype having 70% V beta gene deletion. Next, we performed microarray analysis on 12,488 spleen cDNAs obtained from spleens of naive RIIIS/J and B10.RIII mice. In RIIIS/J mice, 263 cDNAs were overexpressed and 303 cDNAs were underexpressed greater than 2-fold, compared with B10.RIII mice. TCR gene expression was augmented, whereas NK receptor, C1q, and C3 gene expressions were diminished in RIIIS/J mice. RIIIS/J mice also had increased lymph node T cell counts, elevated serum anti-AChR Ab levels, and serum C3 and C1q-conjugated circulating immune complex levels. A direct correlation between increased serum C1q-conjugated circulating immune complex levels and disease severity was observed in RIIIS/J mice.

Theoretical analysis of antibody targeting of tumor spheroids: importance of dosage for penetration, and affinity for retention

The interplay among antibody/antigen binding kinetics, antibody diffusion, and antigen metabolic turnover together determines the depth of penetration of antitumor antibodies into prevascular tumor spheroid cell clumps. A sharp boundary between an outer shell of bound high-affinity antibody and an inner antibody-free core has been previously observed and mathematically modeled and was termed the "binding site barrier." We show here that this process is well described by a simplified shrinking core model wherein binding equilibration is much more rapid than diffusion. This analysis provides the following experimentally testable predictions: (a) the binding site barrier is a moving boundary whose velocity is proportional to the time integral of antibody concentration at the spheroid surface (i.e. plasma antibody AUC); (b) the velocity of this moving boundary is independent of binding affinity, if the affinity is sufficiently high to strongly favor antibody/antigen complex formation at prevailing antibody concentrations; and (c) maximum tumor retention is achieved when the antibody/antigen dissociation rate approaches the rate of antigen metabolic turnover. The consistency of these predictions with published experimental results is demonstrated. The shrinking core model provides a simple analytic relationship predicting the effects of altered antibody pharmacokinetics, antibody molecular weight, antigen turnover rate, antigen expression level, and micrometastasis size on antibody penetration and retention. For example, a formula is provided for predicting the bolus dose necessary to accomplish tumor saturation as a function of antibody and tumor properties. Furthermore, this analysis indicates certain attributes necessary for an optimal tumor targeting agent.

Future directions in the treatment of IgA nephropathy

IgA nephropathy (IgAN) is the most common primary glomerulonephritis yet its etiology remains uncertain. Recent data suggest a structural aberration of the IgA molecule in IgAN that may exert pathophysiologic effects on target cells, reduce clearance of IgA-immune complexes (IC), or favor mesangial IC trapping. Mesangial reactivity to immune complexes triggers off the release of cytokines and the alteration of prostaglandin and thromboxane A(2) production promoting mesangial cell proliferation. Angiotensin II-induced mesangial cells contraction with efferent arteriolar vasodilatation initiates glomerular injury and eventually lead to glomerulosclerosis following increased local production of transforming growth factor-beta (TGF-beta) and platelet-derived growth factor (PDGF). This paper highlights the potential therapeutic strategies in the future. These strategies include: (i) decreasing the synthesis of IgA-IC; (ii) limiting the mesangial uptake of IgA-IC; (iii) antagonizing the effect of PDGF and TGF-beta to reduce mesangial proliferation and glomerulosclerosis; and (iv) reducing the noxious glomerular injury due to infiltrating neutrophils. The effective treatment of IgAN requires a better clarification of the pathogenesis of the nephropathy. Future therapeutic attempts to slow down the renal deterioration should target at prevention of mesangial IgA deposition and the amelioration of inflammatory injury induced by infiltrating neutrophils and the released cytokines.

Heparin-induced thrombocytopenia with thrombotic sequelae: a review

Heparin-induced thrombocytopenia (HIT) occurs in 1-5% of patients treated with heparin. The pathogenesis involves the formation of antibodies to heparin-platelet factor 4 complexes, and the major clinical sequelae are thrombotic. Diagnosis is based on a combination of clinical and laboratory data. Treatment consists of stopping heparin, but, insofar as the risk of thrombosis remains high, treatment by alternative antithrombotic agents is indicated. Most clinical experience has been with danaparoid sodium and hirudin. The use of low-molecular-weight heparins (LMWH) in subsequent HIT episodes has been described, but is not recommended, especially with the introduction of new agents, such as oral thrombin inhibitors and pentasaccharides, which are hoped to reduce the use of heparins and the occurrence of HIT.

Expression of complement receptor type 1 (CR1) on erythrocytes of paracoccidiodomycosis patients

Complement receptor type 1 (CR1) is a membrane glycoprotein that acts as a receptor for the C3b, iC3b and C4b fragments of complement. In primates, one function of erythrocytes is to promote safe clearance of immunocomplexes (IC) from the circulation through CR1. Theoretically, in diseases characterized by high levels of circulating IC, an erythrocyte CR1 (CR1/E) deficiency may favor IC deposition in tissues or facilitate inappropriate activation of leukocytes in the circulation. Depression of the cell immune response occurs in paracoccidioidomycosis (PCM), especially in the more severe cases, and is frequently associated with high serum IC levels. In the present study we quantified the number of CR1/E in patients with the acute and chronic forms of PCM before and after treatment and correlated it with serum IC levels and CD4+ and CD8+ T cell concentration in the peripheral blood of these patients. Patients with PCM, particularly those with active disease and who had received treatment for shorter periods of time, had low numbers of CR1/E. In addition, an increase in serum IC concentration and a reduction in the CD4+/CD8+ T cell ratio were observed. After treatment there was a significant increase in mean CR1/E number and a reduction in serum IC levels. In patients with the chronic form of the disease the CD4+/CD8+ T cell ratio tended to increase after treatment and was associated with increased CR1/E levels. These results suggest that the reduction in CR1/E observed in patients is a phenomenon acquired with the disease and that CR1 could play a role in the pathogenesis of PCM.

Autoantigen glycoprotein 70 expression is regulated by a single locus, which acts as a checkpoint for pathogenic anti-glycoprotein 70 autoantibody production and hence for the corresponding development of severe nephritis, in lupus-prone PXSB mice

Retroviral envelope glycoprotein gp70 is present in the sera of immunologically normal and autoimmune-prone strains of mice. However, only lupus-prone mice spontaneously develop gp70-anti-gp70 immune complexes (gp70IC), and these have been implicated in the development of nephritis. We investigated the genetic factors that affect the production of both free serum gp70 and gp70IC in the lupus-prone BXSB mouse strain by analyzing (BXSB x (C57BL/10 x BXSB)F(1))- and (C57BL/10 x (C57BL/10 x BXSB)F(1))-backcrossed male mice. Production of gp70 mapped to a single major locus located on chromosome 13 (Bxs6) with a maximum log likelihood of the odds of 36.7 (p = 1.6 x 10(-38)). The level of gp70IC was highly dependent on Bxs6-related gp70 production, and high titer autoantibody production only occurred when serum gp70 levels were greater than a threshold value of approximately 4.0 microg/ml. The subdivision of the (BXSB x (C57BL/10 x BXSB)F(1))-backcrossed mice into those homozygous or heterozygous for Bxs6 enabled a remarkable association to be observed between high levels of gp70IC and severe nephritis in the Bxs6 homozygote population. A further mapping study in these two subgroups identified a previously unrecognized interval associated with the production of autoantibodies.

Enhanced susceptibility to lupus contributed from the nonautoimmune C57BL/10, but not C57BL/6, genome

Genes from New Zealand Black and New Zealand White mice have been implicated in the development of a disease similar to human systemic lupus erythematosus. In an attempt to define the MHC class II genes involved in disease, we previously studied similarly designed backcrosses of New Zealand Black mice with C57BL/6 (B6) mice transgenic for Ez genes or with C57BL/10 (B10) mice transgenic for Az genes. Although the transgenes showed no effect on the development of autoantibody production or lupus nephritis in either backcross, surprisingly, there was greatly increased expression of these disease traits in the backcrosses involving B10 compared with B6 mice. These studies therefore implicated genetic contributions in B10 vs B6 backgrounds, despite their 98% identity. A genome-wide linkage analysis uncovered a B10 locus on mid-chromosome 13, which enhanced nephritis and was strongly linked with the production of pathogenic retroviral gp70-anti-gp70 immune complexes when contributed by B10, but not B6, mice. The subsequent identification of a single marker polymorphic between B10 and B6, along with the extreme genetic similarity between the two strains in this region, is likely to permit expedited identification of the lupus-susceptibility gene from this nonautoimmune strain.

C1q-containing immune complexes purified from sera of juvenile rheumatoid arthritis patients mediate IL-8 production by human synoviocytes: role of C1q receptors

Immune complexes that vary in size and composition are present in the sera and synovial fluid of juvenile rheumatoid arthritis (JRA) patients. They are believed to be potent inducers of the ongoing inflammatory process in JRA. However, the precise composition and role of these complexes in the pathophysiology of JRA remain unclear. We hypothesized that circulating ICs have the potential to interact with resident joint synovial fibroblasts (synoviocytes) and induce the expression of inflammatory cytokines. To test this hypothesis, cultures of synoviocytes from healthy individuals were treated with ICs isolated from the sera of JRA patients. Studies reported in this work demonstrate that IgM affinity-purified ICs from the sera of JRA patients contain IgM, C1q, IgG, and C3 to a variable extent. These ICs induce IL-8 mRNA and protein production in normal synoviocytes. Our data indicate that C1q in these ICs mediates, in part, IL-8 induction in synoviocytes. This is based on our findings of C1q-binding proteins for collagen stalks (cC1qR) and globular heads (gC1q-binding protein) of C1q in synoviocytes. In addition, collagen stalk and to some extent globular head fragments of C1q inhibit IC-mediated IL-8 induction in synoviocytes. Together, these findings provide evidence for a novel mechanism of IL-8 production by synoviocytes, which could play a key role in inflammation by recruiting leukocytes to synovial tissue and fluid-and subsequently contributing to joint disease.

An unexpected effect of an ouabain-sensitive ATPase activity on the amount of antigen-antibody complexes formed in situ

A classical method of indirect immunofluorescence was applied on various kinds of lightly fixed and permeabilized cells to analyze the formation of the complexes between a nuclear antigen and its antibody (AAC). The amount of AAC decreased dramatically when the incubation with the first antibody was realized in the presence of ATP in a sodium-rich medium with 0.5 mM KCl. Addition of sodium vanadate, a general inhibitor of ATPases, ouabain or tetrabutylammonium ion, specific inhibitors of the Na+,K+-ATPase, prevented this effect. The established role of this enzyme is to increase free-K+ concentration and decrease free Na+ concentration in the cell. It is not surprising to find an ATPase still active since light fixation and permeabilization do not destroy phosphatases. But it is rather surprising to find something looking like Na+,K+-ATPase activity in permeabilized cells. The importance of potassium in this puzzling result is suggested by the fact that appearance of ACC was equally suppressed if the incubation was made in the absence of ATP in a potassium-rich medium without sodium. Results are discussed, taking into account the properties of cell-associated water and recently found interrelation between Na+,K+-ATPase and tubulin. In any case, the results seem interesting in the field of immunocytochemistry.

Effects of immune complex formation and complement activation on circulating platelets in the primate

Primate platelets are different from rodent and rabbit platelets in that they do not express receptors for C3a or C5a or immune adherence receptors. This study assessed the effects of immune complex (IC)-induced complement activation on primate platelets in the circulation. Cynomolgus monkeys (CYN, N = 4) immunized to bovine gamma globulin (BGG) were infused with BGG over 5 min to induce acute intravascular IC formation and complement activation. The studies were carried out under normal complement conditions (N = 12), partial complement inhibition (CAB-2 treated, N = 3), or total complement inhibition (CVF treated, N = 1). Under normal complement conditions, BGG infusion increased C3a levels from undetectable to an average of 11.9 +/- 2.6 micrograms/ml. At this time, decreases occurring in both circulating neutrophils (85 +/- 6%) and monocytes (78 +/- 6%) were significantly greater than decreases in circulating platelets (13 +/- 3%, p < 0.001). Partial complement inhibition had an equivocal effect on the BGG-induced changes in circulating leukocytes, while total complement inhibition abrogated these changes. In contrast, platelet changes were unaffected by complement inhibition. We conclude that, compared to circulating leukocytes, circulating platelets are insensitive to intravascular complement activation induced by IC in the nonhuman primate. These results contrast with previous studies in rodents which demonstrate strong effects of IC-induced intravascular complement activation on both circulating neutrophils and platelets.

Risk and safety of immunotherapy

The risk and safety of specific immunotherapy (SIT) has been the subject of many well-designed studies since it was introduced. Most authors consider SIT an efficient and safe mode of treatment despite the occurrence of life-threatening anaphylactic reactions. They emphasize the importance of a proper selection of patients as well as the requirement for highly qualified physicians to provide the treatment. Another problem associated with the safety of SIT is the potential enhancement of the synthesis of immune complexes after the treatment. SIT causes a decrease in allergen-specific IgE which is slower in circulating immune complexes than in the serum. No data are available to show that SIT induces immune-complex diseases, in either the immunologic or the clinical sense. As far as anaphylactic reactions are concerned, new alternative methods different from the conventional parenteral mode of delivery seem to be safe. Our increased understanding of the altered functions of the immune system justifies the assumption that the more specific the method of SIT administration, the more effective and safe it is.

Molecular mechanisms of glomerular injury in rat experimental membranous nephropathy (Heymann nephritis)

The molecular pathogenesis of human membranous nephropathy (MN) is unknown, despite the relatively high incidence and severity of this glomerular immune disease. Heymann nephritis (HN) in rats is considered an instructive experimental model of MN. This study summarizes current molecular aspects of two key events common to both MN and HN, i.e., formation of characteristic subepithelial immune deposits in the glomerular basement membrane (GBM), and development of glomerular capillary wall damage resulting in proteinuria. In HN, the antigenic targets of immune deposit-forming antibodies were identified in cell membranes of glomerular epithelial cells as a 515-kd glycoprotein (megalin, or gp330), which is a polyspecific receptor related to the low-density lipoprotein receptor family, and an associated 44-kd protein (receptor associated protein, RAP). One epitope was recently narrowed to 14 amino acids in RAP, and several others on megalin/gp330 are under investigation. Proteinuria requires formation of the complement C5b-9 membrane attack complex, which is presumably triggered by antibodies directed against lipid antigens that associate with immune deposit-forming megalin/gp330 immune complexes. Sublytic C5b-9 attack on glomerular epithelial cells causes upregulation of expression of the NADPH oxidoreductase enzyme complex by glomerular cells, which is translocated to their cell surfaces, similar to activated neutrophil granulocytes in the respiratory burst reaction. Subsequently, reactive oxygen species (ROS) are produced locally, which reach the GBM matrix. Here formation of lipid peroxidation (LPO) adducts is found, preferentially on monomeric and dimerized NCl domains of covalently crosslinked Type IV collagen. These structural changes within the GBM could be of functional relevance because treatment with the potent LPO-antagonist probucol reduces proteinuria by < 80%. Intact or fragmented apoprotein E-containing lipoproteins were identified as potential sources of the polyunsaturated lipids required for the production of LPO adducts. Lipoproteins accumulate within immune deposits and show signs of oxidative damage, similar to oxidized LDL within atherosclerotic lesions. Collectively, the results obtained so far in HN permit the compilation of a sequence of events, linking formation of immune deposits with proteinuria. However, despite this relatively detailed knowledge of pathogenic events in HN, the bridge to human NM remains to be built.

Differential expression of CLIP:MHC class II and conventional endogenous peptide:MHC class II complexes by thymic epithelial cells and peripheral antigen-presenting cells

Major histocompatibility complex (MHC) class II molecules expressed by thymic epithelial cells are involved in positive selection of CD4 T cells, whereas the high-avidity interaction of T cell receptors with the endogenous peptide: MHC class II complexes expressed on bone marrow (BM)-derived antigen-presenting cells (APC) and, to a lesser extent, on thymic epithelial cells mediate negative selection. To understand better the generation of the CD4 T cell repertoire both in the thymus and in the periphery we analyzed relative levels of expression of specific endogenous peptide: MHC class II complexes in thymic epithelial cells (TEC) and peripheral APC. Expression of E alpha52-68: I-A(b) and class II-associated invariant chain peptide (CLIP): I-A(b) complexes in thymic epithelial cells and in the bone-marrow derived splenic APC, i.e. B cells, was studied using YAe and 30-2 monoclonal antibodies which are specific for the corresponding complexes. To distinguish between expression of both complexes in radioresistant thymic epithelial elements and radiation sensitive BM-derived APC, radiation BM chimeras were constructed. Using immunohistochemical and immunochemical approaches we demonstrated that the level of expression of E alpha52-68: I-A(b) complexes in thymic epithelial cells is approximately 5-10% of that seen in splenic cells whereas total class II levels were comparable. In contrast, CLIP: I-A(b) complexes are expressed at substantially higher levels in TEC vs. splenic APC. This result demonstrates quantitative differences in expression of distinct peptide: MHC class II complexes in thymic epithelial cells and peripheral splenic APC.

CRP-mediated activation of complement in vivo: assessment by measuring circulating complement-C-reactive protein complexes

The in vivo function of C-reactive protein (CRP) is unknown. Among the in vitro functions assigned to CRP is the ability to activate complement via the classical pathway. To date, there is no evidence supporting that CRP exerts this function in vivo. We here show a novel approach to assess CRP-mediated complement activation in vivo, which is based on the property that activated complement factors C3 and C4 fix to CRP during complement activation induced by this acute phase protein. We developed specific ELISAs for complexes between CRP and C4b, C4d, C3b, or C3d. We established that in vitro complement-CRP complexes were formed only during CRP-dependent activation, and not during activation by other activators, even in the presence of high CRP levels. Circulating levels of complement-CRP complexes were undetectable in normal donors, but significantly increased in nine patients following implantation of a renal allograft. Importantly, levels of complement-CRP complexes did not change in these patients upon a bolus infusion of mAb OKT3, which induces activation of the classical complement pathway, demonstrating in vivo that complement-CRP complexes are not formed during CRP-independent activation of complement, even when CRP is elevated. We conclude that measurement of complement-CRP complexes provides a suitable tool to study CRP-mediated activation of complement in vivo. Furthermore, increased levels of these complexes occur in clinical samples, indicating that CRP may induce activation of complement in vivo.

The Heymann nephritis antigenic complex: megalin (gp330) and RAP

Heymann nephritis (HN) has been extensively studied as a model of human membranous nephropathy since it was first described by Heymann in 1959. HN was induced in active form by the immunization of rats with antigens derived from the proximal tubule brush border, resulting in subepithelial glomerular immune deposits. HN was also induced passively by the injection of antibrush border antibodies into normal rats. A breakthrough in the understanding of the pathogenesis of HN was made in the 1970s, when it was established that the disease was due to the binding of circulating antibodies to glomerular components. This in turn led to a search to identify the endogenous antigen(s). In 1982, gp330 (now called megalin), a glycoprotein located in clathrin-coated pits of glomerular and proximal tubular epithelia, was identified as a target antigen. In 1990, a second protein (44 kd), now known as RAP (for receptor associated protein), that binds to megalin was also shown to be a target antigen. Both molecules have been cloned and sequenced, and their role in normal epithelial cells has been explored. It has come to light that megalin (gp330) is a member of the low-density lipoprotein receptor gene family and functions as a multiligand receptor for the uptake of a variety of macromolecules (plasminogen, protease: protease inhibitor complexes, apolipoprotein E-enriched very low-density lipoproteins, lactoferrin, among others). RAP associates with megalin and appears to function as a chaperone assisting in the folding of megalin in the endoplasmic reticulum and its transport to the cell surface. This review considers what is now known about the structure, function, and trafficking of megalin and RAP and the role of these two molecules in the pathogenesis of HN.

Recombinant single-chain antibody peptide conjugates expressed in Escherichia coli for the rapid diagnosis of HIV

Recombinant single chain Fv (scFv) antibody fragments can form the basis of a rapid, whole-blood diagnostic assay. The scFv described in this study is derived from a monoclonal antibody which has a high affinity for glycophorin A, an abundant glycoprotein on the human red blood cell membrane surface. The prototype reagent built around the scFv was designed to detect, in whole blood samples, the presence of antibodies that have arisen through infection with a foreign organism such as human immunodeficiency virus. The scFv was composed of the antibody heavy-chain variable domain (Vh) joined by a 15 residue linker -(GGGGS)3- to the light-chain variable domain (V1) terminated by either a C-terminal octapeptide tail (FLAG) or a 35 amino acid segment from the gp41 surface glycoprotein of HIV-1. Constructs were cloned into a Escherichia coli expression vector, pHFA, and expressed in a soluble form into culture supernatant. The product retained anti-glycophorin activity which could be detected directly in culture supernatants by ELISA. Furthermore, the scFv-epitope fusion functioned efficiently in the whole blood agglutination assay and was able to distinguish between HIV-1 positive and negative sera.

Xenogenic humoral responses to islets transplanted in biohybrid diffusion chambers

It has been hypothesized that chronic antigen leakage from the hybrid artificial pancreas could stimulate a host humoral response. Such antibodies could be induced by antigens shed from the islet cell surface, or by proteins secreted by live cells or liberated after cell death. To determine if this humoral response occurs, porcine (n = 15) or canine (n = 7) islets were seeded (2-5 x 10(4) equivalent islet number, density 30 islets/mm3) into diffusion chambers fabricated from permselective acrylic membranes (nominal M(r) exclusion of 80,000). The chambers were implanted intraperitoneally into streptozotocin-induced diabetic rats. Sera were collected at various intervals (0-12 weeks) and tested against isolated canine and porcine islets, for tissue specificity and interspecies cross-reactivity by fluorescence immunocytochemistry. No immunofluorescence (or only weak background staining) was obtained when islets were exposed to horse sera, or to sera obtained before to xenodevice implantation. Within 2-6 weeks, however, the postimplantation sera showed strong immunoreactivity. The antibodies were found to be reactive to multiple tissues, and to possess little or no interspecies cross-reactivity. The appearance of these xenoantibodies coincided with the appearance of circulating soluble immune complexes. However, none of the respiratory, cutaneous, or gastrointestinal manifestations that are characteristic of an anaphylactic reaction, or of the diseases of immediate-type hypersensitivity, were observed, even after intraperitoneal injection of additional naked islet tissue. Renal glomeruli did not stain for IgG or C3 in islet recipients. These results suggest that islet cell antigens crossed the membrane and stimulated antibody formation in the host, although they did not appear to cause renal or immune complex disease during the course of this study.

The effects of histidine residue modification on the immune precipitating ability of rabbit IgG

Treatment of anti-ovalbumin rabbit IgG with diethylpyrocarbonate (DEPC) at concentrations up to 100 microM led to a progressive decrease in the rates of formation of insoluble immune complexes, without affecting the final extent of immune complex formation. DEPC concentrations approximately 10-fold higher were needed to give comparable decreases in the rates of immune complex formation by F(ab')2. Treatment of DEPC-treated IgG with hydroxylamine led to substantial restoration of the rates of formation of insoluble immune complexes. Carbethoxylation of two histidine residues per IgG molecule had little effect on rates of formation of insoluble immune complexes, but these rates were markedly decreased in samples of IgG with four to five histidines per molecule modified. There were parallel decreases in the protein A-binding activity and in the rates of formation of insoluble immune complexes in IgG treated with increasing concentrations of DEPC. The presence of complement protein C1q restored the rates of formation of insoluble immune complexes of DEPC-treated IgG.

Evaluation of in vivo immune complex formation and complement activation in patients receiving intravenous streptokinase

The usefulness of several different methods for detecting immune complex formation and complement activation in the circulation were applied to samples from patients receiving intravenous Streptokinase therapy for myocardial infarction. Streptokinase is a foreign antigen and can cause immune reactions. We collected samples from 13 patients, before Streptokinase administration (baseline), at the end of infusion (1 h), 12 h later and on day 7. We measured IgG containing immune complexes (IgG-IC), free C3d and antibodies to Streptokinase by ELISA, and CR1, C3d and C4d on erythrocytes by flow cytometric assay. Antibodies to Streptokinase are common, as all but two of the patients had measurable antibody levels. During Streptokinase treatment there was a drop in antibody levels, most prominent in those patients who had high baseline levels. At the same time increased levels of free C3d and erythrocyte-bound C3d were observed. After 12 h free C3d was usually back to baseline level, but C3d on erythrocytes was still raised. These data indicate the formation of Streptokinase immune complexes in patients with high Streptokinase antibody levels, and show that these complexes are cleared rapidly from the circulation, leaving more persistent signs of complement activation. We conclude that free C3d is a good indicator of ongoing complement activation, whereas C3d on erythrocytes indicates that complement activation has recently taken place.

Polyclonal activation of B-lymphocytes and induction of autoimmunity in retrovirus infected NMRI mice

Polyclonal activation of B-lymphocytes accompanies many retroviral infections. Friend derived murine immunosuppressive virus (Fd-MIV) is a non-defective murine retrovirus which was isolated from T-helper cells from mice infected with the acute transforming retrovirus Friend leukaemia complex (FLC). In contrast to FLC, Fd-MIV does not induce acute transformation of lymphoid and erythroid cells but causes immunosuppression and lymphadenopathy in adult NMRI mice. The effect of Fd-MIV infection on B-lymphocytes was studied. Fd-MIV infection led to a persistent hypergammaglobulinemy with a significant increase in the level of circulating IgG, IgM and immune complexes. In the spleen and lymph nodes, B-lymphocyte proliferation was found. Parallel to the development of hypergammaglobulinemy, autoantibodies to a variety of nuclear and other autoantigens was detected. In conclusion, the Fd-MIV infection leads to a B-lymphocyte dysfunction that has many parallels with AIDS. Furthermore, the Fd-MIV infection seems to represent an example of an autoimmune condition caused by an exogenous infectious agent.

[Anti-influenzal antibodies inducing an immune response to the influenza virus]

The injection of anti-influenza antibodies into rabbits induces a specific immune response, including the production of anti-idiotypic antibodies and then the production of immune complexes and anti-influenza antibodies. The injection of antibodies induces the development of immunological memory; as a result, the animals are primed to respond to the injection of influenza vaccine.

Polyclonal amanitin-specific antibodies: production and cytoprotective properties in vitro

The amanitins found in several mushroom species are responsible for many deaths every year. Based on its successful application to cardiac glycoside overdose, immunotherapy could be applicable to amanitin toxicity. Therefore, we produced polyclonal amanitin antibodies by immunizing rabbits with a novel conjugate of alpha-amanitin. Purified antibodies had an average association constant for alpha-amanitin of 1.3 x 10(9) M-1. A partially protective effect of the antibodies against amanitin toxicity in vitro in Chang cells was evident at a molar ratio of antibody binding sites to alpha-amanitin of 4:1. Together with reported studies in vivo, these investigations indicate the potential of immunotherapy for amanitin poisoning.

Humoral immune response during filarial fever in Bancroftian filariasis

Humoral immune responses against filarial parasitic infection were studied in 62 cases of acute filarial disease presenting with filarial fever with adenolymphangitis, in a community where Bancroftian filariasis was endemic, during and about one month before and after the febrile episode. Their total leucocyte and differential peripheral blood cell counts and anti-streptolysin O titre were determined and compared. Polymorphonuclear cellular responses and anti-streptolysin O titre did not show any significant alteration during and after fever. Three of 53 previously amicrofilaraemic subjects (9 of whom were initially microfilaraemic) had microfilaria in their circulation during fever, with a significant increase in their geometric mean microfilaria count. Titres of specific immunoglobulin (Ig) G and IgG4 antibody to Wuchereria bancrofti microfilarial excretory/secretory antigens (measured by enzyme-linked immunosorbent assay) decreased significantly during the fever and the lower levels were maintained one month after fever. The mean circulating immune complex level increased significantly during fever, and a significant percentage of cases demonstrated circulating filarial antigen during fever, which declined after one month, suggesting the release of filarial antigen into the circulation during fever which bound to antibodies to form immune complexes. These observations do not support the suggestion that bacterial infection is the aetiology of filarial fever. It is postulated that antigens released from parasites into the circulation during parturition by adult worms may evoke an allergic response in the host, causing periodic febrile episodes.

Immunological abnormalities in HIV-free haemophiliacs

Since some haemophiliacs manifest profound immunodeficiency with no evidence of human immunodeficiency virus type 1 (HIV) infection, we measured the circulating immune complex (CIC) level in sera obtained from haemophiliacs and addressed the question of whether viral infection is associated directly or indirectly with enhanced CIC production. While more than 90% of HIV-positive individuals had a high level of CIC, around 60% of seronegative ones also showed CIC levels comparable to those of seropositive patients. These sera activated fresh complement in vitro. The patients infected with either HIV or Hepatitis C virus (HCV) or both showed higher frequency and concentration of serum CIC than those free of either pathogens. It is worth noting, however, that 64% of patients with no evidence of infection with HIV or HCV produced significant amounts of CIC. Among the infectious viruses examined, parvovirus is considered as one of the pathogens associated with CIC synthesis, since all the haemophiliacs including the HIV-free patients who had been supplied with heated coagulation factors for several years from birth carried antibodies to parvovirus B19. Strikingly, 60% of the children in this category were positive for CIC, suggesting the possible contribution of parvovirus infection to CIC formation.

Suppression of ADCC by immune complexes formed in vitro in Mycobacterium leprae-infected mice

Antibody-dependent cellular cytotoxicity (ADCC) was assessed in mice infected experimentally with Mycobacterium leprae and injected simultaneously with in vitro-formed immune complexes (IC). Significant decrease in the ADCC function was observed in animals given IC at zero day (0dIC) and 3 months (3mIC) post inoculation with M. leprae, when ADCC activity was assessed at 3, 6 and 9 months period. From the data obtained we believe that ADCC is suppressed by IC formed in vitro.

The role of complement-derived chemotactic factors in lung injury induced by preformed immune complexes

Our previous studies have suggested a role for complement fragments presumably activated by immune complexes in patients with hypersensitivity pneumonitis. The present study has shown that circulating complement depletion by cobra venom factor resulted in the reduction in severity of immune-complex-mediated pulmonary inflammation. The activity of chemotactic factors for neutrophils generated in bronchoalveolar lavage fluids in complement-depleted animals was significantly diminished to 61.2% compared to the undepleted animals. In addition, reduced activity of chemotactic factors resulted in a marked reduction of accumulation of neutrophils in bronchoalveolar lavage fluids indicating that chemotactic factors play an important role in the sequestration of neutrophils on the alveolar side of the lung. In conclusion, chemotactic factors in bronchoalveolar lavage fluids which preceded the accumulation of polymorphonuclear cells are partially derived from complement.

Markers of inflammatory activation: upregulation of complement receptors CR1 and CR3 on synovial fluid neutrophils from patients with inflammatory joint disease

Expression of the C3 receptors CR1 and CR3 was investigated on neutrophils from paired peripheral blood and synovial fluid samples from 34 patients with inflammatory joint disease (21 patients with rheumatoid arthritis (RA) and 13 patients with other articular diseases (OAD)). Using monoclonal antibodies (anti-CD35, anti-CD11b) and immunofluorescence flow cytometric analyses the percentages of positively labeled cells and the relative fluorescence intensities (as a measure of receptor number) were determined. CR1 and CR3 were found to be present on the majority (> 85%) of circulating neutrophils from normal subjects, RA and OAD patients, and on synovial fluid neutrophils from both patient groups. A strong correlation between neutrophil CR1 and CR3 expression was observed in peripheral blood samples from normal subjects (r = 0.81; P = 0.001), RA (r = 0.79; P = 0.001), and OAD patients (r = 0.83; P = 0.001); in each case the levels of CR3 expression were approximately twice those recorded for CR1. Both CR1 and CR3 expression was upregulated on synovial fluid neutrophils compared with that observed on the corresponding peripheral blood cells. Mean percentage increases observed were: RA patients: CR1, 16.5% (P < 0.001) and CR3, 28.7% (P < 0.001); and OAD patients: CR1, 4.1% and CR3, 26.9% (P = 0.001). Correlation of serum and synovial fluid IL-6, IL-8, and immune complex levels with neutrophil CR1 and CR3 expression failed to demonstrate any significant relationship between the concentrations of these soluble factors and receptor expression. Upregulation of CR1 and CR3 receptors, reflecting neutrophil activation within the inflamed joint, is a consistent finding in patients with inflammatory arthropathies.

Production of rheumatoid factor in adoptively immune guinea-pigs after challenge with Treponema pallidum

Guinea-pigs of inbred strains 2 and C4D were infused with various concentrations (1 x 10(8) to 4 x 10(8) of syngeneic nylon wool-purified Treponema pallidum-immune T lymphocytes (TPI-T) and challenged 24 hr later with virulent T. pallidum (10(8) organisms). The degree of protection depended on the number of infused T cells and was associated with an accelerated production of IgM rheumatoid factor (RF). Fully protected animals (4 x 10(8) TPI-T) did not produce treponemal antibodies or circulating immune complexes (CIC) but produced IgM RF detectable 10 days after infection. Partially protected animals (< or = 2 x 10(8) TPI-T) produced, 30 days post-infection, relatively low levels of treponemal antibodies but high levels of CIC and RF. Control animals infused with 2 x 10(8) TPI-T lymphocytes but not infected with T. pallidum, when monitored for a period of 6 weeks, did not produce treponemal antibodies, CIC, or RF, excluding the possibility that IgM RF could be generated by the donor's B cells contaminating (circa 3%) the TPI-T lymphocytes. Moreover, unprotected syngeneic control animals infused, prior to infection, with T. phagedenis biotype Reiter-immune T cells or with T. pallidum-free testicular inflammatory fluid-immune T cells responded with increasing levels of treponemal antibodies; only a few animals produced RF and CIC 5 months after infection similarly to control guinea-pigs infected only. The production of RF in partially protected animals responding to infection with treponemal antibodies and CIC was apparently associated with the presence of the CIC; but the mechanism of RF production in fully protected animals in which no antibodies or CIC were detected is currently unknown.

The contribution of antibody-mediated cytotoxicity and immune-complex formation to tubulointerstitial disease in passive Heymann nephritis

Passive Heymann nephritis (PHN), an experimental model of membranous nephropathy, is produced by Fx1A antiserum, which also reacts with antigens on the brush border (gp 330) and basolateral membrane (gp 90) of proximal tubules. We examined tubulointerstitial disease in PHN, identifying two distinct processes occurring on the luminal and basolateral membranes, respectively. Injected antibody bound diffusely to the tubular brush border from Day 1 to Day 7, followed by sloughing of microvilli and tubular-cell regeneration. Fine granular deposits of Fx1A antibody were present along the basolateral cell membrane by Day 1. These deposits rearranged in situ, enlarged, and became more focally distributed along tubular basement membranes (TBM). Interstitial inflammation, dominated by macrophages (Ia+, ED-1+) in association with a smaller number of T-cytotoxic cells (OX19+, OX8+) began by Day 3, reached peak intensity and persisted throughout the autologous phase (to Day 21). The distribution of focal clusters of interstitial macrophages predominately in association with TBM-immune deposits was demonstrated. Complement depletion prevented proteinuria but TBM deposits developed and the interstitial inflammation was unchanged. All aspects of the tubulointerstitial disease were amplified by a second injection of Fx1A antiserum. In vitro, Fx1A antibody bound to the surface of isolated proximal tubular epithelial cells and redistributed to form clusters of immune aggregates. Anti-Fx1A-induced cytotoxicity of tubular cells was demonstrated by prelabeling cells with 2'-7'-bis(carboxyethyl)-5(6)-carboxyfluorescein. The degree of cytotoxicity was dependent on complement concentration and the duration of incubation at 37 degrees C. PHN induced by Fx1A antiserum causes tubular-cell injury following interactions with brush-border antigens and TBM immune-complex disease associated with interstitial inflammation. These findings may be relevant to the acute and chronic interstitial disease of human membranous nephropathy.

Evaluation of chemotherapy in experimental toxocarosis by determination of specific immune complexes

Parasitism by the larval phase of Toxocara canis is a chronic process in which the larvae survive in the tissues, resulting in the constant stimulation of the immune system. As a result, the detection of specific antibodies may not reflect the active state of the parasite. We have studied the dynamics of the production of specific immune complexes by ELISA with the monoclonal antibody TC-1 in rabbits inoculated with single and multiple doses of T. canis eggs. We also compared this with the production of specific antibodies and their possible modification after treatment with mebendazole. The specific antibodies against excretory-secretory antigen were detected with peaks at 10 and 12 weeks depending on the dose and remained positive during the entire experiment (62 weeks). Treatment caused an increase in the level of detectable antibodies dropping to similar levels to the controls. Specific immune complexes were detected only in multiple doses, and were then positive during the entire experiment. From the beginning of treatment the values of immune complexes fell quickly, remaining at undetectable levels during the rest of the experiment. For this reason the detection of specific immune complexes is a valid technique for monitoring the efficiency of treatment.

Echinostoma caproni in mice: ultrastructural studies on the formation of immune complexes on the surface of an intestinal trematode

The binding of mouse antibodies to the surface antigens of juvenile and 7 and 28 day old Echinostoma caproni was examined by transmission electron microscopy of thin sections of parasites, which were treated with antibodies in a double sandwich technique with ferritin-conjugated antibody. The surface of freshly recovered mature adult parasites was covered with an irregular but often rather intensive mouse antibody containing matrix, which probably represents a layer of mouse antibody/parasite antigen complexes. The complexes were lost after in vitro culturing of the parasites for 24 h, but incubation of the in vitro-maintained antibody-negative adult parasites with immune mouse serum led to reformation of a similar but less intensive cover with immune complexes. Juvenile and young stages of E. caproni, which had never been exposed to host antibodies, obtained a layer of immune complexes on their surface after incubation with immune mouse serum in vitro. In both young and mature parasites, the antibody-antigen complexes were observed to be rather loosely attached to the outer surface of the parasites, where the antigens probably constitute a part of the irregular glycocalyx of the organisms. It may also be that the antigens are present as isolated excretion along the surface of the parasites. Several sections indicated that the parasite surface antigens may be present in the tegument in vesicles which fuse with the outer membrane of the parasite whereby their contents are released to the exterior.