Cross-reacting idiotypes in human sera

Human immune response to allergens of house dust mite, Dermatophagoides pteronyssinus. V. Auto-anti-idiotypic antibody characterization and cross-reactivity

From the serum of 10 allergic subjects we have prepared IgG antibodies recognizing idiotopes carried by specific antibodies to Dermatophagoides pteronyssinus (Dpt) allergens, and studied cross-reactivity of anti-Dpt IgG bystander and antigen-binding site-associated idiotopes by latex agglutination assays. Idiotopes of specific anti-Dpt IgE were evaluated by radioimmunoassays. Depending on the assay, a binding or inhibition of more than 50%, as compared to the reactivity of specific antibodies with the corresponding anti-idiotypic (anti-Id) IgG, was considered significant. Cross-reactivity of antigen-binding site-associated idiotopes attained a mean proportion of 6/10 for IgG and 9.6/10 for IgE. By contrast, bystander idiotopes cross-reacted only occasionally with a mean proportion of 2/10 for both IgG and IgE antibodies. Anti-Id antibodies from two subjects have been isolated by adsorption on insolubilized anti-Dpt antibodies of the corresponding patient. Using this purified material we have confirmed that (a) the majority of anti-Id antibodies carry an "internal image" of the initial antigen and compete in a dose-dependent manner with Dpt allergens for the binding to the anti-Dpt antibodies and (b) paratope-associated idiotopes of anti-Dpt antibodies are shared by unrelated individuals.

A cross-reactive idiotype on anti-collagen antibodies in collagen-induced arthritis: identification and relevance to disease

Immunization of mice with type II collagen (CII) leads to the production of anti-CII antibodies and, in susceptible strains, to the induction of arthritis. Specifically purified anti-CII antibodies from arthritic DBA/1 mice were used to prepare a rabbit anti-idiotypic antiserum. This antiserum recognizes a cross-reactive idiotype (CRI) present on 20-25% of anti-CII antibodies from DBA/1 mice immunized with bovine CII. The CRI is not present on DBA/1 anti-trinitrophenyl, undetectable in normal Ig and not Igh allotype linked. The presence of this CRI was examined after antigen specific suppression of the anti-CII antibody response by intravenous administration of chick or bovine CII. While intravenous injection of bovine CII, prior to immunization with chick CII, greatly reduces both the incidence of arthritis and the anti-CII response, the fraction of anti-bovine CII which expresses the CRI is increased by this treatment. These findings suggest that the CRI characterizes a disease-unrelated fraction of anti-CII which recognizes bovine and chick CII, but probably not mouse CII. In addition, attempts at idiotypic regulation of arthritis incidence and antibody response by in vivo administration of anti-idiotypic serum also indicate that the CRI-bearing antibody is not important for the induction of arthritis.

Human immune response to allergens of house dust mite, Dermatophagoides pteronyssinus. III. Cross-reactivity of bystander idiotopes on allergen-specific IgE antibodies

Rabbits were inoculated with affinity-purified human antibodies to the common house dust mite Dermatophagoides pteronyssinus (DPT) to produce anti-idiotypic (Id) antibodies. The Id carried by human IgE antibodies were studied in a radioimmunoassay in which specific anti-DPT IgE were first insolubilized on rabbit F(ab')2 fragments against human Fc epsilon. In a single individual specific anti-DPT IgE antibodies shared bystander idiotopes (i.e. idiotopes located outside the antigen-binding site) with IgG antibodies of the same specificity, since the adsorption on insolubilized anti-DPT IgG almost completely eliminated the binding of anti-Id antibodies to IgE. This differed from our previous observations (J.-M. R. Saint-Remy et al., Eur. J. Immunol. 1986. 16: 575) wherein distinct paratope-associated idiotopes were identified on IgG and IgE anti-DPT antibodies. The frequency of cross-reactions between idiotopes of anti-DPT IgE antibodies observed in ten unrelated individuals was less than 10% for bystander idiotopes. This finding confirmed the private character of the above idiotopes that we found earlier on anti-DPT IgG antibodies. However, one anti-Id antibody preparation was found to react with bystander idiotopes of anti-DPT IgE of most individuals, thereby suggesting the existence of a recurrent idiotope. The low frequency of inter-individual bystander idiotope cross-reactivity contrasted with the public character of paratope-associated idiotopes.

Anti-idiotypic antibodies to anti-DR in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) sera were evaluated for anti-idiotypic (anti-id) antibodies to HLA-DR antigens (anti-DR) using an ELISA method with murine monoclonal anti-DR antibody-coated microtiter plates incubated serially with either normal or RA sera and peroxidase-conjugated goat anti-human IgG (Fc specific). Specificity was examined using other monoclonal antibodies including anti-Leu 3a, OKM5, OKT8, anti-cytochrome c, and anti-breast tumor antigen. Significant binding of 11/33 (33%) RA to anti-DR was found compared with 0/44 normals (P less than 0.001). Two groups were identified: RA sera reacting with anti-DR and anti-Leu 3a and sera which did not bind to anti-DR but bound to irrelevant monoclonal antibodies. Anti-DR reactivity was differentiated from anti-Leu 3a by competitive inhibition studies. Binding of whole sera and IgG from RA patients to anti-DR was significantly inhibited by DR+ cell extract. The same extract was not inhibitory after selective removal of DR antigen by adsorption on an anti-DR-Sepharose column. These data suggest that anti-id antibodies are directed against the antigen-binding site of id. We conclude that some RA patients have anti-id antibodies potentially involved in immunoregulation of anti-DR antibodies.

Anti-DNA antibody idiotypes in primary biliary cirrhosis

A significant increase in 16/6 Id--a major cross-reactive idiotype of anti-DNA antibodies (Ab) derived from a patient with systemic lupus erythematosus (SLE) and hitherto identified in SLE patients and their relatives, was found in 16/17 patients with primary biliary cirrhosis (PBC). The increased serum level of Ab with the 16/6 idiotype (16/6 Id) in PBC patients (median 50 ng/ml) was not found in 6/7 of the patients' spouses nor among 27/28 healthy controls or most patients with other types of cirrhosis. The quantity of 16/6 Id was not correlated to either the stage of disease or the presence of antimitochondrial, antinuclear, or anti-dsDNA antibodies. However, 16/6 Id could be shown to be associated with anti-ssDNA antibodies. The high frequency of the lupus-derived 16/6 Id in PBC may accompany the polyclonal B-cell activation seen in that disease. Of 14 healthy first-degree relatives of the PBC patients, 4 (29%) also had elevated serum 16/6 Id (20-25 ng/ml) and the cluster of 3 of them in a single family may indicate a genetic predisposition to develop PBC.

The origin of autoantibodies

Autoimmune diseases are characterized by the appearance of autoantibodies (autoAb) which may participate in their pathogenesis, but autoAb have also been found in normals with a variety of other conditions. The production of hybridomas from lymphocytes of unimmunized normal mice and healthy humans and analysis of the monoclonal autoAb (m-autoAb) obtained, showed that many had polyspecific autoAb reactivity, binding to many seemingly unrelated self-antigens, or to several organs. Most m-autoAb were of the IgM class and shared a common cross-reactive idiotype (CRI). Low levels of Ab with similar binding pattern and idiotype are continuously represented in the serum of mice and humans who have no evidence of autoimmune or other disease. Very similar Ab appear in autoimmune diseases. Studies of m-autoAb derived from lupus-prone mice and from patients with systemic lupus erythematosus (SLE) and other autoimmune diseases also revealed polyspecific binding, IgM isotype and CRI. Moreover, these CRI, which were almost identical with the idiotypes of natural autoAb in normals, may identify a group of pathogenic Ab in the lupus mice and SLE patients. Since the data clearly suggest that lymphocytes that make autoAb are common and are part of the normal B cell repertoire coded by widely dispersed germline genes, there remain the basic problems of the function of these autoAb in health, as well as the question of their regulation and activation in vivo. Several postulated functions and immunoregulatory mechanisms are discussed and the possible role of certain factors, especially viruses, in enhancing autoAb production and autoimmunity, is assessed.

The human immune response against major allergens from house dust mite, Dermatophagoides pteronyssinus. II. Idiotypic cross-reactions of allergen-specific antibodies

Antisera were prepared in rabbits against the idiotypic (Id) determinants of antiallergen antibodies. These antibodies were isolated from the plasma of 10 unrelated patients by immunoabsorption. Three major allergens isolated from the house dust mite, Dermatophagoides pteronyssinus (DPT), were used. The anti-Id antisera were rendered specific by successive absorption on insolubilized allergens, IgG and IgM from a pool of human sera and Ig from the donor after removal of anti-DPT antibodies by absorption. Anti-Id antibodies raised essentially against IgG antibodies were found to inhibit the agglutinating activity of both IgG and IgM anti-DPT antibodies toward allergen-coated latex. These anti-Id antibodies were also able to inhibit partly the binding of radiolabeled allergen to IgE anti-DPT antibodies. Matching the anti-Id antisera with the various individual anti-DPT antibodies revealed an Id cross-reactivity of about 71% for IgG, 61% for IgM and 62% for IgE. A second and predominant type of anti-Id antibodies recognized bystander idiotopes as the allergen did not inhibit Id-anti-Id reaction. These idiotopes were apparently more specific to individuals (private) as the anti-DPT antibodies of a given patient did not agglutinate latex particles coated with anti-Id antibodies prepared against Id of another patient.

The human anti-myelin-associated glycoprotein IgM system

Two mouse monoclonal antiidiotypic antibodies that react with human monoclonal IgM antibodies with specificity for myelin-associated glycoprotein (MAG) have been used to study the immunological specificity of the reported cross-reactions involving the anti-MAG IgM. Both of the antiidiotypic antibodies are shown to react with the combining site of their respective idiotypic IgM and to inhibit the reaction between IgM and MAG. Using these antiidiotypic antibodies as "surrogate" antigen, we have demonstrated immune cross-reactivity between MAG, a human peripheral nerve glycolipid, and a low-molecular-weight protein of human peripheral nerve myelin. In addition, we have used the two antiidiotypic antibodies to conduct a search for evidence of shared idiotypy among 34 different neuropathy-associated paraproteins. Our results provide no evidence for a neuropathy-associated idiotype, suggesting a degree of polymorphism in the human anti-MAG IgM system.