Increased levels of autoantibodies against copper-oxidized low density lipoprotein, malondialdehyde-modified low density lipoprotein and cardiolipin in patients with rheumatoid arthritis

OBJECTIVES

To analyse the association of autoantibodies against cardiolipin (CL) and oxidized low density lipoproteins [copper-oxidized low density lipoprotein (oxLDL), malondialdehyde-modified LDL (MDA-LDL)] with rheumatoid arthritis (RA) and cardiovascular complications.

METHODS

One hundred and twenty-one patients with RA were consecutively included. Autoantibodies were determined by ELISA. Healthy individuals from the same region were used as controls.

RESULTS

Levels of IgG, IgM and IgA antibodies against MDA-LDL and CL, as well as IgG and IgA antibodies against oxLDL were increased in the patients (P<0.01). The prevalence of IgG, IgM and IgA antibodies against CL was higher than in the normal population (74, 82 and 14%, respectively). The prevalence of IgG and IgA antibodies against oxLDL was also significantly increased (35 and 25%, respectively) and so was the prevalence of IgG and IgM antibodies against MDA-LDL (17 and 26%, respectively) compared with controls. The levels of IgM and IgA antibodies against aCL and IgM against MDA-LDL were increased in patients with extra-articular manifestations. Patients who developed myocardial infarction had a higher prevalence of IgG antibodies against MDA-LDL (P=0.04). There were substantial correlations between the levels of antibodies against oxLDL, MDA-LDL and CL.

CONCLUSIONS

RA patients had increased levels and prevalence of autoantibodies against CL, oxLDL and MDA-LDL, with associations to severity of disease and cardiovascular complications.

Anticardiolipin and anti-beta2-glycoprotein-I antibodies in hypertensive disorders of pregnancy

BACKGROUND

This study was undertaken in order to determine the frequency of anticardiolipin (aCL) and anti-beta2-glycoprotein-I antibodies (anti-beta2 GP-I) in patients with hypertensive disorders of pregnancy.

METHODS

We studied aCL (IgG and IgM) and IgG anti-beta 2 GP-I by ELISA in the serum and IgG aCL and anti-beta 2 GP-I in the urine of 125 women with hypertensive disorders of pregnancy (cases) (75 had preeclampsia, 25 had eclampsia, and 25 had chronic hypertension). One hundred and twenty seven normal women were used as controls. Antibody positivity was defined as above the 90(th) percentile of the controls.

RESULTS

We found no differences in frequency of serum anti-beta 2 GP-I or serum and urinary aCL between cases and controls. In contrast, we found that frequency of IgG anti-beta 2 GP-I was higher in the urine of cases (26.1%) compared to controls (9.4%, p = 0.001). Strength of association was stronger for urinary anti-beta2-glycoprotein-I in women with preeclampsia (odds ratio [OR] = 4.3, 95% confidence limit [CI 95%] = 1.95-9.62, p <0.0001). Cases and the subgroup of preeclamptic patients also had higher titers of urinary IgG anti-beta 2 GP-I than control women (p <0.0001).

CONCLUSIONS

Our work suggests that urine testing is necessary in order to ascertain whether antibodies to beta(2)GP-I are associated with preeclampsia.

Anti-beta(2)-glycoprotein I antibodies in children with atopic dermatitis

beta(2)-Glycoprotein I (beta(2)GPI) appears to be the major antigen for antiphospholipid antibodies (aPL) in patients with antiphospholipid syndrome (APS). In early infancy, virtually all children initiate transient immune response to non-pathogenic nutritional antigens, which fails to terminate in children with atopic diseases. To examine the possibility that a prolonged immune response to beta(2)GPI could also spread to the human protein, antibodies against human beta(2)GPI (anti-beta(2)GPI) were determined in 93 randomly selected children with different allergic diseases. A high frequency (42%) of IgG anti-beta(2)GPI was found in children with atopic dermatitis (AD), but not in those with other allergic diseases. Anti-beta(2)GPI in children with AD were exclusively of the IgG1 subclass and bound to bovine beta(2)GPI as well, but not to either beta(2)GPI combined with the phospholipid cardiolipin. The epitopes were identified in domain V of beta(2)GPI and the antibody binding was abolished upon the specific proteolytic cleavage of the phospholipid-binding C-terminal loop in domain V of beta(2)GPI. These results indicated that the epitopes for anti-beta(2)GPI in children with AD most likely resided in close vicinity of the phospholipid-binding site of beta(2)GPI. The epitopic difference from anti-beta(2)GPI in APS may explain presumed non-thrombogenicity of anti-beta(2)GPI in children with AD.

Delayed apoptotic cell clearance and lupus-like autoimmunity in mice lacking the c-mer membrane tyrosine kinase

Mice lacking the membrane tyrosine kinase c-mer have been shown to have altered macro-phage cytokine production and defective phagocytosis of apoptotic cells despite normal phagocytosis of other particles. We show here that c-mer-deficient mice have impaired clearance of infused apoptotic cells and that they develop progressive lupus-like autoimmunity, with antibodies to chromatin, DNA, and IgG. The autoimmunity appears to be driven by endogenous antigens, with little polyclonal B cell activation. These mice should be an excellent model for studying the role of apoptotic debris as an immunogenic stimulus for systemic autoimmunity.

Antiphospholipid antibodies after surgical exposure to topical bovine thrombin

Exposure to topical bovine thrombin during surgery frequently results in the development of antibodies to multiple protein and carbohydrate antigens. We investigated the frequency of increased levels of antibodies to cardiolipin and beta(2)-glycoprotein I (beta(2)-GPI) in two groups of patients, one exposed to bovine thrombin during cardiovascular surgery (n = 151) and a "control" group undergoing cardiovascular surgery but without exposure to bovine thrombin (n = 11). Anticardiolipin antibody levels were increased before surgery in 10 of the 151 patients exposed to topical thrombin (6.6%). Four to 8 weeks after surgery, 84 patients (55.6%) had increased anticardiolipin antibody levels (P <.0001). In the control group, an increased anticardiolipin antibody level was present in a single patient before and after surgery (9%). Increased levels of antibodies to bovine and human beta(2)-GPI were also observed after surgery in the patients exposed to topical thrombin (37.7% and 38.2%, respectively). Increased anticardiolipin levels correlated with higher levels of antibody to bovine, but not human, beta(2)-GPI. In addition, increased levels of anticardiolipin antibody were associated with higher levels of antibodies to bovine factor V and prothrombin, as well as human factor V. Antibody binding on an enzyme-linked immunosorbent assay conducted to detect anticardiolipin antibody was dependent on the presence of anionic phospholipid, indicating that binding was not linked to the fetal bovine serum in the blocking buffer alone. Seven of 8 patients with delayed thromboembolic complications had increased anticardiolipin IgG antibody levels after surgery, but this association was not statistically significant. Nevertheless, our findings support the recommendation that the clinical safety of these commonly used hemostatic agents should be reassessed.

Value of autoantibodies to beta(2)-glycoprotein 1 in the diagnosis of antiphospholipid syndrome

OBJECTIVES

To define the specificity and positive predictive value of anti-beta(2)-glycoprotein 1 (anti-beta(2)GP1) antibodies for the diagnosis of antiphospholipid syndrome (APS).

METHODS

We determined the presence of anticardiolipin (aCL) antibodies and anti-beta(2)-glycoprotein 1 (anti-beta(2)GP1) immunoglobulin (Ig) G and IgM in 191 consecutive sera from 191 patients and reviewed clinical data separately. aCL IgG and IgM were detected separately using commercial ELISA kits. Anti-beta(2)GP1 antibodies were detected with an in-house ELISA using beta(2)GP1.

RESULTS

Seven patients were diagnosed as having APS and 184 as having other diseases. Thirty-six patients were aCL-positive and 12 were anti-beta(2)GP1-positive, seven of these 12 were APS patients. The specificity for anti-beta(2)GP1 in our population was 97%, with a positive predictive value (PPV) of 58%. Among the aCL-positive patients, specificity was 90% and PPV 70-87%.

CONCLUSIONS

This study shows that anti-beta(2)GP1 antibodies have a higher specificity and PPV than aCL for APS. The PPV of anti-beta(2)GP1 was greater in aCL-positive than in all patients. We conclude that screening for anti-beta(2)GP1 antibodies in aCL-positive patients increases the specificity and the PPV of aCL testing. In addition, we show that there is no need to screen for anti-beta(2)GP1 antibodies in the absence of aCL antibodies and in the absence of strong clinical suspicion of APS.

Immunization of naive BALB/c mice with human beta2-glycoprotein I breaks tolerance to the murine molecule

OBJECTIVE

Immunization of naive mice with beta2-glycoprotein I (beta2GPI) leads to the generation of pathogenic anticardiolipin antibodies associated with clinical manifestations of the antiphospholipid syndrome (APS). The aim of this study was to determine whether immunization of naive mice with human beta2GPI, which shares homology with mouse beta2GPI molecules, breaks tolerance to murine beta2GPI and leads to the generation of anti-mouse beta2GPI.

METHODS

Twenty-four female BALB/c mice were immunized in the footpads with 10 microg of human beta2GPI. Twelve age- and sex-matched BALB/c mice were immunized in the same manner with Freund's complete adjuvant and served as controls. The reactivity of whole sera, polyclonal IgG, and affinity-purified anti-beta2GPI IgG antibodies against human, bovine, and mouse beta2GPI was evaluated by enzyme-linked immunosorbent assay.

RESULTS

High titers of anti-human beta2GPI IgG antibodies were detected 1 month after immunization. Progressively increasing titers against murine and bovine beta2GPI were recorded 1-4 months after injection.

CONCLUSION

Immunization of mice with human beta2GPI resulted in the generation of antibodies reacting with human, bovine, and murine beta2GPI. The loss of tolerance to mouse beta2GPI is attributable to the high interspecies homology of beta2GPI. These results may point to molecular mimicry as a possible cause of APS.

IL-4 and T cells are required for the generation of IgG1 isotype antibodies against cardiolipin

Infection with Mycobacterium tuberculosis induces Abs against a vast array of mycobacterial lipids and glycolipids. One of the most prominent lipid Ags recognized is cardiolipin (CL). The kinetics of the generation of anti-CL Abs during infection reveals that IgM titers to CL increase over time. Interestingly, at day 30 postinfection CL-specific IgG1 appears, an isotype usually dependent on T cell help. Using an immunization schedule with CL/anti-CL Ab complexes, which induces antiphospholipid syndrome in mice, we show that the generation of IgG1 to CL requires IL-4 and that optimal production is T cell dependent. IgG1 production to CL was impaired in nude (nu/nu) mice devoid in conventional T cells, but was not affected in mice deficient for either alphabeta TCR(+), gammadelta TCR(+), CD4(+), CD8(+), or NK1.1(+) T cells. We conclude that IgG1 production to CL depends on T cell help and IL-4, which can be provided by different T cell populations. This is the first report that IL-4 is indispensable for the induction of IgG1 Abs to lipid Ags.

Action of nonviral gene delivery vectors on human complement system: low anticomplementary activity of lipoplexes based on lacZ plasmid and phospholipid/oligocation liposomes

A simple test-system has been developed for the first time in order to detect the ability of effectors (lipoplexes) to activate the complement system in an antibody-independent manner to serve as acceptors of nascent C4b and to inhibit formation of the key enzyme of complement, C3-convertase. The effect of plasmid DNA (pCMV-SPORT-LacZ), negatively charged cardiolipin (CL), neutral phosphatidylcholine (PC) vesicles and their lipoplexes, on the complement system was studied using the method developed. It was revealed that PC vesicles did not affect the complement system, while CL vesicles manifested low activation. The influence of plasmid DNA and its lipoplex based on PC liposomes as well on the complement system was very low. PC/LacZ lipoplex (143 microg/ml) acted on the complement system like 5.36 microg/ml heat aggregated IgG (agg) (the level of no pathological ruptures), whereas CL/LacZ lipoplex (143 microg/ml) acted similar to 10.7 microg/ml IgG (agg). Thus, weak activation of the complement system with CL lipoplex, and even weaker for the PC lipoplex testified to the use of neutral and positively charged lipoplexes preferably in gene therapy protocols. The technique can also be used for testing the influence of injectable gene therapy vectors on the complement system.

Antibodies to oxidised low-density lipoproteins and cardiolipin in pre-eclampsia and eclampsia

The objective of this study was to test the hypothesis that autoantibodies to phospholipids and to oxidised low-density lipoprotein (ox-LDL) are increased in pre-eclamptic and eclamptic women compared with normal pregnancy. Serum concentrations of autoantibodies to ox-LDL and to cardiolipin were measured in 21 non-pregnant controls, 29 pregnant controls, 21 pre-eclamptic and six eclamptic women. Concentrations of IgG antibodies to ox-LDL and to cardiolipin were not significantly different in women with eclampsia as compared with the non-pregnant controls, pregnant controls and pre-eclampsia. Concentrations of IgM antibodies to cardiolipin were significantly lower in women with pre-eclampsia compared with non-pregnant controls and eclampsia. All three pregnant states differ markedly from the non-pregnant controls, of whom only 5% (1 of 21) had "high positive" IgG antibodies. These results suggest that ACAs rise as a result of the pregnant state rather than as a result of preeclampsia or eclampsia. According to these results, there is no evidence of increased production of serum autoantibodies against modified LDL in African women with pre-eclampsia, which may reflect reduced lipid peroxidation involving lipoproteins or no link at all. In addition, IgG and IgM anticardiolipin antibodies have no diagnostic value in preeclampsia and eclampsia.

Beta2-glycoprotein I dependent anticardiolipin antibodies and lupus anticoagulant in patients with recurrent pregnancy loss

AIM

The present study was aimed to define the incidence of antiphospholipid antibodies of different types lupus anticoagulant (LAC), venereal disease research laboratory test (VDRL) and Beta2-glycoprotein I dependent anticardiolipin antibodies Beta2 I aCL) in our cohort of population experiencing recurrent pregnancy loss (RPL) from Andhra Pradesh, South India.

SETTING AND DESIGN

A referral case-control study at a tertiary centre over a period of 5 years.

PARTICIPANTS

150 couples experiencing 3 or more recurrent pregnancy losses with similar number of matched controls.

MATERIAL AND METHODS

LAC activity was measured by the activated partial thromboplastin time (aPTT) according to the method of Proctor and Rapaport with relevant modifications. VDRL analysis was performed by the kit method supplied by Ranbaxy Diagnostics Limited and Beta2 Glycoprotein I dependent anticardiolipin antibodies were estimated by ELISA kit (ORGen Tech, GmbH, Germany) with human Beta2 Glycoprotein I as co-factor.

STATISTICAL ANALYSIS

Statistical analysis was performed using Student's t test.

RESULTS

LAC activity was found positive in 11 women (10.28%). The mean +/- SE Beta2 I aCL concentration in the study group was 14.53 (micro/ml) +/- 1.79 (range 0 to 90.4 micro/ml) which was higher than the control group with a mean +/- SE of 7.26 (micro/ml) +/- 0.40 (range 0 to 18 u/ml). The binding of the antibodies to the antigen was observed in 40.24% (n=33) of the cases compared to 6.09% (n=5) in controls. VDRL test was positive in 7(2.34%) individuals (3 couples and 1 male partner) and none among controls.

CONCLUSIONS

The present study indicates the importance of antiphospholipid antibodies in women experiencing RPL and suggests the usefulness of screening for these antibodies as a mandatory routine for instituting efficient therapeutic regimens for a successful outcome of pregnancy.

Autoantibodies specificity in acute anterior uveitis according to the presence of the HLA-B27 allele

PURPOSE

To study HLA-B27(+) and HLA-B27(-) patients with AAU with respect to the frequency and specificity of organ-specific and non-organ-specific autoantibodies.

METHODS

Fifty-seven consecutive patients with AAU were subjected to ophthalmologic and rheumatologic evaluation as well as to autoantibody determination: antinuclear antibodies (ANA), rheumatoid factor (RF), anticardiolipin, anti-smooth muscle, and anti-parietal cell antibodies, and immunoblot for antibodies to HeLa cells and to bovine iris extract. HLA-B27 was determined by a microlymphocytotoxicity assay. Statistical analysis employed chi-square test, Fisher's exact test, and McNemar test.

RESULTS

Thirty-four patients had the HLA-B27 allele (B27(+)/AAU) and 23 did not (B27(-)/AAU). ANA, RF, anticardiolipin, and anti-parietal cell antibodies appeared in low frequency. No patient presented anti-smooth muscle antibody. Immunoblot showed a high frequency of antibodies to HeLa cell proteins in B27(-)/AAU patients with predominant reactivity at 46 kDa and 56 kDa. In contrast, sera from B27(+)/AAU patients reacted poorly against HeLa cell antigens. Immunoblot with bovine iris extract showed a significant frequency of antibodies in both groups, with a predominant response to antigens with an estimated mobility of 35, 52, and 54 kDa.

CONCLUSION

Antibodies specific to iris antigens were equally frequent in both acute uveitis groups, whereas non-organ-specific autoantibodies, especially those to HeLa cell proteins, were far less frequent in B27(+)/AAU than in B27(-)/AAU patients.

Effect of cardiolipin oxidation on solid-phase immunoassay for antiphospholipid antibodies

Diagnostic assays for antiphospholipid antibodies are routinely performed on microtitre plates coated with cardiolipin. Here we show that contact between cardiolipin and NUNC-Immuno plates leads to extensive oxidation, generating a series of peroxy-cardiolipins which were identified by electrospray ionization mass spectrometry. To investigate the impact of oxidation on the antibody assay. cardiolipin was resolved into 12 molecular species, including oxidized species and non-oxidized species with different degrees of unsaturation. All 12 species reacted under anaerobic conditions with serum from patients with primary antiphospholipid syndrome. Immune reactivity was similar for tetralinoleoyl-cardiolipin, trilinoleoyl-oleoyl-cardiolipin, and peroxycardiolipins, but somewhat lower for tristearoyl-oleoyl-cardiolipin. Oxidative treatment of cardiolipin with air, cytochrome c, or Cu2+/tert-butylhydroperoxide, either before or during the assay, did not enhance immune reactivity. Similar results were obtained with a monoclonal IgM from lupus-prone mice, that binds cardiolipin in the absence of protein cofactors. We conclude that the solid-phase assay for antiphospholipid antibodies can be supported by various oxidized and non-oxididized molecular species of cardiolipin.

Oxidation of beta2-glycoprotein I (beta2GPI) by the hydroxyl radical alters phospholipid binding and modulates recognition by anti-beta2GPI autoantibodies

We investigated whether beta2-glycoprotein I (beta2GPI), the key antigen in the antiphospholipid syndrome, is susceptible to oxidative modifications by the hydroxyl radical (*OH) that may influence its lipid-binding and antigenic properties. The effects on human and bovine beta2GPI of *OH free radicals generated by gamma-radiolysis of water with 137Cs were studied. Radiolytic *OH caused a dose-dependent loss of tryptophan, production of dityrosine and carbonyl groups. dimerization and/or extensive aggregation of beta2GPI. It ensued a reduction in affinity binding to cardiolipin liposomes and loss of beta2GPI-dependent autoantibody binding to immobilized cardiolipin. Patient anti-beta2GPI antibodies (n = 20) segregated into two groups based on the effect in the beta2GPI-ELISA of beta2GPI pretreatment with *OH: enhancement (group A, n = 10) or suppression (group B, n = 10) of IgG binding. The avidities of group A antibodies for fluid-phase beta2GPI were low but increased in a dose-dependent manner upon beta2GPI irradiation, in relation to protein crosslinking. Distinguishing features of group B antibodies included higher avidities for fluid-phase beta2GPI that was no longer recognized after *OH treatment, and negative anticardiolipin tests suggesting epitope location near the phospholipid binding site. The *OH scavengers thiourea and mannitol efficiently protected against all above changes. Therefore, oxidative modifications of beta2GPI via *OH attack of susceptible amino acids alter phospholipid binding, and modulate recognition by autoantibodies depending on their epitope specificities. These findings may be of clinical relevance for the generation and/or reactivity of anti-beta2GPI antibodies.

Temporal profile of anti-ganglioside antibodies and their relation to clinical parameters and treatment in Guillain-Barré syndrome

Elevated anti-ganglioside antibody levels mainly of anti-GM1 and anti-GD1a specificities have been reported in THE serum of patients with Guillain-Barré syndrome (GBS). The relevance of anti-ganglioside antibodies other than anti-GM1 and anti-GD1a IgG antibodies and the temporal profile of anti-ganglioside antibodies in GBS is less clear. We studied serum antibodies to GM1, GD1a, GD1b, GQ1b, sulfatide and cardiolipin of the IgM, IgG and IgA classes over the course of GBS in patients who were untreated or treated with high dose intravenous immunoglobulin (IvIg). Antibodies to GD1b, GQ1b, sulfatide and cardiolipin were not detected in the sera of the GBS patients examined in this study. Anti-GM1 IgG titers peaked around 40 days and anti-GD1a IgM around 90 days after GBS onset. Titers of anti-GM1 IgG antibodies decreased following IvIg treatment. Patients with antibody peaks, defined as fivefold or higher increase in antibody titer compared to the lowest antibody titer over the course of GBS, had higher disability scores during the first two weeks of GBS and a worse clinical outcome (anti-GM1 IgG and anti-GD1a IgM antibody peaks) and axonal damage (anti-GD1a IgM antibody peaks), compared to patients without peak antibody titers. Anti-GM1 IgG and anti-GD1a IgM antibodies are thus strongly associated with more severe- and predominantly axonal cases of GBS. The appearance of anti-GM1 IgG and anti-GD1a antibody peaks in the serum after the termination of the acute phase of GBS suggests that these antibodies are produced secondary to nerve damage in GBS. The data does not exclude the possibility that secondarily secreted anti-GM1 IgG and anti-GD1a IgM antibodies may themselves be biologically active and play a role in disease propagation and/or recovery from disease in some patients with GBS.

Coronary artery disease but not coronary calcification is associated with elevated levels of cardiolipin, beta-2-glycoprotein-I, and oxidized LDL antibodies

BACKGROUND

Autoimmune factors have been shown to play a role in atherosclerosis. The aim of this study is to correlate 5 autoantibodies (anticardiolipin, anti-CL, beta2-glycoprotein-I, beta2GPI, phosphatidylcholine, oxidized low-density lipoprotein, oxLDL, endothelial cell) with the presence of coronary heart disease, angiographic findings, and with coronary artery calcification.

METHODS

The levels of the 5 autoantibodies and a control antifibroblast line of 126 coronary heart disease patients and 20 healthy controls were measured. Fifty-one patients underwent coronary angiography, and 98 patients had coronary artery calcium determination using spiral computerized tomography (dual mode).

RESULTS

Levels of 3 autoantibodies (anti-CL, beta2GPI, oxLDL) were significantly elevated in coronary heart disease patients compared with controls (p < 0.001, p = 0.001, p < 0.001, respectively). Within the subgroup of patients with significant coronary artery stenosis, anti-CL antibodies were also elevated (p = 0.008). No correlation was found between anti-CL, and anti-beta2GPI autoantibody levels and coronary calcium scores as measured by spiral computerized tomography. However, anti-oxLDL antibodies were raised in patients with no calcification detected by spiral computerized tomography, compared with the patients with any coronary calcification (p = 0.046).

CONCLUSION

Anti-CL, beta2GPI and oxLDL antibodies are elevated in coronary heart disease patients regardless of coronary calcification.

[Antibodies to phospholipids and ischemic disorders of cerebral circulation in young age]

Antibodies to phospholipids (APL) were studied in 97 patients which had ischemic stroke in young age (up to 46 years). These antibodies (Abs) were found in 25 patients (26%): Abs to cardiolipin--in 15 patients (60%), Abs to lupoid anticoagulant in 18 from 24 patients (75%), Abs to phosphatidylethanolamine--in 4 from 13 patients (31%). Disorders of cerebral circulation (DCC) usually began at the age of 14-45 years and were characterized by ischemic strokes and by transitory DCC. There was no correlation between the occlusion of extracranial arteries and their hemodynamic significant stenosis. There was occlusion of intracranial arteries in 7 from 12 patients (58%). Other risk factors of the stroke development were also found in 19 patients (76%) together with Abs to phopholipids. Other manifestations of antiphospholipid syndrome (APLS) were observed in 68% of the patients: miscarriage of pregnancy (63%), thrombosis of peripheric veins (16%), thrombocytopenia (32%), ischemic heart disease (28%). Comparison of APL+ and APL- patients revealed that transitory DCC, occlusion of intracranial arteries, intact extracranial arteries, widening or condensation of the cardial valves on echo-ECG, abortions, increase of ESR were significantly more frequently observed in the former group. For confirmation of APLS diagnosis it was necessary to study simultaneously Abs to cardiolipin and lupoid anticoagulant. Prophylaxis of repeated DCC in APLS included administration of both aspirin and anticoagulants of indirect action.

Anti-cardiolipin antibodies, Raynaud's phenomenon with digital ischemia, and non small cell carcinoma of the lung

Raynaud's phenomenon, digital ischemia, antinuclear antibodies and anticardiolipin antibodies are uncommon features of malignancy. The association of all of these in a patient with malignancy has not previously been reported. We describe a 52 year old woman with non small-cell carcinoma of the lung who also had Raynaud's phenomenon, digital ischemia, anti-nuclear antibodies and anticardiolipin antibodies.

Effect of adverse storage conditions of antigen reagent on performance of the rapid plasma reagin test

The aim of this study was to evaluate the performance of rapid plasma reagin (RPR) testing using expired and adversely stored antigen reagent. The sensitivity of RPR using antigen stored at 36 degrees C was compared at 3-monthly intervals with RPR using fresh antigen on 116 sera reactive by RPR and by Treponema pallidum particle agglutination (TPPA). After multiple phases of freezing and thawing, 8.3% of initial RPR reactive sera seroreverted. After storage at 36 degrees C for one year and 24 weeks after expiration the overall sensitivity of the adversely stored antigen was 93.8% compared with fresh antigen; the sensitivity was 100% for sera with RPR titres > or = 1:4 and 85.4% for sera with RPR titres of 1:1 and 1:2. The high stability of the reagent may increase the feasibility of the RPR test for use in poorly-equipped healthcare centres in developing countries.

Expression of the Fabs of human auto-antibodies in Escherichia coli: optimization and determination of their fine binding characteristics and cross-reactivity

The Fabs of three human auto-antibodies (B3/33H11, anti-DNA; UK4, anti-phospholipid) and six related hybrids have been cloned and expressed in Escherichia coli, and their relative binding to single-stranded or double-stranded DNA or to cardiolipin has been assessed in the presence of modulators (salts and serum). We describe optimized conditions that have led to significant improvement in the quality and quantity of the purified auto-antibodies. Protein expression of the assembled and functionally active Fabs was achievable with a yield of up to 5 to 9 mg/l of culture. The comparative DNA/cardiolipin-binding analyses of the nine Fabs in the presence of modulators demonstrated that B3 and 33H11 L chains possess both anti-DNA and anti-cardiolipin activities. This is the first report of the demonstration that both anti-DNA and anti-cardiolipin activities may lie on the same light chain of a human auto-antibody. We provide evidence that the auto-antibodies that appeared to be similar, in that they bound DNA or cardiolipin in conventional ELISA immunoassays, exhibited significant difference in their cross-reactivity and binding to the antigen in the presence of modulators. Such auto- antigen specificity and/or cross-reactivity may dictate the potential of an auto-antibody to cause pathogenicity and may provide an explanation as to why apparently similar auto-antibodies behave differently in vivo.

Anti-apolipoprotein A-I autoantibody: characterization of monoclonal autoantibodies from patients with systemic lupus erythematosus

OBJECTIVE

The autoantibody to apolipoprotein A-I (apoA-I), a major constituent of high density lipoproteins (HDL), has been detected in sera of patients with systemic lupus erythematosus (SLE). We established a series of monoclonal anti-apoA-I antibodies (MAAI) from 2 patients with SLE and report the reactivities of MAAI with oxidized HDL, anionic substances, and blood coagulation factors.

METHODS

Peripheral blood B cells from patients with SLE were immortalized by Epstein-Barr virus, and B cells secreting anti-apoA-I antibodies (AAI) were fused with mouse myeloma cells. Six MAAI reactive with human apoA-I in both ELISA and immunoblotting analysis were established. The reactivities of MAAI with HDL, ssDNA and dsDNA, phospholipids such as cardiolipin (CL), and coagulation factors were examined by ELISA.

RESULTS

Although all MAAI bound effectively to apoA-I after the protein had been denatured and transferred to the filter membrane (in immunoblotting analyses), they bound less effectively to apoA-I present in HDL. Both oxidation of HDL in the presence of Mn2+ and an association of apoA-I with autoxidized trilinolein strongly enhanced the binding of MAAI to apoA-I, suggesting that MAAI recognize a defined region of apoA-I, which is exposed upon interacting with oxidatively modified lipids. MAAI showed a functional heterogeneity in their cross-reactivity with self-components: some MAAI were shown to cross-react with anionic substances such as CL and ssDNA, and one MAAI was shown to bind effectively to thrombin.

CONCLUSION

We identified a novel family of AAI that shows preferential binding to apoA-I in oxidatively modified HDL. These AAI are composed of antibodies with heterogeneous cross-reactivities to various self-components such as anionic phospholipids, ssDNA, and thrombin.

[Laboratory tests for detection of antiphospholipid antibodies]

Antiphospholipid antibodies(APA) have been reported to be a heterogeneous family of immunoglobulins. Some APA can be detected via phospholipid dependent coagulation assays when they present as an aspecific coagulation inhibitor, lupus anticoagulant(LA), other antibodies can be measured via immunological assays mostly via their capability to bind to immobilized cardiolipin (anticardiolipin antibody; aCL). Despite their name, APA associated with antiphospholipid syndrome(APS) do not bind phospholipids, but are directed at plasma proteins bound with anionic phospholipids. The antigenic targets of these antibodies include beta 2 glycoprotein I(beta 2 GP I), prothrombin, high- and low-molecular-weight kininogens, annexin V, protein C and protein S. In this article, the current knowledge on the methods of detection and their functional properties are reviewed, and the interaction of these antibodies and acquired activated protein C resistance are discussed.

Anticardiolipin antibodies from patients with the antiphospholipid antibody syndrome recognize epitopes in both beta(2)-glycoprotein 1 and oxidized low-density lipoprotein

BACKGROUND

We recently suggested that many anticardiolipin antibodies bind only to oxidized cardiolipin (OxCL) and/or to OxCL-beta(2)-glycoprotein 1 (beta(2)GP1) adducts but not to a "reduced" cardiolipin that is unable to undergo oxidation. To test this hypothesis, we investigated 24 sera, 4 protein A-purified IgG fractions, and 3 human monoclonal antibodies that were all isolated from patients with antiphospholipid antibody syndrome (APS); testing was also performed in 7 controls. Two monoclonal antibodies (IS3 and IS4) were selected for binding to CL and one was selected for binding to beta(2)GP1 (LJB8).

METHODS AND RESULTS

By chemiluminescent immunoassay, all APS sera samples bound only to OxCL and not to reduced CL, and the binding was inhibited >95% by OxCL but not reduced CL. All purified IgG fractions bound to beta(2)GP1 but only when the beta(2)GP1 was plated on microtiter wells coated with OxCL. All 3 monoclonal antibodies bound only to OxCL. On Western blots, IS4 and LJB8 bound to beta(2)GP1 as well as to delipidated apoB of oxidized LDL but not to native apoB. IS3 also bound to oxidized apoB on Western blot. Covalent modification of beta(2)GP1 with oxidation products of CL made it more antigenic for APS serum samples, for purified IgG fractions, and for the monoclonal antibodies.

CONCLUSIONS

These data support the hypothesis that oxidation of CL is needed to generate epitopes for many anticardiolipin antibodies and that some of these epitopes are covalent adducts of OxCL with beta(2)GP1 or apoB.