Serum levels of autoantibodies against C-reactive protein correlate with renal disease activity and response to therapy in lupus nephritis

Introduction  

Serum levels of C-reactive protein (CRP) seldom reflect disease activity in systemic lupus erythematosus (SLE). We have previously shown that autoantibodies against neo-epitopes of CRP often occur in SLE, but that this does not explain the modest CRP response seen in flares. However, we have repeatedly found that anti-CRP levels parallel lupus disease activity, with highest levels in patients with renal involvement; thus, we aimed to study anti-CRP in a material of well-characterized lupus nephritis patients.     

Lupus serum and normal human serum contain anti-DNA antibodies with the same idiotypic marker

We have previously shown that serum from patients with active SLE contain high levels of Id-16/6 and anti-DNA antibodies. In this study we investigated whether serum Id 16/6 is related to anti-DNA antibodies. Sera from 12 patients with active SLE were absorbed individually with poly(dT) cellulose (to purify anti-DNA antibodies) and rabbit (R) anti-Id-16/6 Sepharose (to purify Id 16/6 Ig). Removal of all anti-DNA activity removed most of the Id-16/6. Conversely, removal of all Id 16/6 removed most of the anti-DNA activity. Although there was no measurable anti-DNA antibody activity in normal serum, such antibodies were isolated by absorption with poly(dT) cellulose. The eluted immunoglobulins also had Id 16/6 activity. Similarly, Id 16/6 with anti-DNA activity were isolated from normal serum by absorption with R anti-Id 16/6 Sepharose. We conclude that a large fraction of anti-DNA antibodies in SLE serum are Id-16/6+, and that most Id 16/6 immunoglobulins in lupus serum have anti-DNA activity. Our observations suggest that lupus anti-DNA antibodies result from an overproduction of autoantibodies that are present in normal people.     

Autoantibodies from patients with systemic lupus erythematosus can affect DNA and RNA synthesis in cultured cells

Sera reacting positively for anti-DNA antibodies from systemic lupus erythematosus (SLE) patients were tested for their effect on DNA and RNA synthesis in permeabilized cultured cells and isolated nuclei. The immunoglobulin fraction obtained by ammonium sulfate precipitation of serum was shown to exert considerable influence on DNA and RNA synthesis in cultured cells and nuclei. A component of this antibody population is anti-DNA. These antibodies exert different effects on DNA template activity which is a function of their conformational specificity. Intracellular penetration of autoantibodies as noted in SLE may be one of the reasons for clinical manifestations of disease in these patients.     

血β2微球蛋白水平在系统性红斑狼疮中的临床意义

目的：探讨系统性红斑狼疮（systemic lupus erythematosus,SLE）患者血β2-MG水平与疾病活动的相关性及其临床意义。方法：随机抽取2012年2月-2012年7月我科收治的62例SLE患者（SLE组）和同期在我院门诊体检的健康体检者40例（对照组）,检测和比较两组血清β2-MG、自身抗体、补体水平,并对SLE患者进行SLEDAI评分,分析SLE患者血清β2-MG水平与自身抗体、补体水平和SLEDAI评分的相关性。结果：SLE组血β2-MG水平（3．11±0．40μg／mL）显著高于对照组（2．23±0．23μg/mL）,差异有统计学意义（P〈0．05）;其中发生口腔溃疡、浆膜炎及蛋白尿的SLE患者的血β2-MG水平与无此三种表现的患者相比显著升高,差异有统计学意义（P〈0．05）。SLE患者的血β2-MG水平与抗ds—DAN抗体、SLEDAI均呈显著正相关（分别为r=0．289,r=0．361,P〈0．01）,与C3呈负相关（r=-0．271,P〈0．05）。结论：SLE患者血β2-MG水平高于正常,可作为SLE疾病活动指标用于监测疾病活动。     

A conserved anti-DNA antibody idiotype associated with nephritis in murine and human systemic lupus erythematosus

In order to identify unique structural features of pathogenic autoantibodies to DNA in SLE, a murine anti-anti-DNA (anti-Id) mAb (mAb 1C7) was produced in response to immunization of lupus mice with a syngeneic anti-DNA mAb (mAb 3E10). Immunization of lupus mice with mAb 3E10 inhibited production of native anti-DNA antibodies, suppressed development of lupus kidney disease (nephritis), and induced production of anti-anti-DNA (anti-Id) antibodies. mAb 1C7 bound F(ab')2 fragments of mAb 3E10, and it bound other murine anti-DNA mAb, but not murine mAb or polyclonal serum antibodies unreactive with DNA. Moreover, binding of mAb 1C7 anti-Id to mAb 3E10 was inhibited by DNA, suggesting anti-Id binding within or near the binding site for DNA. Furthermore, mAb 1C7 bound serum IgG immunoglobulins from 9/12 patients with lupus nephritis and serum anti-DNA antibodies compared to only 3/12 SLE patients with comparable serum levels of anti-DNA antibodies, but without nephritis (p = 0.04), and only 1/53 SLE patients without serum anti-DNA antibodies, 0/49 patients with rheumatoid arthritis, and 1/47 healthy subjects (p less than 0.001). These results provide evidence that mAb 1C7 identifies a conserved Id associated with anti-DNA antibodies in murine and human SLE and may be useful as a structural probe to characterize pathogenic anti-DNA antibodies in SLE.     

Anti-C1q Antibodies as a Follow-Up Marker in SLE Patients

In cross-sectional studies autoantibodies against complement C1q (anti-C1q) were found to be highly associated with active lupus nephritis. The aim of this retrospective study was to determine the value of anti-C1q as follow-up marker of disease activity and renal involvement in patients with systemic lupus erythematosus (SLE). Fifty-two patients with SLE and a minimum of three anti-C1q measurements during follow-up were analyzed. Anti-C1q levels correlated with global disease activity scores. In subgroup analyses, patients without renal involvement did not show a significant correlation between anti-C1q levels and disease activity. In contrast, in patients with renal involvement, anti-C1q levels correlated well with global disease activity. In addition, a positive correlation with the urine protein-to-creatinine ratio and anti-dsDNA antibody levels as well as a negative correlation with complement levels was observed. Anti-C1q antibodies were found to strongly correlate with parameters of SLE disease activity during follow-up, in particular with regard to renal involvement.     

系统性红斑狼疮患者血清MBL水平变化及其临床意义

目的：研究系统性红斑狼疮（SLE）患者外周血中甘露糖结合凝集素（MBL）水平与SLE的临床表现、经典的血清学指标及疾病活动性指数的相关性。方法：应用固相酶联免疫吸附（ELISA）法检测54例（其中活动期39例、缓解期15例）SLE患者和45名健康志愿者外周血MBL水平,同时检测SLE患者外周血抗dsDNA抗体、C3补体、白细胞计数及循环免疫复合物（CICs）水平,并记录SLE患者主要临床症状（肾脏系统受累、神经系统受累、严重感染等）,疾病活动度用SLEDAI记分。结果：系统性红斑狼疮患者外周血MBL水平显著低于健康志愿者（P〈0．01）;特别是活动期SLE患者血清MBL水平明显降低,与缓解组比较差别具有统计学意义（P〈0．01）;SLE患者血清MBL水平与SLEDAI、抗dsDNA抗体、CICs水平呈负相关,与白细胞计数及C3补体水平呈正相关;并发严重感染的SLE患者组血清MBL水平显著低于无受累组（P〈0．01）。结论：SLE患者血清MBL水平明显降低,血清MBL水平与SLEDAI、抗dsDNA抗体、C3水平、CIC水平、白细胞水平之间明显相关,血清MBL水平较低的患者更易发生比较严重的感染,血清MBL水平可能是SLE潜在生物学标记。     

Detection of masked anti-DNA antibodies in lupus sera by a monoclonal anti-idiotype

We report here the use of a monoclonal anti-idiotype 3I to human anti-DNA antibodies to detect in serum idiotype-positive antigen-binding antibodies lacking DNA-binding activity as measured by conventional antigen binding assays. We studied paired serum samples from 13 patients with systemic lupus obtained at two times in the course of their disease: in each patient, one serum sample has anti-DNA activity and the second serum sample has no anti-dsDNA activity detectable by Millipore filter, ELISA, or Crithidia assay. Reactivity with 3I as detected with a radioimmunoassay (RIA) was present in all 13 sera with anti-dsDNA activity. Six patients showed a decrease in 3I reactivity to normal levels in the second serum sample, in which anti-dsDNA antibodies were not detectable by conventional antigen-binding assays. The other seven patients' second serum sample continued to show elevated 3I reactivity by RIA even though no anti-dsDNA activity was apparent. When the 3I-reactive antibodies from these latter patients' sera were eluted from a 3I affinity column, they revealed DNA-binding activity. Furthermore, dsDNA binding by these sera was apparent when they were displayed on Western blots of isoelectric focusing gels run in 8 M urea and incubated with radiolabeled dsDNA. These results indicate that the 3I anti-idiotype can detect anti-DNA antibodies in some sera of SLE patients that lack anti-DNA activity by ordinary assays. These antibodies may be inhibited in binding dsDNA by excess antigen or autologous anti-idiotype, and their DNA binding activity can be unmasked by procedures promoting immune complex dissociation.     

Adhesive force behavior of single ATDC5 cells in chondrogenic culture

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease affecting many organs. Many autoantibodies have been associated with the disease, but either in low specificity or low sensitivity of detection. In an aim to screen for better autoantibodies, we profiled the autoantibody repertoire in sera from 30 SLE patients versus 30 healthy controls using a protein microarray containing 5011 non-redundant human proteins, and identified four candidates. We then selected CLIC2 for further verification by ELISA in an extended cohort including 110 SLE, 121 non-AD, 118 RA, 117 SSc, and 105 pSS patients. The positive rate of anti-CLIC2 was 28.18% in SLE patients, significantly higher than those in non-AD, RA, and SSc patients. The presence of anti-CLIC2 in SLE had positive correlation with disease activity in terms of SLEDAI score and several indexes (p<0.05).     

Use of anti-idiotypic antibodies to explore genetic mechanisms of production of anti-DNA antibodies

Systemic lupus erythematosus (SLE) is characterized by the production of autoantibodies with a broad range of antigenic specificities, including specificity for double-stranded DNA. Analysis of the idiotypic profile of anti-DNA antibodies both in humans and mice has demonstrated presence of cross-reactive idiotypes, suggesting that they arise from a restricted number of germline genes. Our laboratory has previously reported the generation of 3I, a monoclonal anti-idiotypic antibody which recognizes a cross-reactive idiotype on anti-DNA antibodies in a majority of unrelated humans with SLE. We have recently studied the expression of 3I in sera of three human kindreds with familial SLE. We found 6 of 8 SLE patients and 15 of 19 unaffected family members had elevated 3I reactivity. Eleven of these family members had no anti-DNA activity despite elevated 3I reactivity, suggesting that expression of this idiotype in certain individuals is part of the normal immune response. In another set of experiments using an in vitro culture system we examined somatic mutants of the S107 mouse myeloma cell line. This line makes an antibody which bears the T15 idiotype, a common idiotype on antibodies to the bacterial antigen phosphoryl choline (PC). U4, a mutant, makes an immunoglobulin which varies by one amino acid from the parent protein, retains the T15 idiotype, but loses reactivity with PC and acquires reactivity with DNA. We have found that some anti-DNA antibodies in mice with spontaneous lupus and in mice immunologically induced to make anti-DNA antibodies bear the T15 idiotype and may represent somatic mutants arising in vivo.     

Specific and shared idiotypes found on hybridoma anti-DNA autoantibodies derived from rheumatoid arthritis and systemic lupus erythematosus patients

The idiotype determinants found on hybridoma anti-DNA autoantibodies produced from the fusion of peripheral blood lymphocytes from 13 systemic lupus erythematosus (SLE) and five rheumatoid arthritis (RA) patients with the GM 4672 human lymphoblastoid line were analyzed. A total of 47 SLE and 21 RA hybridomas were studied, of which 26 SLE and 10 RA produced anti-DNA autoantibodies. Rabbit antisera, raised to six of the SLE hybridoma anti-DNA IgM antibodies, were rendered idiotype specific by multiple absorptions on human IgM and IgG immunoabsorbent columns. In direct binding radioimmunoassays, all six anti-idiotype antisera reacted specifically with the anti-DNA antibody used as immunogen. In competition studies, five anti-idiotype antisera were able to inhibit the binding of their homologous idiotype to DNA-coated tubes. In addition, DNA and polynucleotides inhibited the binding of the five idiotypes to anti-idiotype-coated tubes, suggesting that these anti-idiotypes react with idiotype determinants located within the antigen-combining sites of the anti-DNA antibody molecules. Shared idiotypes were detected among the 68 hybridoma antibodies by direct binding studies on anti-idiotype-coated tubes. Our results revealed that 58% (21/36) of the anti-DNA antibodies and 16% (5/32) of the non-DNA-binding antibodies reacted with at least one anti-idiotype serum. Five anti-idiotype antisera reacted only with hybridoma anti-DNA antibodies from SLE patients. The other anti-idiotype antiserum reacted with both SLE- and RA-derived hybridoma anti-DNA and non-DNA-binding antibodies. These studies indicate that some anti-idiotype antisera may detect specific idiotypes found only on SLE-derived anti-DNA auto-antibodies, whereas other antisera detect shared idiotypes found on both RA and SLE DNA-binding and non-DNA-binding antibodies.     

Elevated Concentrations of Serum Immunoglobulin Free Light Chains in Systemic Lupus Erythematosus Patients in Relation to Disease Activity,Inflammatory Status,B Cell Activity and Epstein-Barr Virus Antibodies

Objective

In this study, we examined the concentration of serum immunoglobulin free light chains (FLCs) in systemic lupus erythematosus (SLE) patients and investigated its association with various disease parameters in order to evaluate the role of FLCs as a potential biomarker in SLE. Furthermore, FLCs’ association with Epstein-Barr virus (EBV) antibodies was examined.

Methods

Using a nephelometric assay, κFLC and λFLC concentrations were quantified in sera from 45 SLE patients and 40 healthy controls. SLE patients with renal insufficiency were excluded in order to preclude high concentrations of serum FLCs due to decreased clearance.

Results

Serum FLC concentrations were significantly elevated in SLE patients compared to healthy controls (p<0.0001) also after adjusting for Ig levels (p<0.0001). The concentration of serum FLCs correlated with a global disease activity (SLE disease activity index (SLEDAI)) score of the SLE patients (r = 0.399, p = 0.007). Furthermore, concentrations of FLCs correlated with titers of dsDNA antibodies (r = 0.383, p = 0.009), and FLC levels and SLEDAI scores correlated in the anti-dsDNA-positive SLE patients, but not in anti-dsDNA-negative SLE patients. Total immunoglobulin (IgG and IgA) concentrations correlated with FLC concentrations and elevated FLC levels were additionally shown to associate with the inflammatory marker C-reactive protein and also with complement consumption determined by low C4 in SLE patients. Collectively, results indicated that elevated serum FLCs reflects increased B cell activity in relation to inflammation. SLE patients had an increased seropositivity of EBV-directed antibodies that did not associate with elevated FLC concentrations. An explanation for this could be that serum FLC concentrations reflect the current EBV activity (reactivation) whereas EBV-directed antibodies reflect the extent of previous infection/reactivations.

Conclusion

SLE patients have elevated concentrations of serum FLCs that correlate with global disease activity scores and especially serologic markers for active disease. These findings are suggestive of circulating FLCs having potential as a new supplementary serologic biomarker in SLE.     

Association between anti-Sm and anti-ribosomal P protein autoantibodies in human systemic lupus erythematosus and MRL/lpr mice

Anti-Sm and anti-ribosomal P protein antibodies show a high degree of specificity for the disease SLE. To determine whether a relationship between these two autoantibodies existed, the frequency of anti-P was determined in sera with and without anti-Sm activity. Of sera from lupus patients with anti-Sm 18/65 (28%), and 6/55 (11%) of sera without anti-Sm had anti-P as determined by an ELISA using a recombinant P2-beta-galactosidase fusion protein as Ag (p less than 0.05). The levels of anti-P were significantly higher in sera containing anti-Sm (0.37 +/- 0.45) than in sera without anti-Sm antibodies (0.18 +/- 0.20) (p less than 0.01). Similarly, a significantly higher proportion of anti-P positivity was found in autoimmune MRL/Mp-lpr/lpr mice positive for anti-Sm (11/53 = 21%) compared to age- and sex-matched mice without anti-Sm (3/53 = 6%) (p less than 0.05). The IgG subclass distributions for anti-Sm and anti-P antibodies were similar in the MRL mice (IgG2a greater than IgG2b greater than IgG3 greater than IgG1). The association did not reflect polyclonal B cell activation in a proportion of MRL mice because no significant differences were observed in anti-DNA, antichromatin or total serum IgG levels in mice with and without anti-Sm or, in mice positive for both anti-P and anti-Sm compared to mice positive for anti-Sm alone. Cross-inhibition experiments excluded the possibility that the Sm and P protein Ag shared a common epitope. Longitudinal measurement of anti-P and anti-Sm antibody levels by ELISA in three mice indicated that both antibodies first appeared at about 3 to 4 mo of age and fluctuated two- to threefold over 3 to 8 mo with independent peaks of activity. Recent observations regarding a relationship between anti-Sm and autoantibodies to other ribosomal proteins suggest that the association may be explained by an immune response to epitopes coassociated on the ribosome.     

The role of anti-α-actinin antibodies in the pathogenesis and monitoring of lupus nephritis

Antibodies to double-stranded DNA are important in the pathogenesis of nephritis, a major clinical manifestation in lupus patients. Since earlier diagnosis of renal involvement may lead to better outcomes, identification of the nephritogenic specificity of lupus-associated autoantibodies is important in understanding the disease, while monitoring their titer clinically may serve as an improved biomarker. Based upon work in animal models and cross-sectional human studies, kidney α-actinin was thought to be a plausible cross-reactive target for pathogenic lupus antibodies. Manson and colleagues longitudinally evaluated anti-nucleosome, anti-DNA, and anti-α-actinin antibodies in 16 lupus patients with new-onset nephritis. While anti-nucleosome and anti-DNA antibody levels were significantly associated and correlated with measures of kidney disease, these were not found to be significant with anti-α-actinin antibodies. While in lupus patients the diagnostic use of serum anti-α-actinin antibodies, alone or with other novel biomarkers, is still under investigation, such studies are vital in improving our monitoring of systemic lupus erythematosus patients and in developing new treatment paradigms that meet the continuing clinical challenge of lupus nephritis.     

Anti-histone antibodies in idiopathic and drug-induced lupus recognize distinct intrahistone regions

We have identified regions within core histones that are antigenic for autoantibodies in systemic lupus erythematosus (SLE) and drug-induced lupus. An immunoblotting technique was used to determine the reactivity of lupus antibodies for intact histones and for trypsin-resistant histone fragments that lack the amino- and carboxyl-terminal amino acids that are normally exposed in native nucleosomes. In SLE, the predominant anti-histone response was restricted to epitopes in the trypsin-sensitive regions. Of 20 SLE sera that had strong antibody activity for multiple intact histones, 17 showed minimal activity with any of the corresponding trypsin-resistant fragments. A markedly different pattern of reactivity was present in sera of patients with procainamide (Pr)-induced lupus in which antibodies to H2A, H2B, and the H2A-H2B complex had strong fragment activity. Interestingly, recognition of trypsin-resistant fragments was also noted in a small number of SLE sera that contained antibodies to the H2A-H2B complex. In contrast to both SLE and Pr-induced lupus, antibodies induced by hydralazine (Hy) reacted primarily with H3 and H4. Furthermore, these antibodies bound equally well to the corresponding trypsin-resistant regions that are thought to be relatively unexposed in native nucleosomes. Thus, the specificities of anti-histone antibodies in SLE, Pr-induced lupus, and Hy-induced lupus are markedly different, but in each disease reactivity appears to be restricted to a limited number of histone determinants. The data raise the possibility that autoantigen in the form of native nucleosomes may be recognized in SLE and possibly in Pr-induced lupus. In contrast, the propensity of Hy to induce autoantibodies to determinants usually not recognized in SLE or Pr-induced lupus may suggest a different immunogenic stimulus in this disease.     

Pathogenic idiotypes of autoantibodies in autoimmunity: lessons from new experimental models of SLE

Systemic lupus erythematosus (SLE) is considered a classical autoimmune disease that involves many biological systems. Similar to other autoimmune conditions, its etiology is multifactorial entailing genetic, environmental, hormonal, and immunologic factors. In this review we demonstrate that by using a pathogenic idiotype of anti-DNA autoantibodies, it is possible to explain some of the pathogenesis and diversity of clinical and serological manifestations reported by SLE patients. The 16/6 idiotype (Id) is a representative pathogenic idiotype of anti-DNA autoantibodies. The serum titers of 16/6 Id in SLE patients correlate with clinical activity of the disease, and are deposited in afflicted tissues in SLE patients. SLE was experimentally induced in naive mice after immunization with 1 microgram of the Id. The disease is characterized clinically (proteinuria), serologically (e.g., anti-dsDNA, anti-Sm antibodies), and by pathological findings (e.g., deposition of 16/6 Id in the kidneys). The condition can be induced by other human and mouse antibodies carrying the 16/6 Id, as well as by mouse antimonoclonal-16/6 Id and by T cell lines and clones specifically reactive with 16/6 Id. There are strain-dependent differences in susceptibility to the induction of systemic lupus erythematosus (SLE). Induction of SLE is directly correlated with the ability to respond to the 16/6 idiotype (or 16/6 Id)2 by anti-Id antibody production. It is easier to induce the disease in females, and it can be modulated by manipulation of sex hormones. Being able to identify the pathogenic idiotype allowed us to generate T suppressor (Ts) cells specific for the 16/6 Id. Treatment of mice with these T cells abrogated the disease. Our studies point to the importance of pathogenic idiotypes of autoantibodies in autoimmunity, which suggests that SLE may represent a dysregulation of a functional network of idiotypes-anti-idiotypes interactions among autoreactive B cells, T helper cells, and T suppressor cells.     

Anti-RNP monoclonal antibodies derived from a mouse strain with lupus-like autoimmunity

systemic lupus erythematosus (SLE) and related rheumatic and connective-tissue diseases are often associated with the production of antibodies directed against a variety of specific cellular components. Recent evidence indicates that two such autoantigens, the Sm and RNP antigens recognized by SLE sera, exist in small ribonucleoprotein complexes found in the nuclei of higher eukaryotes. Studies of the structure and function of these autoantigenic particles with human sera used as probes have been limited because of the multiplicity of autoantibodies often found in an individual serum. Through this communication, we report that MRL/Mp-+/+ (MRL/n) mice, which spontaneously develop a disease exhibiting many of the characteristics of human SLE, possess anti-RNP antibodies in addition to anti-Sm and anti-DNA as previously reported. Spleen cells from one such autoimmune mouse were used to produce a stable hybridoma secreting antibodies that react simultaneously with a protein of Mr 40,000 and a doublet of approximately 70,000, a pattern of reactivity identical to and characteristic of human SLE anti-RNP autoantibodies.     

系统性红斑狼疮患者血清中CD83与自身抗体的表达及其相互关系

目的：检测系统性红斑狼疮（systemic lupus erythematosus,SLE）患者血清中CD83（soluble CD 83,sCD 83）和多种自身抗体的表达水平,并探讨其相互关系。方法：ELISA检测患者可溶性CD 83和AnuA的表达,应用间接免疫荧光的方法检测抗cmDNA抗体,应用乳凝法检测血清中的DNP,采用胶体金标记和快速膜渗滤技术测定血清中的抗dsDNA抗体。结果：对照组患者血清中可溶性CD 83的表达为（0.26±0.10）ng/ml,实验组患者血清中可溶性CD 83的表达为（5.56±0.72）ng/ml。与对照组相比,实验组患者血清中可溶性CD 83的平均浓度明显升高。在抗dsDNA抗体阴性的51例系统性红斑狼疮患者中AnuA的阳性率明显高于抗DNP抗体和抗cmDNA抗体,同样在抗DNP抗体阴性的58例系统性红斑狼疮患者中AnuA的阳性率明显高于dsDNA抗体和抗cmDNA抗体。系统性红斑狼疮患者中可溶性CD83的水平（〈2.68 ng/ml）与各种自身抗体（抗dsDNA抗体、AnuA、抗DNP抗体和抗cmDNA抗体）水平的相关系数分别为（r=0.542,0.613,0.489和0.367）。具有高水平可溶性CD83的系统性红斑狼疮患者（≥2.68 ng/ml）,与各种自身抗体（抗dsDNA抗体,AnuA,抗DNP抗体和抗cmDNA抗体）水平的相关系数分别为（r=0.711,P〈0.05）、（r=0.845,P〈0.01）、（r=0.862,P〈0.01）和（r=0.724,P〈0.051）。结论：可溶性CD83通过活化DC细胞并激活补体系统,参与系统性红斑狼疮的发生发展,联合可溶性CD83和多种自身抗体的检测,能更明确系统性红斑狼疮患者病情的严重程度,有利于SLE的诊断和治疗。     

Expression of anti-idiotypic clones against auto-anti-DNA antibodies in normal individuals

A serum pool from 280 blood donors and individual samples from blood donors were assayed for anti-idiotypic activity to auto-anti-DNA antibodies by competitive radioimmunoassays. We found that serum from several normal blood donors inhibited the binding activity of anti-DNA antibodies affinity purified from the sera of patients with systemic lupus erythematosus. This inhibition was due to immunoglobulin molecules but was not due to rheumatoid factor activity. Antiallotypic antibodies were not responsible for the anti-anti-DNA activity detected. Because this inhibition was blocked by DNA molecules, the observed reactivity was probably caused by idiotype-anti-idiotype interactions. These results provide evidence that anti-idiotype antibodies against anti-DNA autoantibodies are present in certain normal human sera. Anti-anti-DNA antibodies could play a role in the regulation of autoimmunity to DNA.     

Detection of cross reactive anti-DNA antibody idiotypes on tissue-bound immunoglobulins from skin biopsies of lupus patients

Cross-reactive anti-DNA antibody idiotypes have been identified on tissue-bound immunoglobulins from skin biopsies of patients with systemic lupus erythematosus (SLE) and discoid lupus erythematosus (DLE). Four polyclonal and two monoclonal anti-idiotypic reagents were used to screen biopsies from 24 patients with SLE, 23 patients with DLE, and 15 other patients with IgM-positive skin biopsies. Up to 46% of the SLE patients and 30% of the DLE patients were found to share idiotypes present on immunoglobulins deposited at the dermal-epidermal junction. Inhibition studies in four patients indicated that the idiotypes were on anti-DNA antibodies. In contrast, none of the anti-idiotypic antibodies bound to any of the control biopsies. These findings imply that some tissue-bound autoantibodies are derived from related families of high-frequency germ-line genes that are expressed in both SLE and DLE.