Anti-idiotypic antibodies and disease

An improved phage-display panning method to produce an HM-1 killer toxin anti-idiotypic antibody

BACKGROUND

Phage-display panning is an integral part of biomedical research. Regular panning methods are sometimes complicated by inefficient detachment of the captured phages from the antigen-coated solid supports, which prompted us to modify. Here, we produce an efficient antigen-specific single chain fragment variable (scFv) antibody by using a target-related molecule that favored selection of recombinant antibodies.

RESULTS

To produce more selective and specific anti-idiotypic scFv-antibodies from a cDNA library, constructed from HM-1 killer toxin (HM-1)-neutralizing monoclonal antibodies (nmAb-KT), the method was modified by using an elution buffer supplemented with HM-1 that shares structural and functional similarities with the active site of the scFv antibody. Competitive binding of HM-1 to nmAb-KT allowed easy and quick dissociation of scFv-displayed phages from immobilized nmAb-KT to select specific anti-idiotypic scFv antibodies of HM-1. After modified panning, 80% clones (40/50) showed several times higher binding affinity to nmAb-KT than regular panning. The major populations (48%) of these clones (scFv K1) were genotypically same and had strong cytocidal activity against Saccharomyces and Candida species. The scFv K1 (K(d) value = 4.62 x 10(-8) M) had strong reactivity toward nmAb-KT, like HM-1 (K(d) value = 6.74 x 10(-9) M) as judged by SPR analysis.

CONCLUSION

The scFv antibodies generated after modified subtractive panning appear to have superior binding properties and cytocidal activity than regular panning. A simple modification of the elution condition in the phage-display panning protocol makes a large difference in determining success. Our method offers an attractive platform to discover potential therapeutic candidates.

Inhibition of fungal beta-1,3-glucan synthase and cell growth by HM-1 killer toxin single-chain anti-idiotypic antibodies

Single-chain variable-fragment (scFv) anti-idiotypic antibodies of an HM-1 killer toxin (HM-1) from the yeast Williopsis saturnus var. mrakii IFO 0895 have been produced by recombinant DNA technology from the splenic lymphocytes of mice immunized by idiotypic vaccination with a neutralizing monoclonal antibody (nMAb-KT). The fungicidal activity of scFv anti-idiotypic antibodies against the isolates of four Candida species was assessed by MIC analysis. scFv antibodies were fungicidal at concentrations of 1.56 to 12.5 microg/ml in vitro against four Candida species. The scFv antibodies exerted a strong candidacidal activity in vitro, with 50% inhibitory concentration (IC(50)) values ranging from 7.3 x 10(-8) to 16.0 x 10(-8) M, and were neutralized by adsorption with nMAb-KT. Furthermore, all scFv antibodies effectively inhibited fungal beta-1,3-glucan synthase activity in vitro, with IC(50) values ranging from 2.0 x 10(-8) to 22.7 x 10(-8) M, values which almost coincide with the values that are inhibitory to the growth of fungal cells. Binding assays showed that the scFv antibodies specifically bind to nMAb-KT, and this binding pattern was confirmed by surface plasmon resonance analysis. The binding ability was further demonstrated by the competition observed between scFv antibodies and HM-1 to bind nMAb-KT. To the best of our knowledge, this is the first study to show that an antifungal anti-idiotypic antibody, in the form of recombinant scFv, potentially inhibits beta-1,3-glucan synthase activity.

Therapeutic potential of antiidiotypic single chain antibodies with yeast killer toxin activity

Single chain fragment (ScFv) antiidiotypic antibodies (antilds) of a killer toxin (KT) from the yeast Pichia anomala have been produced by recombinant DNA methodology from the splenic lymphocytes of mice immunized by idiotypic vaccination with a KT-neutralizing monoclonal antibody (Mab KT4). ScFv KT-like antilds (KTIdAb) react with specific Candida albicans KT cell wall receptors (KTR) exerting a candidacidal activity in vitro could be neutralized by adsorption with Mab KT4. ScFv KTIdAb displayed an effective therapeutic activity in an experimental model of rat candidal vaginitis.

Patterns of nuclear immunofluorescence and reactivities to recombinant nuclear antigens in autoimmune hepatitis

BACKGROUND/AIMS

Antibodies to nuclear antigens have not been fully characterized in autoimmune hepatitis. The aims of this study were to determine the different patterns of immunofluorescence associated with antinuclear antibodies and to correlate these patterns with reactivities to recombinant nuclear antigens and clinical manifestations of autoimmune hepatitis.

METHODS

Sera from 65 patients were tested by indirect immunofluorescence and by enzyme immunoassay for antibodies to recombinant centromere, ribonucleoproteins, and ribonucleoprotein complexes.

RESULTS

Homogeneous and speckled patterns of immunofluorescence occurred with similar frequencies (34% vs. 38%) in the majority of patients (72%). Patients with speckled patterns were younger and had higher serum aspartate aminotransferase levels at presentation than counterparts with other patterns. Antibodies to centromere (42%) and 52K ribonucleoprotein complex (23%) were the most common reactivities. Of the 35 patients with antibodies, 16 (46%) had multiple specificities. Individual reactivities were not associated with specific immunofluorescent patterns, and they did not identify patients with distinctive features.

CONCLUSIONS

Antinuclear antibodies produce mainly homogeneous and speckled patterns of immunofluorescence in patients with autoimmune hepatitis. Speckled patterns are associated with a younger age and greater aminotransferase activity. Multiple autoantibodies are frequently associated with each immunofluorescent pattern. Antibodies to centromere and the 52K ribonucleoprotein complex have a previously unrecognized high frequency and uncertain significance.

Interfaces of the yeast killer phenomenon

A new prophylactic and therapeutic antimicrobial strategy based on a specific physiological target that is effectively used by killer yeasts in their natural ecological competition is theorized. The natural system exploited is the yeast killer phenomenon previously adopted as an epidemiological marker for intraspecific differentiation of opportunistic yeasts, hyphomycetes, and bacteria. Pathogenic microorganisms (Candida albicans) may be susceptible to the activity of yeast killer toxins due to the presence of specific cell wall receptors. On the basis of the idiotypic network, we report that antiidiotypic antibodies, produced against a monoclonal antibody bearing the receptor-like idiotype, are in vivo protecting animals immunized through idiotypic vaccination and in vitro mimicking the antimicrobial activity of yeast killer toxins, thus acting as antibiotics.

Production and characterization of monoclonal anti-CD18 anti-idiotype antibodies

Three leukocyte adhesion receptors have been described which mediate intercellular binding of leukocytes: LFA-1 (CD11a/CD18), Mac-1 (CD11b/CD18), and p150/95 (CD11c/CD18). We have previously reported the production of several monoclonal antibodies against the common subunit of these receptors (CD18). We have describe the production of monoclonal anti-idiotype antibodies against one of the anti-CD18 antibodies (H52) which has been shown to inhibit potently the function of leukocyte adhesion receptors. Three IgG1 and two IgM anti-idiotype antibodies were derived which recognized private idiotopes on the H52 molecule. Two of these antibodies blocked the binding of H52 to purified LFA-1 and to cell surface expressed antigen. One of the antibodies (AIM.6) was shown to be an internal image-type (Ab2 beta) antibody based on inhibition of its binding to H52 by purified LFA-1 and by its ability to induce Ab3 which recognize LFA-1 when used as immunogen. The AIM.6 Ab2 beta antibody was tested for recognition of leukocyte adhesion ligands in LFA-1-mediated leukocyte adhesion and activation assays. The AIM.6 antibody did not block intercellular adhesion of leukocytes or mitogen stimulation of T cells, functions which were completely inhibited by low concns of H52. AIM.6 Ab2 beta antibody bound to H52 very well at 0 degrees C but bound very poorly or not at all at 37 degrees C. Binding studies on a panel of anti-CD18 monoclonal antibodies showed that the idiotope defined by AIM.6 was unique to H52 and an antibody recognizing the same epitope on CD18 (H5B9). This result showed that inhibitory anti-CD18 monoclonal antibodies utilize at least two distinct paratopes in binding to CD18. The above results are in contrast to those obtained in other systems in which Ab2 beta antibodies against receptor-specific Ab1 antibodies recognize receptor ligands and are discussed in the context of ligand recognition by leukocyte adhesion receptors.

Anti-idiotype modulation of the in vitro immune response to hepatitis B surface antigen (HBsAg) following remote infection by hepatitis B virus in man

An antigen-inhibitable Ab-2 that exhibits internal image activity will selectively stimulate the in vitro production of anti-HBs in individuals with remotely established immunity to hepatitis B virus. This response is seen (1) in the absence of a polyconal increase in total IgG, (2) with the F(ab')2 component of the Ab-2, (3) in cultures depleted of T-cells, and (4) in the absence of stimulation by antigen. This observation demonstrates that the Ab-2-mediated stimulation of specific IgG production may be an important regulatory function in man.

Methods for generating reagents to examine idiotype networks within antiviral immune responses

The use of anti-idiotypic antibodies to examine and/or modulate the immune response to various viral antigens has the potential to be of use in many diverse systems. This paper details the method and immunologic parameters used in our laboratory to generate and characterize anti-idiotypic antibodies (anti-Id or Ab-2) with specificity for antibodies directed against viral antigens. These anti-Id reagents have been used in our laboratory for studies involving the immune responses to hepatitis B virus and simian virus 40, which we describe here, as well as herpes simplex virus, and the human immunodeficiency virus. We have utilized these anti-Id reagents to examine the fine specificity of the idiotypes on antiviral antibodies in these systems and have attempted to modulate or induce specific antiviral immune responses. It is anticipated that the methods described herein will be helpful in analyzing the immune response in other viral systems including studies involving viral-receptor interactions.

Induction of neutralizing antibodies to transmissible gastroenteritis virus by anti-idiotypic antibodies

The potential of anti-idiotypic antibodies (anti-ids) as immunogens against transmissible gastroenteritis virus (TGEV) was tested in a heterologous system. A month-old pig was immunized with a neutralizing murine monoclonal antibody (MAb, 5A5) of the IgG2a isotype, specific for the E2 glycoprotein of TGEV. The anti-ids were isolated from the serum of the immunized pig by affinity chromatography, initially on a 5A5-Sepharose column, followed by repeated adsorption on a mouse IgG2a column. The swine anti-ids thus obtained bound to the MAb 5A5 (the idiotype), but not to MAbs of the same isotype IgG2a but of different idiotypes. The anti-ids also inhibited the binding of 5A5 to TGEV in a concentration-dependent manner. Mice immunized with the anti-ids produced antibodies to TGEV. These antibodies, neutralized TGEV in vitro and inhibited the binding of 5A5 to TGEV.

Idiotypic control of the immune response

Anti-idiotypic antibodies are antibodies against the antigenic determinants (idiotypes) of an antibody's antigen-binding region. Anti-idiotypes can bind near (Ab2 gamma) or away (Ab2 alpha) from the antigen-combining site or can carry the internal image of the antigen (Ab2 beta). Idiotypes and anti-idiotypes have been described in T- and B-cell systems. They have been used in basic research to purify and characterize receptors and ligands against receptors, to treat tumors, to make vaccines and to diagnose and suppress the immune response. In experimental myasthenia gravis anti-idiotypes protect animals against the disease, block idiotype binding and share idiotypic specificities.

A Subgroup of Rheumatoid Arthritis (RA) Associated with Selective Binding of Rheumatoid Factors to Antigen Structures of Cytomegalovirus (CMV)

We compared antibodies (Ab) with both, antiviral and anti IgG properties in patients with rheumatoid arthritis with malignant progress, short remissions and no improvement to therapy. The selective binding of Rheumatoid Factor (RF) to antigen structures of CMV were tested in 180 patients by a newly established ELISA with antiidiotypic goat antibodies of CMV neutralizing human monoclonal Ab and against the virus antigen directly. Displacement reactions on the idiotypic bindingsite as well as comparative ELISA gave proof of the special RF activity. 24,2% of the patients suffering from RA, with IgM RF, showed selective binding to antigen structures of CMV and anti IgG activity.

The evidence of the specific binding capacity of RF to the virus antigen in chronic CMV infection as well as their defined binding capacity to the Fc Fragment of IgG suggest CMV specific RF as the pathogenetic factor of malignant forms of inflammatory rheumatism.

Sperm antibodies induced by anti-idiotype antibodies: a strategy in development of immunocontraceptive vaccines

The potential of using anti-idiotype antibodies as immunocontraceptive vaccines is evaluated in this study. Two sperm monoclonal antibodies, HS 63 and MS 204, which have significant inhibitory effect on the in vitro and in vivo fertilization of mouse were selected to elicit heterologous anti-idiotype antibodies. Rabbit antisera against HS 63 or MS 204 were collected after the third immunization. After the removal of anti-Fc fragments with an irrelevant mouse IgG immunoadsorbent column, anti-idiotype antibodies (anti-Id HS 63 or anti-Id MS 204) were purified from the antisera with affinity chromatography. HS 63 or MS 204 was used as respective ligand. The purified anti-idiotype antibodies conjugated with hemocyanin were used to immunize female CD-1 mice as the experimental group. Another group of female CD-1 mice were immunized with adjuvant only as the control group. Each group had three mice. The immune responses varied significantly among individual mice. The antisera could stain the acrosomal region of sperm in the indirect immunofluorescent assay in a way which is similar to the original monoclonal antibodies (HS 63 and MS 204). The inhibitory effect of antisera on the sperm fertilization of mouse oocytes in vitro was significant in both cases. In the case of antisera against anti-Id HS 63, the control group showed 81.8% and 49.3% of fertilization rates, whereas the corresponding rates of the experimental group were only 35.7% and 20.5%, respectively. Similarly, for antisera against anti-Id MS 204, the experimental group also revealed lower fertilization rates as compared with those of the controls (50.0% vs. 95.8% and 36.8% and 81.3%). The results of this study suggest that anti-idiotype antibodies against HS 63 and MS 204 contain the internal image of the sperm antigen and they could elicit an immune response with a significant antifertility effect. Therefore, they might not only be contributory to further study and understanding of the original antigens in structure and function but also be used as an alternative in the development of immunocontraceptive vaccines.

Molecular mechanisms of autoimmunity

Autoimmune diseases result from a combination of genetic susceptibility factors and exogenous influences such as infection or chemical (including drug) exposure. Germline DNA variations in genetic type as well as defects in antigen recognition acquired during thymic education of developing T-lymphocytes both contribute to impaired self: nonself discrimination and set the stage for later development of such diseases as myasthenia gravis, polymyositis, or systemic lupus erythematosus. In addition, drugs such as D-penicillamine, hydralazine, procainamide, or quinidine induce T-cell or B-cell changes which precipitate auto-reactivity and cause drug-induced disease. Intervention in autoimmune diseases with prednisone, alkylating agents or the future use of more selective monoclonal antibody reagents may be life-saving in some of these disorders.