Anti-idiotypic antibodies against the receptor antibodies in myasthenia gravis

Production and characterization of a human monoclonal anti-idiotype to anti-ribosomal P antibodies

Autoantibodies to ribosomal P protein (anti-P) are a specific hallmark of systemic lupus erythematous (SLE). Several authors found significant associations of anti-P antibodies with neuropsychiatric, hepatic, and renal disease. We now report the isolation by phage display of human anti-idiotype (Id) monoclonal antibody fragments as single-chain Fv fragment (scFv) against anti-P antibodies. The V gene repertoires were derived from the RNA obtained from the B cells of a SLE patient. Affinity-purified anti-P antibodies were used for the selection of bacterial clones producing anti-P-specific scFv antibody fragments and little reactivity with normal IgG and other IgG antibodies. The anti-Id antibody recognizes a public idiotope broadly cross-reactive with polyclonal anti-P antibodies and inhibited binding of anti-P to ribosomal P antigen in immunoassays and on Jurkat cells. The anti-Id scFv antibody fragment may have therapeutic implications in SLE. They may also be used as probes in the study of the structure of the idiotype.

Production and characterization of human monoclonal anti-idiotype antibodies to anti-dsDNA antibodies

Anti-dsDNA autoantibodies are the hallmark of systemic lupus erythematosus (SLE) and frequently correlate with disease activity. In this study we report the isolation and characterization of human anti-Id monoclonal antibody fragments as single-chain Fv fragments (scFv) against anti-dsDNA antibody. The anti-Id monoclonal antibodies, specific for anti-dsDNA antibodies, have been cloned from phage display antibody scFv libraries derived from a patient with SLE. The V gene repertoires were derived from the RNA obtained from the B cells of an SLE patient with anti-Ro/SSA and anti-La/SSB antibodies. Affinity-purified anti-dsDNA antibodies were used for selection of bacterial clones producing specific scFv antibody fragments against anti-dsDNA antibodies and little reactivity with normal IgG and other IgG antibodies by ELISA. The anti-Id antibody recognizes a public idiotope that is broadly cross-reactive with polyclonal and monoclonal anti-dsDNA antibodies. This binding was largely inhibited by dsDNA antigen. The anti-Id antibody inhibited anti-dsDNA binding to dsDNA antigen in immunoassays and in the Crithidia luciliae assay. The anti-Id scFv antibody fragments derived from human genes could modulate the pathogenicity of anti-dsDNA autoantibodies and may have therapeutic implications in SLE. They may also be used as probes in studies of the structure of the idiotype.

Isolation of human anti-idiotypes broadly cross reactive with anti-dsDNA antibodies from patients with Systemic lupus erythematosus

Antibodies to double stranded (ds)DNA play a central role in clinical diagnosis and disease expression in Systemic lupus erythematosus (SLE). This paper describes the isolation of anti-idiotype reagents (anti/antidsDNA) from four SLE sera and the demonstration of broad and quantitatively similar cross reactivity to both polyclonal and monoclonal anti-dsDNA antibodies isolated from SLE patients. Seven affinity-purified polyclonal and three monoclonal human anti-dsDNA preparations reacted preferentially with anti-idiotype F(ab')(2) coated plates compared to normal immunoglobulin (Ig)G F(ab')(2) coated plates in ELISA. In contrast, autoantibodies of other specificities (anti-Ro/SSA, anti-La/SSB, and anti-U(1)RNP) reacted equally with anti/anti-dsDNA F(ab')(2) and normal IgG F(ab')(2) coated plates. Such anti-idiotypic antibodies could play a significant role in the regulation of anti-dsDNA antibody levels in SLE.

Immunoglobulin treatment in refractory Myasthenia gravis

Failure to induce and maintain remission in severe exacerbations of myasthenia gravis (MG), despite optimal care, is a common problem. We evaluated the efficacy and safety of high-dose intravenous immunoglobulin (IVIg) therapy in an open-label study of 10 patients with severe generalized myasthenia and an acute deterioration unresponsive to conventional therapy including high-dose corticosteroids, cyclosporine, and azathioprine. Intravenous Ig at a loading dose of 400 mg/kg was administered daily for 5 consecutive days, with maintenance IVIg treatment at a dose of 400 mg/kg, once every 6 weeks. Significant improvement occurred in all patients, beginning at 6 +/- 2 days of treatment as measured by the Osserman scale, fatigue variables, muscle strength, and respiratory function tests. No side effects were observed during induction of remission. Further IVIg treatments were highly efficacious in maintaining the remission. The severity of the disease decreased by 2.5 +/- 0.8 grades of the Osserman scale over a period of 1 year (P <0.001), in parallel with reduction of immunosuppressive therapy as well as a decrease in acetylcholine receptor antibody titers (P < 0.01). Intravenous Ig therapy seems to be highly potent for inducing rapid improvement in refractory myasthenia during acute deterioration as well as for maintaining remission.

Lupus autoantibodies interact directly with distinct glomerular and vascular cell surface antigens

We have identified monoclonal anti-DNA antibodies derived from lupus prone MRL-lpr/lpr mice that produce glomerular immune deposits and nephritis after passive transfer to normal mice. Particularly noteworthy is that the location of immune deposition varied among nephritogenic Ig, and this was associated with distinctive histologies and clinical disease profiles. Although their autoantigen binding properties differed, they were highly cross-reactive, in a manner similar to Ig deposited in glomeruli of lupus mice. This antigen binding profile was also typical of other previously described nephritogenic autoantibodies that bound directly to glomerular antigens to initiate immune deposit formation. In this study, we questioned whether ligation of different glomerular antigens by individual autoantibodies could contribute to the observed differences in the location of immune deposits. To examine this possibility, monoclonal anti-DNA antibodies (IgG2a) that produced glomerular immune deposits in different locations were evaluated. H221 produced mesangial, intracapillary (that is, intraluminal or within the capillary lumen) and subendothelial deposits associated with heavy proteinuria, whereas H147 produced mesangial, subendothelial and linear basement membrane deposits associated with proliferative glomerulonephritis. Initially, the capacity of H221 and H147 to bind directly to glomerular and vascular cell surfaces was evaluated. As demonstrated by FACS, H221 bound preferentially to mesangial cells whereas H147 bound preferentially to endothelial cells. To identify possible target cell surface antigens, Western blots, immunoprecipitation of surface labeled cells, and 2D gel electrophoresis were employed. H221 reacted with a 108 kDa protein on mesangial cells not identified by H147, whereas H147 reacted with a 45 kDa protein on endothelial cells not identified by H221. These results support the hypothesis that some nephritogenic lupus autoantibodies initiate immune deposit formation through direct interaction with glomerular antigens. Furthermore, they suggest that the site of immune deposition is determined by both antigen binding properties of the relevant antibody and the location of its target ligand within the glomerulus. In a given individual, therefore, the predominant autoantibody-glomerular antigen interaction may influence the morphologic and clinical phenotype expressed. Variation in the predominant interaction may also contribute to variations in disease expression among individuals with lupus nephritis.

Some autoantibodies to Ro/SS-A and La/SS-B are antiidiotypes to anti-double-stranded DNA

OBJECTIVE

To determine the relationship of anti-Ro/SS-A and anti-La/SS-B antibodies to anti-double- stranded DNA (anti-dsDNA) in sera from patients with systemic lupus erythematosus.

METHODS

Sera with anti-Ro/SS-A alone (n = 5) or those with anti-Ro/SS-A and anti-La/SS-B (n = 7) were absorbed with purified Ro/SS-A and La/SS-B, respectively. The absorbed sera were then tested for reactivity with MOLT-4 extract by Western blot and dsDNA by enzyme-linked immunosorbent assay (ELISA). With selected sera, anti-dsDNA was isolated on DNA cellulose columns and anti-Ro/SS-A and anti-La/SS-B were isolated on antigen-affinity columns. Reactivity between anti-dsDNA and autologous anti-Ro/SS-A or anti-La/SS-B, as well as inhibition by cognate antigens, was studied.

RESULTS

After absorption, all sera showed reactivity with small nuclear RNP A and D bands in Western blots, and some showed reactivity with dsDNA by ELISA. Anti-dsDNA populations (n = 4) were purified on dsDNA cellulose columns. Anti-Ro/SS-A (n = 1) and anti-La/SS-B (n = 3) were affinity purified from the same sera as the anti-dsDNA. In all cases, anti-dsDNA bound autologous anti-Ro/SS-A and anti-La/SS-B much more strongly than it bound normal pooled IgG. Moreover, dsDNA, but not RNA, blocked these interactions. In addition, Ro/SS-A blocked anti-Ro/SS-A and La/SS-B blocked anti-La/SS-B in these same interactions.

CONCLUSION

In sera with anti-Ro/SS-A and anti- La/SS-B, there are subpopulations of these antibodies that bind and mask anti-dsDNA. We hypothesize that these anti-Ro/SS-A and anti-La/SS-B antibodies are antiidiotypes to idiotypes on anti-dsDNA and that they both mask and down-regulate these anti-dsDNA antibodies.

Expression of cross-reactive idiotypes at the basement membrane zone in patients with bullous pemphigoid

The purpose of the present study was to determine whether tissue-bound anti-basement membrane zone (BMZ) autoantibodies in patients with bullous pemphigoid (BP) express a cross-reactive idiotype. We assayed 34 skin biopsies from 26 patients with BP and nine biopsies from control subjects, including normal subjects and patients with epidermolysis bullosa acquisita for the presence of a cross-reactive idiotype at the BMZ. Perilesional split-skin biopsies were assayed for the presence of immunoreactants, immunoglobulin G, and complement and for reactivity with a monoclonal anti-idiotypic antibody specific for a circulating anti-BMZ antibody, anti-Id 3-17. Anti-Id 3-17 bound in a linear band to the BMZ in 12 of 26 patients with BP (46%) and in 0 of 9 control subjects. In serial biopsy specimens, the presence or absence of cross-reactive idiotype at the BMZ in six patients was stable during the disease course. This cross-reactive idiotype has been previously identified in the serum of 36% of patients with BP; however, in this study, no correlation was noted between the presence of the cross-reactive idiotype in skin and serum of individual patients. Because cross-reactive idiotypes occur as a consequence of restricted variable-region gene utilization, the demonstration of a cross-reactive idiotype at the BMZ previously identified in the serum of patients with BP supports the hypothesis that circulating and tissue-bound autoantibodies in this disease arise from a common genetic origin.

Detection of cross-reactive idiotypes in the serum of patients with bullous pemphigoid

To further characterize the circulating antibasement membrane zone (antiBMZ) antibodies present in the sera of patients with bullous pemphigoid (BP), we have generated a mouse monoclonal anti-idiotypic antibody (antiId 3-17) specific for an IgG antiBMZ antibody. AntiId 3-17 is specific for an idiotype expressed on antiBMZ IgG in the serum of a patient with BP, and not expressed on pooled normal human IgG or IgG from patients with other autoimmune skin diseases. AntiId 3-17 binds to non-reduced, but not reduced, antiBMZ IgG on immunoblot, suggesting that the idiotype is composed of a conformational epitope expressed on native antibody. By a competitive inhibition ELISA, antiId 3-17 detects a cross-reactive idiotype (CRI) expressed in 18 of 50 (36%) of the sera of patients with BP, but in the sera of only 1 of 50 (2%) normal blood bank controls (p less than 0.001, Fisher's exact test) and 1 of 12 (8%) patients with pemphigus (p = 0.005). Thus, antiId 3-17 recognizes a public idiotype on a native antiBMZ antibody from a patient with BP, which is expressed in the sera of 36% of the unrelated patients with BP studied.

Anti-idiotypes against autoantibodies in normal immunoglobulins: evidence for network regulation of human autoimmune responses

This manuscript summarizes observations indicating that anti-idiotypes against human autoantibodies may be found in sera from patients recovered from autoimmune disease and in pooled normal polyspecific immunoglobulins (IVIg). The evidence that IVIg contain anti-idiotypes against autoantibodies includes: 1) inhibition by F(ab)2 from IVIg of the binding of F(ab)2 autoantibodies to their autoantigens; 2) specific retention of autoantibodies upon affinity chromatography of F(ab)2 fragments containing autoantibody activity on Sepharose-bound F(ab)2 from IVIg; 3) lack of detection of anti-allotypes and lack of significant anti-Fc activity in IVIg; 4) specific competitive displacement by polyclonal heterologous F(ab)2 anti-idiotypes of the binding of IVIg to affinity-purified F(ab)2 autoantibodies. The high number of donors contributing to IVIg endows the preparations with anti-idiotypic specificities that may not necessarily be detectable in plasma from single healthy individuals. Our observations of the presence in IVIg of anti-idiotypes against pathogenic autoantibodies and against IgG and IgM autoantibodies found in low amounts in normal sera supports the concept of a functional network regulating expression of autoimmunity in humans. We suggest that IVIg may be efficient in selected autoimmune diseases by providing a source of anti-idiotypes with a wide range of specificities brought as interconnected antibody species that may conpensate for altered connectivity of the immune network of patients with autoimmune diseases.

Antiidiotypic suppression of autoantibodies with normal polyspecific immunoglobulins

A mechanism by which therapeutic normal polyspecific immunoglobulins (IVIg) may suppress autoimmune responses in vivo is that of antiidiotypic suppression of autoantibodies mediated by anti-idiotypes present in IVIg. In vitro incubation with IVIg of either the plasma or the IgG fraction from plasma of patients with autoantibodies against procoagulant factor VIII (VIII:C), DNA, thyroglobulin, peripheral nerve and intrinsic factor resulted in dose-dependent inhibition of autoantibody activity. The pattern of inhibition curves showed a prozone phenomenon. Maximal inhibition was achieved at a ratio of patient's IgG to IVIg which was specific for each antibody tested. Inhibition was dependent on idiotypic/antiidiotypic interactions between autoantibodies and IVIg since: 1) F(ab')2 from IVIg inhibited autoantibody activity in F(ab')2 fragments from patients' IgG; 2) IVIg contained no antigen-like activity and no antibodies against the commonest allotypes expressed in F(ab')2 fragments of human IgG; 3) autoantibody activity in F(ab')2 fragments from patients' IgG was specifically retained on affinity columns of Sepharose-bound F(ab')2 fragments from IVIg. The presence of antiidiotypes against autoantibodies in pooled normal IgG supports the concept of a functional idiotypic network regulating autoimmune responses in man.

The start of an autoimmune disease: idiotypic network during early progression of myasthenia gravis

Anti-acetylcholine-receptor antibodies of IgG and IgM classes and antiidiotypic antibodies were determined in patients with myasthenia gravis at various times after the start of the disease. Patients with a disease duration of less than one year had a higher prevalence of antiidiotypic antibodies (31/32) than patients who had had the disease for more than 5 years (49/79), and the concentration of antiidiotypic antibodies was also higher in patients with early disease (p less than 0.005). The concentrations of antiidiotypic antibodies decreased during progression of the disease concomittant with an increase in IgG anti-receptor antibodies. A change from IgM to IgG anti-receptor antibody production was also found. In two patients, who developed myasthenia after bone-marrow grafting and who were followed before start of disease, antiidiotypic antibodies appeared before anti-receptor antibodies and before symptoms of myasthenia were present. The high prevalence and concentration of antiidiotypic antibodies in early disease indicate that development and expression of antiidiotypic antibodies are important in early myasthenia gravis.

Idiotypes, anti-idiotypes, and autoimmunity

Over the past two decades it has become clear that the ability of a host to generate antibodies against a wide variety of potential antigens is due to structural diversity in the antibody molecule within the variable region. This diversity results in sites within the molecule that are themselves immunogenic. These immunogenic sites are called idiotopes, and the collection of idiotopes on a single antibody molecule determines that antibody's idiotype. The idiotype of an antibody molecule is defined serologically by a second antibody termed an anti-idiotype. Anti-idiotypic antibodies can recognize antibody molecules bearing similar or identical structures within the variable regions, which are often on or near sites of antigen binding. Investigation into the nature of idiotype and anti-idiotype interactions has increased our knowledge of antibody structure, antigen-antibody interactions, the regulation of antibody production, and the nature of autoimmune disorders. This review will discuss the nature of idiotypes and anti-idiotypes and their potential role in the diagnosis, management, and treatment of autoimmune, infectious, and malignant diseases.

Are spontaneous anti-idiotypic antibodies against anti-acetylcholine receptor antibodies present in myasthenia gravis?

The presence of anti-acetylcholine receptor anti-idiotypic antibodies in sera from 102 myasthenia gravis patients and from 33 first-degree relatives was investigated by: (a) Enzyme linked immunosorbent assay (ELISA) using monoclonal antibodies raised against human acetylcholine receptor, (b) immunoprecipitation of 125I-monoclonal anti-acetylcholine receptor antibodies; (c) inhibition of anti-acetylcholine receptor monoclonal antibody binding to the receptor and/or (d) inhibition of autologous and heterologous anti-acetylcholine receptor antibody binding to the receptor. No clear evidence for the presence of abnormal levels of spontaneous anti-idiotypic antibodies to anti-acetylcholine receptor antibodies was found.

Anti-acetylcholine receptor antibody related idiotypes in myasthenia gravis

Anti-acetylcholine receptor antibody associated idiotypes were defined by six murine monoclonal antibodies raised against purified receptor antibodies. Four of the monoclonal antibodies bound to idiotopes located within or close to the antigen binding site of the anti-receptor antibodies; the other two monoclonal antibodies were directed against framework determinants. These monoclonal antibodies recognized idiotopes present on immunoglobulins in 14-60% of patients presenting myasthenia gravis, indicating substantial idiotype sharing. These idiotopes were also found in patients with no detectable anti-receptor antibody activity in their serum. In all patients studied, the pattern of idiotypes fluctuated considerably during the course of the disease regardless of clinical symptoms. This suggests continuous modulation of the autoimmune process in myasthenia gravis.

Crossreacting idiotypes of kappa-monoclonal immunoglobulins M in sera of patients with Waldenström's macroglobulinemia

Seventeen anti-idiotypic antisera (anti-Id) were prepared against kappa-monoclonal IgM from patients with Waldenström's macroglobulinemia. Their reactivity against homologous and heterologous IgM was tested using an ELISA. Crossreacting idiotypes were only found in two out of 289 investigated antigen-antibody reactions. One anti-Id IgG crossreacted with determinants on polyclonal IgM. These rare crossreactions were observed in Waldenström's macroglobulinemia patients with and without polyneuropathy. The scarcity of common idiotypes on different monoclonal IgM does, however, not constitute a decisive argument against common or related antibody specificities of such monoclonal IgM.

Antibody heterogeneity and specificity in myasthenia gravis

Anti-AChR is heterogeneous within individuals and between individuals. Anti-AChR idiotypes are not shared to any large extent. Ten monoclonal antibodies raised against human AChR: (a) bind to five partially overlapping regions; (b) are not idiotypically identical even within a region; (c) do not all bind to the main immunogenic region; (d) four distinguish between normal and denervated human AChR; (e) can be used to define the antigenic determinants in MG. Antigenic specificities vary in different clinical groups. Antigenic specificities can change during the course of the disease, but some remain relatively constant. Thymus cultures make antibodies with the same specificity as those present in the serum of the individual. All monoclonal antibodies bind to myoid cells of normal and MG thymus. We find no convincing evidence of naturally occurring antiidiotype antibodies in MG sera.

Anti-idiotypic antibodies to anti-acetylcholine receptor antibody: characterization by ELISA and immunoprecipitation assays

The idiotype network is important both as a means of autoregulation of immune mechanisms and a potential tool for manipulation of abnormal responses. In the autoimmune disease myasthenia gravis the acetylcholine receptor (AChR) is the target of an aberrant immune response. In this study we compare 2 widely used methods of antibody determination--immunoprecipitation radioimmunoassay (IPRA) and enzyme-linked immunoassay (ELISA)--for their ability to detect both anti-AChR antibodies (polyclonal and monoclonal) and anti-idiotypic antibodies raised against polyclonal anti-AChR antibodies. Although the IPRA is considerably more sensitive for the detection of monoclonal anti-AChR antibodies, the 2 methods produce similar results in the detection of anti-idiotypic antibodies to the anti-AChR immune response. The 2 techniques also demonstrated specificity of the reagents for idiotypes associated with the anti-AChR response and absence of effect on an idiotype associated with the control antigen, ovalbumin. The results demonstrate that the idiotypic repertoire of the polyclonal anti-AChR response in C57B1/6 mice is sufficiently restricted that antigen-specific blocking anti-idiotypic antibodies can be raised in rabbits by immunization with anti-AChR antibodies.

Immunological similarities between an experimental autoimmune myasthenia gravis model and human myasthenia gravis

The induction of experimental autoimmune myasthenia gravis (EAMG) in rabbits after immunization with an acetylcholine (ACh) conjugate was found to possess immunological similarities with human myasthenia gravis. Anti-ACh antibodies, present in human sera, recognized the antigenic determinant, glutarylcholine, used to raise anti-ACh antibodies in rabbits. Identification of anti-anti-ACh antibodies in MG patients enabled us to test for recognition of the anti-ACh antibodies present in rabbit sera. The reverse, the recognition of rabbit auto-anti-anti-ACh antibodies by human anti-ACh antibodies was also tested and found to be specific.

Anti-idiotypic immunity in autoimmunity

It has been hypothesized that autoimmune disease may result from a derangement of the idiotype-anti-idiotype network. However, the evidence in favor of a role of anti-idiotypic immunity in autoimmunity is still scarce. For this reason, we have investigated animal models of autoimmune thyroiditis and glomerulonephritis, addressing the following questions: Are autoimmune responses idiotypically heterogeneous? Are auto-anti-idiotypic antibodies detectable in autoimmunity? Is it possible to demonstrate quantitative or qualitative changes in idiotypic and anti-idiotypic lymphocytes during the course of autoimmune disease? To date, results obtained in our laboratory may be summarized as follows: Cross-reacting idiotypes were present on human and animal autoantibodies; Circulating auto-anti-idiotypic antibodies were not detected in any of the models studied; Changes in idiotypic and anti-idiotypic lymphocytes were observed in animals with autoimmune disease.

Detection of cross-reactive anti-DNA antibody idiotypes on renal tissue-bound immunoglobulins from lupus patients

Cross-reactive anti-DNA antibody idiotypes have been identified on tissue-bound immunoglobulins in a study of renal biopsies from 26 systemic lupus erythematosus (SLE) patients. 12 (46%) biopsies were shown to have one or both the idiotypes tested for by anti-idiotypic reagents. The idiotypes were identified in the glomerular basement membrane, the mesangial cell cytoplasm, and in focal tuft proliferations. In contrast, in none of 24 immunoglobulin-positive disease control biopsies could either idiotype be demonstrated. Blocking studies in two patients indicated that the idiotypes were on anti-DNA antibodies. These findings indicate that some tissue-bound auto-antibodies are derived from related families of high-frequency germ line genes that are expressed in SLE patients. The potential role of anti-idiotypic therapy in SLE is discussed.

Myasthenia gravis and myasthenic syndromes

More than a decade ago myasthenic symptoms were observed in rabbits immunized with acetylcholine receptor (AChR) [119] and AChR deficiency was found at the neuromuscular junction in human myasthenia gravis (MG) [36]. By 1977 the autoimmune character of MG and the pathogenic role of AChR antibodies had been established by several measures. These included the demonstration of circulating AChR antibodies in nearly 90% of patients with MG [87], passive transfer with IgG of several features of the disease from human to mouse [149], localization of immune complexes (IgG and complement) on the postsynaptic membrane [30], and the beneficial effects of plasmapheresis [20, 123]. Substantial subsequent progress has occurred in understanding the structure and function of AChR and its interaction with AChR antibodies. The relationships of the concentration, specificities, and functional properties of the antibodies to the clinical state in MG have been carefully analyzed, and the mechanisms by which AChR antibodies impair neuromuscular transmission have been further investigated. The clinical classification of MG has been refined, the role of the thymus gland in the disease has been further clarified, and new information has become available on transient neonatal MG. The prognosis for generalized MG is improving, but there is still no consensus on its optimal management. Novel therapeutic approaches to MG are now being explored in animal models. Recognition of the autoimmune origin of acquired MG also implied that myasthenic disorders occurring in a genetic or congenital setting had a different cause. As a result, a number of congenital myasthenic syndromes have come to be recognized and investigated. Finally, an acquired disorder of neuromuscular transmission different from MG, the Lambert-Eaton myasthenic syndrome, has also been shown to have an autoimmune basis. In this syndrome, active zone particles of the presynaptic membrane are direct or indirect targets of the pathogenic autoantibodies.

Idiotypic cross-reactions of monoclonal human lupus autoantibodies

Idiotypic cross-reactions were evaluated in 60 polynucleotide-binding monoclonal lupus autoantibodies produced by human-human hybridomas that were derived from seven unrelated patients with SLE. Three antiidiotype reagents were prepared by immunization of rabbits or a mouse with monoclonal autoantibodies from two patients. Binding of the three reagents to their corresponding idiotypes was inhibited by one or more polynucleotides, an indication that the antiidiotypes reacted with the variable regions of the autoantibodies. Each antiidiotype appeared to detect a different idiotypic determinant. Of the 60 monoclonal autoantibodies tested, 40 reacted in one or more competitive immunoassays; 15 reacted with one antiidiotype, 10 reacted with two antiidiotypes and 15 reacted with three antiidiotypes. A monoclonal antiidiotype reagent cross-reacted with autoantibodies from six of the seven patients. The idiotypic cross-reactions of immunoglobulins from unrelated patients suggest that the autoantibodies are derived from related families of germ line genes that are expressed by patients with SLE.

Mechanisms of autoimmunity: a role for cross-reactive idiotypes

Ehrlich was rarely given to trivial pronouncements and his recognition of the central importance of the distinction between self and non-self by the immune system, embodied in his concept of 'horror autotoxicus'(1), is no exception. This is despite the apparent paradox of the idiotype network in which antibodies recognize self-epitopes on other antibody molecules or antigen receptors as part of the normal process of immune regulation. In this review Anne Cooke and her colleagues examine the possible factors which may contribute to the breakdown of self-tolerance and the establishment of autoimmune states.

Anti-idiotypic immunity and autoimmunity. II. Idiotypic determinants of autoantibodies and lymphocytes in spontaneous and experimentally induced autoimmune thyroiditis

In a previous report, it was demonstrated that heterologous anti-idiotypic antibodies to autoantibodies against rat thyroglobulin (ART) were capable of inhibiting the in vitro binding between ART and rat thyroglobulin. It has also been shown that repeated injections of anti-idiotypic antibodies into Buffalo (BUF) rats with spontaneous autoimmune thyroiditis were followed by a significant decrease in the levels of circulating ART. In this report, cross-reacting idiotypic determinants, detectable by rabbit anti-idiotypic antibodies to ART, are shown to also be present on ART from rats with experimentally induced autoimmune thyroiditis. In addition, antibodies to rat thyroglobulin from animals of various strains and species are shown to also express idiotypes cross-reacting with those of spontaneous ART of BUF rats. Finally, it is reported that idiotypic determinants similar to those of circulating ART are present on spleen lymphocytes from rats with autoimmune thyroiditis.