Monoclonal human anti-DNA antibodies from EB virus-transformed lymphocytes of systemic lupus erythematosus (SLE) patients

A ssDNA Aptamer That Blocks the Function of the Anti-FLAG M2 Antibody

Using SELEX (systematic evolution of ligands by exponential enrichment), we serendipitously discovered a ssDNA aptamer that binds selectively to the anti-FLAG M2 antibody. The aptamer consisted of two motifs (CCTTA and TGTCTWCC) separated by 2-3 bases, and the elimination of one or the other motif abrogated binding. The DNA aptamer and FLAG peptide competed for binding to the antigen-binding pocket of the M2 antibody. In addition, the aptamer eluted FLAG-tagged proteins from the antibody, suggesting a commercial application in protein purification. These findings demonstrate the feasibility of using SELEX to develop ssDNA aptamers that block the function of a specific antibody, a capability that could lead to the development of novel therapeutic modalities for patients with systemic lupus erythematosus, rheumatoid arthritis, and other autoimmune diseases.

Nrf2 deficiency improves autoimmune nephritis caused by the fas mutation lpr

BACKGROUND

Nrf2 is a basic leucine zipper transcriptional activator essential for the coordinate transcriptional induction of antioxidant and phase II drug metabolizing enzymes. We previously reported that Nrf2-deficient female mice develop lupus-like autoimmune nephritis (Kidney Int 60:1343-1353, 2001). The result suggested that nrf2 is a possible candidate gene in determining susceptibility to autoimmune diseases. MRL/lpr mice, defective in Fas-mediated apoptosis, develop glomerulonephritis due to the production of autoantibodies.

METHODS

To investigate the mechanism whereby Nrf2 contributes to the susceptibility to autoimmune diseases, we generated nrf2-/-lpr/lpr mice.

RESULTS

Unexpectedly, the lifespan of nrf2-/-lpr/lpr female mice was markedly prolonged and these mice showed an improvement in nephritis compared to nrf2+/+lpr/lpr female mice. Immunologic abnormalities and hypergammaglobulinemia were also alleviated in nrf2-/-lpr/lpr female mice. Furthermore, lymphadenopathy was suppressed as a result of increased apoptosis. To elucidate the molecular mechanism causing a stimulation of apoptosis, we analyzed the response made by nrf2-/-lpr/lpr mice to death signals. We show that nrf2-/-lpr/lpr mice are sensitive to tumor necrosis factor-alpha (TNF-alpha)-mediated apoptosis. Since intracellular glutathione levels are decreased in Nrf2-deficient cells, it is probable that a prolonged depletion in glutathione levels leads to the enhancement in TNF-alpha-mediated apoptosis.

CONCLUSION

These results indicate that a deficiency in Nrf2 enhances TNF-alpha-mediated apoptosis which in-turn ameliorates the abnormal apoptotic response that arises from a mutation in the lpr gene. Therefore, Nrf2 deficiency acts as a suppressor of the autoimmune accelerating gene lpr.

Bone marrow cell transfer of autoimmune diseases in a MRL strain of mice with a deficit in functional Fas ligand: dissociation of arteritis from glomerulonephritis

MRL/MpTn-gld/gld (MRL/gld) mice, which are deficient in a functional Fas ligand (FasL), spontaneously develop autoimmune diseases involving both lethal glomerulonephritis and systemic arteritis, while MRL/Mp-+/+ (MRL/+) and C3H/HeJ-gld/gld (C3H/gld) do not. To determine the cells responsible for the development of glomerulonephritis and arteritis, we transferred bone marrow cells from MRL/gld mice to undiseased MHC-compatible gld/gld or +/+ mice. In bone marrow irradiation chimeras, MRL/gld bone marrow cells were transferred to lethally irradiated MRL/+ or C3H/HeJ-+/+ (C3H/+) mice, and both recipients developed glomerulonephritis associated with hypergammaglobulinemia without causing graft-versus-host (GVH)-like diseases. However, a striking difference between them was that MRL/+ recipients developed arteritis, but C3H/+ recipients did not. In bone marrow mixed chimeras formed by transferring MRL/gld bone marrow cells to unirradiated mice, the MRL/gld bone marrow cells induced glomerulonephritis in C3H/gld mice, but not in C3H/+ and MRL/+ mice. These results indicate that bone marrow cells from MRL/gld mice can cause glomerulonephritis in mice, even in those with a C3H background, possibly if they survive longer by escaping from Fas-mediated apoptosis, while the development of arteritis requires the MRL genetic background in the recipients. This is the first report of the transfer of arteritis in lupus mice to undiseased recipients.

Nrf2-deficient female mice develop lupus-like autoimmune nephritis

BACKGROUND

NF-E2-related factor 2 (Nrf2) is a basic leucine zipper transcriptional activator essential for the coordinate transcriptional induction of antioxidant enzymes and phase II drug metabolizing enzymes through the antioxidant response element/electrophile response element. The Nrf2-deficient mice were found to develop normally under standard laboratory conditions. However, upon closer examination, we found that aged female Nrf2-deficient mice displayed a shortened lifespan and developed severe glomerulonephritis. The present study investigated the glomerulonephritis findings in Nrf2-deficient mice.

METHODS

To evaluate glomerular lesions of Nrf2-deficient mice, histological and functional analyses were performed. The amounts of serum immunoglobulins, anti-double-stranded (ds) DNA antibody, and lipid peroxidation using thiobarbituric acid reactive substances (TBARS) also were measured.

RESULTS

Nrf2-deficient female mice over 60 weeks of age developed severe nephritis characterized by cellular proliferation, lobular formation, crescent formation, and subepithelial electron-dense deposits. In immunofluorescent assays, Nrf2-deficient female mice showed mesangial deposits and massive granular deposits of IgG, IgM, and C3 along the capillary walls. Higher serum levels of IgG, anti-dsDNA antibody, lower creatinine clearance, and slight splenomegaly also were found in Nrf2-deficient female mice. A higher concentration of TBARS also was found in Nrf2-deficient female mice.

CONCLUSIONS

These data indicate that the aged Nrf2-deficient female mice develop lupus-like autoimmune nephritis and suggest that nrf2 is one of the genes determining susceptibility to autoimmune disease. Analysis of nephritis in the Nrf2-deficient female mouse may clarify the mechanisms leading to the development of lupus disease.

Effective treatment of autoimmune disease and progressive renal disease by mixed bone-marrow transplantation that establishes a stable mixed chimerism in BXSB recipient mice

Male BXSB mice spontaneously develop autoimmune disease with features similar to systemic lupus erythematosus. To determine whether this autoimmune disease can be treated as well as prevented by bone-marrow transplantation (BMT) and, at the same time, whether the immunity functions of lethally irradiated recipients can be reconstituted fully, male BXSB mice were engrafted with mixed T cell-depleted marrow (TCDM) both from fully allogeneic autoimmune-resistant BALB/c mice and from syngeneic autoimmune-prone BXSB mice, after the onset of autoimmune disease in the recipient mice. BMT with mixed TCDM from both resistant and susceptible strains of mice (mixed BMT) established stable mixed chimerism, prolonged the median life span, and arrested development of glomerulonephritis in BXSB mice. BMT with mixed TCDM also reduced the formation of anti-DNA antibodies that are observed typically in male mice of this strain. Furthermore, mixed BMT reconstituted the primary antibody production in BXSB recipients impressively. These findings indicate that transplantation of allogeneic autoimmune-resistant TCDM plus syngeneic autoimmune-prone TCDM into lethally irradiated BXSB mice can be used to treat autoimmune and renal disease in this strain of mice. In addition, this dual bone-marrow transplantation reconstitutes the immunity functions and avoids the immunodeficiencies that occur regularly in fully allogeneic chimeras after total body irradiation. This report describes an effective treatment of progressive renal disease and autoimmunity by establishing a stable mixed chimerism of TCDM transplantation from allogeneic autoimmune-resistant BALB/c mice plus syngeneic autoimmune-prone BXSB mice into BXSB mice.

Prevention of development of autoimmune disease in BXSB mice by mixed bone marrow transplantation

Transplantations of fully allogeneic, autoimmune-resistant T-cell-depleted marrow (TCDM) plus syngeneic, autoimmune-prone TCDM into lethally irradiated BXSB mice were carried out to investigate the ability of the mixed bone marrow transplantation (BMT) to prevent development of autoimmune disease and, at the same time, to reconstitute fully the immunity functions of heavily irradiated BXSB recipients. Male BXSB mice were engrafted with mixed TCDM from both allogeneic, autoimmune-resistant BALB/c mice and syngeneic, autoimmune-prone BXSB mice. BMT with mixed TCDM from both resistant and susceptible strains of mice (mixed BMT) prolonged the median life span and inhibited development of glomerulonephritis in BXSB mice. BMT with mixed TCDM also prevented the formation of anti-DNA antibodies that is typically observed in male mice of this strain. Moreover, mixed BMT reconstituted primary antibody production in BXSB recipients, so that no annoying immunodeficiencies that are regularly observed in fully allogeneic chimeras were present in the recipient of the mixed TCDM. These findings indicate that transplanting allogeneic, autoimmune-resistant TCDM plus syngeneic, autoimmune-prone TCDM into lethally irradiated BXSB mice prevents development of autoimmune disease in this strain of mice. In addition, this dual BMT reconstitutes the immunity functions and avoids the immunodeficiencies that occur regularly in fully allogeneic chimeras after total-body irradiation.

Genetic selection for crescent formation yields mouse strain with rapidly progressive glomerulonephritis and small vessel vasculitis

We have established a recombinant inbred strain of mouse named spontaneous crescentic glomerulonephritis-forming mouse/Kinjoh or SCG/Kj. Mice of this strain spontaneously develop rapidly progressive glomerulonephritis. This strain of mice was derived from (BXSB/Mp x MRL/Mp-lpr/lpr)F1 hybrid mice by brother x sister mating coupled with repeated histopathologic selection for breeding of mice whose parents had the highest frequency of crescent formation in the kidneys. In this strain of mice, nephritis appears earlier and is more rapidly progressive than in any other murine model of systemic lupus erythematosus. Histopathologically, the characteristic renal lesions in the mice of this strain express a most dramatic form of crescentic glomerulonephritis. The lesions in the kidneys show only slight fine granular immune deposits along the glomerular basement membrane associated with remarkable extraglomerular proliferation and hemorrhage in Bowman's space. Although selection was not based on vasculitis, mice of this strain also exhibit a high incidence of necrotizing vasculitis. These vascular lesions involve primarily small arteries and arterioles and many organs and tissues but spare the kidneys. Thus this form of vasculitis has been found to be correlated with the crescentic form of glomerulonephritis but not with lymphoid hyperplasia of the spleen. We conclude that, in this strain of mouse, the rapidly progressive glomerulonephritis is genetically restricted and that this genetic restriction is firmly linked to that responsible for the vasculitis.

Age-associated increase of CD5+ B cells in the liver of autoimmune (NZB x NZW) F1 mice

The liver has been demonstrated to be a major site for extrathymic differentiation of T cells. In this study, an identification of CD5+ B cells, which are responsible for the onset of autoimmune disease by virtue of autoantibody production, was performed in autoimmune (NZB x NZW) F1 mice. An age-associated increase of CD5+ B cells was demonstrated in the liver of these mice. Although CD5+ B cells (i.e., CD5+IgM+ and CD5+B220+) constituted a minor population of hepatic mononuclear cells (MNC) (< 5%) when mice were young (8 weeks), a large population of CD5+ B cells (10 to 30% of whole MNC) was identified in the liver of mice aged 25 to 30 weeks after the onset of disease. Such age-dependent increase of CD5+ B cells was not observed in any other strains including NZB, NZW, C3H/He and BALB/c mice. The phenotype of hepatic CD5+ B cells was the same as that of CD5+ B cells in the peritoneal cavity and spleen, showing dull-CD5, bright-IgM and dull-B220. High levels of CD5+ B cells were observed in the peritoneal cavity and liver, but not in the spleen nor in any other lymphoid organs in mice aged 30 weeks. Radioimmunoassay of autoantibodies in the 5-day culture supernatants demonstrated that hepatic MNC were unable to produce any amounts of IgM- and IgG-autoantibodies against double-stranded DNA and single-stranded DNA, despite the increased proportion of CD5+ B cells. On the other hand, peritoneal exudate cells produced only IgM-, but not IgG-, autoantibodies, whereas splenic cells were able to produce both IgM- and IgG-autoantibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Lupus-derived human monoclonal IgM anti-DNA antibody displays monospecificity, high affinity and private idiotype specificity

A human monoclonal IgM k anti-DNA antibody, designated 2F7, was prepared by somatic hybridization of peripheral blood lymphocytes from a lupus patient with a human-mouse heterohybridoma cell line, K6H6/B5. 2F7 was tested for its antigen binding and idiotypic specificity by direct binding and inhibition enzyme-linked immunosorbent assays. 2F7 had a high binding activity to single-stranded DNA (ssDNA) but not to double-stranded DNA. It cross-reacted with single-stranded homopolymers with pyrimidine bases and double-stranded polynucleotides containing those homopolymers, suggesting that 2F7 recognizes a conformational determinant made up of both deoxyribose-phosphate backbone and specific nucleotide base. 2F7 did not cross-react with eight structurally unrelated self-antigens. Dissociation constant (Kd) of 2F7 for sonicated ssDNA was approximately 4.5 x 10(-9) M, indicating its relatively high affinity. Idiotypic characterization with rabbit anti-idiotype raised against 2F7 suggested that 2F7 expressed an idiotype at or near its antigen-binding sites that was not detected in sera from 20 unrelated lupus patients, 10 lupus family members and 10 normal individuals. These results suggest that certain IgM class anti-DNA antibodies in human systemic lupus erythematosus may arise by antigen stimulation and not simply by polyclonal B-cell activation.

Clonal frequency analysis of B cells producing pathogenic anti-DNA antibody-associated idiotypes in systemic lupus erythematosus

In order to identify the mechanism responsible for autoantibody production in systemic lupus erythematosus (SLE), B cell repertoires associated with anti-DNA idiotypes were explored by a limiting dilution analysis using Epstein-Barr virus (EBV) transformation methods and ELISA spot assays. The frequencies of B cell clones producing antibodies to DNA and to conventional antigens, tetanus toxoid, dinitrophenyl, or keyhole limpet hemocyanin were higher in active SLE compared to those in inactive SLE and in normal subjects. In addition, there was a disproportionate increase in anti-DNA antibody- and anti-DNA idiotype (Id)-producing clones at the precursor cell levels as well as at the mature cell level. On the other hand, numbers of anti-Id clones against anti-DNA-Id, termed 0-81 Id, were markedly increased at inactive stages of the disease but not at active stages. These were confirmed by serial studies in some patients with SLE. These results support a two-step mechanism for autoantibody production, in which initial polyclonal activation is followed by an antigen-driven process, and indicate an alteration of the precursor B cell repertoire in SLE, which may also associate with a preferential expansion of anti-DNA clones.

Circulating anti-DNA immune complexes in active lupus nephritis

PURPOSE

The role that circulating anti-DNA immune complexes play in autoimmunity has not yet been elucidated in humans. The aim of this study was to relate circulating anti-DNA immune complexes to a variety of renal histologic features and to immunoglobulin deposits in active lupus nephritis.

PATIENTS AND METHODS

The study population consisted of 47 patients with active lupus nephritis, 28 with active systemic lupus erythematosus (SLE) in the absence of renal lesions, and 40 with other categories of the disease. All patients were examined for anti-DNA circulating immune complexes (CIC) and their anti-DNA idiotype expression by an isoelectrofocusing analysis. Patients with renal lesions were also examined for renal histologic and immunofluorescent findings in renal biopsy specimens.

RESULTS

Anti-DNA CIC expressing an anti-DNA idiotype termed 0-81 Id occurred in patients with active lupus nephritis but not in acute episodes lacking renal involvement or in remission. Positive test results for anti-DNA CIC were associated with the incidence of diffuse proliferative glomerulonephritis (DPGN). Patients with anti-DNA CIC were also found to have a statistically significant increase in the prevalence of immunoglobulin immune deposits in the subendothelial area of the renal glomeruli.

CONCLUSION

The findings suggest that anti-DNA CIC preferentially occurred in lupus patients with DPGN. Examination for anti-DNA CIC may be a useful predictor of renal lesions, and therefore may contribute to the management of SLE. The results also indicate that anti-DNA CIC may be associated with immunoglobulin deposition in the subendothelial area of the renal glomeruli.

Anti-DNA idiotypes deposited in renal glomeruli of patients with lupus nephritis

Idiotypes (Id) of human anti-DNA antibodies, designated as O-81 Id, were specifically detected on the immune deposits of renal glomeruli in 46% of patients with lupus nephritis. Id-binding to anti-Id antibodies was blocked by free O-81 Id and to some extent by free DNA. DNase or acid buffer treatment failed to reveal new Id determinants on the deposits. O-81 Id and NE-1 Id activity were also detected on the renal eluate-derived IgG, but not IgM from the autopsy cases with lupus nephritis. The incidences of O-81 Id were not associated with histological features in the glomeruli, but the distribution patterns were similar to those of IgG deposits. Our study also showed that 65% to 70% of patients with IgG deposits either in the subendothelium or in the subepithelial area of the glomerular basement membrane (GBM) showed positive tests for O-81 Id. It was also noted that most patients with massive proteinuria had O-81 Id in their glomeruli. It is concluded that O-81 Id deposits are relatively specific for active lupus nephritis and that immunofluorescence studies using anti-Id antibodies may be clinically useful for specifying the renal lesions of systemic lupus erythematosus (SLE).

Heterogeneity of immune complex-derived anti-DNA antibodies associated with lupus nephritis

The mechanisms responsible for the tissue injuries associated with lupus nephritis have not yet been well explained. We have investigated the characteristics of anti-DNA antibodies in circulating immune complexes (CIC) and in the deposits of renal glomeruli in patients with active lupus nephritis. The CIC-derived antibodies expressed anti-DNA idiotypes (Id) designated as 0-81 Id and NE-1 Id, and bound mainly to single-stranded DNA but never to glomerular basement membrane (GBM) antigens. On the other hand, the immunoglobulins (Ig) eluted from renal glomeruli of lupus patients reacted not only with DNA but also with GBM, proteoglycan, and heparan sulfate. The binding of glomeruli-deposited Ig was markedly low when GBM antigens were used after treatment with heparitinase, suggesting that some anti-DNA antibodies may bind directly to GBM antigens associated with heparan sulfate, and form in situ IC in renal glomeruli. It was also revealed that the renal eluates obtained after passing through GBM antigen-coupled Sepharose lost the binding ability with GBM but still retained DNA-binding and 0-81 Id activity, showing the participation of circulating IC-derived anti-DNA antibodies in the glomerular deposits. Theoretically there may be two mechanisms in the pathogenesis of lupus nephritis through the deposition of circulating IC and through in situ formation of anti-DNA IC in renal glomeruli. The diversity of histological features in lupus kidneys may be attributed to the heterogeneity of the mechanisms.

Selective absorption of anti-DNA antibodies and their idiotype-positive cells in vitro using an anti-idiotypic antibody-affinity column: possible application to plasma exchange

We examined the possibility of using affinity columns coupled with anti-idiotype (Id) antibodies to selectively remove nephritogenic anti-DNA antibodies in order to determine their possible application to therapeutic plasmapheresis. Monoclonal anti-Id antibodies termed D1E2 or 1F5 were directed to idotypes of human anti-single-stranded and anti-double-stranded DNA antibodies. The mixture of D1E2- and 1F5-coupled Sepharose absorbed 26 to 92% of human anti-DNA antibodies in sera. The affinity columns were also effective in removing anti-DNA idiotype-positive cells from the blood samples of patients, especially those with active lupus nephritis. Thus, an anti-idiotypic antibody-coupled affinity column could, in theory, serve as a tool for selective plasma exchange in the therapy of autoimmune disease.

Therapeutic treatment of New Zealand mouse disease by a limited number of anti-idiotypic antibodies conjugated with neocarzinostatin

-81 and NE-1 idiotypes (Id) of human nephritogenic anti-DNA antibodies are interspecies Id expressed also in NZB/W F1 mice. We tried to manipulate the synthesis of spontaneously occurring anti-DNA antibody using monoclonal anti-Id antibodies (D1E2 and 1F5) conjugated with a cytotoxic agent, neocarzinostatin (NCS). In vivo administration of anti-Id antibodies conjugated with NCS brought about an improvement in the survival rate of female NZB/W F1 mice. It also caused a retardation of development of lupus nephritis and decreased the numbers of anti-DNA-producing cells. The suppression of anti-DNA antibody synthesis was specific and Id-mediated. The results indicate that the use of a limited number of anti-Id antibodies in combination with a cytotoxic agent may be applicable therapeutically to autoimmune diseases.

Incidence of anti-DNA idiotype-positive cells in human peripheral blood

Human anti-DNA idiotype (Id)-bearing cells in peripheral blood were sought using mouse monoclonal anti-Id antibodies to human monoclonal anti-DNA antibodies. Pretreatment with acid pH or pronase P or preincubation in human serum-free medium markedly decreased the number of anti-Id-reactive cells. Pronase P-treated cells were able to bind to anti-Id once more after incubation for 18 hr at 37 degrees C, indicating the resynthesis of internal idiotypic determinants on the cells. Antiidiotype-reactive cells retained the same idiotypes in their cytoplasma. The cells expressing anti-DNA idiotypes, termed 0-81 and NE-1, were detected in the circulation of most patients with active lupus nephritis but not in those of inactive systemic lupus erythematosus (SLE) and healthy subjects. The idiotype-positive cells occurred in up to 5-10% of B cells from some patients with SLE in the active stage but became undetectable in remission. A limited number of anti-DNA Id-positive cells responsible for anti-DNA production might be preferentially expanded during acute episodes of the disease in some patients with SLE.

Binding properties of human anti-DNA antibodies to cloned human DNA fragments

The DNA-anti-DNA antibody immune complexes were isolated from plasma of systemic lupus erythematosus (SLE) patients and DNA fragments separated from immune complexes were subjected to molecular cloning. The resulting recombinant DNA clones showed a molecular size of 37-79 base pairs, a high guanine and cytosine content, high frequencies of CpG dinucleotides, and palindromic sequences, and also clusters of G + C- and A + T-rich segments. These clones hybridized randomly to total human DNA. The reactivity of dsDNA antibodies, both monoclonal and polyclonal, from SLE was examined with a cloned SLE antigen DNA. A competitive inhibition assay showed that human monoclonal antibodies had at least one magnitude higher affinity to the cloned DNA than to the native DNA fragments. In order to characterize the factors that were recognized by antibodies, human G + C-rich and also A + T-rich 100 bp DNA fragments were cloned, and their base sequences determined. The antibody showed a higher affinity to the G + C-rich DNA fragment (71% G + C) than to the A + T-rich DNA fragment (46% G + C). When cytosines in CpG doublets in G + C-rich fragments were methylated (mCpG), the reactivity increased up to 100-fold. The native anti-DNA antibodies from SLE patients also showed preferential binding to G + C-rich fragments. These observations suggested that human anti-dsDNA antibodies may recognize some unique structures around the G + C regions or G + C clusters of DNA.

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.

Epstein-Barr virus-transformed B cells bearing idiotypes of anti-DNA autoantibodies

Epstein-Barr virus (EBV)-transformed B cells obtained from healthy subjects had the same idiotypes of anti-DNA autoantibodies on their surface as those obtained from patients suffering from systemic lupus erythematosus. These clones secreted anti-single-stranded or anti-double-stranded DNA antibodies. Among them, some produced anti-DNA idiotype-positive antibodies but failed to bind DNA. This was confirmed by a competitive inhibition radioimmunoassay. It was then considered whether or not the expression of anti-DNA idiotype on B-cell clones related to the anti-DNA antibody activity in vivo. The amounts of anti-DNA antibodies were not associated with the incidence of idiotype-positive B cells in the EBV-transformed cell lines from normals. The results indicate that the clones committed to the synthesis of anti-DNA idiotype-positive antibodies commonly exist at a resting state in the circulation of healthy subjects, probably through the self-tolerance regulatory system.

Specific purification of monoclonal anti-DNA antibodies from culture medium using a DNA-coupled Sepharose 4B affinity column

Human monoclonal antibodies against DNA were specifically purified from the culture medium of an EBV transformant of SLE patients' lymphocytes using a DNA-coupled Sepharose 4B affinity column. The monoclonal antibodies were eluted from the column with 5% dimethylsulfoxide (pH 10.7) containing 0.5 M NaCl without loss of immunological activity and without contamination by other proteins.

Selective elimination of anti-DNA antibody-producing cells by antiidiotypic antibody conjugated with neocarzinostatin

A new strategy was shown for the manipulation of autoantibody production in humans. Antiidiotypic antibody to human anti-DNA autoantibody was conjugated with neocarzinostatin (NCS), a cytotoxic agent, by using N-succimidyl 3-(2-pyridyldithio) propionate as a coupling agent. Human B cell clones, which produce anti-DNA autoantibodies, were killed by in vitro treatment with antiidiotype (Id)-NCS conjugates, while clones expressing an Id with irrelevant specificity were unaffected. These results indicate that treatment with anti-Id-NCS conjugates can act as a potent and specific means of generating immunosuppression of autoantibody production. This approach will have a significant advantage in aborting clones that are not effectively suppressed for the autoantibodies by anti-Id antibodies alone, and will result in a potential therapeutic treatment for systemic lupus erythematosus.