Antiphospholipid antibodies are induced by in vitro fertilization and correlate with paraoxonase activity and total antioxidant capacity of plasma in infertile women

The objectives of this study were to determine whether antiphosholipid antibodies are associated with in vitro fertilization (IVF), and assess the potential biological effects of these antibodies. Sera from seventy infertile women (18 before IVF, 13 submitted to one IVF cycle and 39 after three cycles) and 28 healthy controls were collected. Anticardiolipin (anti-CL) and antiphosphatidylserine (anti-PS) antibodies, paraoxonase (PON) and Total Anti-oxidant Capacity of plasma (TAC) were measured. Anti-CL and anti-PS titres were significantly increased in treated patients compared with patients before treatment or controls ( P < 0.001). There were no differences regarding anti-CL and anti-PS titres between controls and untreated patients nor when different types of infertility were considered. PON activity and TAC were significantly reduced in treated patients when compared to untreated and controls ( P < 0.001; P < 0.002). PON correlated inversely with anti-CL and anti-PS IgG ( r = 20.734; P < 0.001) and directly with TAC ( r = 0.720, P < 0.001). In conclusion PON activity is decreased in women submitted to IVF treatment and is associated with the presence of antiphospholipid antibodies. These factors might contribute to the increased oxidative status found in these patients.

p185, an immunodominant epitope, is an autoantigen mimotope

An immunodominant peptide (p185(378-394)) derived from the c-erbB2 gene product, was recognized by an anti-DNA antibody, B3, and importantly by two classical DNA-binding proteins, Tgo polymerase and Pa-UDG. These reactivities were inhibited by DNA, confirming that the peptide mimicked DNA. BALB/c mice immunized with p185(378-394) developed significant titers of IgG anti-dsDNA antibodies. Screening of 39 human lupus sera revealed that 5% of these sera possessed reactivity toward p185(378-394). Representative mouse and human sera with anti-p185(378-394) reactivity bound intact p185, and this binding was inhibited by dsDNA. This is the first demonstration of a naturally occurring autoantigen mimotope. The present study identifies a potential antigenic stimulus that might trigger systemic lupus erythematosus in a subset of patients.

Beta-2-glycoprotein specificity of human anti-phospholipid antibody resides on the light chain: a novel mechanism for acquisition of cross-reactivity by an autoantibody

We have recently shown that the anti-cardiolipin activity of human anti-phospholipid antibody UK4 (lambda) resides on its heavy chain. We now show that UK4 possesses strong reactivity to the plasma-protein beta2-Glycoprotein I (beta2-GPI) also. Utilizing chain shuffling experiments involving an unrelated anti-p185 antibody 4D5 (kappa) with no reactivity to beta2-GPI, we now demonstrate that both the constructs possessing the auto-antibody-derived light chain exhibited significant binding to beta2-GPI. However, the construct possessing UK4 heavy chain in association with 4D5 light chain, exhibited no anti-beta2-GPI activity. Furthermore, there was a low increase (approximately 10%) in the binding of UK4 to cardiolipin in the presence of beta2-GPI. The results demonstrate that anti-beta2-GPI activity resides on UK4 light chain and, importantly, this activity could be transferred to a novel antibody construct via the light chain alone. Computer-generated models of the three-dimensional structures of UK4 and its hybrids, suggest predominant interaction of UK4 light chain with domain IV of beta2-GPI. Molecular docking experiments highlight a number of potential sites on beta2-GPI for interaction of UK4 and indicate as to how beta2-GPI recognition may occur primarily via the autoantibody light chain. The study provides first demonstration of the occurrence of anti-phospholipid and anti-beta2-GPI activities separately on heavy and light chains of an autoantibody. The possible mechanisms that such antibodies may employ to recognise their antigens, are discussed.

Fine binding characteristics of human autoantibodies—partial molecular characterization

The fine binding characteristics of three well-characterized human autoantibodies B3, RH14 (anti-DNA) and UK4 (anti-cardiolipin) in their IgG and cloned Fab formats, were investigated. Although in severe combined immunodeficiency (SCID) mice B3 and RH14 both induce proteinuria, only RH14 induces early features of lupus nephritis, whereas UK4 exhibits lupus anticoagulant activity. RH14 exhibited up to 10 fold higher binding to DNA compared to that shown by B3 or UK4 and involved significant electrostatic and phosphate group interactions. Only RH14 exhibited strong anti-Sm cross-reactivity residing on the C-terminus of the antigen as determined by the use of 76 overlapping 15mer peptides. Chain shuffling experiments indicate that anti-Sm/RNP and anti-Jo-1 activities of B3 and UK4 co-exist on one of the two chains (light, B3; heavy, UK4). The present study provides evidence that a human anti-DNA antibody can also be an anti-ENA antibody. Furthermore, the anti-DNA antibodies also exhibited cross-reactivity against glutathione-S-transferase and DNA polymerase PolIV of bacterial origin. This is the first demonstration of the presence of such cross-reactivities on lupus anti-DNA antibodies. We now demonstrate that subsets of sera from the patients with lupus, recognise these antigens. This observation may in some cases provide a mechanism for the common expression of a variety of autoantibodies observed in systemic lupus erythematosus (SLE).

Is alpha-actinin a target for pathogenic anti-DNA antibodies in lupus nephritis?

OBJECTIVE

Following recent reports that pathogenic murine anti-DNA antibodies bind to alpha-actinin, it was obviously of interest to assess the ability of human pathogenic anti-double-stranded DNA (anti-dsDNA) antibodies to bind this antigen. Both human monoclonal anti-DNA antibodies and antibodies affinity purified from the sera of patients with systemic lupus erythematosus (SLE) were investigated.

METHODS

An enzyme-linked immunosorbent assay was established to measure immunoglobulin binding to alpha-actinin. Antibodies binding dsDNA were purified from the sera of SLE patients who either had active renal disease or had never had renal disease. Serum samples were selected at times when the patients' sera exhibited high IgG binding to dsDNA. The binding of supernatants from 3 high-affinity human anti-dsDNA IgG hybridomas (RH14, B3, and DIL-6) and 7 human IgM anti-DNA hybridomas was also investigated.

RESULTS

A greater proportion of anti-dsDNA IgG-binding antibodies purified from patients with renal disease bound to alpha-actinin than did those purified from the sera of patients without renal disease. The specificity of binding to the 100-kd alpha-actinin molecule was confirmed by Western blotting. The pathogenic human antibodies RH14 and B3 bound strongly to alpha-actinin, while nonpathogenic DIL-6 bound very weakly. RT84, the IgM antibody that binds dsDNA with the highest affinity, exhibited the greatest binding to alpha-actinin.

CONCLUSION

The results of our study support the findings of previous studies using murine anti-DNA monoclonal antibodies, which suggest that pathogenic anti-dsDNA antibodies cross-react with alpha-actinin.

Structure–function analysis and the molecular origins of anti-DNA antibodies in systemic lupus erythematosus

Patients with the autoimmune rheumatic disease systemic lupus erythematosus (SLE or ‘lupus’) develop a wide variety of clinical and serological manifestations including the presence of antibodies to double-stranded DNA (dsDNA), which are often diagnostic and potentially pathogenic. In this review, we have examined the links between the structure and function of anti-dsDNA antibodies, emphasising their clinical associations. We have also reviewed studies involving animal models, the analysis of human antibody sequences and studies of, and using, computer modelling and crystal structure.

Effect of neutralizing antibodies to IL-10 and C5 on the renal damage caused by a pathogenic human anti-dsDNA antibody

OBJECTIVES

There is considerable evidence suggesting that anti-double-stranded deoxyribonucleic acid (anti-dsDNA) antibodies are involved in the pathogenesis of lupus nephritis. It was shown previously using severe combined immune deficient (SCID) mice that when the hybridomas secreting human immunoglobulin G (IgG) anti-dsDNA antibodies, RH14 and DIL-6, were implanted intraperitoneally the antibodies produced by RH14, but not DIL-6, deposited in the kidneys, caused pathological changes in the renal tissues and induced proteinuria. In this study we have further analysed the effect of activated terminal complement proteins and interleukin-10 (IL-10) in the pathogenesis of glomerulonephritis caused by the RH-14.

METHODS

SCID mice implanted with RH-14 or DIL-6 cell lines were treated with neutralizing antibodies to IL-10 (mAb B-S10) or anti-complement factor 5 (anti-C5) (mAb BB5.1) intraperitoneally. Control groups received either an isotype control antibody (135.8) or phosphate-buffered saline (PBS). Serum human IgG levels and proteinuria were estimated and the extent of renal involvement was examined by histopathological and electron microscopic techniques.

RESULTS

While there was a tendency to reduce proteinuria in the anti-IL-10 injected group the anti-C5 injected group showed a significant reduction in proteinuria (P<0.01) compared with the groups injected with either the control mAb or PBS. There was a considerable reduction in the serum human IgG levels in the anti-IL-10 but not in the anti-C5 treated animals. Both anti-IL-10 and anti-C5 treated groups showed significantly reduced renal impairment as revealed by histopathological examination and proteinuria assessment.

CONCLUSION

The findings, while confirming the role of IL-10 and activated terminal complement component in the production of antibody at the cellular level and at the site of glomerular immune deposition in this model, respectively, also suggest the beneficial effect of a combined therapy using both anti-IL-10 and anti-C5 mAb to prevent or reduce the effect of the humoral immune response in lupus disease.

Anti-cardiolipin/beta-2 glycoprotein activities co-exist on human anti-DNA antibody light chains

We have recently shown that the human anti-DNA antibodies B3 and 33H11 also bind cardiolipin and that the anti-autoantigen activity resides predominantly on their lambda light chains. We now show that the two auto-antibodies possess strong reactivity to the plasma-protein 2-Glycoprotein I (beta2-GPI) also. Utilizing chain shuffling experiments involving an unrelated anti-p185 antibody 4D5 with insignificant reactivity to cardiolipin or to beta2-GPI, we now demonstrate that hybrid Fabs with constituent light chain, but not the heavy chain, of B3 or 33H11, exhibit anti-cardiolipin activity. Furthermore, the constructs possessing the auto-antibody-derived light chain also exhibited significant reactivity to beta2-GPI. The results suggest that anti-DNA, anti-cardiolipin and anti-beta2-GPI activities co-exist on the light chains of the antibodies studied and, importantly, these activities could be transferred to antibody constructs by their light chains alone. Computer-generated models of the three-dimensional structures of the auto-antibodies and their hybrids, suggest predominant interaction of their light chains with domain IV of beta2-GPI.

Transgenic models of tolerance and autoimmunity: with special reference to systemic lupus erythematosus

Transgenic and knockout mouse carrying rearranged antigen-receptor genes have been invaluable for the elucidation of basic mechanisms in autoimmunity and have contributed new models of human autoimmune diseases. Several examples of transgenic models expressing rearranged immunoglobulin genes have been described. These models have provided a window into the events involved in this process, allowing the development and fate of self-reactive lymphocytes to be followed in vivo. In the B cell lineage, as in T cells, self-reactive cells have been found to undergo several distinct fates in vivo: they can be physically eliminated, functionally inactivated, or they can persist unchanged or become activated. Nevertheless the precise understanding of the molecular events leading to lymphocyte deletion, anergy or activation remains a challenge.

Molecular expression systems for anti-DNA antibodies--2

Antibodies to double-stranded DNA are the best-known serological markers of systemic lupus erythematosus, and are closely associated with its renal pathogenesis. How these antibodies recognize DNA is not fully understood. An understanding of the relationship between the functional attributes of an antibody with the three-dimensional structure of its antigen-combining site would allow an insight into the rules that dictate auto-antibody-nucleic acid interaction and consequent pathogenicity of the autoantibody. Data from such studies could assist the development of novel drugs as an approach to specific therapies that can inhibit or disrupt protein-nucleic acid interactions. A full understanding of the binding specificities can be achieved only by experimental determination of detailed three-dimensional structure of these antibodies alone, and of their complexes with specific DNA antigens. A prerequisite of such a study is the ability to produce multimilligram quantities of the antibody protein. However, these antibodies are particularly difficult to express, probably due to their DNA-binding activity. This review attempts to focus on the recent developments on the over-expression of anti-DNA antibody fragments in heterologous cell expression systems and their purification to homogeneity that would in turn allow their structural studies via crystallization.

An analysis of clinical disease activity and nephritis-associated serum autoantibody profiles in patients with systemic lupus erythematosus: a cross-sectional study

OBJECTIVE

To establish the correlation between lupus nephritis-associated autoantibody levels and the presence/activity of lupus nephritis and global disease activity using cross-sectional data in patients with systemic lupus erythematosus (SLE).

METHODS

Disease activity was assessed using the British Isles Lupus Assessment Group (BILAG) index. Antibody levels against single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), histones, nucleosomes and heparan sulphate (HS) were analysed by ELISA in SLE patients with (n=11) and without (n=22) nephritis and in normal controls (n=21). Antibody subclasses were also analysed.

RESULTS

Higher levels of anti-dsDNA and anti-HS antibodies were found in patients with lupus nephritis, the level of anti-HS antibodies correlating with the BILAG renal score. Predominant subclasses were IgG1 and IgG3 for dsDNA antibodies, IgG2 for anti-nucleosome antibodies, and IgG2 and IgG3 for anti-HS antibodies.

CONCLUSION

Correlation was demonstrated between antibodies to dsDNA, ssDNA, histones, nucleosomes and HS. There is a strong correlation between the level of anti-HS antibodies and disease activity in patients with lupus nephritis as measured by BILAG.

A human anti-dsDNA monoclonal antibody caused hyaline thrombi formation in kidneys of 'leaky' SCID mice

There are few studies assessing the pathogenicity of human monoclonal anti-DNA antibodies. The use of SCID mice avoids the problem of rejection of the human hybridoma cells thus allowing in vivo assessment of human immunoglobulins. Using electron microscopy we have shown that the human IgG anti-dsDNA monoclonal antibody, RH14, is nephritogenic in SCID mice, causing morphological changes in the kidney due to immunoglobulin deposition. The problem with using SCID mice is that they have an abnormal immune system; normally they are used at about 2 months of age, at which time they have virtually no functional T or B cells. It is known that older SCID mice become increasingly 'leaky', that is they develop some mature lymphocyte clones. Our aim was to assess if implanting anti-DNA antibodies into older 'leaky' SCID mice would result in pathology which was observable by light microscopy. Eight-month-old SCID mice were implanted with human hybridoma cells secreting either RH14 an anti-dsDNA IgG, CL24, an antiphospholipid antibody or an irrelevant human IgG control. As previously, RH14 deposited in the kidney and caused proteinuria but unexpectedly we also observed hyaline thrombi in the kidney glomeruli and peritubular capillaries. These thrombi occurred only in the case of RH14 implanted mice and were found to stain positively for human IgG and fibrin. However, apart from the interesting thrombi, we did not observe any greater pathological damage resulting from the anti-dsDNA antibody deposition than we had seen in the younger mice; indeed, the electron microscopic findings were more limited.

Molecular cloning and expression of the Fabs of human autoantibodies in Escherichia coli. Determination of the heavy or light chain contribution to the anti-DNA/-cardiolipin activity of the Fab

The Fabs of three human autoantibodies (B3/33H11, anti-DNA; UK4, anti-phospholipid) and six related hybrids have been cloned, expressed in Escherichia coli, and purified to homogeneity. SDS-polyacrylamide gel electrophoresis and Western blot analysis of the recombinant Fab demonstrated the purified Fab to be of correct size and in assembled form. Protein expression levels of up to 5-9 mg per liter of culture were achievable. A sensitive and reliable comparative anti-DNA enzyme-linked immunosorbent assay, involving a defined biotinylated 35-mer oligonucleotide in its single- or double-stranded form, is also described. Crithidia assay and anti-DNA or anti-cardiolipin antibody enzyme-linked immunosorbent assay analyses demonstrated convincing binding of the recombinant Fab proteins to DNA/cardiolipin, confirming the expression of functional molecule. The comparative DNA/cardiolipin binding analyses of the nine Fabs revealed that the anti-DNA (light, B3/33H11) or anti-cardiolipin (heavy, UK4) activity lies predominantly on one of the two chains. However, a compatible partner chain is necessary for optimum antigen binding activity of the antibody.

The prevalence of antibodies to anionic phospholipids in patients with the primary antiphospholipid syndrome, systemic lupus erythematosus and their relatives and spouses

OBJECTIVES

Antiphospholipid antibodies (aPL) have been associated with syndromes involving thrombosis, fetal loss and thrombocytopenia. Genetic and environmental conditions are among the factors attributed to the cause of autoimmune diseases such as the antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE). The aim of this study was to determine whether these factors determine the prevalence of aPL.

METHODS

Three groups of patients were tested for the presence of IgG, IgM and IgA anticardiolipin (aCL), antiphosphatidylinositol (aPI), antiphosphatidylglycerol (aPG) and antiphosphatidylserine (aPS) antibodies: (i) patients with primary APS (PAPS); (ii) patients with SLE and secondary APS; and (iii) patients with SLE without APS. First-degree relatives and spouses of patients with SLE/APS were also tested for circulating aPL.

RESULTS

IgG aPL were particularly prevalent in patients with PAPS. IgG aPI and aCL were more prevalent in patients with PAPS than the IgM equivalents (P < 0.0001). Notably, none of the patients with PAPS had IgA aPL. A significantly higher number of relatives of patients with SLE/APS possessed IgG aPL than the normal controls. Except for aPG (P < 0.03), the prevalence of these antibodies in the relatives was not significantly different from patients with SLE/APS. The relatives also had significantly higher prevalence of IgG aPI, aPS and aCL antibodies than IgM aPL antibodies. In contrast, the prevalence of IgG aPL in the spouses was no different than in the healthy controls.

CONCLUSIONS

Genetic factors, shared by patients and their relatives, seem to have some effect on the prevalence of aPL in the subjects studied, while environmental factors shared by spouses appear to have no influence.

Apoptosis in human autoimmune diseases

The description of apoptosis or programmed cell death nearly thirty years ago did not initially stimulate a great deal of interest. However, the ways cells die is clearly an essential part of biological homeostasis and well worth of study in its own right as the enormous literature on the subject in the past 15 years confirms. In the past decade new avenues of apoptosis research have opened up as the relationship between this form of cell death and autoimmune disease has come under increasing scrutiny. Although most research to date has been in animal study models, there are a variety of studies which have begun to explore links between apoptosis and a wider range of human autoimmune conditions. In this review we analyse briefly the background to what is known about apoptosis and focus on the increasing likelihood that abnormalities in apoptosis are contributory factors in the development of human autoimmunity.

Human monoclonal anti-phospholipid antibodies selectively bind to membrane phospholipid and beta2-glycoprotein I (beta2-GPI) on apoptotic cells

The ability of an anti-phospholipid (LJ1) and an anti-beta2-GPI (RSP-57) human MoAb to bind to apoptotic but not viable cells was demonstrated in this study. Both MoAbs were derived from patients with systemic lupus erythematosus and anti-phospholipid antibody syndrome. The parallel analysis of the specificity and affinity of four anti-phospholipid human MoAbs suggests that the binding of LJ1 MoAb to apoptotic cells is a specific property of this MoAb. RSP-57 MoAb recognizes apoptotic cells through beta2-GPI which becomes available for binding after the interaction with negatively charged phospholipids. This observation provides evidence that the binding of human anti-phospholipid antibodies to apoptotic cells occurs in both a beta2-GPI-dependent and independent way and involves a restricted group of epitopes. The finding that LJ1 and RSP-57 MoAbs bind apoptotic cells underlines the property of these MoAbs to act as cell membrane markers of apoptosis. Major pathological implications derive from the observation that LJ1 and RSP-57 MoAbs recognize epitopes expressed on 'early' apoptotic cells. The interference with the in vivo clearance and processing of apoptotic cells is a potential pathogenic mechanism of these antibodies.

The engineered human anti-tumor necrosis factor-alpha antibody CDP571 inhibits inflammatory pathways but not T cell activation in patients with rheumatoid arthritis

OBJECTIVE

We investigated the effect of an engineered human anti-tumor necrosis factor-alpha antibody, CDP571, on immune functions as well as bone and cartilage turnover in patients with rheumatoid arthritis (RA) in a placebo controlled trial. We also assessed the effects of repeated treatment with CDP571 in an open label continuation study.

METHOD

Thirty-six patients were treated with either placebo or 0.1, 1, or 10 mg/kg of CDP571 given as an intravenous infusion. The followup period was 8 weeks. Lymphocyte phenotype, soluble CD4 (sCD4), soluble interleukin 2 receptor (sIL-2R), IL-6, and stromelysin levels in the blood were measured before and after treatment; bone and cartilage markers (pyridinoline, deoxypyridinoline, N-terminal telopeptide) were similarly assessed in the urine. Patients who completed a placebo controlled trial of CDP571 were offered further treatment with CDP571. They received a maximum of 2 further doses of 1 mg/kg (7 patients) or 10 mg/kg (9 patients) in an open study.

RESULTS

Plasma IL-6 level was statistically significantly reduced in the 1 and 10 mg/kg groups. In the 10 mg/kg group, there were also reductions in plasma stromelysin and urine bone markers, although there was no change in sCD4 and sIL-2R levels. Repeat doses of CDP571 were well tolerated and continued to suppress the acute phase response and disease activity.

CONCLUSION

Treatment with 10 mg/kg of CDP571 reduced IL-6 and surrogate markers of bone turnover in RA, suggesting that CDP571 might prevent joint damage in RA. Since there was no effect on lymphocyte markers despite the marked reduction in inflammation, CDP571 appears to have no effect on ongoing CD4 T cell activation.

Anti-beta2-glycoprotein I, anti-prothrombin and anticardiolipin antibodies in a longitudinal study of patients with systemic lupus erythematosus and the antiphospholipid syndrome

OBJECTIVE

To determine anti-beta2 glycoprotein-I (anti-beta2GPI) and anti-prothrombin (anti-ProT) antibody levels, and the IgG subclass distribution of anti-beta2GPI antibodies, in serial samples from patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) having initial or recurrent thrombotic/neurological (T/N) events during the study period. To investigate the correlations between these antibodies and beta2GPI antigen, anticardiolipin antibody (aCL), anti-double-stranded (ds) DNA, C3 levels and disease activity.

METHODS

Fifty serum samples were identified from seven patients with SLE who had had T/N events during the follow-up from a cohort under long-term follow-up. IgG anti-beta2GPI, anti-ProT, aCL, IgG subclasses of anti-beta2GPI and beta2GPI antigen levels were determined by ELISA. Corresponding disease activity [British Isles Lupus Assessment Group (BILAG)], anti-dsDNA and C3 levels were compared.

RESULTS

IgG anti-beta2GPI antibody levels were elevated in six of the patients before and after the T/N events with less marked fluctuations than aCL antibody levels. The predominant subclass of anti-beta2GPI antibodies was IgG2 before and after the T/N events. IgG anti-ProT antibodies were negative in all cases. There was a significant but weak correlation between anti-beta2GPI and aCL antibodies. No correlation was found between disease activity and IgG anti-beta2GPI antibody and beta2GPI antigen levels. There were fluctuations in beta2GPI antigen levels and a trend to increase after T/N events was observed in some patients.

CONCLUSION

Most of the patients with a T/N event during the study period had IgG anti-beta2GPI, but not IgG anti-ProT antibodies. Many IgG aCL-negative samples were found to have IgG anti-beta2GPI activity during the follow-up period. The predominant subclass of IgG anti-beta2GPI was IgG2, which may have importance in the pathogenesis of APS. beta2GPI antigen levels were found to be increased in some patients with SLE after T/N events. IgG anti-beta2GPI antibodies may be used as an adjunctive marker of future T/N events in patients with SLE and APS with aCL antibodies and lupus anticoagulant.

Genetic, structural and functional properties of an IgG DNA-binding monoclonal antibody from a lupus patient with nephritis

Antibodies binding to double-stranded (ds) DNA are strongly associated with renal involvement in patients with systemic lupus erythematosus (SLE). We have generated two new IgG DNA-binding monoclonal antibodies (mAb), RH-14 and DIL-6, from the peripheral blood lymphocytes of two SLE patients with glomerulonephritis using the heteromyeloma cell line CB-F7. RH-14 is an IgG1 lambda antibody which also bound to single-stranded DNA, histones and nucleosomes. DIL-6 is an IgG3 lambda antibody with restricted antigen binding specificity. cDNA encoding the variable regions of the heavy (V(H)) and light (V(L)) chains of RH-14 was sequenced and the antigen binding site of this mAb was computer modelled. Sequence analysis of V(H) and V(L) regions of RH-14 showed that V(H) is derived from germ-line gene V3-7, a member of the V(H)3 family, and V(L) is derived from DPL 11, a member of the V(lambda)2 family. Somatic mutations and basic amino acid residues are identified in the complementarity-determining regions of both V(H) and V(L) regions. The nephritogenic properties of these mAb were analyzed by implanting and growing the hybridoma cells secreting the mAb in the peritoneum of SCID mice. The animals that received the RH-14 hybridoma produced higher levels of proteinuria (3 to > or = 4) (p < 0.001) compared to the groups that received DIL-6 (trace to > or = 1) or CB-F7 (trace). Electron microscopy of kidney sections from all the RH-14-implanted animals showed granular immunoglobulin deposition in the renal glomerular capillaries and mesangium. In this study we have shown for the first time using electron microscopy that a human IgG anti-dsDNA mAb, RH-14, is nephritogenic and that deposition of such an antibody alone is sufficient to induce renal damage.

The production, binding characteristics and sequence analysis of four human IgG monoclonal antiphospholipid antibodies

Antiphospholid antibodies (APL) have a notable association with recurrent miscarriages, arterial and venous thrombosis and thrombocytopenia. Analysis of the potential pathogenic effects of such human antibodies has been hampered by the considerable difficulty in producing IgG as opposed to IgM monoclonal immunoglobulins. We have developed four human monoclonal IgG APL (LJ1, AH2, DA3 and UK4) by fusing the peripheral blood lymphocytes of three patients with SLE with a mouse human heteromyeloma cell line, CB-F7. These antibodies bind to a variety of anionic phospholipids, two (LJ1 and AH2) bind total histones but none binds to ssDNA or dsDNA. Binding to beta 2 GPI is non-specific. UK4 alone demonstrates lupus anticoagulant activity. All four have lambda light chains, two are IgG1 (AH2 and UK4) and two are IgG3 (LJ1 and DA3). These APL utilize VH genes present in the fetally restricted repertoire and multiple somatic mutations in the CDR suggest an antigen-driven process. In contrast, there is no restriction in V lambda gene usage and only one lambda chain is extensively mutated. Two clonally related hybridomas were isolated from a single patients. This supports the theory that clonal expansion is the mechanism whereby antigen selects high affinity mutations.

Interplay of four idiotypes and interaction with autoantibodies in lupus patients, their relatives and their spouses

Our aim was to investigate links between systemic lupus erythematosus (SLE)-associated autoantibodies, idiotypes (Id) and genetic predisposition to their development. We studied four public Ids (16/6, WRI 176 beta, RT72 and RT84), identified the Km and Gm phenotypes and sought six selected autoantibodies in 32 SLE patients, 174 of their relatives and 15 spouses. Though anti-double-stranded DNA antibody was uncommon in the relatives (9%), the range of antinuclear reactivities was as broad in the relatives as in the probands. Antibodies to the synthetic peptide U1-RNP-A 35-38 were found in 56% of the patients, 28% of their relatives and 20% of the spouses, whereas antibodies to the Golgi apparatus was present in 7% of the patients, 26% of their relatives and 33% of the spouses. However, most of these family members were unaffected. RT84 Id was positively associated with antibodies to Sm-D peptide 1-20 and to Ro/SSA 60 kD peptide 304-324, but negatively associated with anti-dsDNA activity. The median of age was significantly lower in the RT84 Id-positive than in the RT84 Id-negative individuals. These data suggest that genetic as well as environmental factors are involved in the aetiology of SLE. In addition, RT84-carrying immunoglobulins (Ab2) might be directed to one of many cross-reactive Ids of dsDNA-binding antibodies (Ab1), perhaps down-regulating their production.

An analysis of apoptosis in lymphoid organs and lupus disease in murine systemic lupus erythematosus (SLE)

Apoptosis is a programmed cell death process that helps to regulate both T cell and B cell development. In this study, we have investigated the levels of apoptotic death in cells of the thymuses and spleens (white matter) of autoimmune MRL-lpr/lpr mice with progressive lymphadenopathy and SLE disease activity; we also examined the renal pathology in these animals. Fas is a cell surface receptor, which when activated initiates the sequence of events that lead to apoptosis. In MRL-lpr/lpr mice Fas is defective, so the competency for apoptosis may be reduced. In young animals of advancing age the thymuses enlarged until in 5-month-old females the average weight was three times that at 1 month, and spleen and kidney weights also increased in size disproportionately. At light microscope level apoptotic cells in tissue sections were counted using both routine eosin and haematoxylin staining (to identify them by their morphology) and in situ end-labelling of cells with DNA strand breaks; their presence was further confirmed by electron microscopy. As the mice aged, the numbers of apoptotic cells in thymic cortex, thymic medulla and spleen white pulp areas reduced significantly (P < 0.01-0.001), whereas in BALB/c normal controls they increased significantly (P < 0.05). These changes were coincident with the development of severe lupus, whose activity was assessed by measuring serum anti-ssDNA and anti-dsDNA antibody titres and urinary protein (albumin) level which were elevated significantly by 5 months of age (P < 0.001 for both ssDNA and dsDNA and P < 0.01 for urine albumin) compared with their younger counterparts. Thus, lymphoid organ enlargement, decrease in apoptotic indices, elevated serum anti-ssDNA and anti-dsDNA antibody levels, and impaired renal function coincided with the onset and severity of lupus disease in lpr mice. It seems likely that there is a causal relationship between defective deletion of autoreactive lymphoid cells, imperfect Fas-mediated apoptosis and development of murine SLE.

Diverse antigen specificity of erythrocyte-reactive monoclonal autoantibodies from NZB mice

The specificities of a panel of erythrocyte-reactive MoAbs derived from NZB mice with autoimmune haemolytic anaemia (AIHA) were determined by immunoprecipitation and immunoblotting. Of the eight antibodies, two (IgG1 MoAb 105-2H and IgG2a MoAb 34-3C) immunoprecipitated a 105-kD component identified as the erythrocyte anion channel band 3. A similar band was also immunoprecipitated by the IgG2b MoAb 34-2B when used at relatively high concentrations, but none of the remaining hybridoma antibodies precipitated any labelled erythrocyte components. In immunoblotting experiments only 34-2B reacted with band 3, indicating that the epitope recognized by this MoAb is robust and differs from the determinant(s) recognized by 105-2H and 34-3C. The remaining MoAbs to react by immunoblotting were the IgM antibodies IE10 and 4C8, both of which bound to a doublet corresponding to band 4.1 from the internal erythrocyte membrane skeleton. Of the three MoAbs which gave negative results in immunoprecipitation and immunoblotting, the IgM antibodies 103-7E and 106-10E reacted poorly with intact erythrocytes by flow cytometry, but the IgG1 antibody 31-9D bound well. ELISAs demonstrated that all four IgM MoAbs are polyreactive, since they bound to histones from a panel of nuclear antigens, and additionally 103-7E reacted with phosphatidyl choline. It is concluded that band 3 is an important autoantigen in NZB AIHA. However, since 3/5 haemolytic MoAbs failed to participate this antigen, either these antibodies represent minor components of the total autoantibody response, or responses to diverse possibly non-protein surface antigens also contribute to the pathogenesis of the disease.

Analysis of variable region genes encoding anti-Sm and anti-cardiolipin antibodies from a systemic lupus erythematosus patient

We have analysed the heavy and light chain variable region genes of two monoclonal antibodies, specific for the Sm antigen (RSP1; IgG kappa) and for cardiolipin (RSP4; IgM lambda), derived from a patient with active systemic lupus erythematosus (SLE). We have established that the variable region genes of the RSP1 autoantibody are somatic mutants of two germ line genes from the VH4 and V kappa 1 gene families. RSP4 antibody uses gene segments closely related to a VH3 gene member and to a V lambda 1 gene. The presence and distribution of the somatic mutations on both monoclonal autoantibodies are compatible with an antigen-driven immune process. These data suggest that in SLE a common antigenic stimulus may govern the autoantibody response against a wide spectrum of unrelated antigens, including native DNA, cardiolipin or Sm antigens, and provide further evidence that disease-associated autoantibodies are generated through antigen-selected somatic mutations.

Analysis of three new idiotypes on human monoclonal autoantibodies

We have identified and characterised three new idiotypes on human IgM McAbs generated from the splenocytes of a SLE patient with active disease. RT-6, which binds H1 and Sm/RNP, expresses essentially a private Id. Its expression is limited to a small number of human McAbs and the sera from patients with infectious diseases. In contrast RT-72Id and RT-84Id, expressed on McAbs which are polyreactive for two or more antigens, have a public distribution. RT-72Id and RT-84Id are found on McAbs from murine and human adult, and foetal tissues. In sera, significant numbers of SLE, RA and patients with other autoimmune diseases are positive for both Ids. RT-84Id is also elevated in SLE relatives and spouses, and in patients with Klebsiella infection. No correlation with disease activity, IgM or IgG levels was observed with either Id. However, RT-72Id was significantly associated with anti-ssDNA antibodies and RhF. RT-6Id and RT-72Id are located on the framework regions of the mu heavy chain, whereas RT-84Id is present on the kappa light chain, within the binding site. The McAbs are encoded by mainly germline genes: heavy chains of RT-6, RT-72 and RT-84 are encoded by the genes VH26, VH4.22 and VH4.21, respectively, and the light chain sequences of RT-6 and RT-72 are derived from DPL11 and HK102. Immunofluorescent staining revealed the presence of RT-72Id and RT-84Id positive immunoglobulin deposits in 18% and 45%, respectively, of the lupus renal sections compared with none in the disease control group, suggesting that these Ids may contribute to the pathology of the disease.

Phospholipid binding specificities and idiotype expression of hybridoma derived monoclonal autoantibodies from splenic cells of patients with systemic lupus erythematosus

OBJECTIVE

To analyse the phospholipid binding specificity, functional characteristics and idiotype expression of human hybridoma derived monoclonal autoantibodies (MAb) derived from the spleens of two patients with active systemic lupus erythematosus (SLE).

METHODS

The IgM MAbs binding to phospholipids were generated from spleen cells of two patients (RSP and RT) with active SLE and their specificity of binding to neutral phospholipids (phosphatidyl ethanolamine, phosphatidyl choline, platelet activating factor, sphingomyelin) and negatively charged phospholipids (phosphatidyl glycerol, phosphatidyl serine, phosphatidic acid, phosphatidyl inositol and cardiolipin (CL)) analysed. Binding specificity of cross reactive antibodies (those binding to CL and DNA) was confirmed by fluid phase inhibition assays. Lupus anticoagulant activity and beta 2-glycoprotein-1 (beta 2 GP-1) requirement for the antigen binding of these MAbs were detected using the modified dilute Russell's viper venom test and modified anti-CL enzyme linked immunosorbent assay (ELISA), respectively. Expression of idiotypes (Id) Id RT-84 and Id H3 was analysed using rabbit polyclonal and murine monoclonal anti-idiotype reagents, respectively.

RESULTS

Twelve clones from the patient RSP and eight clones from patient RT were reactive with phospholipids. Marked differences in phospholipid binding of these MAbs were noted, varying from truly polyreactive (RT-72 bound to most phospholipids tested) to monospecific (RT-84 bound only to CL). Furthermore, MAbs RT-84, RT-129, and RSP-57 had lupus anticoagulant activity and required beta 2 GP-1 for CL binding. It was found that 75% of phospholipid binding antibodies from RT clones expressed RT-84 Id, but none from RSP clones did so, and that Id H3 was expressed only by the RT-83 antibody.

CONCLUSION

These results show that human anti-phospholipid MAbs are heterogeneous with respect to phospholipid binding, functional characteristics, and Id expression.

Expression of a human fetal anti-DNA antibody idiotype BEG-2 beta in the families of patients with rheumatoid arthritis

BEG-2 is a monoclonal antibody produced by the human-human hybridoma technique from a 12 weeks old human fetus. A polyclonal antiserum was raised in an (NZW x Half-lop hybrid) rabbit against BEG-2 and the anti-BEG-2 anti-idiotype was purified and characterised. Using this rabbit reagent the expression of the BEG-2 beta idiotype was analysed in 12 patients with active rheumatoid arthritis and their close family members (n = 54). Twenty five sera from healthy controls were analysed to establish a normal range. Ten of 12 patients (83%) with rheumatoid arthritis expressed the BEG-2 idiotype as well as 11 of 54 healthy unaffected relatives (20%).

Effect of histone and histone-RNA complexes on the disease process of murine systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterised by the production of a variety of autoantibodies against cell surface, nuclear and cytoplasmic antigens. The antigen or antigens responsible for the induction of this disease is/are unknown. We have analysed the antigenicity and pathogenicity of free histones and histones complexed with RNA in Balb/c, B10 Br, C57BL/6 and MRL-lpr/lpr mice by giving 1 microgram and 25 micrograms of each antigen intraperitoneally in complete and incomplete Freund's adjuvant. The same number of control animals were injected with either adjuvant or PBS. In the initial experiment we gave three doses of antigen at three weekly intervals. B10 Brown and C57BL/6 mice had no response to the antigens. Balb/c mice developed a mild transient antibody response against H1 histone, branched peptide of ubiquitinated H2A (peptide T4) and also against ssDNA. However in repeated experiments when the histone-RNA complex was injected into young MRL-lpr/lpr animals at two weekly intervals, a significantly increased antibody response was detected against H1, peptide T4 and some histone peptide residues (204-218 of H1, 1-20 and 65-85 of H2A, 1-25 of H2B, 1-21 of H3 and 1-29 of H4) compared to the control groups. Moreover, this group also showed elevated serum anti-DNA antibody levels and early impairment of renal function assessed by the urine protein levels. These experiments have demonstrated that there is a genetic variation in antibody responses against histones and histone-RNA complexes and that histone-RNA complexes exaggerate the disease in young MRL-lpr/lpr mice by inducing antibodies to basic regions of histones and other autoantigens.

Utilization of the VH4-21 gene segment by anti-DNA antibodies from patients with systemic lupus erythematosus

A monoclonal antibody (9G4) which detects an idiotope (Id) rising from heavy chains encoded by the VH4-21 gene segment has been utilized to investigate the role of this gene in encoding anti-DNA antibodies in SLE. Two hybridomas secreting Id-positive anti-DNA antibodies were established from two patients with SLE, with one (RT-79) an IgM kappa and the other (D-5) IgG kappa. Nucleotide sequence analysis of the heavy chain variable regions revealed involvement of the VH4-21 gene; the IgM antibody used the gene in germ line configuration, whereas the IgG antibody had 18 nucleotide changes. The CDR3 sequences for both the antibodies had a predominance of basic amino acids, with RT-79 having five and D-5 two arginine residues respectively. The VH4-21 gene segment, often in germ line configuration, is also used by IgM autoantibodies against red cell Ii antigens. However, IgM from a panel of six hybridomas secreting antibodies of Ii specificity, had no detectable activity against DNA. Conversely, RT-79 had only a weak ability to agglutinate red cells. Comparisons of Ig variable regions indicate that the amino acids in the CDR3 region of the mu chain influence the ability of IgM encoded by the VH4-21 gene segment to discriminate between a carbohydrate Ii antigen and DNA, and strongly support the suggested role of arginine in interaction with DNA. Sera from patients with SLE were found to have significantly raised levels of Id which was expressed by anti-DNA antibodies against both ss and dsDNA.

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)

IgG subclasses in systemic lupus erythematosus and other autoimmune rheumatic diseases

In this study the concentration of the different subclasses of IgG in sera from patients with a range of autoimmune rheumatic diseases (ARD) was detected by radial immunodiffusion. In the second part the IgG subclasses of autoantibodies that recognize single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), Ro, La, Sm and RNP in patients with ARD were measured by enzyme-linked immunosorbent assay. We studied 15 patients with lupus, 20 patients each with primary and secondary Sjögren's syndrome (SS) and 10 each with rheumatoid arthritis (RA), scleroderma and myositis. Twenty healthy controls were also measured. The serum concentration of IgG2 in ARD patients was generally reduced. In contrast, the concentrations of IgG1, IgG3 and IgG4 subclasses were normal or raised. A high degree of correspondence in the IgG1, IgG2 and IgG3 responses to dsDNA and ssDNA in SLE was found. Notable differences in the IgG1 anti-Ro and ssDNA responses compared to the other subclasses were seen in 1 degree and 2 degrees SS. In addition, an unexpected high level of IgG4 antibodies to ssDNA in 1 degree SS (65%) and IgG4 antibodies to Sm/RNP in RA was observed.

Antigen-binding diversity of human hybridoma autoantibodies derived from splenocytes of patients with SLE

The antigen-binding specificity of human hybridoma-derived monoclonal autoantibodies (mAb) was analysed with mAbs derived from the spleens of two patients with active systemic lupus erythematosus (SLE). From one patient 72 mAbs (RSP clones) and from the other 173 mAbs (RT clones) were obtained. The binding specificity of these mAbs was analysed by solid- and fluid-phase ELISA against the autoantigens ssDNA, dsDNA, cardiolipin, SmRNP, histones, Sm-D and SS-B (La) synthetic peptides, and foreign antigens including bacterial polysaccharides. In addition, antinuclear antibody activity and anti-dsDNA binding were confirmed by fluorescence staining methods. Reflecting the patient's serological profile, none of the antibodies from the RSP clones reacted with ssDNA or dsDNA but 12 reacted with cardiolipin. In addition, three mAbs reacted with H4, five with U1 RNP, two with Sm-D peptides and 12 with SS-B peptides. In contrast, from the RT fusion, nine mAbs reacted with ssDNA, HI and SS-B peptides, seven with cardiolipin, four with dsDNA, two with Sm-D peptides and one each with H2A, H3 and H4. In many cases one mAb showed reactivity with more than one antigen: for example, mAb RT 72 binds to ssDNA, dsDNA, cardiolipin, H1, H4 and an Sm-D peptide; RT 6 binds to H1, SmRNP and ubiquitinated histone H2A. However, none of the antibodies showed 'across the board' polyreactivity; indeed, the selectivity of the reactions was notable and marked variation in antibody affinity was recorded. Eight of the mAbs bound to Salmonella typhimurium and two to the Klebsiella polysaccharide K-30.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of antibody reactivity in the sera of 42 patients with paraproteinaemia

The clinical expression of disease in patients with conditions in which autoimmunity is thought to contribute to the pathogenesis of disease is the result of an unfortunate combination of predisposing and environmental factors. The presence of autoantibodies showing a variety of antigen specificities in sera from many of these patients has been closely correlated with particular spectra of organ involvement or tissue destruction. Their precise role in the disease process is as yet unclear. Sera from patients with paraproteinaemia also often contain autoantibodies to a variety of cell components, although symptoms of autoimmune disease are rarely found in this group of individuals. In this study of 42 sera from patients with paraproteinaemia we have confirmed the presence of autoantibodies in 33% (13/42) of samples. Amongst the autoantibodies detected were those to human neutrophils (3), U1RNP (8) and cardiolipin (4). In five sera, the immunoglobulin class of autoantibody did not correlate with that of the monoclonal band. This study extends previous reports of the repertoire of autoantibodies present in sera from patients with paraproteinaemia.

Involvement in lupus disease of idiotypes Id.F-423 and Id.IV-228 defined, respectively, upon foetal and adult MRL/Mp-lpr/lpr DNA-binding monoclonal autoantibodies

The derivation of a monoclonal IgG3K autoantibody, designated F-423, from a foetal MRL/Mp-lpr/lpr mouse is described. It has immunochemical properties similar to DNA-binding monoclonal antibodies derived from adult mice with lupus disease in that it reacts with single-stranded DNA and, to a lesser extent, with double-stranded DNA and some forms of RNA. Its similarities to antibodies from adults extend further: it carries a public idiotype, Id.F-423, that can also be detected on antibodies from adult MRL and (NZB x NZW)F1 mice, and F-423 itself expresses other idiotypes defined originally on antibodies from adult lupus mice of both strains. Its potential involvement in pathological processes is demonstrated by two observations: (i) immunization of young MRL/Mp-+/+ mice with antibody F-423 induced the nephritic and immunological changes associated with systemic lupus erythematosus; and (ii) heterologous rabbit anti-Id.F-423 anti-idiotypic antibodies suppressed the progression of lupus disease in adult MRL/Mp-lpr/lpr mice. Similar effects were found with monoclonal antibody IV-228, an antibody derived from an adult MRL mouse and previously known to be directly nephrotoxic, and with anti-Id.IV-228 antibodies. It is concluded that even during foetal life mice of lupus-prone strains have lymphocytes capable of making pathogenic autoantibodies long before symptoms of lupus disease appear.

Detection of human and murine common idiotypes of DNA antibodies in tissues and sera of patients with autoimmune diseases

The expression in tissue and serum of a panel of murine and human common DNA antibody idiotypes (Ids) (BEG 2, PR 4, F-423, I-402, II-28, IV-228, V-88) has been investigated. The murine V-88 Id was detected in eight out of 10 and the human BEG 2 Id in five out of 10 labial biopsies from patients with Sjögren's syndrome. The murine F-423, I-402 and IV-228 Ids were identified in one out of 10 biopsies. In each case the pattern of staining was similar with staining of the acinar basement membrane and a cell population. Using double-labelling immunohistochemistry this cell population were identified as plasma cells. No staining was seen in four normal labial biopsies. The V-88 Id was detected on the epithelial aspect of the thickened basement membrane in three out of nine renal biopsies from patients with systemic lupus erythematosus (SLE). None of the other Ids (BEG 2, PR4, IV-228, F-423 or I-402) could be detected in renal tissue. None of the Ids were found in skin biopsies from SLE patients. Id V-88 may, like the 16/6 Id to which it is phenotypically related, play a role in the pathogenesis of renal lesions in SLE. The BEG 2 Id could be detected in the serum of patients with rheumatoid arthritis (RA) and active untreated tuberculosis. Ids II-28, V-88 and I-402 were elevated in serum from patients with Sjögren's syndrome and II-28 Id in serum from patients with myositis and RA. None of the Ids were elevated in serum from patients with SLE. Apart from the BEG 2 Id, none of the Ids were elevated in serum from patients with tuberculosis or Gram-negative infections. The presence of murine Ids in human tissue and serum suggests that they are cross-species idiotypes and have been conserved through evolution.

A human fetal monoclonal DNA-binding antibody shares idiotypes with fetal and adult murine monoclonal DNA-binding antibodies

A human DNA-binding monoclonal antibody was produced by fusing the hepatocytes from a 12-week-old human fetus with the lymphoblastoid cell line GM 4672 using polyethylene glycol. This antibody, designated BEG 2, binds to single-stranded (ss) DNA but also binds to double-stranded (ds) DNA, poly(dT), polyI and poly(ADP-ribose), but not to RNA, cardiolipin or K-30. The binding of BEG 2 to these polynucleotides can be inhibited by incubation with polynucleotides in the fluid phase. A rabbit polyclonal anti-idiotype was raised, and using this reagent it was shown that the BEG 2 idiotype is present in normal human serum (7%), systemic lupus erythematosus (SLE) sera (8%) and rheumatoid arthritis sera (23%). The extent of idiotypic sharing between BEG 2 and murine monoclonal DNA-binding antibodies, in particular monoclonal antibody (mAb) 423 (derived from a 15-day-old fetal MRL/Mp-lpr/lpr mouse) and mAb 402 (derived from an adult MRL/lpr mouse), was also investigated. Using a competition ELISA, it was shown that preincubation of BEG 2 with rabbit anti-423 and rabbit anti-402 inhibits the binding of BEG 2 to DNA, and the binding of 402 to DNA by anti-BEG 2 and anti-423. These data suggest that mAb BEG 2, 423 and 402 share common idiotypes, that autoreactivity is present in early fetal life, and that autoantibodies may be encoded for by germline genes, which have been conserved through evolution.