The pathogenic 16/6 idiotype in patients with silica associated systemic lupus erythematosus (SLE) and uranium miners with increased risk for development of SLE

OBJECTIVE

To investigate the prevalence of the 16/6 idiotype (16/6 Id), a major cross reactive idiotype of anti-DNA antibodies involved in the pathogenesis of experimental lupus, in subjects with an exogenous risk for the development of systemic lupus erythematosus (SLE).

METHODS

The titer of 16/6 Id was determined by ELISA in sera of uranium miners exposed to heavy quartz dust: 15 developed definite and 12 probable SLE, 34 had clinical symptoms, and 27 had only serological signs (medium to high titer anti-dsDNA antibodies) of possible connective tissue disease (CTD) development.

RESULTS

The prevalence of 16/6 Id was higher in all groups compared to healthy blood donors. It was 18.5% in miners with SLE (definite and probable) and 22.2-26.5% in miners with clinical and/or serological signs for developing CTD. All 16/6 Id positive miners were positive for anti-dsDNA antibodies and other autoantibodies associated with CTD. The prevalence of 16/6 Id in anti-dsDNA positive miners correlated slightly with CTD/SLE symptoms: 55.6% in patients with SLE, 47.4% in miners with possible CTD/SLE, and 22.2% in miners without CTD symptoms. Further, at short term followup, disease progressed in 2 miners of the 16/6 Id positive, but not in 16/6 Id negative miners.

CONCLUSION

The detection of 16/6 Id in miners exposed to quartz dust may indicate a higher risk for development of SLE, warranting further studies of the role of 16/6 Id in the development of SLE in a cohort with the same sex, ethnicity, geographic region, and occupation.

Differential distribution of beta-dystroglycan in rabbit and rat retina

The distribution of the dystrophin-associated glycoprotein complex was investigated in rabbit and rat retina by using the monoclonal antibody 43DAG/8D5, which specifically recognizes beta-dystroglycan, a central component of the complex. In cryostat sections of retinae from both species, the authors observed staining of blood vessels, continuous labeling around the vitreal border, and strong immunoreactivity in the outer plexiform layer (OPL). Electron microscopy showed that the immunoreactivity associated with the vitreal border of the retina was the result of a subcellular concentration of beta-dystroglycan in the endfeet of Müller glial cells. A similar concentration was observed in endfeet of perivascular astrocytes in the region of contact with the capillary basal lamina. In the OPL, beta-dystroglycan was associated with the terminals of both rods and cones. The label was almost exclusively found outside the synaptic area and was particularly strong in the extensions of the photoreceptor terminals protruding into the OPL. In the OPL of the rabbit retina, the authors found additional immunoreactivity associated with the tips of postsynaptic horizontal and bipolar cell processes. These results show that the dystrophin-associated glycoprotein complex is subcellularly concentrated in photoreceptor terminals and glial cell endfeet, and that the rabbit retina differs from the rat retina by the additional expression of this complex in bipolar and horizontal cells.

Differential effects of anti-beta2-glycoprotein I antibodies on endothelial cells and on the manifestations of experimental antiphospholipid syndrome

BACKGROUND

The antiphospholipid syndrome (APS) entails a prothrombotic state associated with the presence of anticardiolipin antibodies (aCL). aCL were shown to promote endothelial cell and platelet activation and to induce an APS-like syndrome in mice when administered intravenously. Recent data suggest that aCL target the plasma cofactor beta2-glycoprotein I (beta2GPI) rather than negatively charged phospholipids. However, it has not been determined whether different epitope-specific anti-beta2GPI antibodies obtained from one patient possess pathogenic properties.

METHODS AND RESULTS

Three beta2GPI-binding IgM monoclonal antibodies (mAbs) (ILA-1, ILA-3, and ILA-4) were cloned from a patient with APS. The three antibodies were shown to bind beta2GPI immobilized on irradiated plates, yet only ILA-1 bound beta2GPI coated onto nonirradiated plates. Furthermore, when using the anti-beta2GPI enzyme-linked immunosorbent assay, ILA-1 was the only mAb inhibited by fluid phase beta2GPI. ILA-1 and ILA-3, but not ILA-4, induced adherence of U937 cells to endothelial cells in vitro (reflecting activation of endothelial cells). mAbs ILA-1 and ILA-3 as opposed to ILA-4 induced significant expression of adhesion molecules when preincubated with human umbilical vein endothelial cells. Passive administration of ILA-1 and ILA-3 to pregnant BALB/c mice induced clinical findings consistent with APS (increased fetal resorptions, reduced platelet counts, and prolonged activated partial thromboplastin time), whereas both ILA-4 and the control human IgM did not produce similar effects.

CONCLUSIONS

The results of the study demonstrate the differential effects of various populations of anti-beta2GPI antibodies on endothelial cell activation and on experimental APS.

Ciprofloxacin immunomodulation of experimental antiphospholipid syndrome associated with elevation of interleukin-3 and granulocyte-macrophage colony-stimulating factor expression

OBJECTIVE

To evaluate the immunomodulatory potential of ciprofloxacin in mice with experimental antiphospholipid syndrome (APS).

METHODS

Ciprofloxacin or ceftazidime (control antibiotic) was given to mice with experimentally induced APS. The titers of autoantibodies, levels of cytokines, and number of cytokine-producing cells were determined by enzyme-linked immunosorbent assay. Myeloid progenitor cells were determined by granulocyte-macrophage colony-forming unit, and interleukin-3 (IL-3) messenger RNA (mRNA) was tested by Northern analysis.

RESULTS

A decrease in the incidence of pregnancy loss and an improvement in the clinical manifestations of APS were noted in the mice treated with ciprofloxacin, compared with the mice given ceftazidime. The effect of ciprofloxacin was found to be associated with increased serum levels of IL-3 and with increased IL-3 mRNA transcription in the splenocytes. Expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) was documented by elevated titers in the sera and elevated numbers of colony-forming cells in the bone marrow.

CONCLUSION

Ciprofloxacin prevents the manifestations of experimental APS. This effect may be associated with increased IL-3 levels and GM-CSF expression.

Anti-DNA and antiphospholipid antibodies in IVIG preparations: in vivo study in naive mice

Intravenous immunoglobulins (IVIG) are therapeutic preparations of pooled normal polyspecific immunoglobulin G. We investigated the presence and the in vivo pathogenic potential of autoantibodies against phospholipids and DNA in several commercial IVIG preparations. The presence of autoantibodies and their antiidiotypic antibodies in the IVIG preparations was detected by ELISA. Naive mice were actively immunized with either IVIG preparations or pathogenic monoclonal antibodies (mAbs) against cardiolipin (CL) or DNA, in an attempt to induce autoimmune conditions. The mice were tested for the presence of mouse autoantibodies (auto-Abs) and for clinical parameters of autoimmune diseases. We found high levels of auto-Abs against a panel of phospholipids and DNA, as well as their antiidiotypic Abs, in all the IVIGs. Affinity studies pointed to a lower affinity of auto-Abs of IVIG origin to their respective antigens compared to pathogenic mAbs. Mice immunized with pathogenic anti-CL mAb had high levels of antiphospholipid auto-Abs, accompanied by thrombocytopenia, prolonged aPTT, and an increased fetal resorption rate. Mice immunized with pathogenic anti-DNA mAb had elevated anti-DNA and anti-CL auto-Abs, along with a high erythrocyte sedimentation rate, leukopenia, and significant proteinuria. Following immunization with IgGs from IVIG batches, mice developed high levels of auto-Abs against phospholipids and DNA, similar to mice immunized with pathogenic anti-DNA or anti-CL mAbs, but none of the mice expressed the clinical manifestations compatible with the presence of these autoantibodies. We conclude that commercial IVIG preparations contain high levels of antiphospholipid and anti-DNA auto-Abs, as well as their antiidiotypic Abs. Although these Abs induced the generation of mouse auto-Abs upon active immunization, following idiotypic manipulation they did not prove to be pathogenic in vivo.

Cloning and functional expression of the human GlcNAc-1-P transferase, the enzyme for the committed step of the dolichol cycle, by heterologous complementation in Saccharomyces cerevisiae

The gene for the human dolichol cycle GlcNAc-1-P transferase (ALG7/GPT) was cloned by screening a human lung fibroblast cDNA library. The library was constructed in a Saccharomyces cerevisiae expression vector, and the positive clone was identified by complementation of the conditional lethal S.cerevisiae strain YPH-A7-GAL. This strain was constructed by replacing the endogenous promoter of the GPT-gene by the stringently regulated GAL1-promoter. This construct allows to specifically suppress the endogenous enzyme activity. The insert of the positive clone displayed an open reading frame of 1200 nucleotides, coding for a putative protein of 400 amino acids with a calculated molecular weight of 44.7 kDa. The deduced protein sequence shows a homology of over 90% when compared with other mammalian GPT sequences, thus resembling the close phylogenetic relationship between mammalian species. This homology however decreases to 40-50% when compared to more distantly related organisms such as S.cerevisiae , Schizosaccharomyces pombe , or Leishmania amazonensis . Biochemical characterization of the recombinant protein showed that it is functionally expressed in the S.cerevisiae strain YPH-A7-GAL. GlcNAc- and GlcNAc2-PP-Dolichol biosynthesis could be shown with isolated S.cerevisiae membranes from cells harboring the recombinant plasmid and grown on glucose thus suppressing transcription of the endogenous gene. Synthesis could be stimulated by dolicholphosphate and was inhibited by tunicamycin. These results show that we have cloned the human GlcNAc-1-P transferase by heterologous complementation in S. cerevisiae, a strategy that may be useful for the cloning and characterization of glycosyltransferases from a variety of organisms.

Atherosclerosis in LDL-receptor knockout mice is accelerated by immunization with anticardiolipin antibodies

Atherosclerosis is a process initiated by accumulation of macrophages in distinct areas of endothelial cell damage and uptake of large amounts of lipids. Recently, it has been shown that the immune system plays an active part in the progression of the atherosclerotic plaque although its precise role has not yet been elucidated. Anticardiolipin antibodies (aCL) are generally found in the sera of patients with the antiphospholipid syndrome (APS) and are associated with a prothrombotic state. Several authors have demonstrated that aCL can activate platelets and endothelial cells as well as increase oxidized low density lipoprotein (LDL) uptake by macrophages. In the present study we sought to assess the effect of immunization with aCL (Ab1, leading to the production of mouse aCL-Ab3) on the progression of atherosclerosis. Two groups of 8-weeks old female LDL-receptor knockout mice (n = 13 per group) were immunized with IgG purified from the serum of an APS patient or with normal human IgG, respectively. The aCL immunized mice developed high titres of 'self' aCL (detected using the standard aCL ELISA) as compared with the normal human IgG immunized mice, whereas no differences were noted between both study groups with respect to the serum lipid levels. The extent of fatty streak formation was significantly higher in the aCL immunized mice in comparison with the human IgG injected mice (mean aortic lesion size of 5308 +/- 471 microns2 vs 1027 +/- 184 microns2, respectively, P < 0.01). The immunohistochemical analysis of the atherosclerotic plaques from both mouse groups did not display differences in cellular composition. The results of the study show that mouse aCL induced by immunization with human aCL from an APS patient enhance atherogenesis in LDL-RKO mice and imply that these antibodies may play a role in atherosclerosis development in patients with the APS.

Subcellular concentration of beta-dystroglycan in photoreceptors and glial cells of the chick retina

Mutations in the dystrophin-glycoprotein complex cause muscle degeneration and dysfunctions in the central nervous system, including an impaired synaptic transmission in the outer plexiform layer (OPL) of the retina. To investigate the basis for this ocular phenotype, we analyzed the distribution of beta-dystroglycan, a central member of the dystrophin-glycoprotein complex, in the chick retina by using the 43DAG/8D5 monoclonal antibody. This antibody reacted specifically with chick beta-dystroglycan, as indicated by its staining of the neuromuscular junction, and its reactivity with a single 43-kilodalton band in Western blots. In the retina, beta-dystroglycan was highly concentrated in the OPL and at the vitreal border of the retina, around the inner limiting membrane. Mechanically isolated and flat-mounted inner limiting membranes were stained by the anti-beta-dystroglycan antibody, and this immunoreactivity could be extracted by detergent, indicating that beta-dystroglycan is associated with membranous structures bound to the basal lamina. Consistently, electron microscopy showed a concentration of beta-dystroglycan in the endfeet of Müller glial cells exclusively in the region of direct contact to the inner limiting membrane. In the OPL, beta-dystroglycan immunoreactivity was concentrated in the distal extensions of rod and cone terminals protruding into the outer plexiform layer. There, beta-dystroglycan codistributed with the alpha1beta subunit of the N-type voltage-gated calcium channel. By contrast to previous reports, we did not detect beta-dystroglycan directly associated with the synaptic regions of conventional or ribbon synapses of the retina. These results show that in the retina beta-dystroglycan is exclusively expressed by photoreceptors and glial cells and that beta-dystroglycan is highly concentrated in subcellular regions of glial cell endfeet and photoreceptor terminals. Moreover, the colocalization of beta-dystroglycan with N-type calcium channels in the outer plexiform layer indicates that both proteins might be part of a macromolecular complex.

Electromagnetic field exposure induces rapid, transitory heat shock factor activation in human cells

Stimulation of human promyelocytic HL60 cells by a 60Hz magnetic field at normal growth temperatures results in heat shock factor 1 activation and heat shock element binding, a sequence of events that mediates the stress-induced transcription of the stress gene HSP70 and increased synthesis of the stress response protein hsp70kD. Thus, the events mediating the electromagnetic field-stimulated stress response appear to be similar to those reported for other physiological stresses (e.g., hyperthermia, heavy metals, oxidative stress) and could well be the general mechanism of interaction of electromagnetic fields with cells.

Immunologic characterization and functional properties of murine antibodies raised against deleted mutants of human beta 2-glycoprotein I

beta 2-Glycoprotein I (beta 2GPI) is a 50 kDa molecule proposed as a principal target of 'autoimmune' antiphospholipid antibodies (aPL). We have used deleted mutants (DM) representing different domains of beta 2GPI (I-IV, IV-V and V) for immunization of naive mice and studied the characteristics of the respective murine IgG preparations in comparison with affinity-purified IgG from two patients with primary antiphospholipid syndrome. Immunization with beta 2GPI and with the DM produced anti-beta 2GPI antibodies, part of which reacted with negatively charged phospholipids (PL), whereas reactivity with cardiolipin was evident only in the IgG from mice immunized with beta 2GPI. These results are consistent with the presumption that aPL are induced following the in vivo association of beta 2GPI (used for immunization) with resident negatively charged PL. Accordingly, DM which either lack the PL binding site or aPL attachment locus did not elicit, upon immunization, antibodies reactive with PL. Further, murine anti-beta 2GPI IgG and human 'autoimmune' aPL were similar, albeit not identical, in terms of DM requirement for PL binding and charge dependency. Murine antibodies and human aPL, regardless of their binding characteristics, were found to bind significantly to platelets upon their activation with thrombin and to promote platelet activation. The results of the current study emphasize the dissimilarities between human 'autoimmune' aPL and murine anti-beta 2GPI. Thus, anti-beta 2GPI antibodies to different DM as well as human aPL are capable of binding and activating human platelets provided beta 2GPI is present.

Oxidized low-density lipoprotein (Ox-LDL) but not LDL aggravates the manifestations of experimental antiphospholipid syndrome (APS)

Ox-LDL is thought to play a major role in atherogenesis. The mechanisms mediating the deleterious influences of Ox-LDL include foam cell formation and cell cytotoxicity. The production of anti-Ox-LDL antibodies results in the formation of immune complexes which are taken up at enhanced rate by macrophages, leading to foam cell formation. APS is characterized by repeated venous and arterial thromboembolic phenomena, recurrent fetal loss and thrombocytopenia, associated with the presence of antibodies to negatively charged phospholipids (aPL) (i.e. cardiolipin, phosphatidylserine). Phospholipids bear structural resemblance to LDL, and several studies have indeed proved that aPL display cross-reactivity with anti-Ox-LDL antibodies. In this study we assessed the capacity of oxidized and native forms of LDL to aggravate the clinical picture of experimentally induced APS in naive mice. Mice were actively immunized intradermally with anticardiolipin antibodies and developed a clinical picture resembling APS in humans. Subsequently, the mice were infused with either Ox-LDL, native LDL or PBS, and similar regimens were applied to controls. APS mice infused with Ox-LDL were found to exhibit a significantly more severe form of the disease in comparison with native LDL- and PBS-infused mice, expressed by lower platelet counts (261,000/mm3, 535,000/mm3 and 455,000/mm3, respectively), longer activated partial thromboplastin time (aPTT) (99 +/- 12 s, 63 +/- 8 s and 74 +/- 8 s, respectively) and higher fetal resorption rates (72.7%, 34.4% and 32.6%, respectively). The results of this study show that Ox-LDL, compared with native LDL, aggravates the clinical manifestations of experimental APS and suggest that cross-reactivity of Ox-LDL with phospholipids may provide a pathogenic explanation for this effect.

Pathogenicity of human anti-platelet factor 4 (PF4)/heparin in vivo: generation of mouse anti-PF4/heparin and induction of thrombocytopenia by heparin

Heparin-induced thrombocytopenia/thrombosis (HIT) is a severe thrombotic disorder that occurs in approximately 1% of patients treated with heparin. Affected patients commonly develop antibodies that recognize PF4/heparin complexes that may form on the surface of activated platelets and on the endothelium. However, it has not been established that anti-PF4/heparin antibodies are responsible for the clinical manifestations of HIT. To address this issue, we employed a recently developed model of active immunity to study the effect of IgG anti-PF4/heparin antibody in vivo. In previous studies we have shown that it is possible to induce autoimmune diseases such as systemic lupus erythematosus (SLE), anti-phospholipid syndrome (APS) or vasculitis in naive mice by active immunization with anti-DNA, anti-cardiolipin and anti-neutrophil cytoplasmic antibodies, respectively. Immunized animals develop anti-idiotypic antibodies (Ab2) and, after 2-4 months, anti-anti-idiotypic antibodies (Ab3). Ab3s generated in this manner often simulate the binding activity of Ab1 and their expression correlates with the development of specific clinical manifestations typical of the respective human disease. Based on this experience, naive BALB/c mice were immunized with IgG anti-PF4/heparin antibodies isolated from two patients with HIT. The actively immunized mice developed mouse anti-PF4/heparin antibody (Ab3). Administration of unfractionated heparin, but not low molecular weight heparin (LMWH), to the actively immunized animals induced thrombocytopenia by day 4 of drug exposure. There was no evidence of thrombosis. The results of this study support the importance of anti-PF4/heparin antibodies in the pathogenesis of HIT. Further, this model may help to elucidate the factors responsible for thrombosis as well as providing means to assess new treatment options for patients with this disorder.

Anatomic variation of the coracoacromial ligament: a macroscopic and microscopic cadaveric study

The operative management of the subacromial impingement syndrome includes reconstruction in cases with ruptured tendons and enlargement of the subacromial space by arthroscopic or open resection of the coracoacromial ligament and acromioplasty. In nearly 20% of all cases, however, surgical treatment fails. This study was conducted with 124 cadaver shoulders of older specimens with a balanced male/female ratio. The coracoacromial ligament did not present homogenous morphologic characteristics. We found 25.8% of all ligaments undivided, 59.7% bipartite, and 14.5% consisted of three parts. The third part, located most medially, took a hidden path to the coracoid process and was not visible during dissection until after the clavicle was resected. This medially situated third part of the coracoacromial ligament has not been described in the medical literature before the time of our investigation. It could well be responsible for persisting subacromial pain after surgery, if it is not identified and resected during surgery.

Animal models for antiphospholipid syndrome in pregnancy

Experimental models for antipospholipid syndrome (APS) have been established recently in lupus-prone mice and induced in naive mice. The induction of APS is performed by passive infusion or active immunization of antiphospholipid antibodies (aPL) or the cofactor beta 2GP-1. High levels of diverse aPL develop in the animals in conjunction with clinical manifestations similar to the human disease, entailing low fecundity rate, fetal resorptions, thrombocytopenia, prolonged activated partial thromboplastin time, and neurological and behavioral impairments. The pathogenicity of aPL was confirmed in an in vivo thrombosis model. Immunomodulation of APS manifestations and treatment regimens in the experimental models are discussed.

New methods of treatment in an experimental murine model of systemic lupus erythematosus induced by idiotypic manipulation

In this article we have presented our experiences and those of others with various experimental and novel treatments in an experimental model of murine SLE, induced by immunisation with pathogenic anti-DNA antibody (fig 4). Many of the treatments (summarised in the table) were highly effective in ameliorating clinical, serological, and histological manifestations of the disease. According to our results, it seems that hormonal treatments--such as testosterone metabolites, anti-oestrogens, or bromocriptine--as well as immunomodulation with IVIG or anti-CD4 antibodies, hold the most promising potential for application in lupus patients. We believe, therefore, that these types of treatment should receive high priority in human trials. It should be emphasised, however, that the timing of treatment may be critical, since several treatments were effective when used before or during the induction of the disease. This limitation may pose difficulty for human application, since the aetiology of SLE is still obscure and is probably multifactorial38; therefore it is not yet possible to identify patients at risk of developing SLE. Nevertheless, those treatments which proved to be effective might be used early in the course of the disease in lupus patients and hence influence the outcome of the disease, or may even induce partial or complete remission.

Treatment of systemic lupus erythematosus and antiphospholipid syndrome: from experimental models to patients' bedside

Animal models are of great value in the evaluation of novel and experimental treatments that cannot be tested directly on patients. In this article, we summarize the spectrum of murine models for systemic lupus erythematosus and antiphospholipid syndrome, focusing on animal models based on idiotypic immunization. Several therapeutic modalities that have been tested in those models had promising potential for application in human patients.

Immunomodulation of experimental APS: lessons from murine models

During the last few years several murine models for APS have been described. These include spontaneous occurring disease, or APS induced by immunization with pathogenic autoantibodies. Employing those models, several treatment modalities, in different stages of the disease, were studied. Treatments which showed promising potential for application in patients with APS include immunomodulation with specific anti-idiotypic or anti-CD4 antibodies, treatment with IL-3, high-dose intravenous immunoglobulins, ciprofloxacin or bromocriptine, as well as antithrombotic and anticoagulant treatments using aspirin and/or low-molecular-weight heparin. Bone-marrow transplantation was also found to improve clinical and serological manifestations of the disease. These studies might promote the handling of controlled clinical trials assessing their efficacy in APS patients.

Modulation of experimental systemic lupus erythematosus with linomide

OBJECTIVE

The objective of this study was to assess the beneficial effects of an early administration of low dose linomide, a new immunomodulator, in an animal model of experimental systemic lupus erythematosus (SLE).

METHODS

Experimental SLE was induced in naive BALB/c mice, by immunization with anti-DNA mAb (MIV-7). Control Mice immunized with irrelevant human IgM served as controls. The immunized mice were treated with linomide (0.1 mg/ml in the drinking water), four weeks prior to the first immunization, at an early stage of the disease induction (one month after boost injection), or at a later stage (3 months following boost immunization). The treatment duration was 3 months in all schedules. The follow-up studies continued for 8 weeks after discontinuation of the treatment. The presence in the serum of autoantibodies against ssDNA, dsDNA histones, phospholipids and an irrelevant autoantigen-pyruvate dehydrogenase, was determined by enzyme-linked immunosorbent assay (ELISA). The clinical parameters assessed included erythrocyte sedimentation rate, peripheral blood cell counts and proteinuria.

RESULTS

There was a 50-64% decrease in autoantibody levels in the sera of mice immunized with anti-DNA (MIV-7) mAb at the early stage of experimental SLE in mice which received linomide for a period of 3 months. No effect of linomide was noted in mice which received the drug during the later stages of experimental SLE when the disease was fully developed. Linomide had a preventive effect on the induction of experimental SLE in naive mice, when the treatment was initiated before the induction of the disease. This effect was abolished following cessation of the treatment.

CONCLUSIONS

Linomide proved to be effective at the early stages of induction of the experimental SLE. However, the autoantibody levels rose following discontinuation of the therapy.

Superantigens and experimental SLE induced by idiotypic dysregulation

OBJECTIVE

The effects of the superantigens (SAgs) Staphylococcal Enterotoxin B (SEB), Toxic Shock Syndrome Toxin-1 (TSST-1) and Mycoplasma Arthritidis Mitogen (MAM) were examined on the induction and on the course of experimental SLE-like disease.

METHODS

Immunization of BALB/c mice with human anti-DNA mAb (MIV-7) carrying the pathogenic idiotype 16/6 emulsified in complete Freund's adjuvant (CFA), followed by a boost of MIV-7/PBS 3 weeks later, generated an experimental SLE via an idiotypic dysregulation.

RESULTS

After immunization with MIV-7/SAg, replacing the MIV-7 boost by SAg, and then injecting SAg 7 weeks after the regular induction of the SLE-like disease, the mice failed to produce anti-hIgM and dsDNA Ab up to 6 months after the induction. The mice immunized with MIV-7/CFA and boosted with the SAg had high titers of anti-hIgM but no detectable anti-dsDNA Ab. In both experimental groups low titers of anti-CL Abs developed in 25/40 (62%) and 30/38 (79%) of the mice respectively, including the control mice immunized with non-pathogenic human IgM/SAg or PBS/SAg. The mice immunized according to the "classical" protocol showed increased titers of anti-dsDNA Ab (22%) and anti-CL Ab (28%) during 10 weeks of observation. In contrast SEB, TSST-1 and MAM induced a 29%, 1% and 17% reduction in the anti-DNA titers and a 32%, 15% and 12% reduction in the anti-CL titers, respectively.

CONCLUSIONS

These data suggest that the SAg tested here cannot replace the effect of CFA in the induction of the primary humoral response. The SAgs TSST-1, SEB and MAM did not induce the SLE-like disease following idiotypic modulation. Moreover, they may have had a suppressive effect on the idiotypic network in our model. The appearance of anti-CL Abs in almost all the experimental groups including the naive mice supports the possibility that microbial SAgs can induce the production of autoantibodies by different mechanisms. The SAgs TSST-1, SEB and MAM reduced autoantibody production in the serologically established idiotypic-induced experimental SLE-like murine model. This beneficial effect may indicate new directions for research on the management of SLE.