Ab2 Alpha Research Articles

933 POSTER Immunotherapy in patients with recurrent epithelial ovarian cancer with the anti-idiotypic monoclonal antibody ACA125 (AGO-OVAR, phase I/II trial)

Idiotypes (Ab1) are the antigenic determinants of immunoglobulin molecules that are located in the variable region of the antibodies. Anti-idiotypic antibodies (Ab2) are directed against the idiotypic determinants. They are classified into (a) Ab2 alpha, which recognize Ab1 framework region antigen, (b) Ab2 beta, which bind the antigen-binding site of the antibody molecule, (c) Ab2 gamma, which refer to antibodies directed against idiotypes close to, rather than within, the antigen-binding site, and (d) Ab3, which are anti-anti-idiotypic antibodies.Under physiological conditions, each antigenic stimulation leads to the production of idiotypes Ab1 and anti-idiotypes (Ab2 and Ab3) as a network of interacting antibodies; this idiotypic network has a crucial role in the regulation of immune response to external and self-antigens.Manipulation of idiotypic network can also be implicated in the production of pathogenic autoantibodies and induction of autoimmune diseases. Experimental autoimmune diseases, including systemic lupus erythematosus, anti-phospholipid syndrome, and others, have been induced by immunization of mice with polyclonal human anti-DNA and anti-cardiolipin antibodies. In subjects susceptible to autoimmune diseases, the immune response to particular antigens extends over weeks to months and ends with production of idiotypic antibodies that recognize pathogenic epitopes and eventually with the development of an overt autoimmune disease.

Induction, via immunization with a monoclonal antiidiotypic antibody, of viral envelope specific Ab3 antisera that neutralize retrovirus infectivity.

We have developed five mouse monoclonal antiidiotypic antibodies to the 35/56 (Ab1) rat monoclonal that neutralizes retroviral infectivity by binding to the gp70f epitope of murine leukemia retrovirus. The anti-Id nature of these five Ab2s was evidenced by their inability to react with a panel of six other rat IgG2a kappa monoclonals isotype-matched to the 35/56 anti-gp70f mAb1, including two to the distinct epitopes "g" and "h" of gp70, or to normal rat IgG2a. On the basis of several competition assays four mAb2 were clearly either directed to the paratope of anti-gp70f mAb1 (.1C7, .1B, and .E) or not (.A, representing a noninternal image Ab2 alpha anti-Id). The P3E8 mAb2 was difficult to classify. Based on relative efficiency in these assays, .1C7 was chosen for further study, and upon injection was able to induce Ab3 responses in C57BL/6, BALB/c, and CBA mice. The fact that the Ab3 activity was detected in a competitive ELISA in which the hyperimmune antisera blocked the binding of Ab1 to Ab2, plus the ability to raise Ab3 neutralizing antibodies in three different mouse strains were consistent with .1C7 as an internal image Ab2 beta anti-Id. These results thus indicate the potential for internal-image monoclonal antiidiotypic antibody-based vaccines for retroviral diseases.

Autoantibody to the alternative pathway C3/C5 convertase and its anti-idiotypic response. A study in affinity.

In an effort to understand the development and control of autoantibody production, we studied the affinity of autoantibody to the alternative pathway C3/C5 convertase (C3 nephritic factor (C3NeF)) and its autoanti-idiotypic antibodies, Ab2 alpha and Ab2 beta. These were isolated and purified from newborns, normal adults, and patients with membranoproliferative glomerulonephritis. In all cases, both IgG and IgM C3NeF were available for study. The affinity of IgG and IgM C3NeF for their natural Ag (10(8) liters/mol) as well as for the internal image of that Ag displayed on Ab2 beta was high (10(10) liters/mol). Furthermore, the affinity of IgG C3NeF was nearly 100-fold higher in patients than in newborns, whereas there were no significant changes with IgM C3NeF. By contrast, there were not differences in the affinity of IgG Ab2 alpha (which does not display any likeness to the native Ag) from normal adults and patients to any C3NeF isolate. There was, however, a progressive increase in affinity between both Ab2 alpha preparations and IgG C3NeF from newborns, adult normal subjects, and patients, implying an alteration in C3NeF to account for the changes in affinity. These data suggest that Ag-driven affinity maturation occurs with autoantibody but may not occur within the idiotypic network. These data also indicate that as autoantibody affinity matures, it appears to modify its idiotype, perhaps in an effort towards autoregulation.

Binding specificity of antiidiotypic autoantibodies to anti-DNA antibodies in humans.

Human antiidiotypic antibodies to anti-DNA antibodies can be separated into at least two categories based on their binding to anti-DNA, antiidiotypic antibodies, and antigens. One type was found mainly in inactive stage of SLE. The antiidiotypic antibodies appear to be directed towards idiotype (Id) determinants in the antigen-binding sites of anti-DNA antibodies. Antibody from patient T.K. acted like a mirror image of anti-single-stranded DNA antibodies, O-81, as determined by a competitive inhibition RIA. Antibodies from patient S.U. also seemed to be Ab 2 beta and Ab 2 gamma to anti-double-stranded(ds) DNA antibodies, NE-1. Most of normal subjects, on the other hand, had antibodies that bound to the human monoclonal anti-ds DNA antibodies, NE-1, NE-13, 7F4, and O-81. The Id-anti-Id interaction was not inhibited by the addition of DNA. Thus, normal subjects had Ab2 alpha activity that recognizes Id determinants in the framework region common among anti-DNA antibodies, whereas antiidiotypic antibodies in most SLE sera appear to show Ab 2 beta and Ab 2 gamma activity. The results provide evidence that the Id network system regulates immunological tolerance to DNA in humans.

Induction of an anti-hepatitis B surface antigen response in mice by noninternal image (Ab2 alpha) anti-idiotypic antibodies.

Abstract Anti-idiotype antibodies to a mouse monoclonal antibody A-12 directed against HBsAg were produced in rabbits. The anti-Id consisted of an Ab-2 alpha preparation that did not display any detectable internal image activity. Immunization of BALB/c mice with the anti-Id (Ab-2 alpha) coupled to KLH induced an anti-HBs response without subsequent HBsAg exposure. No anti-HBs was detected in control groups of mice immunized with other rabbit anti-Id-KLH preparations. The anti-HBs containing sera from mice immunized with the Ab-2 alpha were able to inhibit the Id-anti-Id reaction, indicating that an Id-positive, anti-HBs response was induced. This idiotype is not normally expressed during the murine immune response to HBsAg and suggests that noninternal image anti-Id activates silent clones. This study, along with our previous results obtained with the use of internal image anti-Id, suggests that there is more than one Id network operational during the BALB/c murine immune response to HBsAg.

Addendum: J. Autoimmune Diseases

Idiotypes (Ab1) are the antigenic determinants of immunoglobulin molecules that are located in the variable region of the antibodies. Anti-idiotypic antibodies (Ab2) are directed against the idiotypic determinants. They are classified into (a) Ab2 alpha, which recognize Ab1 framework region antigen, (b) Ab2 beta, which bind the antigen-binding site of the antibody molecule, (c) Ab2 gamma, which refer to antibodies directed against idiotypes close to, rather than within, the antigen-binding site, and (d) Ab3, which are anti-anti-idiotypic antibodies.Under physiological conditions, each antigenic stimulation leads to the production of idiotypes Ab1 and anti-idiotypes (Ab2 and Ab3) as a network of interacting antibodies; this idiotypic network has a crucial role in the regulation of immune response to external and self-antigens.Manipulation of idiotypic network can also be implicated in the production of pathogenic autoantibodies and induction of autoimmune diseases. Experimental autoimmune diseases, including systemic lupus erythematosus, anti-phospholipid syndrome, and others, have been induced by immunization of mice with polyclonal human anti-DNA and anti-cardiolipin antibodies. In subjects susceptible to autoimmune diseases, the immune response to particular antigens extends over weeks to months and ends with production of idiotypic antibodies that recognize pathogenic epitopes and eventually with the development of an overt autoimmune disease.

Idiotope antigens (Ab2 alpha and Ab2 beta) can induce in vitro B cell proliferation and antibody production.

We previously showed that immunization of various strains of mice with three types of antigen--PC-Hy (nominal antigen), F6-Hy (Ab2 alpha-Hy, and 4C11-Hy (Ab2 beta-Hy)--induces a differential PC-specific, T15-Id+ antibody response. In this report, the in vitro phosphorylcholine (PC)-specific B cell responses induced by these three antigens were studied. A hemocyanin-specific long-term T helper cell line was used to provide help for primary and secondary in vitro T cell-dependent B cell responses. At low doses (0.005 to 0.5 micrograms/ml) of antigen, a significant increase in the proliferation of PC-OVA-primed BALB/c B cells was observed with Ab2-Hy or PC-Hy conjugate, but not unconjugate, antigens. Similar low doses of antigen could stimulate naive B cells to secrete IgM and stimulate PC-OVA- or 4C11-Hy-primed B cells to secret IgM and IgG1 anti-PC antibodies. The percentage of T15-Id of the PC-specific antibodies produced in the in vitro T-B culture was found to be less dominant than that produced by in vivo immunization, suggesting that certain regulatory mechanisms occur in the in vivo environment that may help to maintain the T15-Id dominance. Taken together, our in vivo and in vitro results indicate that idiotope antigens can function like nominal antigens to induce antigen-specific B cell responses. The mechanisms of thymic-dependent B cell activation induced by idiotope and nominal antigen are similar in that the T-B interaction is MHC-restricted and requires cognate recognition.