Congenital heart block and immune mediated sensorineural hearing loss: possible cross reactivity of immune response

Immune-mediated sensorineural hearing loss may complicate systemic autoimmune diseases. We have previously reported the presence of antibodies directed against inner ear antigens in patients with Cogan syndrome, a disease characterized by sudden hearing loss and interstitial keratitis. Such autoantibodies cross-react with an epitope of SSA/Ro60 protein. Anti-Ro/SSA antibodies in pregnant women cross the placenta and reach the fetal tissues inducing an immune-mediated damage of the cardiac conduction system. We wanted to evaluate whether mothers with anti-Ro/SSA antibodies who gave birth to children with congenital heart block have antibodies directed against inner ear antigens and whether these antibodies are connected with the presence of immune-mediated sensorineural hearing loss. We did not find anti-inner ear antibodies in the majority of the mothers. On the contrary a 13-year-old boy with congenital heart block and sensorineural hearing loss was positive for the presence of anti-inner ear antigens antibodies. Moreover his serum was positive for the presence of anti-Ro60 peptide antibodies but did not recognize the entire protein Ro60 (TROVE2), a behaviour similar to that of sera from patients with Cogan syndrome. In conclusion the data obtained so far show that anti-inner ear antibodies do not recognize the entire protein TROVE2 and do not support the hypothesis that such antibodies may be involved in the pathogenesis of congenital heart block.

Secondary hypogammaglobulinemia in Waldmann's disease treated with subcutaneous immunoglobulins

Primary intestinal lymphangiectasia (PIL) is rare disorder characterized by congenital malformation or obstruction of intestinal lymphatic drainage; it is responsible for protein losing enteropathy leading to lymphopenia, hypoalbuminemia and hypogammaglobulinemia. A low-fat diet associated with medium-chain triglyceride supplementation is the cornerstone of PIL management. The administration of intravenous immunoglobulins does not always lead to satisfactory plasma levels and therefore the replacement therapy with immunoglobulins is controversial. We describe here the case of a patient with PIL and severe hypogammaglobulinemia treated with immunoglobulins. The striking aspect of this case is the clinical and serological benefit obtained with the subcutaneous compared to the intravenous immunoglobulins administration.

Infections and autoimmunity: role of human cytomegalovirus in autoimmune endothelial cell damage

Molecular mimicry between infectious agents and normal human host cell proteins represents one of the possible mechanisms responsible for autoimmunity. Among infectious agents, human cytomegalovirus (HCMV) is an ideal candidate for involvement in autoimmune disorders because of its lifelong persistence through periods of reactivation and latency and because of the extensive manipulation of innate and adaptive immunity. HCMV has been implicated in the pathogenesis of vascular damage in systemic sclerosis (SSc) and atherosclerosis. Based on our data, which demonstrate a cause-and-effect relationship between HCMV and endothelial cell aggression in SSc and atherosclerosis, we propose that immune responses to particular HCMV proteins may result in autoaggression through a mechanism of molecular mimicry of normally expressed endothelial cell surface molecules.

Endothelin‐1 serum levels correlate with MCP‐1 but not with homocysteine plasma concentration in patients with systemic sclerosis

OBJECTIVES

To determine whether homocysteine (Hcy) plasma levels are correlated with molecules indicative of endothelial cell and fibroblast activation, including endothelin-1 (ET-1) and monocyte chemoattractant protein-1 and -3 (MCP-1, MCP-3), in patients with systemic sclerosis (SSc).

METHODS

Eighty-two patients were enrolled in this study; the control group included 75 age- and sex-matched subjects. Plasma Hcy was determined by high-performance liquid chromatography; folic acid, and vitamin B(12) plasma levels were determined by a chemiluminescence method. ET-1, MCP-1, and MCP-3 were determined by enzyme-linked immunosorbent assay (ELISA). Analysis of the 677C-->T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene was performed by polymerase chain reaction (PCR) and digestion with the enzyme HinfI.

RESULTS

Hcy levels were lower in patients whereas ET-1 was significantly higher in patients and correlated with MCP-1. Stratification of the patients on the basis of Hcy levels was not associated with any statistical difference in the concentration of ET-1, MCP-1, and MCP-3. Patients with diffuse disease presented the highest levels of ET-1 and MCP-1. The distribution of the MTHFR genotypes was not different in patients and controls.

CONCLUSIONS

In SSc, Hcy plasma concentration does not influence ET-1, MCP-1, or MCP-3 levels. On the contrary, ET-1, a marker of vascular activation, correlates with MCP-1, a chemokine involved in the fibrotic process of SSc.

Schnitzler's syndrome treated successfully with intravenous pulse cyclophosphamide

Schnitzler's syndrome is a rare clinical condition characterized by chronic urticaria, intermittent fever, bone pain, arthralgia or arthritis, and monoclonal immunoglobulin M (IgM) gammopathy. Here we describe the case of a 48-year-old Italian female with a long history of arthralgia, leucocytosis, spiking fever, and chronic urticaria with severe pruritus. The IgM-kappa monoclonal component in the serum and bone densification on conventional X-ray with hyperfixation on bone technetium scanning at the distal part of the femurs and at the proximal part of the tibias were detected 4 years after the onset of the symptoms. After many ineffective treatments, the use of pulse cyclophosphamide (CPX) resulted in complete remission of the disease that is still lasting after a 2-year follow-up.

Antiflagellin antibodies recognize the autoantigens Toll-Like Receptor 5 and Pals 1-associated tight junction protein and induce monocytes activation and increased intestinal permeability in Crohn's disease

BACKGROUND AND OBJECTIVES

Bacterial flagellin is considered an important antigen in Crohn's disease (CD) as it activates innate immunity through Toll-Like Receptor 5 (TLR5) engagement and induces an elevated adaptive immune response. Little is known about the presence of an autoimmune process in CD. We aimed to identify pathogenically relevant autoantigen targets in CD.

METHODS

We screened a random peptide library with pooled sera of patients with active CD. Transepithelial flux of [3H] mannitol in T84 human intestinal epithelial cell line was used to study the epithelial barrier function. Monocyte activation was evaluated by surface expression of activation markers and by production of pro-inflammatory cytokines. Gene modulation of T84 cells exposed to antipeptide antibodies was analysed by gene array.

RESULTS

We identified a peptide that shares homology with Salmonella typhimurium flagellin and with self-antigens such as TLR5 and cell junction protein, Pals 1-associated tight junction protein. The affinity-purified antipeptide antibodies recognized the self-antigens and induced increased intestinal epithelial cell permeability. Moreover, the antibodies induced monocyte activation upon binding TLR5. Finally, in cultured intestinal cells (T84) the purified antibodies induced the modulation of clusters of proinflammatory genes similar to the one induced by the engagement of TLR5 by its natural ligand flagellin.

CONCLUSIONS

Antibodies directed against an immunodominant peptide of flagellin recognize self-antigens and are functionally active suggesting the presence of an autoimmune process that can both facilitate loss of tolerance to intestinal microflora by increasing cell permeability and amplify the innate immunity involvement through a novel mechanism of TLR5 activation.

In chronic idiopathic urticaria autoantibodies against Fc epsilonRII/CD23 induce histamine release via eosinophil activation

BACKGROUND

Chronic idiopathic urticaria is a common skin disorder characterized by recurrent, transitory, itchy weals for more than 6 weeks. An autoimmune origin has been suggested based on the findings of auto-antibodies (Abs) directed against either the alpha subunit of the high-affinity IgE receptor or the IgE molecule in nearly half of the patients.

OBJECTIVE

To identify other autoantigen targets in patients with chronic idiopathic urticaria.

METHODS

We used pooled IgG derived from 133 patients with chronic idiopathic urticaria to screen a random peptide library to identify disease-relevant autoantigen peptides. Among the identified peptides, one was recognized by the vast majority of patients' sera. Abs against this peptide were affinity purified from the patients' sera and assayed for their ability to induce histamine release from basophils.

RESULTS

We identified a peptide that showed similarity with the low-affinity IgE receptor (Fc epsilonRII/CD23) expressed on lymphomonocytes and eosinophils. Anti-peptide IgG Abs purified from the patients' sera bound cell surface CD23 and were able to induce histamine release from basophils. This effect appeared to be mediated by the release of major basic protein from eosinophils upon engagement of CD23. The same effects were obtained with the sera from mice immunized with the CD23 peptide.

CONCLUSION

Our results indicate that patients with chronic idiopathic urticaria have Abs against CD23 and that eosinophils, which infiltrate the skin of these patients, play a crucial role in maintaining the disease through the release of major basic protein upon engagement of the low-affinity IgE receptor by such auto-Abs.

Juvenile psoriatic arthritis and acquired sensorineural hearing loss in a teenager: is there an association?

Autoimmune inner ear disease is a cause of sensorineural hearing loss, first described in 1979 by McCabe. The occurrence during rheumatic diseases is already documented in adults, but to our knowledge, this evidence is still lacking in children. A 13-yr-old girl affected by juvenile psoriatic arthritis, treated with etanercept, developed a bilateral and asymmetric sensorineural deafness. The patient significantly improved after steroid administration. Once ruled out the principal causes of sensorineural hearing loss, we also considered the hypothesis of an anti-TNF side effect. However, the clinical presentation, the efficacy on steroid treatment and the presence of inner ear auto-antibodies prompt us to consider autoimmune-SNHL as the most plausible diagnosis. The young age of our patient seems to suggest a genetic susceptibility to autoimmunity and supports the concept of associated autoimmune diseases.

Efficacy of intravenous immunoglobulin in chronic idiopathic pericarditis: report of four cases

Human intravenous immunoglobulins (hIVIgs) are used in two broad categories of diseases: immunodeficiency and autoimmunity. Among the immune-mediated diseases hIVIgs are of benefit in idiopathic thrombocytopenic purpura, autoimmune hemolytic anemia, and dermatomyositis. Chronic idiopathic pericarditis (CIP) is a chronic disease of unknown origin characterized by recurrent episodes of pericardial inflammation. The cause of the recurrence is unknown, although in some cases it may be traced to a viral infection and to the presence of antimyocardial antibodies. Since a viral infection can induce an autoimmune process through a mechanism of molecular mimicry, and since the optimal therapy for prevention of the recurrences has not been established, we reasoned that treatment with hIVIgs could be beneficial in our patients unresponsive to previous immunosuppressive therapies. We describe four patients affected by CIP treated with monthly high-dose hIVIgs (0.4 g/kg daily for 5 consecutive days) for five times followed by administration every 2 months. Three of the four patients could permanently discontinue steroid therapy and are still in remission after years of follow-up. Our experience suggests that hIVIgs therapy may be a useful and safe treatment for CIP in steroid-dependent patients.

Surface expression and function of p75/AIRM-1 or CD33 in acute myeloid leukemias: engagement of CD33 induces apoptosis of leukemic cells

p75/AIRM-1 is a recently identified inhibitory receptor expressed by natural killer and myeloid cells displaying high homology with CD33. Crosslinking of p75/AIRM-1 or CD33 has been shown to sharply inhibit the in vitro proliferation of both normal myeloid cells and chronic myeloid leukemias. In this study, we analyzed acute myeloid leukemic cells for the expression of p75/AIRM-1. p75/AIRM-1 marked the M5 (11/12) and M4 (2/2) but not the M1, M2, and M3 subtypes according to the French-American-British classification. Cell samples from 12 acute myeloid leukemias were cultured in the presence of granulocyte/macrophage colony-stimulating factor. Addition to these cultures of anti-CD33 antibody resulted in approximately 70% inhibition of cell proliferation as assessed by [(3)H]thymidine uptake or by the recovery of viable cells. Anti-p75/AIRM-1 antibody exerted a strong inhibitory effect only in two cases characterized by a high in vitro proliferation rate. After crosslinking of CD33 (but not of p75/AIRM-1), leukemic cells bound Annexin V and displayed changes in their light-scattering properties and nucleosomal DNA fragmentation, thus providing evidence for the occurrence of apoptotic cell death. Remarkably, when anti-CD33 antibody was used in combination with concentrations of etoposide insufficient to induce apoptosis when used alone, a synergistic effect could be detected in the induction of leukemic cell death. These studies provide the rationale for new therapeutic approaches in myeloid leukemias by using both chemotherapy and apoptosis-inducing mAbs.

DNase I mediates internucleosomal DNA degradation in human cells undergoing drug-induced apoptosis

Internucleosomal DNA fragmentation following the activation of endonucleases is the common end point of apoptosis. DNase I, a Ca(2+) / Mg(2+)-dependent endonuclease ubiquitously expressed in mammalian tissues, is believed to play a role in this process. To analyze the in vivo function of this enzyme in human cells, we have generated a cell line with targeted disruption of the DNase I gene, as well as several stable cell lines which overexpress the DNase I gene. Inactivation of the human DNase I gene was obtained in the Jurkat T cell clone JA3, characterized by high susceptibility to apoptotic cell death induced by pharmacological stimuli. JA3 cells, after disruption of the DNase I gene, became resistant to apoptotic stimuli. DNase I was overexpressed in the human cell lines JA3, K562 (erythroleukemia), M 14 (melanoma) and CEM (T cell lymphoma). Remarkably, stable overexpression of DNase I gene resulted in accelerated apoptosis in JA3 cells and induced apoptosis in K562, CEM and M14 cell lines, which are otherwise resistant to internucleosomal DNA degradation following pharmacological stimuli. Our study provides the first in vivo evidence that DNase I mediates internucleosomal DNA degradation in human cells undergoing drug-induced apoptosis.

Systemic sclerosis immunoglobulin G autoantibodies bind the human cytomegalovirus late protein UL94 and induce apoptosis in human endothelial cells

Systemic sclerosis is an autoimmune disease characterized by immunological and vascular abnormalities. Autoantibodies against intracellular antigens are associated with particular clinical features of the disease, whereas autoantibodies against cell surface antigens may be pathogenic by inducing endothelial cell damage, considered the primary event in the pathogenesis of the disease. Latent human cytomegalovirus infection may contribute to progression of systemic sclerosis through its ability to infect endothelial cells; however, direct links between human cytomegalovirus infection and systemic sclerosis are still lacking. Molecular mimicry is one of the mechanisms that account for the link between infection and autoimmunity. Here we have identified an immunodominant peptide using systemic sclerosis serum screening of a random peptide library; such peptide shares homology with autoantigens and with the human cytomegalovirus late protein UL94 (ref. 9). Immunoglobulin G antibodies against the peptide affinity-purified from the sera of patients with systemic sclerosis specifically recognized the viral product and autoantigens; moreover, such antibodies induced endothelial cell apoptosis through specific interaction with the cell surface integrin-NAG-2 protein complex. Our results provide evidence that antibodies against human cytomegalovirus cause apoptosis of endothelial cells, considered the initial pathogenic event of systemic sclerosis, and indicate a previously unknown mechanism for the etiological link between human cytomegalovirus infection and autoimmunity.

Glycine-rich cell wall proteins act as specific antigen targets in autoimmune and food allergic disorders

Our objective was to investigate the presence of a B and T cell immune response directed against the glycine-rich cell wall protein (GRP) in patients with different autoimmune disorders and with food allergy. GRP is an ubiquitous food protein that has high homology with cytokeratins and other self proteins [Epstein-Barr virus nuclear antigen-1 (EBNA-I), heterogeneous nuclear ribonucleoprotein, fibrillar collagen] which are common targets in autoimmune disorders. A peptide (GGYGDGGAHGGGYGG) derived from GRP was used to screen human sera in direct and competitive ELISA assay. Anti-GRP-specific IgG were analyzed for their ability to cross-react with autoantigens. The intracellular cytokine profiles of the peptide-specific T cell clones obtained from representative patients have been studied. BALB/c mice were immunized with the peptide coupled to the carrier protein keyhole limpet hemocyanin (KLH). Serum IgG antibodies directed against the GRP peptide were detected in several autoimmune disorders and in food allergic patients, and were able to cross-react with autoantigens including keratin, collagen and EBNA-I. Twenty-five T cell clones showed a specific proliferative response to the GRP peptide and were of the T(h)0 phenotype. Eight of the 10 BALB/c mice immunized with the peptide coupled to KLH developed an autoimmune response. Our data suggest that phylogenetically highly conserved epitopes in plants, viruses and humans may be responsible for an autoimmune response in susceptible individuals. They also indicate that the antigen spreading of a particular sequence among apparently divergent proteins may participate to initiate or amplify an immune response.

Chronic parvovirus B19 infection induces the production of anti-virus antibodies with autoantigen binding properties

Human parvovirus B19 infection in adults shows some clinical features similar to those found in autoimmune connective tissue diseases. To better clarify the relationship between viral infection and autoimmunity, we have evaluated the ability of anti-parvovirus antibodies to specifically recognize autoantigens in ten patients with chronic symmetric arthritis resembling rheumatoid arthritis or with recurrent episodes of arthritis and cutaneous manifestations and persistence of specific IgM antibodies against B19 parvovirus. We synthetized a 24-amino acid immunodominant peptide corresponding to a part of the virus protein 1 and virus protein 2 overlapping region. The peptide has been used to test patients' sera at different time points with an enzyme-linked immunosorbent assay (ELISA) and to purify anti-virus antibodies by affinity chromatography on a peptide-Sepharose column. Eluted immunoglobulins recognized the B19 peptide in both direct and competitive ELISA. Affinity-purified anti-parvovirus antibodies were then tested on a panel of autoantigens including human keratin, collagen type II, thyreoglobulin, single-strand (ss)DNA, cardiolipin and ribonucleoprotein antigen Sm. Eluted antibodies specifically recognized keratin, collagen type II, ssDNA and cardiolipin. Autoantibody activity was not detected in the immunoglobulin fraction after complete removal of anti-peptide antibodies and in antibodies eluted from normal donors. Epstein-Barr virus-transformed cell clones obtained from two subjects produced antibodies which simultaneously recognize the viral peptide and several autoantigens. To further confirm the role of the virus in inducing an autoantibody response, eight BALB/c mice were immunized with the viral peptide coupled to a carrier protein. Autoantibody activity against keratin, collagen II, cardiolipin and ssDNA was detected in six of the eight mice which developed a strong anti-virus response. Together, these data indicate that B19 parvovirus may be linked to the induction of an autoimmune response.

Receptor-mediated cellular entry of nuclear localizing anti-DNA antibodies via myosin 1

A unique subset of anti-DNA antibodies enters living cells, interacts with DNase 1, and inhibits endonuclease activity, before their nuclear localization and subsequent attenuation of apoptosis. We now report that endocytosis of these immunoglobulins is mediated by cell surface binding to brush border myosin (myosin 1). Cellular entry and internalization via this unique receptor provides initial contact for entry and sorting these immunoglobulins to translocate to the nuclear pore and enter the nucleus, interact with DNase 1 within the cytoplasm, or recycle back to the cell surface. This internalization pathway provides clues to the translocation of large proteins across cell membranes and the functional effects of intracellular antibodies on cytopathology. This is the first demonstration that brush border myosin functions as a specific cell surface receptor for internalization of large proteins.

Spontaneously produced anti-DNA/DNase I autoantibodies modulate nuclear apoptosis in living cells

Apoptosis has received increased attention over the past decade, and it is established as an essential process in physiological and disease states. Much effort has been devoted to understanding the intracellular mechanisms culminating in apoptosis; intense investigation has also focused on its role during inflammation. Despite these efforts, these events remain incompletely understood. It has been suggested that the Ca(2+)- and Mg2+-dependent endonuclease that mediates DNA fragmentation is DNase I; however, the precise role of DNase I during apoptosis has been debated. Recent observations using anti-DNA antibodies derived from autoimmune mice (MRL-lpr/lpr) provided both the means and the reagents to approach these issues in a more direct manner. We previously discovered that many anti-DNA antibodies cross-react with DNase I, and a subset of these Ig inhibited DNase I enzymatic activity in vitro. Serendipitously, in separate studies, a subset of these antibodies were observed to enter and localize within the nuclei of living cells. The aim of the present investigation was to determine whether these nuclear-localizing anti-DNA antibodies could interact with DNase I in living cells. We found that, once internalized, these autoantibodies bound DNase I and inhibited activity of the enzyme. Furthermore, living cells containing the intracellular antibodies appeared resistant to apoptotic stimuli; both morphological features of nuclear apoptosis and DNA fragmentation were inhibited. These results support a pivotal role for DNase I in apoptosis, and they provide a novel paradigm for autoantibody-mediated inflammatory disease.

Anti-collagen antibodies in systemic sclerosis and in primary Raynaud's phenomenon

The frequency and specificity of antibodies to native and denatured collagens were evaluated in systemic sclerosis (SSc) and in primary Raynaud's phenomenon (PRP) by direct and competitive ELISA. Antibodies reactive with denatured collagen type I (CI) were found in 43% of the SSc sera, and anti-CIV and anti-CV in 31%. In PRP, anti-CI, anti-CIV and anti-CV antibodies were detected in 8% of patient sera. Anti-CI, anti-CIV and anti-CV antibodies reacted with determinants expressed on the native as well as on the denatured molecule. Anti-CI and anti-CIV were cross-reactive; a reactivity with CII and a lower one with CV were detected. Anti-CV antibodies also reacted with CI and CII and, in a smaller proportion of cases, with CIV. Anti-collagen antibodies, affinity-purified from blotted collagen IV and V and cyanogen bromide (CBr)-digested CI, displayed the cross-reactivities shown by inhibition studies on sera. Moreover, antibodies eluted from a CBr fragment of CI reacted with the other CBr fragments as well. These data show that one-third of SSc sera contain antibodies that react with epitopes expressed on native as well as on heat-denatured CI, CII, CIV and CV, and therefore have the potential to bind collagens in vivo.

Anti-DNA antibodies bind to DNase I

Polyspecificity is a well-known property of the anti-DNA antibodies produced by autoimmune animals. In our search for antigen targets of anti-DNA antibodies within tissue extracts, we identified a 32-kD polypeptide that was recognized by a large panel of anti-DNA antibodies. Direct sequencing of this protein disclosed its identity with DNase I. 22 monoclonal anti-DNA antibodies bound to DNase I in direct and competitive immunoassays; out of 15 autoantibodies that did not bind DNA, none had the ability to bind DNase I. The ability of anti-DNA antibodies to interfere with DNase I enzymatic activity was evaluated in an assay based on the enzyme digestion of phage double strand DNA. Six monoclonal anti-single strand DNA antibodies that did not bind double strand DNA were tested in this assay. Three out of six inhibited DNase I-mediated digestion of phage DNA. The interaction of anti-DNA antibodies with DNase I was further investigated by testing their ability to bind a synthetic peptide that corresponds to the catalytic site of the molecule. 4 out of 22 anti-DNA antibodies bound the active site peptide; two of these had been shown to inhibit DNase I enzymatic activity. This report show that anti-DNA antibodies recognize both DNA and its natural ligand DNase I. Some anti-DNA antibodies inhibit DNase I enzymatic activity, thus displaying the potential to modulate DNA catabolism. The dual specificity of anti-DNA antibodies offers a clue for understanding the mechanisms that lead to anti-DNA antibody production in autoimmune animals.

Induction of anti-DNA antibodies in non autoimmune mice by immunization with a DNA-DNAase I complex

Recent studies suggest that anti-DNA antibodies may arise from the immune response to a complex of DNA and a DNA-binding protein. One of the protein targets frequently recognized by anti-DNA antibodies is the enzyme DNAase I. To investigate the possible role of DNAase I in the induction of anti-DNA antibodies, we immunized mice with a complex of DNA and DNAase I. Mammalian double strand DNA was crosslinked with DNAase I by ultraviolet light (UV) treatment and emulsified in complete Freund's adjuvant. BALB/c mice were immunized at the base of the tail with the DNA-DNAase complex, boosted after 2 weeks with the immunogen in incomplete adjuvant and bled one week after the boost. Control mice received UV treated DNA in adjuvant. In one-third of the mice immunized with the DNA-DNAase complex, IgG anti-DNA antibodies were detectable in serum; the antibodies reacted with single and double strand DNA. No anti-DNA response was elicited by immunization with DNA alone. These data show that immunization with a DNA-DNAase complex can induce anti-DNA antibodies in non-autoimmune mice strains and suggest that DNA-binding proteins may act as carriers in the immune response that leads to anti-DNA antibody production.

Adhesion molecule expression on B-cell chronic lymphocytic leukemia cells: malignant cell phenotypes define distinct disease subsets

Expression of surface adhesion molecules of the Ig superfamily (CD54 and CD58), of the integrin family (beta 1, beta 2, and beta 3 chains), of the selectin family (L-selectin), and of the lymphocyte homing receptor (CD44) was analyzed on B-cell chronic lymphocytic leukemia (B-CLL) cells from 74 patients. The aim of the study was the definition of phenotypically distinct disease subsets and the correlation of adhesion molecule phenotypes with clinical parameters. Expression of CD58 on B-CLL cells defined more advanced disease stages. In comparison with beta chain-positive cases, patients whose cells did not express beta 1, beta 2, and beta 3 integrin chains fell into the most favorable prognostic group, with lower lymphocytosis and the absence of splenomegaly, diffuse bone marrow infiltration, and therapy requirement. A novel finding was the expression of beta 3 chains on cells from a minority (12 of 74) of B-CLL cases. beta 3 chains were always coexpressed with beta 1 and beta 2 chains. Two-color immunofluorescence analyses of adhesion molecules such as alpha x beta 2 integrin (LeuM5) and L-selectin (Leu8) showed that these markers were detectable on variable proportions of leukemic cells, thus confirming the intraclonal phenotypic heterogeneity of B-CLL. Differences in the intensity of CD44 expression were also shown among the various B-CLL clones. Finally, no major variations were shown by comparison of adhesion molecule phenotypes of leukemic cells simultaneously obtained from blood and bone marrow, and of CD5+ versus CD5- clones.

Molecular heterogeneity of auto-anti-idiotypic antibodies in MLR-lpr/lpr mice

The VH and V kappa gene families expressed by 20 monoclonal auto-anti-idiotypes (Ab2) derived from unmanipulated MLR-lpr/lpr mice were determined by Northern blotting. Complete variable region sequences of six Ab2, along with three additional V kappa-JH Ab2 sequences, were obtained. These auto-anti-idiotypes arose spontaneously in the animals, and they bound specifically to an idiotypic determinant (Id/r) on mAb 28/12, a monoclonal IgG2b MLR-lpr/lpr anti-small nuclear ribonucleoprotein antibody. The 16 Ab2 heavy chains belonged to 7 different VH gene families, and the 10 Ab2 light chains were derived from 8 V kappa families. The light chains of two Ab2 were approximately 99% identical; the remaining variable region sequences were highly heterogeneous. There was no correlation between primary amino acid sequence of either heavy or light chain and idiotypic properties of the auto-anti-idiotypes. Six Ab2 used VH or V kappa genes that are identical to known germ-line genes. A high proportion of the spontaneous auto-anti-idiotypes was shown to have autoantibody activity (anti-DNA, anti-ribonucleoprotein), or specific binding reactions with lipopolysaccharide of Salmonella RE, or both properties. The structural diversity of spontaneous MLR-lpr/lpr auto-anti-idiotypes differs sharply from the structural homogeneity reported for Ab2 induced in normal animals against syngeneic Ab1. Our results suggest that auto-anti-idiotypes might arise independently of an immunogenic stimulus from an Ab1.

Human and murine anti-DNA antibodies induce the production of anti-idiotypic antibodies with autoantigen-binding properties (epibodies) through immune-network interactions

To examine the potential role of immune-network interactions in the production of lupus autoantibodies, normal NZW rabbit antibody responses were analyzed after immunization with one of the following Ig preparations: human lupus serum anti-dsDNA antibodies, human lupus serum anti-ssDNA antibodies, a mixture of human lupus serum anti-dsDNA and anti-ssDNA antibodies, the MRL-lpr/lpr anti-dsDNA mAb H241, and the MRL-lpr/lpr anti-ssDNA mAb H130. Four of five rabbits produced Ig typical of lupus autoantibodies: individual rabbit Ig cross-reacted with multiple autoantigens including nucleic acids, cardiolipin, SmRNP, glomerular extract, laminin, and exogenous Ag. Rabbit anti-Id against human anti-dsDNA antibodies were highly specific for dsDNA. Notably, in each serum the autoantibody activity was confined to the anti-Id Ig fraction. A similar spontaneously occurring Id-anti-Id interaction was also found between anti-ssDNA and anti-dsDNA antibodies isolated from an individual lupus patient. These results indicate that lupus autoantibodies which share Ag binding properties with pathogenic Ig, including both cross-reactive and anti-dsDNA antibodies, can induce the production of Ig with similar autoantigen binding properties through immune-network interactions. This phenomenon, if unregulated, could lead to the amplification of pathogenic autoantibody production in individuals with systemic lupus.

Human and murine anti-DNA antibodies induce the production of anti-idiotypic antibodies with autoantigen-binding properties (epibodies) through immune-network interactions

To examine the potential role of immune-network interactions in the production of lupus autoantibodies, normal NZW rabbit antibody responses were analyzed after immunization with one of the following Ig preparations: human lupus serum anti-dsDNA antibodies, human lupus serum anti-ssDNA antibodies, a mixture of human lupus serum anti-dsDNA and anti-ssDNA antibodies, the MRL-lpr/lpr anti-dsDNA mAb H241, and the MRL-lpr/lpr anti-ssDNA mAb H130. Four of five rabbits produced Ig typical of lupus autoantibodies: individual rabbit Ig cross-reacted with multiple autoantigens including nucleic acids, cardiolipin, SmRNP, glomerular extract, laminin, and exogenous Ag. Rabbit anti-Id against human anti-dsDNA antibodies were highly specific for dsDNA. Notably, in each serum the autoantibody activity was confined to the anti-Id Ig fraction. A similar spontaneously occurring Id-anti-Id interaction was also found between anti-ssDNA and anti-dsDNA antibodies isolated from an individual lupus patient. These results indicate that lupus autoantibodies which share Ag binding properties with pathogenic Ig, including both cross-reactive and anti-dsDNA antibodies, can induce the production of Ig with similar autoantigen binding properties through immune-network interactions. This phenomenon, if unregulated, could lead to the amplification of pathogenic autoantibody production in individuals with systemic lupus.

An immunoglobulin light chain from a lupus-prone mouse induces autoantibodies in normal mice

Autoantibodies against the 70-kD U1 RNP nucleoprotein autoantigen and DNA were elicited in normal BALB/c mice with a purified Ig light chain. This light chain, derived from a lupus-prone MRL-lpr/lpr mouse, has two distinctive properties: it contains an idiotypic marker recognized by a monoclonal MRL-lpr/lpr anti-snRNP autoantibody, and the amino acid sequence of its third hypervariable region (CDR3) is homologous to a sequence in an antigenic region of the 70-kD U1 RNP polypeptide. The results demonstrate that an Ig idiotype that mimics an autoantigen can induce autoimmunization.

A method for retracing the putative antigen/antibody ratio of immune complexes in biological fluids

It is well known that immune complex (ICs) diseases are caused by a number of factors which influence the localization, clearance and inflammatory potential of ICs. Several studies suggest that the Ag/Ab ratio is one of the most important of these. Previous studies have clarified that IC detection methods which differ, either in their recognition unit or in the phase used (solid or liquid), show a very poor correlation with each other. This study was developed in order to verify the hypothesis that different methods recognise different kinds of ICs on the basis of their Ag/Ab ratio. We used 3 homogeneous EIAs employing a probe complex enzyme--anti enzyme which competes with circulating ICs for the recognition unit (bovine conglutinin, C1q or monoclonal rheumatoid factor) to detect 10 unrelated in vitro-made ICs at different relative Ag/Ab concentrations (from 8 x Ag excess to 8 x Ab excess). We demonstrated that the 3 recognition units recognised the ICs principally on the basis of their Ag/Ab ratio. These results were then used to set up a mathematical model capable of retracing the Ag/Ab ratio of the ICs present in unknown samples. This was employed to test a panel of sera from patients with systemic lupus erythematosus, essential mixed cryoglobulinemia and rheumatoid arthritis; we obtained very suggestive results but they require further prospective studies to understand the full significance of this parameter.

Erosive immune complex-mediated arthritis associated with meningococcal meningitis

A case of erosive sterile arthritis following meningococcal meningitis is described. High levels of immune complexes were detected in serum and synovial fluid. This is the first case in literature in which destruction of subchondral bone is documented. The erosion showed a progressive remineralization in the six months following clinical recovery.

Immune complex behaviour during prolonged plasma exchange in essential mixed cryoglobulinemia and systemic lupus erythematosus

A number of immunological parameters were measured in 9 patients with essential mixed cryoglobulinemia and 12 patients with systemic lupus erythematosus undergoing plasma exchange alone or without cytotoxic drugs. Only cryocrit significantly decreased in the majority of patients with essential mixed cryoglobulinemia. In contrast, immune complex levels, measured in two different ways, did not change on the whole, although variable and unpredictable changes were often present in individual patients. Thus, these data do not support the view that the mechanism(s) of action of plasma exchange in these diseases is only due to the quantitative removal of circulating immune complexes, and qualitative changes in the immune complex moiety may also occur.