The role of the human anti-DNA idiotype 16/6 in autoimmunity

The Significance of a Common Idiotype (1F7) on Antibodies against Human Immune Deficiency Virus Type 1 and Hepatitis C Virus

In this review, we trace the concept and potential functional role of regulatory idiotypes in the immune response to human immunodeficiency virus type 1 (HIV-1), simian immunodeficiency virus, and hepatitis C virus (HCV). A major idiotype involved in these viral infections is recognized and defined by a murine monoclonal antibody (1F7). Antibodies expressing the idiotype defined by 1F7 are dominant in HIV-1 infection and are also found on many broadly neutralizing antibodies against HIV-1. This regulatory idiotypic axis offers opportunities for exploitation in vaccine development for HIV-1, HCV, and other chronic viral infections.

Systemic lupus erythematosus: molecular cloning and analysis of recombinant DNase monoclonal κ light chain NGK-1

Because DNase antibodies are cytotoxic, enter the nucleus and cause DNA fragmentation inducing cell death by apoptosis, they can play an important role in the pathogenesis of different autoimmune pathologies and especially systemic lupus erythematosus (SLE). The interesting goal of catalytic antibodies research is not only to study a possible biological role of such antibodies, but also to develop in future new human and animal therapies that use the advantages offered by abzymes. An immunoglobulin κ light chain library from SLE patients was cloned into a phagemid vector. Phage particles displaying recombinant monoclonal antibody light chains (MLChs) capable of binding DNA were isolated by affinity chromatography on DNA-cellulose. Sixteen of the 46 MLChs efficiently hydrolyzed DNA; one MLCh (approximately 27-28kDa) was expressed in Escherichia coli and purified by metal chelating and gel filtration. MLCh NGK-1 was electrophoretically homogeneous and demonstrated a positive answer with mouse IgGs against light chains of human antibodies after western blotting. SDS-PAGE in a gel containing DNA demonstrated that the MLCh hydrolyzes DNA and is not contaminated by canonical DNases. The DNase MLCh was activated by several metal ions. The protein sequence of the DNase MLCh has homology with mammalian DNases I and shares with them several identical or similar (with the same side chain functionality) important amino acid residues, which are necessary for DNA hydrolysis and binding of Mg(2+) and Ca(2+) ions. The affinity of DNA for this first example of a MLCh (K(M) = 0.3 microM) was 150- to 200-fold higher than for human DNase I.

IgGs containing λ- and κ-type light chains and of all subclasses (IgG1-IgG4) from the sera of patients with autoimmune diseases and viral and bacterial infections hydrolyze DNA

We present the first evidence demonstrating that small fractions of IgGs of all four subclasses (IgG1-IgG4) from patients with viral (tick-borne encephalitis), bacterial infections (streptococcal infection or erysipelas), and suppurative surgical infections caused by epidermal staphylococci as well as from patients with autoimmune diseases (systemic lupus erythematosus and multiple sclerosis) are catalytically active in the hydrolysis of supercoiled DNA. The hydrolysis of DNA was analyzed by agarose gel electrophoresis. The catalytic activities of nonfractionated IgGs increased in the following order: tick-borne encephalitis < suppurative surgical infection < streptococcal infection < multiple sclerosis < systemic lupus erythematosus, whereas IgGs of healthy donors were inactive. However, the pools of antibodies corresponding to any particular disease were characterized by a specific ratio of IgGs of all four subclasses (IgG1-IgG4) and IgGs containing λ- and κ-type light chains, and each of these subfractions of immunoglobulins demonstrated characteristic relative DNase activity. The relative activities of IgGs containing λ-type light chains may on average be higher, lower, or comparable with those for IgGs with κ-type light chains. The relative contributions of IgGs of different subclasses to the total activity of IgGs also varied widely in the case of various diseases: IgG1 (7%-45%), IgG2 (0.4%-73%), IgG3 (0%-12%), and IgG4 (9%-66%). Thus, immune systems of patients with different diseases can generate a variety of anti-DNA abzymes of different types and with different catalytic properties, which can play an important role in the pathogenesis or protection from the development of these diseases.

IgGs containing light chains of the lambda and kappa type and of all subclasses (IgG1-IgG4) from sera of patients with multiple sclerosis hydrolyze DNA

We present the first evidence demonstrating that small fractions of IgGs of all four subclasses (IgG1-IgG4) are catalytically active in the hydrolysis of DNA and on average their relative activity (nM supercoiled DNA/1mg IgG/1 h) increases in the order: IgG1 (0.58) < IgG2 (0.94) < IgG3 (1.4) < IgG4 (4.1), while their approximate relative contribution to the total activity of abzymes increases in the order: IgG1 (6.9%) < IgG3 (9.3%) < IgG2 (18.2%) < IgG4 (65.6%). On average IgGs containing light chains of the lambda-type are severalfold more active in the hydrolysis of DNA than IgGs with light chains of the kappa-type. Using different physicochemical methods of antibody analysis we have shown that the immune system of multiple sclerosis patients generates a variety of anti-DNA abzymes of different type and with different catalytic properties, which can play an important role in multiple sclerosis pathogenesis.

Novel functional activities of anti-DNA autoantibodies from sera of patients with lymphoproliferative and autoimmune diseases

DNA-hydrolyzing activity of IgG autoantibodies from sera of patients with various types of lymphoproliferative diseases was investigated. The association of DNA-hydrolyzing activity with the antibody (Ab) fraction has been proved by newly developed affinity-capture assay. Study of abzyme incidence in blood tumors and systemic lupus erythematosis (SLE) revealed linkage of anti-DNA Ab catalysts to mature B-cell tumors, and increased probability of DNA-abzymes formation on the background of autoimmune manifestations. These data suggest possible similarity between mechanisms of abzyme formation in SLE and B-cell lymphomas. A new mechanism of formation of DNA-specific catalytic Abs has been proposed based on the increased crossreactivity of polyclonal DNA-abzymes to DNA-depleted nuclear matrix proteins. The possibility of the abzyme production as Ab to the energetically destabilized ground state of the antigen has been discussed. Preliminary results were obtained that indicate the complement-independent cytotoxicity of anti-DNA autoantibodies isolated from blood of patients with SLE and chronic lymphocytic leukemia.

Affinity columns containing anti-DNA Id+ human myeloma proteins adsorb human epibodies from intravenous gamma globulin

OBJECTIVE

To study eluates of intravenous gamma globulin (IVGG) prepared from affinity columns of human cationic IgG myeloma proteins bearing anti-DNA idiotype (Id) markers 16/6, F4, 3I, and 8.12 for possible anti-Id (combining site) blocking activity.

METHODS

Anti-DNA idiotypic antibody activity was studied in 3 preparations of IVGG containing high, medium, and low levels of IgG anti-F(ab')2, and in 4 other commercial IVGG preparations. Affinity-purified IgG anti-DNA (APAD) from systemic lupus erythematosus (SLE) patients was biotinylated, and binding to DNA coated on enzyme-linked immunosorbent assay plates was used to measure anti-DNA antibody activity. IVGG was adsorbed to Sepharose 4B affinity columns linked to a panel of cationic human IgG myeloma proteins positive for anti-DNA Id markers 16/6, F4, 3I, and 8.12. Material adsorbing to such columns was eluted at low pH (2.5) and after neutralization, tested for its ability to inhibit biotinylated APAD reacting with DNA.

RESULTS

Only 0.05-0.9% of IVGGs bound firmly to Id affinity columns. These IVGGs were then eluted, using pH 2.5 glycine-saline and eluates neutralized to pH 7.4. Column flowthrough and eluate fractions were compared for their ability to block SLE APAD reacting with DNA. Significant inhibition of SLE APAD combining sites was observed with eluates from anti-DNA Id affinity columns; however, no correlation between IVGG anti-F(ab')2 activity and true anti-Id blocking of APAD was apparent. No residual anti-Id activity remained in column flowthrough fractions. No anti-Id blocking activity was recorded for IVGG eluates from human cationic myeloma columns devoid of the 4 anti-DNA Id markers. DNase treatment of IVGG or Id column eluates did not affect anti-Id blocking activity. Thus, all detectable anti-DNA idiotypic antibody capable of blocking SLE anti-DNA combining sites bound to Id+ affinity columns. Column eluates also showed some relative concentration of IgG anti-DNA activity, which was of lower affinity for DNA than antibodies also present in eluates which blocked anti-DNA combining sites.

CONCLUSION

The presence of both anti-DNA and antiidiotypic (anti-combining site) activity in human anti-DNA Id column eluates indicates that epibodies from IVGG are relatively concentrated when this strategy is used. This approach may lead to a new strategy for treatment of SLE nephritis.

Frequency of B cells in normal mice which recognize self proteins

The mechanism whereby the immune system avoids self-aggression is one of the central issues of Immunology. The discovery of natural autoantibodies, mainly of IgM isotype, and of idiotypic interactions between antibodies indicates that elements of the immune system interact with self constituents and with themselves. Results of studies with soluble antibodies have indicated that the pool of circulating IgM represents the end result of a highly selective process of B cell activation and differentiation by self proteins resulting in the formation of a network. The objective of the present work was to determine the frequency of self-reacting B cells in normal mice. We were able to detect B cells that recognize self proteins present in extracts of different organs in normal adult, 2-3-month old, BALB/c and C57BL/6 mice with an ELISA spot assay. About 1% of total IgM-secreting cells among small, LPS-stimulated spleen cells reacted with organ extracts, whereas among large spleen cells the frequency was 5- to 10-fold lower. Immunization induced an increase in the frequency of IgM-secreting cells. The present results provide cellular evidence for the results of studies done at the serological level. The physiological role of these self-recognizing cells, as well as their participation in autoimmune processes, remain to be established.

Prevalence of 13 autoantibodies and of the 16/6 and related pathogenic idiotypes in 465 patients with systemic lupus erythematosus and their relationship with disease activity

With a cross sectional study of 465 consecutive systemic lupus erythematosus (SLE) patients tested for 13 autoantibodies (Aab) and two idiotypes we determined the prevalence of Aab according to disease activity, both general and at particular organ systems. Seventy seven percent of SLE sera had at least one Aab and 56% had it at high titres. Pathogenic idiotypes had a prevalence of less than 10% and 166 sera had Aab to 5 or more antigens and 9 sera had Aab against all 13 antigens tested. Patients with active disease had increased prevalence of Aab to DNP, ssDNA, ENA, mitochondria and histones when considered at 5 s.d. above the mean of normal controls. The higher positivity of Aab in patients with active disease was confirmed in logistic regression analysis adjusted by age, disease duration, and intensity of treatment. A trend was observed of increased prevalence and titres of Aab from inactive disease without treatment, to inactive disease but still being treated, to active disease. Only 22% of patients with active disease had no Aab and the higher the number of Aab the higher the frequency of active disease. Patients with active arthritis, and to a lesser degree those with active mucocutaneous involvement, had higher prevalence and titres of most autoantibodies than patients with disease activity at other organ systems. Active renal disease associated only with anti-dsDNA, whereas active CNS disease associated with anti-mitochondrial Aab. Our findings support the vision of SLE as an immune dysregulation leading to polyclonal B cell activation with resulting production of multiple Aab. Their profiles seem influenced by genetical, hormonal and environmental factors and, in turn, they contribute to the clinical picture in each patient. Disease activity influences the presence of some, but not all, Aab and some of them may remain present in some patients, even in remission.

Incidence and disease associations of a proteinase 3-antineutrophil cytoplasmic antibody idiotype (5/7 Id) whose antiidiotype inhibits proteinase 3-antineutrophil cytoplasmic antibody antigen binding activity

OBJECTIVE

To evaluate the potential of a monoclonal proteinase 3-antineutrophil cytoplasmic antibody (PR3-ANCA) antiidiotype autoantibody (5/7 anti-Id) as a candidate for specific immunotherapy in Wegener's granulomatosis (WG), and to estimate the immunodiagnostic value of the corresponding idiotype (5/7 Id).

METHODS

We analyzed the incidence of 5/7 Id in patients with ANCA-associated vasculitides (WG, microscopic polyangiitis, Churg-Strauss syndrome), in disease controls (systemic lupus erythematosus patients), and in healthy donors. We then investigated the presence of 5/7 Id in relation to disease stage, clinical activity, and organ manifestations in 86 patients with WG. Finally, we investigated the ability of the 5/7 anti-Id reagent to inhibit the binding of PR3-ANCA to corresponding antigen in 19 WG patients.

RESULTS

The incidence of 5/7 Id was significantly more frequent in WG patients (43 of 86; 50%). We did not find a significant correlation between the prevalence of idiotype expression and disease activity or organ manifestations. Further, we demonstrated in vitro suppression of PR3-ANCA antigen binding activity by 5/7 anti-Id in 11 of 19 WG patients who were positive for 5/7 Id.

CONCLUSION

This study shows that 5/7 Id is a common idiotype with a significantly increased incidence in WG and that 5/7 anti-Id inhibits PR3-ANCA antigen binding activity. Based on these observations, we conclude that 5/7 anti-Id is a promising tool for the development of a specific immunotherapy for WG.

Pathogenic natural anti-cardiolipin antibodies: the experience from monoclonal gammopathy

Anti-cardiolipin antibodies (ACA) were detected in 19% of sera from patients with monoclonal gammopathies (MG). ACA were purified from the sera of patients with MG. One of the IgG-ACA was found to be monospecific with high affinity for cardiolipin, and to carry a pathogenic ACA Id (1.10). Active immunization of naive BALB/c mice with the purified IgG-ACA was followed by production in the mice of sustained high titres of ACA, associated with prolonged activated partial thromboplastin time (APTT) (61 +/- 14s versus 31 +/- 2s in control mice; P < 0.001) and thrombocytopenia (468,000 +/- 224,000/mm3 versus 994,000 +/- 92,000/mm3 in controls; P < 0.001). The titres of other autoantibodies (e.g. anti-DNA, anti-histones), although being high after immunization, decreased rapidly and were undetected after 1 month following the boost injection. The mice immunized with the IgG-ACA exhibited low fecundity (36% of mice became pregnant versus 62% observed in the group immunized with control IgG). The pregnant mice had increased resorption rate (the equivalent of fetal loss in the human) of 52 +/- 8% (versus 5 +/- 4% in the control group). The mean (+/- s.d.) embryo and placental weights in mice with anti-phospholipid syndrome (APLS) were significantly lower compared with the mice injected with control IgG (682 +/- 304 mg and 102 +/- 12 mg versus 1303 +/- 105 mg and 145 +/- 8 mg, respectively; P < 0.001). Serum monoclonal immunoglobulins having autoantibody activity may be regarded as an expansion of clones producing natural autoantibodies. Our results confirm the pathogenic role of natural ACA in the pathogenesis of the anti-phospholipid syndrome.

Host-microflora interaction in systemic lupus erythematosus (SLE): colonization resistance of the indigenous bacteria of the intestinal tract

Experimental data suggest a role for the microflora in Systemic Lupus Erythematosus (SLE). Anti-ds-DNA antibodies may be pathogenic in SLE by forming immune complexes with DNA. Foreign bacteria in the intestines could constitute the stimulus for anti-ds-DNA antibody production in SLE. Colonization Resistance (CR) is the defence capacity of the indigenous microflora against colonization of the intestines by foreign bacteria. A low CR implies increase of translocation of bacteria and a higher chance of subsequent, possibly DNA-cross-reacting antibacterial antibody production. We measured CR by a comprehensive biotyping technique in healthy individuals and patients with inactive and active SLE. CR tended to be lower in active SLE patients than in healthy individuals (P = 0.09, Wilcoxon one sided, with correction for ties). This could indicate that in SLE more and different bacteria translocate across the gut wall due to a lower CR. Some of these may serve as polyclonal B cell activators or as antigens cross-reacting with DNA.

Expression and relationships of seven public idiotypes of DNA-binding autoantibodies on monoclonal antibodies and serum immunoglobulins

Many studies have shown that DNA-reactive autoantibodies share cross-reactive public idiotypes that are defined, usually, by single anti-idiotype reagents. Because anti-idiotype antibodies or antisera will be limited in their ability to detect all the idiotopes of a particular antibody, their use will tend to underestimate the full extent of idiotype sharing between different antibodies. In order to define more comprehensively the extent of idiotype sharing in DNA autoantibodies, a panel of DNA-binding monoclonal autoantibodies from lupus mice was examined with a range of anti-idiotype antisera prepared in rabbits (five sera), guinea pigs (four sera) and a sheep. Each idiotype was detected on more antibodies than its original reference monoclonal antibody, and idiotopes of each were also present on serum immunoglobulins from lupus mice. Of 23 monoclonal antibodies 65% reacted with one or more of the anti-idiotype reagents. On these criteria, all the idiotypes were public; none was private in its expression. In about half the cases the idiotypes were located in or near the antigen-binding sites of the antibodies, but a direct relationship to specificity was not obvious except in the case of Id.228 present on antibodies with a relatively high affinity for single-stranded DNA. In other cases there was no obvious relationship between idiotype and specificity. Antibodies from the same mouse did not each express the same array of idiotopes.(ABSTRACT TRUNCATED AT 250 WORDS)

Familial patterns of learning disabilities

Extended families of 12 young adults (9 LD, 3 non-LD) were given a battery of tests and questionnaires, and 131 persons, ranging in age from 6 to 85, were classified as LD or non-LD on the basis of subtest scores 1 SD below the mean or less on subtests of the PIAT and WRAT achievement tests. Pedigree analysis indicated that LD was strongly familial, with the most probable mode involving a major gene effect, but the type of disability (reading/ math) was not directly inherited. Autoimmune disorders were significantly correlated (P<.005) with LD, especially in families in which LD remained a major handicap into adulthood, a trait that also varied between families. In two of the LD families, adults showed little evidence of the reading/spelling deficits they had shown when tested as children, while adults in other families failed to make gains in reading and spelling.

The putative role of cytokines in the induction of primary anti-phospholipid syndrome in mice

Antiphospholipid syndrome (APLS) is characterized by thrombocytopenia, thromboembolic phenomena and recurrent fetal loss, associated with anti-cardiolipin antibodies (ACA) and/or lupus anticoagulant. The syndrome may be primary or may be associated with other conditions such as systemic lupus erythematosus (SLE). In this study we induced primary APLS following immunization of BALB/c mice with a human monoclonal ACA (H-3). Analysis of the cytokine profile of the mice with experimental APLS indicated low production of IL-2, IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) by concanavalin A (Con A)-stimulated splenocytes of H-3 immunized mice. It seems that the low levels of IL-3 and GM-CSF have a potential role in the fetal loss of the APLS. Whatever the mechanism of IL-3 and GM-CSF in preventing fetal loss, these results may have therapeutic bearing on the reproductive outcome in women and other species with APLS.

Autoantibody activity and V gene usage by B-cell malignancies

Autoreactive B cells account for a substantial part of the B-cell repertoire. They frequently secrete polyspecific natural autoantibodies, which probably bind with low affinity to the different antigens they recognize and which express germinal genes. The role of this pre-immune repertoire still remains to be defined but it has been suggested that it participates in the elimination of cell breakdown products, serves as a first barrier of defense or acts as a template upon which antigen driven selection and somatic recombinations could induce the emergence of high affinity induced antibodies. The present study, reviews the evidence favouring the idea that this autoreactive B-cell repertoire, which expresses a restricted set of V genes, frequently undergoes malignant transformation. This evidence arises from the study of the autoantibody activity and V gene usage in three different models of B-cell malignancies namely monoclonal immunoglobulins; chronic lymphocytic leukemia; and follicular non-Hodgkin's lymphomas.

Diversity and pattern of inheritance of autoantibodies in families with multiple cases of systemic lupus erythematosus

The pattern of inheritance of autoantibodies in eight families chosen from a pool of 110 families of patients with systemic lupus erythematosus (SLE) is described. In all the eight families at least two members were already affected by SLE. In total, 19 patients and 43 first degree relatives were examined. The inheritance of a large set of antinuclear antibodies (for example, DNA, Sm, RNP, Ro, La, histones) and 16/6 idiotype seemed to be related to some unknown genetic factors but not related to HLA. The presence of numerous antinuclear autoantibodies in the serum of a subject was not necessarily associated with overt disease. The incidence of the 16/6 idiotype among patients and their relatives was low. It is not yet clear whether the 'autoantibody burden' is greater in families with multiple cases of SLE than in families with single cases.

Induction of primary antiphospholipid syndrome in mice by immunization with a human monoclonal anticardiolipin antibody (H-3)

Antiphospholipid syndrome (APLS) is characterized by thrombocytopenia, thromboembolic phenomena, and recurrent fetal loss, associated with anticardiolipin antibodies (ACA) and/or lupus anticoagulant. The syndrome may be primary or may be associated with other conditions such as systemic lupus erythematosus. We have previously shown the ability to induce APLS in naive mice following passive transfer of serum and monoclonal ACAs. Similarly we generated the secondary APLS in BALB/c mice following immunization with a pathogenic anti-DNA antibody. In the current study we report on the induction of primary APLS following immunization of BALB/c mice with a human monoclonal ACA (H-3). The mice developed high persistent titers of ACA. The APLS was characterized by prolonged activated partial thromboplastin time, low fecundity rate (21% vs. 48% of control immunized mice), high resorption index of fetuses (25% vs. 3%), and low weights of embryos and placentae. Our study points to the ability of inducing primary APLS in naive mice. The induction of various presentations of APLS by different ACA may explain the diversity of clinical manifestations seen in patients with APLS.

Modulation of SLE induction in naive mice by specific T cells with suppressor activity to pathogenic anti-DNA idiotype

T cells (CD8+) with specific suppressor activity against anti-dsDNA antibody (16/6 Id+) were generated in vitro. The cells were established from BALB/c-enriched T cells exposed in vitro to silica beads coated with the pathogenic anti-DNA idiotype, 16/6. The idiotype specificity of the suppressor cells was demonstrated by (a) specific induction of a decrease in proliferative response of T helper cell lines specific for the pathogenic idiotype (16/6 Id), when exposed to the idiotype, with no effect on T cell lines with other specificities, e.g., against human IgM or synthetic polypeptide. (b) Effectively suppressing in vitro antibody production of anti-16/6 antibody, employing 16/6-primed B cells and specific helper T cell line. The 16/6 Id-specific Ts cells were found to be MHC restricted. Weekly intravenous injections of 10(7) 16/6 Id-specific Ts cells given to BALB/c mice at different stages of experimental SLE disease prevented the clinical, serological, and pathological manifestations. This effect was characterized by decreased titers of autoantibodies (e.g., anti-DNA, anti-Sm antibodies) in the sera, by abolishment of the proteinuria, leukopenia, and the increased ESR, followed by decreased immunoglobulin deposition in the kidneys. Treating the mice with control IgM-specific T cells did not affect the above parameters. These studies demonstrate the ability to generate Ts cells specific for pathogenic idiotypes. The method might be employed therapeutically to modulate the course of autoimmune conditions.

Pathogenesis of SLE: immunopathology in man

Antibodies against native DNA are not only a disease-specific marker for systemic lupus erythematosus (SLE); in addition, there is good direct evidence that these antibodies also play a major part in pathogenic mechanisms leading to systemic and organ-specific disease manifestations. The origin of anti-dsDNA antibodies is still poorly understood, especially as dsDNA per se is not immunogenic. As recently shown, evidence is now accumulating that anti-dsDNA antibodies are not germline-encoded but antigen-driven, as demonstrated by the establishment of human anti-dsDNA antibody clones from SLE patients and sequence analysis. In sera of SLE patients there is an elevated level of nucleic acids, which indicates that defective clearance mechanisms for nucleic acids are present. The question as to whether these nucleic acids could serve as an antigen has been recently addressed by studies of plasma nucleic acids isolated from circulating immune complexes from SLE patients. These studies indicate that plasma nucleic acids in SLE patients have structures of amino acid sequences which have a striking homology with the gag-pol overlap region of HIV-1. Whether these nucleic acids play a role in the pathogenesis of SLE, indicating the involvement of a retrovirus in the pathogenesis, or whether they rather reflect an amino acid homology with an endogenous human retrovirus family is not yet known.

Induction of systemic lupus erythematosus in naive mice with T-cell lines specific for human anti-DNA antibody SA-1 (16/6 Id+) and for mouse tuberculosis antibody TB/68 (16/6 Id+)

Previously we have shown the ability to induce experimental systemic lupus erythematosus (SLE) in naive mice with pathogenic antibodies carrying the 16/6 idiotype (Id) and with the T-cell line specific for the 16/6 Id. In the present study we established and characterized a series of T-cell clones that react against diverse autoantibodies carrying the 16/6 Id and show that they are capable of inducing a SLE-like disease in mice. The T-cell clones were generated from BALB/c mice immunized with the human mAb anti-DNA antibody (SA-1) and the mouse monoclonal anti-tuberculous Ab (TB/68), both carrying the 16/6 Id. The T-cell clones proliferated only in the presence of either human or mouse mAb carrying the 16/6 Id. All the T-cell clones were found to be of the helper type (L3T4) and were H-2 restricted in their function. The injection of the clones to BALB/c mice resulted in serological findings (e.g., anti-DNA, anti-Sm), clinical manifestations (e.g., proteinuria, low white blood cell counts, increased erythrocyte sedimentation rate), and renal insult typical of SLE disease. Our data support the role attributed to pathogenic idiotypes in SLE on the one hand and that played by cellular immunity on the other. The mechanism by which Id-specific T-helper cells may induce SLE is currently not clear. The immunogenicity of the T-cell receptor (anti-16/6) and the cells themselves acting as effector/helper cells, thus leading to damage, may play a role in initiating a chain of events that ends in the production of a panoply of autoantibodies, some of which may also have a regulatory function.

Comparison of natural antibodies to autoantibodies arising during lupus in (NZB x NZW)F1 mice

Autoantibodies arising in (NZB x NZW)F1 (B/W) mice during the lupus-like syndrome were studied and compared to natural antibodies present in normal mice. The antibody activities were tested in sera, circulating immune complexes (CIC) and kidney eluates, using an enzyme immunoassay against a panel of self and non-self antigens: actin, myosin, tubulin, DNA, myoglobin, spectrin and trinitrophenylated bovine serum albumin (TNP/BSA). In the B/M mouse sera, IgM antibodies reacting with all the panel of antigens (PAg) and comparable to those of normal mice, increased moderately from 5 to 9 months and markedly during the last stage preceding death (10 months), when particularly high levels of anti-DNA, anti-tubulin and anti-myoglobin antibodies were noted. Polyreactive IgM antibodies present in CIC were moderately increased while those present in complexes deposited in kidneys were strongly enhanced after the 8th month. IgG antibodies showed an early increase (2 months) in B/W sera for anti-TNP activity, which remained more or less constant until death, while a later (5-6 months) and greater increase of activity, mainly directed against DNA but also against the other antigens of the panel, was observed. In CIC, IgG, mainly anti-DNA but also anti-TNP, were enhanced at the end of the disease while at the same time IgG reacting with all the PAg were found in kidney deposits. Isolation of antibodies from sera on a DNA-immunoadsorbent demonstrated that eluted IgM reacted with all the PAg but mainly with DNA, while IgG reactivity was more restricted to DNA and to a lesser degree to TNP. The D23 idiotype, characteristics of natural polyspecific antibodies, was expressed on IgM and IgG autoantibodies from B/W mice and was enhanced, particularly in kidneys, at the end of the disease. These results demonstrate that natural antibodies are a part of the population of increased autoantibodies in this disease and could participate with IgG anti-DNA antibodies in lupus.

Stress proteins, autoimmunity, and autoimmune disease

At birth, the immune system is biased toward recognition of microbial antigens in order to protect the host from infection. Recent data suggest that an important initial line of defense in this regard involves autologous stress proteins, especially conserved peptides of hsp60, which are presented to T cells bearing gamma delta receptors by relatively nonpolymorphic class lb molecules. Natural antibodies may represent a parallel B cell mechanism. Through an evolving process of "physiological" autoreactivity and selection by immunodominant stress proteins common to all prokaryotes, B and T cell repertoires expand during life to meet the continuing challenge of infection. Because stress proteins of bacteria are homologous with stress proteins of the host, there exists in genetically susceptible individuals a constant risk of autoimmune disease due to failure of mechanisms for self-nonself discrimination. That stress proteins actually play a role in autoimmune processes is supported by a growing body of evidence which, collectively, suggests that autoreactivity in chronic inflammatory arthritis involves, at least initially, gamma delta cells which recognize epitopes of the stress protein hsp60. Alternate mechanisms for T cell stimulation by stress proteins undoubtedly also exist, e.g., molecular mimicry of the DR beta third hypervariable region susceptibility locus for rheumatoid arthritis by a DnaJ stress protein epitope in gram-negative bacteria. While there still is confusion with respect to the most relevant stress protein epitopes, a central role for stress proteins in the etiology of arthritis appears likely. Furthermore, insight derived from the work thus far in adjuvant-induced arthritis already is stimulating analyses of related phenomena in autoimmune diseases other than those involving joints. Only limited data are available in the area of humoral autoimmunity to stress proteins. Autoantibodies to a number of stress proteins have been identified in SLE and rheumatoid arthritis, but their pathogenetic significance remains to be established. Nevertheless, the capacity of certain stress proteins to bind to multiple proteins in the nucleus and cytoplasm both physiologically and during stress or injury to cells, suggests that stress proteins may be important elements in the "immunogenic particle" concept of the origin of antinuclear and other autoantibodies. In short, this fascinating group of proteins, so mysterious only a few years ago, has impelled truly extraordinary new lines of investigation into the nature of autoimmunity and autoimmune disease.

The effect of the immunomodulator agent AS101 on interleukin-2 production in systemic lupus erythematosus (SLE) induced in mice by a pathogenic anti-DNA antibody

The role of the synthetic immunomodulator AS101 on the production of interleukin-2 (IL-2) by spleen cells of mice with SLE was investigated. BALB/c female mice, in which SLE was induced by immunization with the pathogenic idiotype of anti-DNA antibody 16/6 Id were treated with AS101 for 7 weeks 2 and 4 months after induction of the disease. The ability of the splenocytes of the mice with SLE to produce IL-2 was restored after administration of AS101. This effect was particularly impressive when the 7-week AS101 treatment was initiated 4 months after immunization. Despite its beneficial effect on IL-2 production, AS101 exerted no influence on the titres of autoantibodies in the sera of the mice. It also had no effect on clinical parameters of SLE, such as the increased sedimentation rate, proteinuria and low white blood cell counts. Our data indicate that defective IL-2 production in SLE is probably secondary to other disease processes and is not necessarily associated with the production of autoantibodies in this disorder.

The importance of the pathogenic 16/6 idiotype in the induction of SLE in naive mice

We have previously demonstrated the pathogenicity of the common anti-DNA idiotype designated 16/6 Id. Immunization of naive mice with the 16/6 Id induced SLE-like disease characterized by serological (e.g. anti-dsDNA and anti-Sm auto-antibodies), clinical (increased ESR, leucopenia and proteinuria), and pathological (16/6 Id deposition in kidneys) parameters. To elucidate further the role of the 16/6 Id in SLE induction the following studies were carried out: BALB/c mice were immunized with SA-1, a human anti-DNA monoclonal antibody carrying the 16/6 Id; TB-68, a mouse monoclonal anti-tuberculosis (TB) glycolipid, which binds dsDNA and carries the 16/6 Id; TB-72, a mouse monoclonal anti-TB glycolipid that binds DNA and does not harbour the 16/6 Id; and 4B4, a human anti-Sm antibody that carries the 16/6 Id. SLE was induced in BALB/c mice only when immunized with SA-1, TB-68, and 4B4, namely antibodies with diverse binding capacities albeit having the 16/6 Id. Our studies further support previous evidence on the pathogenic role attributed to the 16/6 Id in SLE, and suggest that SLE is most probably an idiotype-induced disease.

Idiotypes and autoimmunity

The reports discussed above have increased our knowledge of idiotypes, mainly with respect to additional CRI on autoantibodies and to a relatively new aspect of 'pathogenic idiotypes'. It is obvious that much remains to be discovered about the normal role of idiotypes and how they might be involved in the pathogenesis of autoimmune disorders. The relationship of the idiotypic network to tolerance is a matter of speculation; tolerance implies the ability to distinguish between 'foreign' and self-antigens and it is important to remember that antibody V regions are also self-antigens. Several mechanisms have been proposed to explain immunological tolerance. Originally, it was envisaged that the repertoires of both T and B lymphocytes were in some way purged of potentially self-reactive clones. However, it is now evident that self-reactive lymphocytes do exist but are normally held under control. Finally, it may be that certain self-antigens are simply never exposed to immune surveillance. It seems that the control of self-reactive lymphocytes is central to the question of tolerance. In the absence of autoimmune disease, autoantibodies can be produced, for example, after many infectious diseases or vaccinations. However, this type of perturbation of the immune system is associated with the short-term production of low titres of low-affinity antibodies, generally of the IgM isotype, which are thought to represent germline gene products. Homeostasis is soon re-established, possibly by regulatory T cells interacting with autoreactive B cells through their idiotypic receptors.(ABSTRACT TRUNCATED AT 250 WORDS)