Idiotypic interactions in the treatment of human diseases

Recognition of the Self Idiotype by T Cells: Induction of a Rapid Increase in Cytoplasmic Free Calcium in T Cells Recognizing a Variable L Chain Determinant

To investigate the initial stages of recognition of the self idiotype (Id) by T cells, we examined the early increase in cytoplasmic free calcium ([Ca2+]i) occurring in murine CD4+ T cells specific for a model Id, Id315, following their interaction with the Id. The changes in [Ca2+]i were monitored with stopped-flow fluorometry by loading T cells with fura 2, a Ca(2+)-binding fluorescent dye. An increase of [Ca2+]i in the Id-specific T cell line was dependent on the presence of both antigen-presenting cells (APC) and Id315. When T cells were mixed with APC pulsed with M315 for 90 min at 37 C, a significant increase in T cell [Ca2+]i was observed within one second. A pronounced elevation in [Ca2+]i was also observed in T cells after their interaction with APC which had been pulsed for 90 min with VL-315 Id-containing proteins (such as VL-315, L315, Fv-315 or Fab'-315 fragments). In contrast, pulsing APC for 5 min with the VL fragment produced little or no change in the [Ca2+]i. These results suggest that VL must be further processed by APC before it can be recognized by T cells. Indeed, a synthetic VL region peptide (positions 91-108, designated as P18) produced an elevation in T cell [Ca2+]i when mixed with APC without pulsing.

New approaches for the development and application of monoclonal antibodies for the diagnosis and therapy of human cancer

Monoclonal antibodies (MAbs) represent potentially important reagents for both the diagnosis and therapy of human cancer. Innovative approaches are resulting in the improved production of MAbs and an enhanced ability to use these molecules therapeutically. Application of genetic engineering to MAb development is also resulting in the production of MAbs displaying enhanced target specificity. Of particular value for cancer therapy will be catalytic, bispecific, anti-idiotypic and human MAbs. By using agents that can augment the expression of tumor-associated antigens on cancer cells, a further increase in the utility of MAbs in cancer therapy will be forthcoming.

Differences in anti-Fab antibodies in adult and late onset rheumatoid arthritis

In the present study the ratio of antigen-bound anti-IgG-Fab antibodies (hidden aFab) to free aFab was found to be significantly increased in patients with adult onset rheumatoid arthritis (AORA) as compared to late onset rheumatoid arthritis (LORA). The overall amount of aFab was similar in both groups. The difference was only seen in seropositive patients. Within the seropositive AORA group, the aFab ratio was correlated with the duration and the stage of disease but not with the patients' age at investigation. This might reflect a higher affinity of anti-Fab antibodies and/or a greater diversity of the idiotypic repertoire in adult onset disease resulting in the formation of immune complexes, the stability of which might be enhanced further by the presence of rheumatoid factors. Although a pathophysiological involvement of aFab cannot be concluded from our observations, it is conceivable that different immunoregulatory mechanisms could be operative in RA with onset at different ages.

A study of autologous anti-idiotypic antibody-forming cells in mice of different ages and genetic backgrounds

Antibody response to phosphorylcholine, an immunodominant epitope of Streptococcus pneumoniae R36a (Pn), is characterized by a public idiotype, T15, that is expressed on a large proportion of antibody molecules produced by all mouse inbred strains. The ability of the immune system to produce an autologous antibody to T15 upon immunization with Pn vaccine was investigated using a modified ELISA plaque assay for detection of single antibody-forming cells (AFC). The limit of ELISA assay for detection of specific anti-T15 AFC is approximately 300 cells/spleen. However, our studies failed to detect any autologous anti-T15 AFC in the course of the primary antibody response to Pn vaccine in young/adult (2-4 months) BALB/c and C57BL/6 mice. Aged mice (20-22 months) also failed to develop any specific auto-anti-T15 AFC upon the primary Pn immunization, despite the fact that the anti-Pn response in these animals changes both quantitatively and qualitatively. In order to generate specific anti-T15 AFC, BALB/c mice had to be immunized repeatedly with Pn vaccine (four weekly injections) or immunized directly with T15 protein in CFA. Different results were obtained with D1.LP mice that are low responders to Pn and express lower levels of T15 Id as compared to BALB/c. Young D1.LP mice produced high numbers of auto-anti-T15 AFC of both IgM and IgG isotypes following a single immunization with Pn vaccine. The kinetics of auto-anti-T15 response in D1.LP mice was similar to that of the antigen-specific response. These results demonstrate that the ability of the immune network to produce autologous antibody to a shared Id depends on the genetic makeup of the host, and that this response may be regulated by the level of Id expression.

Intravenous immunoglobulin treatment for recurrent abortions caused by antiphospholipid antibodies

There is an association between the presence of antibodies that bind to anionic phospholipids and the occurrence of repeated spontaneous abortion. Many uncontrolled studies have reported favorable pregnancy outcome in women treated with steroids, low-dose aspirin, heparin, or their combination. Similarly, treatment failures have been reported with most of these therapeutic regimens. Immunoglobulins play a central role in immune regulation. A wide spectrum of human diseases are associated with decreased or abnormal regulation of Ig levels. Recently, IV preparations of Ig have become available for clinical use, including treatment of patients with recurrent abortions and high levels of antiphospholipid antibodies. The effectiveness of this new mode of therapy can be related to several immunological mechanisms such as blockade of antibody binding to receptors on macrophages, increase in T suppressor cells, or decrease in antibody synthesis. The latter effect may be mediated by anti-idiotypic antibodies in the Ig preparation. Determination of dosage of IV Ig, duration of treatment, and treatment intervals are all empirical in patients with recurrent abortions and high levels of antiphospholipid antibodies because antiphospholipid antibody levels are not useful for monitoring therapy. Although the data available at present are promising, additional randomized trials are needed to determine the efficacy of IV Ig in patients with immunological recurrent abortions.

Identification of anti-idiotypic antibodies in the sera of ryegrass-allergic and nonallergic individuals

Anti-idiotypic (Id) antibodies (Abs) are generated in the humoral response to antigen (Ag). Some of these anti-Id Abs are capable of binding to the combining site or paratope of Abs that bind Ag. These Ab2 can competitively inhibit the binding of Ab1 to Ag may trigger an Ab1 response similar to the response induced by Ag. To determine if specific Ab2 that inhibit the binding of IgE Abs to ryegrass (RG)-pollen allergens are present in the sera of RG-allergic (RGA) individuals before the initiation of allergen-specific hyposensitization with RG-pollen extract, we studied sera from five RGA and four nonallergic (NA) subjects in an IgE anti-RG RAST-inhibition assay. Ab2-enriched serum fractions were prepared from these study subjects by exhaustive mixed grass-pollen affinity chromatography to remove IgE and IgG anti-RG Ab1 from whole serum aliquots containing Ab1. Unabsorbed, twice-concentrated sera were diluted to one-time concentrated sera with equal volumes of either Ab2-enriched sera without Ab1 or borate-buffered saline absorbed by mixed grass-pollen affinity chromatography. IgE anti-RG Ab1 was determined by a standard RG RAST assay. We have detected Ab2 in the sera of the RGA patients, which inhibit the binding of autologous and allogeneic IgE anti-RG to RG Ags in solid phase. Parallel RG RAST assays with sera from NA subjects demonstrated no significant inhibition. Ab2-enriched sera from some grass-allergic and some NA subjects inhibited IgE anti-RG binding found in some RGA patients' sera. We conclude that anti-Id Abs, Ab2, specific for IgE anti-RG, Ab1, are present in some RGA patients and NA individuals.

Maternal caries incidence and salivary close-contacts with children affect antibody levels to Streptococcus mutans in children

Serum and salivary immunoglobulins and antibodies reactive with Streptococcus mutans were determined in 67 5-8-year-old children. The children of mothers whose caries incidence rates exceeded the median value had significantly more serum IgG antibodies to S. mutans than those with a lower maternal caries activity (p less than 0.05). The children (n = 14) who had been exposed to frequent maternal salivary close-contacts in their first year had significantly higher (p less than 0.05) serum total specific IgG antibodies but significantly lower (p less than 0.01) high-avidity IgG antibodies to S. mutans than the other children (n = 53) with less frequent close-contacts. The maternal caries incidence rates were significantly positively associated with children's dfs/DFS-indices (r = 0.41; p less than 0.001). However, the high maternal caries incidence did not increase the risk of caries in those children whose mothers' saliva contained high amounts of lactobacilli during the first nursing year, when compared with matched children with a low maternal level of lactobacilli. This was possibly due to the fact that the former children had significantly (p less than 0.05) more anti-S. mutans IgG antibodies in their sera than the latter.

Immunoregulation of anti-islet cell antibody in insulin-dependent diabetes: failure to detect anti-idiotypic antibody following seroconversion

A search was made for the presence of spontaneous auto-anti-idiotype in sera of three insulin-dependent diabetics when they converted from islet cell antibody positive to islet cell antibody negative states. Rabbit anti-idiotype specific for islet cell antibody was used as the positive control. Using an enzyme-linked immunoabsorbent assay, binding of the rabbit anti-idiotype to idiotype-coated plates could not be inhibited by islet cell antibody negative sera. Using this same assay, there was no significant difference in the binding of islet cell antibody positive or negative sera to either idiotype-coated or normal IgG-coated plates. Binding of islet cell antibody to pancreatic sections could not be inhibited by islet cell antibody negative sera in an immunofluorescent assay. Network regulation by auto-anti-idiotype does not seem to play a role in the decline or absence of islet cell antibody in the early phases of insulin-dependent diabetes mellitus.

The concept of anti-idiotypic regulation of selected autoimmune diseases by intravenous immunoglobulin

Evidence that physiological control of human humoral autoimmune reactions depends, at least in part, on the formation of anti-idiotypic antibodies is accumulating. Upon binding to the corresponding idiotypes, anti-idiotypes will prevent autoantibodies from reacting with the primary antigen and/or eventually expedite removal of autoantibodies from the circulation and down-regulate their formation. In patients with autoantibodies against clotting factor VIII:C or fibrinogen, clinical improvement was associated with formation of anti-idiotypes against the autoantibodies. In addition, iv immunoglobulin (IVIg) preparations derived from plasma pools of thousands of healthy donors expressed anti-idiotypes against such autoantibodies as anti-clotting factor VIII:C, antithyroglobulin, and anti-intrinsic factor, but the specificity of the anti-idiotypes appears to be restricted for particular idiotypes. This explains why not all patients are responders to therapeutic intervention with IVIg. On one hand, definite in vitro neutralization of autoantibody activity by IVIg added in multiple proportions is not followed infallibly by in vivo response, and on the other hand, a good therapeutic effect often lasts long beyond normal half-lives of infused IVIg. The present overview compares the authors' own work with that described in recently published literature on exploring anti-idiotypy in therapy.

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.

Identification of a common idiotype on myelin oligodendrocyte glycoprotein-specific autoantibodies in chronic relapsing experimental allergic encephalomyelitis

The myelin/oligodendrocyte glycoprotein (MOG) is a target antigen for autoantibody-mediated demyelination in chronic relapsing experimental allergic encephalomyelitis (CREAE) in the Strain 13 guinea pig. Anti-idiotypic antibodies directed against a demyelinating MOG-specific monoclonal antibody (8-18C5) have identified a cross-reactive idiotype in 10/10 CREAE sera. In nine of these sera inhibition studies demonstrated that this idiotype was at or in close proximity to the combination site of guinea pig anti-MOG autoantibodies. This cross-reactive anti-MOG idiotype may represent an important target for the anti-idiotypic regulation of demyelinating antibody responses in CREAE.

Immune responses to an adjuvant-free native syngeneic myeloma protein (M315)

Myeloma protein 315 (M315; isotype IgA, lambda 2) is used in this report as a model to explore the immunogenicity of a syngeneic Ig under nearly physiological conditions. We have previously shown that a synthetic peptide spanning the mutated HV3 loop of the L-315 chain, when emulsified in complete Freund's adjuvant, elicits T helper cells (Th) that respond to a boost with L-315 or M315, indicating that M315 is recognized as a processed protein antigen. We now show that the adjuvant-free 7S monomer of native or of mildly reduced and alkylated M315, given in divided doses totalling 300 or 800 micrograms to BALB/c mice, induced persistent anti-M315 antibodies (Ab), a large part of which was IgG1 directed mainly to idiotypes (Id) associated with M315's hapten-binding site. Polymers of M315 IgA (800 micrograms) failed to induce Ab, due probably to their rapid clearance into bile. Short-term treatment with anti-CD4 monoclonal Ab GK1.5 at the time of priming with 7S M315 inhibited the responses almost completely. The spleens of M315-immune mice contained Th that recognized the L-chain subunit of M315 as a carrier indicating that these Th did not require an assembled (VH-VL) pair of 315 V regions to be activated. We also observed low amounts of Ab specific for epitopes of the C alpha region. This evidence opens the possibility that a distinct autoimmune pathway exists for elicitation of rheumatoid factor (RF; autoAb to Fc gamma) that involves help to RF-producing B cells by Id-specific Th. We suggest that these Th recognize V-region peptides from IgG that have been captured, processed and presented by these B cells.

IgE response and its regulation in allergic diseases

The distinguishing feature of the allergic person is his or her elevation of serum IgE. This propensity to develop a sustained IgE response is determined genetically. The biologic effects of IgE are mediated via Fc receptors (Fc epsilon R) present on mast cells and basophils (Fc epsilon R type 1) and subpopulations of monocytes, macrophages, eosinophils, and platelets (Fc epsilon R type 2). Interaction of allergen with IgE on these cells results in receptor "bridging" and the release of histamine and other inflammatory mediators. Fc epsilon R type 2 on lymphocytes and monocytes are upregulated in atopic disease and may play a role in the allergic inflammatory reaction. The activation of B cells to synthesize IgE requires several stages (see Fig. 2). T cells play an important role in the regulation of IgE synthesis. In vitro activation of resting B cells to synthesize IgE requires direct cellular interaction with T cells or the presence of IL4 for activation. The latter effect is inhibited by alpha-interferon. Preactivated B cells are influenced in an isotype-specific manner by T-cell-derived IgE binding factors (IgE-BF), which may act as IgE-potentiating or IgE-suppressive factors, depending on their degree of glycosylation. The regulation of IgE synthesis is an important area of investigation. It provides us with an understanding of the basis of the human allergic response and ultimately may provide the basis for novel strategies in the treatment of allergic diseases.