Antiphospholipid antibodies: discovery, definitions, detection and disease

Prevalence and diagnostic value of non-criteria antiphospholipid antibodies for antiphospholipid syndrome in Chinese patients

Background

The presence of antiphospholipid antibodies (aPLs) plays a pivotal role in the pathogenesis of antiphospholipid antibody syndrome (APS). This study aimed to examine the diagnostic value of a set of non-criteria aPLs and their relevance with APS-related criteria and extra-criteria manifestations.

Methods

From a prospectively constructed database, consecutive APS patients consisting of 114 primary APS (PAPS group), 54 with APS secondary to SLE (SAPS group), 9 seronegative APS (SNAPS), as well as 209 patients with systemic lupus erythematosus (SLE) and 88 healthy controls were included in this study. Levels of criteria aPLs, baseline information, and APS-related criteria and extra-criteria features were extracted from the database. Serum levels of non-criteria aPLs including aPC IgG/IgM, aPI IgG/IgM, aPE IgG/IgM/IgA, aPG IgG/IgM/IgA, anti-phosphatidic acid (aPA) IgG/IgM, aSM IgG/IgM, and aPS/PT IgG/IgM were analyzed with AESKULISA® ELISA Test Kits.

Results

The addition of aPC IgG/M, aPI IgG/M, aPE IgG/M/A, aSM IgG/M, and aPA IgG/M to aCL or aβ2GPI IgG/M could significantly increase diagnostic sensitivity and accuracy. A significant difference between PAPS or SAPS and HC was presented in all non-criteria aPLs except for aSM IgM and aPG IgA. Eight out of nine SNAPS patients were positive for at least 1 aPL. Pregnancy morbidity was associated with aSM IgM (r = 0.22) and aSM IgG (r = 0.15). Pre-eclampsia or premature birth was associated with aSM IgG (r = 0.16), aPI IgG (r = 0.22), aPC IgG (r = 0.16), and aPG IgG (r = 0.18). Stroke was associated with aPI IgG (r = 0.2). The clinical association was also observed in DVT with aPS/PT IgG (r = 0.17). Valve lesion was positively associated with aSM IgM (Fisher test p = 0.039), APS nephropathy was associated with aPC IgG (OR 3.797), and livedo reticularis was associated with aPE IgM (OR 15.391).

Conclusion

Additional detection of non-criteria aPLs including aPC IgG/M, aPE IgG/M/A, aPI IgG/M, aSM IgG/M, and aPA IgG/M could assist in APS diagnosis. The positivity of certain aPLs was statistically associated with both criteria and extra-criteria APS clinical manifestations.

The Antiphospholipid Syndrome in the Pediatric Population

Pediatric antiphospholipid syndrome (APS) is characterized by autoantibodies directed against protein complexes on cellular membranes and leads to a prothrombotic, proinflammatory state. A child with APS may present with venous, arterial, or small vessel thrombosis. Other manifestations of APS include nonthrombotic manifestations, such as hematologic and neurologic symptoms. APS may be a primary condition or related to other autoimmune diseases. If APS-related thrombosis is unrecognized, the child may suffer recurrent thrombotic events after the withdrawal of anticoagulation. Thus, it is important to consider APS as a cause of thrombosis in children. Appropriate testing confirms the diagnosis and directs further care.

The digestive system involvement of antiphospholipid syndrome: pathophysiology, clinical characteristics, and treatment strategies

Antiphospholipid syndrome (APS) is an autoimmune disease mainly characterised by vascular thrombosis and pregnancy morbidity. APS has broad spectrum of clinical manifestations. The digestive system involvement of antiphospholipid syndrome is a critical but under-recognised condition. Digestive system involvement may be the result of direct (autoimmune-mediated) or indirect (thrombotic) mechanisms. Liver is the most commonly involved organ, followed by intestines, oesophagus, stomach, pancreas and spleen. This review describes possible digestive system manifestations in APS patients, and illustrates the epidemiology and possible pathophysiology of APS. The role of different treatment strategies in the management of digestive system manifestations of APS were also discussed.Key messagesAntiphospholipid syndrome is a multi-organ, multi-system disease and its clinical manifestation spectrum is gradually expanding. Since the first diagnosis of APS, the clinical manifestations of digestive system have been reported successively. This narrative review describes the major digestive system manifestations of APS and illustrates the epidemiology, pathophysiology and the role of therapeutic strategies of these patients.

The effect of influenza vaccine immunization on natural antibodies

Natural, polyreactive, low-affinity antibodies are known to play an important role not only in the immediate defense against pathogens, but also in shaping the acquired immune response. On the other hand, antigen specific, high-affinity antibodies can affect the balance of natural antibodies and lead to autoimmune diseases. In this study, we have analyzed the changes that occur in the IgM and IgG pool of natural antibodies after immunization with split or whole virion influenza vaccine. For this purpose, "in-house" developed ELISAs were used. The subjects were divided, according to the vaccination status, into those who had been immunized with the influenza vaccine in previous years and those who had been immunized for the first time. The analysis indicated that the pool of natural antibodies was not impaired by the immunization, evidenced by the lack of changes in any of the groups, and that certain fluctuations were induced in order to maintain the homeostasis of the immune system.

Clinical performance of non-criteria antibodies to phospholipids in Chinese patients with antiphospholipid syndrome

BACKGROUND

Increasing evidence suggests the role of non-criteria aPLs as important supplements to the current criteria aPLs in APS. In this study, we evaluated the clinical performance of a panel of non-criteria antibodies to phospholipid antigens, including, phosphatidylserine (aPS), phosphatidylinositol (aPI), sphingomyelin (aSM), phosphatidylcholine (aPC) and phosphatidylethanolamine (aPE) in a well-defined Chinese APS cohort.

METHODS

A total of 229 subjects were tested, including 86 patients with APS, 104 disease controls (DCs) and 39 healthy controls (HCs). Serum IgG/IgM aCL, IgG/IgM aβ2GP1, IgG/IgM aPS, IgG/IgM aPI, IgG/IgM aSM, IgG/IgM aPC, and IgG/IgM aPE were tested by ELISA.

RESULTS

The presence of aPE, aPS, aPI, aPC, and aSM in patients with APS and Disease Controls were 8.1% (7/86) and 1.0% (1/104), 37.2% (32/86) and 9.6% (10/104), 50.0% (43/86) and 8.7% (9/104), 23.3% (20/86) and 1.0% (1/104), and 18.6% (16/86) and 1.9% (2/104), respectively. In criteria aPLs, aCL IgG demonstrated the highest positive likelihood ratio (LR+) of 35.75, followed by LA (LR+ of 13.51) and aCL IgM (LR+ of 11.64). In non-criteria aPLs, aPC IgG demonstrated the highest LR+ of 24.94 followed by aSM IgM (LR+ of 14.97). Importantly, the non-criteria aPLs were detected in 18.8% (3/16) of seronegative APS patients. The criteria aPLs, including LA, IgG aCL and IgG aβ2GPI, were significantly correlated with both arterial thrombosis and venous thrombosis, while the non-criteria aPLs, including IgG aPS, IgM aPS, IgG aPI and IgG aPC were significantly associated with arterial thrombosis but not venous thrombosis.

CONCLUSIONS

In summary, our findings indicate that those non-criteria aPLs may be particularly helpful for patients in whom APS is highly suspected, but conventional aPLs are repeatedly negative as well as for predicting APS patients with arterial thrombosis.

The Increase of Blood Anticardiolipin Antibody Depends on the Underlying Etiology in Cerebral Ischemia

Although anticardiolipin antibody (aCL) has been suggested to be a potent risk factor for thrombosis and atherosclerosis in multiple arterial beds, conflicting results exist between aCL and cerebral ischemia in the general stroke population. To elucidate if this discrepancy relates to the heterogeneity of underlying etiologies, the blood beta2-glycoprotein I dependent-aCL in 432 Taiwanese adults was examined. The associated cerebral ischemia in these patients was classified into five subtypes according to the cause of cerebral ischemia. The results were compared with those in 100 healthy controls. A definite increase of aCL-IgG isotype was found in 41 patients (9.35%) and four controls (4.0%). The relative risk was 2.52. The frequency of increased aCL-IgG was 12.2%, 12.8%, 8.8%, 3.9%, and 3.5% in patients with large-artery atherosclerotic disease, stroke of unknown etiology, small-artery occlusive disease, cardioembolism, and stroke of other known etiology, respectively. Only patients with large-artery atherosclerotic disease (p<0.025) and stroke of unknown etiology (p<0.05) had higher frequencies of increased aCL than those in control subjects. The frequencies of abnormal results of activated partial thromboplastin time, antinuclear factor, Coombs’ test, and venereal disease research laboratory were 2.84%, 1.22%, 1.02%, and 1.34% in these 41 patients, respectively. Accordingly, aCL-IgG selectively increases in patients with large-artery atherosclerosis and stroke of unknown etiology, reflecting selective activation of humoral immunity for aCL in the pathogenesis of cerebral ischemia.

The Increase of Blood Anticardiolipin Antibody Depends on the Underlying Etiology in Cerebral Ischemia

Although anticardiolipin antibody (aCL) has been suggested to be a potent risk factor for thrombosis and atherosclerosis in multiple arterial beds, conflicting results still exist between aCL and cerebral ischemia in the general stroke population. To elucidate if this discrepancy relates to the heterogeneity of underlying etiologies, blood beta2-glycoprotein I dependent-aCL was evaluated in 432 Taiwanese adults associated with cerebral ischemia who were classified into five subtypes according to their causes of cerebral ischemia. The results were compared with those in 100 healthy controls. A definite increase of aCL-IgG isotype was found in 41 patients (9.35%) and four controls (4.0%). The relative risk was 2.52. The frequency of increased aCL-IgG was 12.2%, 12.8%, 8.8%, 3.9%, and 3.5% in patients with large-artery atherosclerotic disease, stroke of unknown etiology, small-artery occlusive disease, cardioembolism, and stroke of other known etiology, respectively. Only patient with large-artery atherosclerotic disease (p<0.025) and stroke of unknown etiology (p<0.05) had a higher frequency of increased aCL than control. The frequencies of abnormal result of activated partial thromboplastin time, antinuclear factor, Coombs’ test, and venereal disease research laboratory were 2.84%, 1.22%, 1.02%, and 1.34% in these 41 patients, respectively. Accordingly, aCL-IgG selectively increases in patients with large-artery atherosclerosis and stroke of unknown etiology, reflecting selective activation of humoral immunity for aCL in the pathogenesis of cerebral ischemia.

Association of anticardiolipin, antiphosphatidylserine, anti-β2 glycoprotein I, and antiphosphatidylcholine autoantibodies with canine immune thrombocytopenia

Background

In humans, the presence of antiphospholipid antibodies (aPL) is frequently found in immune thrombocytopenia. The present study investigated whether aPL and any aPL subtypes are associated with canine thrombocytopenia, in particular, immune-mediated thrombocytopenia (immune thrombocytopenia) that usually manifests with severe thrombocytopenia.

Results

Sera were collected from 64 outpatient dogs with thrombocytopenia (Group I, platelet count 0 – 80 × 10³/uL), and 38 of which having severe thrombocytopenia (platelet count < 30 × 10³/uL) were further divided into subgroups based on the presence of positive antiplatelet antibodies (aPLT) (subgroup I_A, immune thrombocytopenia, n =20) or the absence of aPLT (subgroup I_B, severe thrombocytopenia negative for aPLT, n =18). In addition, sera of 30 outpatient dogs without thrombocytopenia (Group II), and 80 healthy dogs (Group III) were analyzed for comparison. Indirect ELISAs were performed to compare serum levels of aPL subtypes, including anticardiolipin antibodies (aCL), antiphosphatidylserine antibodies (aPS), antiphosphatidylcholine (aPC), and anti-β₂ glycoprotein I antibodies (aβ₂GPI), and antiphosphatidylinositol antibodies (aPI), among different groups or subgroups of dogs. Among outpatient dogs, aCL, being highly prevalent in outpatient dogs with thrombocytopenia (63/64, 98 %), is an important risk factor for thrombocytopenia (with a high relative risk of 8.3), immune thrombocytopenia (relative risk 5.3), or severe thrombocytopenia negative for aPLT (relative risk ∞, odds ratio 19). In addition, aPS is a risk factor for immune thrombocytopenia or severe thrombocytopenia negative for aPLT (moderate relative risks around 2), whereas aPC and aβ₂GPI are risk factors for immune thrombocytopenia (relative risks around 2).

Conclusions

Of all the aPL subtypes tested here, aCL is highly associated with canine thrombocytopenia, including immune thrombocytopenia, severe thrombocytopenia negative for aPLT, and less severe thrombocytopenia. Furthermore, aPS is moderately associated with both canine immune thrombocytopenia and severe thrombocytopenia negative for aPLT, whereas aβ₂GPI, and aPC are moderately relevant to canine immune thrombocytopenia. In contrast, aPI is not significantly associated with canine immune thrombocytopenia.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0727-3) contains supplementary material, which is available to authorized users.

The role of antiphospholipid antibodies (aPls) in infertile women: the long-lasting experience

Antiphospholipid antibodies (aPls) are generally characterized as heterogeneous and non-specific autoantibodies directed against various phospholipids such as cardiolipin, ph-serine, ph-inositol, ph-acid, ph-glycerol, ph-sphyngomyelin, ph-choline, annexins, and co-factor β2-glycoprotein I. aPls occur not only during autoimmune diseases but also during infectious diseases, essential hypertension, neurological complication, metabolic diseases, some drug abuse, and transplant loss. aPls are very often found in connection with reproductive failure such as repeated pregnancy loss and/or missed abortion, intrauterine fetal death, in preeclampsia, and repeated delivery of hypothrophic fetus. The presence of aPls, thrombosis, and fertility failure create primary or secondary antiphospholipid syndrome. This article explains some aspects and clinical and laboratory significance of the aPls in female infertility.

Antiphospholipid autoantibodies as blood biomarkers for detection of early stage Alzheimer's disease

A robust blood biomarker is urgently needed to facilitate early prognosis for those at risk for Alzheimer's disease (AD). Redox reactive autoantibodies (R-RAAs) represent a novel family of antibodies detectable only after exposure of cerebrospinal fluid (CSF), serum, plasma or immunoglobulin fractions to oxidizing agents. We have previously reported that R-RAA antiphospholipid antibodies (aPLs) are significantly decreased in the CSF and serum of AD patients compared to healthy controls (HCs). These studies were extended to measure R-RAA aPL in serum samples obtained from Alzheimer's Disease Neuroimaging Initiative (ADNI). Serum samples from the ADNI-1 diagnostic groups from participants with mild cognitive impairment (MCI), AD and HCs were blinded for diagnosis and analyzed for R-RAA aPL by ELISA. Demographics, cognitive data at baseline and yearly follow-up were subsequently provided by ADNI after posting assay data. As observed in CSF, R-RAA aPL in sera from the AD diagnostic group were significantly reduced compared to HC. However, the sera from the MCI population contained significantly elevated R-RAA aPL activity relative to AD patient and/or HC sera. The data presented in this study indicate that R-RAA aPL show promise as a blood biomarker for detection of early AD, and warrant replication in a larger sample. Longitudinal testing of an individual for increases in R-RAA aPL over a previously established baseline may serve as a useful early sero-epidemiologic blood biomarker for individuals at risk for developing dementia of the Alzheimer's type.

Aspirin insensitive thrombophilia: transcript profiling of blood identifies platelet abnormalities and HLA restriction

Aspirin is the most widely used antiplatelet agent because it is safe, efficient, and inexpensive. However, a significant subset of patients does not exhibit a full inhibition of platelet aggregation, termed 'aspirin resistance' (AR). Several major studies have observed that AR patients have a 4-fold increased risk of myocardial infarction (MI), stroke, and other thrombotic events. Arachidonic acid-stimulated whole blood aggregation was tested in 132 adults at risk for ischemic events, and identified an inadequate response to aspirin therapy in 9 patients (6.8%). Expression profiling of blood RNA by microarray was used to generate new hypotheses about the etiology of AR. Among the differentially expressed genes, there were decreases in several known platelet transcripts, including clusterin (CLU), glycoproteins IIb/IIIa (ITGA2B/3), lipocalin (LCN2), lactoferrin (LTF), and the thrombopoetin receptor (MPL), but with increased mRNA for the T-cell Th1 chemokine CXCL10. There was a strong association of AR with expression of HLA-DRB4 and HLA-DQA1. Similar HLA changes have been linked to autoimmune disorders, particularly antiphospholipid syndrome (APS), in which autoantibodies to phospholipid/protein complexes can trigger platelet activation. Consistent with APS, AR patients exhibited a 30% reduction in platelet counts. Follow-up testing for autoimmune antibodies observed only borderline titers in AR patients. Overall, these results suggest that AR may be related to changes in platelet gene expression creating a hyperreactive platelet, despite antiplatelet therapy. Future studies will focus on determining the protein levels of these differential transcripts in platelets, and the possible involvement of HLA restriction as a contributing factor.

Permeabilization of the mitochondrial outer membrane by Bax/truncated Bid (tBid) proteins as sensitized by cardiolipin hydroperoxide translocation: mechanistic implications for the intrinsic pathway of oxidative apoptosis

Cytochrome c (cyt c) release upon oxidation of cardiolipin (CL) in the mitochondrial inner membrane (IM) under oxidative stress occurs early in the intrinsic apoptotic pathway. We postulated that CL oxidation mobilizes not only cyt c but also CL itself in the form of hydroperoxide (CLOOH) species. Relatively hydrophilic CLOOHs could assist in apoptotic signaling by translocating to the outer membrane (OM), thus promoting recruitment of the pro-apoptotic proteins truncated Bid (tBid) and Bax for generation of cyt c-traversable pores. Initial testing of these possibilities showed that CLOOH-containing liposomes were permeabilized more readily by tBid plus Ca(2+) than CL-containing counterparts. Moreover, CLOOH translocated more rapidly from IM-mimetic to OM-mimetic liposomes than CL and permitted more extensive OM permeabilization. We found that tBid bound more avidly to CLOOH-containing membranes than to CL counterparts, and binding increased with increasing CLOOH content. Permeabilization of CLOOH-containing liposomes in the presence of tBid could be triggered by monomeric Bax, consistent with tBid/Bax cooperation in pore formation. Using CL-null mitochondria from a yeast mutant, we found that tBid binding and cyt c release were dramatically enhanced by transfer acquisition of CLOOH. Additionally, we observed a pre-apoptotic IM-to-OM transfer of oxidized CL in cardiomyocytes treated with the Complex III blocker, antimycin A. These findings provide new mechanistic insights into the role of CL oxidation in the intrinsic pathway of oxidative apoptosis.

Domain V peptides inhibit beta2-glycoprotein I-mediated mesenteric ischemia/reperfusion-induced tissue damage and inflammation

Reperfusion of ischemic tissue induces significant tissue damage in multiple conditions, including myocardial infarctions, stroke, and transplantation. Although not as common, the mortality rate of mesenteric ischemia/reperfusion (IR) remains >70%. Although complement and naturally occurring Abs are known to mediate significant damage during IR, the target Ags are intracellular molecules. We investigated the role of the serum protein, β2-glycoprotein I as an initiating Ag for Ab recognition and β2-glycoprotein I (β2-GPI) peptides as a therapeutic for mesenteric IR. The time course of β2-GPI binding to the tissue indicated binding and complement activation within 15 min postreperfusion. Treatment of wild-type mice with peptides corresponding to the lipid binding domain V of β2-GPI blocked intestinal injury and inflammation, including cellular influx and cytokine and eicosanoid production. The optimal therapeutic peptide (peptide 296) contained the lysine-rich region of domain V. In addition, damage and most inflammation were also blocked by peptide 305, which overlaps with peptide 296 but does not contain the lysine-rich, phospholipid-binding region. Importantly, peptide 296 retained efficacy after replacement of cysteine residues with serine. In addition, infusion of wild-type serum containing reduced levels of anti-β2-GPI Abs into Rag-1(-/-) mice prevented IR-induced intestinal damage and inflammation. Taken together, these data suggest that the serum protein β2-GPI initiates the IR-induced intestinal damage and inflammatory response and as such is a critical therapeutic target for IR-induced damage and inflammation.

Autoantibody potential of cancer therapeutic monoclonal antibodies

We and others have reported that multiple autoantibodies are unmasked in human polyclonal antibody preparations after exposure to physiological oxidizing agents (hemin) or electromotive force. We now have asked if oxidation unmasks autoantibody reactivities in monoclonal antibodies (mAb). To do this, we have studied 9 FDA approved mAb used therapeutically, including 4 chimeric, 4 humanized and 1 chemically modified chimeric Fab that were exposed to the physiological oxidizing agent hemin at 36 degrees C for 20 hr. These mAb were studied for autoantibody activity to phospholipids and DNA before and after oxidation with hemin and found to develop autoantibody activities after oxidation, while retaining their original specificity as measured by mAb anti-glycophorin A binding of erythrocytes, CD 19 binding to B lymphocytes and anti-HLA-A29 binding to A29-positive lymphocytes. The finding that certain mAb have the potential to unmask autoantibody activities as a consequence of exposure to physiological redox reactions in vitro gives pause to our present understanding of the immunological basis of tolerance and concern for potential autoimmune side effects in patients receiving mAb for diagnosis or treatment.

Antiphospholipid antibodies: paradigm in transition

OBJECTIVES

This is a critical review of anti-phospholipid antibodies (aPL). Most prior reviews focus on the aPL syndrome (APS), a thrombotic condition often marked by neurological disturbance. We bring to attention recent evidence that aPL may be equally relevant to non-thrombotic autoimmune conditions, notably, multiple sclerosis and ITP.

ORGANIZATION

After a brief history, the recent proliferation of aPL target antigens is reviewed. The implication is that many more exist. Theories of aPL in thrombosis are then reviewed, concluding that all have merit but that aPL may have more diverse pathological consequences than now recognized. Next, conflicting results are explained by methodological differences. The lupus anticoagulant (LA) is then discussed. LA is the best predictor of thrombosis, but why this is true is not settled. Finally, aPL in non-thrombotic disorders is reviewed.

CONCLUSION

The current paradigm of aPL holds that they are important in thrombosis, but they may have much wider clinical significance, possibly of special interest in neurology.

Anti-phospholipid antibodies in cerebrospinal fluid but not serum from a boy with psychosis

A 12-year-old African American boy with mental retardation and Asperger's disorder presented with acute psychosis. Antiphospholipid antibody testing with enzyme-linked immunosorbent assay showed increased levels of immunoglobulin G anticardiolipin antibodies in the cerebrospinal fluid, but not in the serum. Although antiphospholipid antibodies have been reported in the serum of patients with thrombotic and neurologic disorders, there are only a few reports of these antibodies in cerebrospinal fluid. This finding is consistent with a recent report of antiphospholipid antibodies found in the cerebrospinal fluid of adults with acute psychosis.

Clinical and neuroimaging correlates of antiphospholipid antibodies in multiple sclerosis: a preliminary study

Background

The presence of antiphospholipid antibodies (APLA) in multiple sclerosis (MS) patients has been reported frequently but no clear relationship between APLA and the clinical and neuroimaging features of MS have heretofore been shown. We assessed the clinical and neuroimaging features of MS patients with plasma APLA.

Methods

A consecutive cohort of 24 subjects with relapsing-remitting (RR) MS were studied of whom 7 were in remission (Rem) and 17 in exacerbation (Exc). All subjects were examined and underwent MRI of brain. Patients' plasma was tested by standard ELISA for the presence of both IgM and IgG antibodies using a panel of 6 targets: cardiolipin (CL), β2 glycoprotein I (β2GPI), Factor VII/VIIa (FVIIa), phosphatidylcholine (PC), phosphatidylserine (PS) and phosphatidylethanolamine (PE).

Results

In exacerbation up to 80% of MS subjects had elevated titers of IgM antibodies directed against the above antigens. However, in remission, less than half of MS patients had elevated titers of IgM antibodies against one or more of the above antigens. This difference was significant, p < 0.01, for all 6 target antigens. Interestingly, none of the MS patients had elevated plasma titers of IgG against any of the target antigens tested. Correlation analysis between MRI enhancing lesions and plasma levels of APLA revealed high correlation for aPC, aPS and aFVIIa (p ≤ 0.0065), a trend for aPE and aCL (p = 0.056), and no correlation for aβ2GP1. The strongest correlation was for aFVIIa, p = 0.0002.

Conclusion

The findings of this preliminary study show that increased APLA IgM is associated with exacerbations of MS. Currently, the significance of this association in pathogenesis of MS remains unknown. However, systematic longitudinal studies to measure APLA in larger cohorts of patients with relapsing-remitting MS, particularly before and after treatment with immunomodulatory agents, are needed to confirm these preliminary findings.

Antiphospholipid antibodies in blood and cerebrospinal fluids of patients with psychosis

Antiphospholipid antibodies (aPL) have been reported in the cerebrospinal fluids (CSF) of neurology patients but no CSF studies with psychiatric patients exist. We tested serum from 100 hospitalized psychotic patients having hallucinations and/or delusions for aPL. Patients with positive serum aPL findings were asked to submit CSF for aPL testing. Five CSF samples had aPL specificities not found in the patient's serum suggesting the possibility of intrathecal synthesis. Specificity and isotype discordance between CSF and blood aPL in these psychiatric patients implicates a central nervous system independent autoimmune process that may have an underlying association with the pathophysiology of their diseases.

Platelet activation rather than endothelial injury identifies risk of thrombosis in subjects positive for antiphospholipid antibodies

BACKGROUND

Anti-phospholipid antibodies (APLA) are often associated with thrombosis, defining the antiphospholipid syndrome (APS) but it remains unclear why many subjects who are positive for APLA chiefly anti-cardiolipin (aCL) or anti-beta2GPI (abeta2GPI) do not develop thrombosis. A related question addressed in this study is whether the target of cellular injury in APS is predominately platelets or endothelial cells (EC).

METHODS

aCL and abeta2GPI were determined by ELISA in 88 patients, 60 of whom were thrombotic and 28 non-thrombotic. Platelet activation was measured by CD62P and by concentration of platelet microparticles (PMP) and EC activation was assessed by endothelial microparticles (EMP), both by flow cytometry. Lupus anticoagulant (LAC) was measured in the hospital laboratory.

RESULTS

There was no difference in frequency of aCL or abeta2GPI, neither IgG or IgM, between the thrombotic and non-thrombotic groups. Both groups showed elevated EMP compared to controls but this did not differ between thrombotic and non-thrombotic groups. In contrast, PMP were not significantly elevated in non-thrombotic but were elevated in thrombotic compared to non-thrombotic (p=0.03) and controls. CD62P, an independent marker of platelet activation, was also elevated in thrombotic vs. non-thrombotic. There was a trend for increased LAC in the thrombotic group but not significant.

CONCLUSION

Although all subjects had evidence of endothelial activation, only platelet activation differed between thrombotic and non-thrombotic. This supports the hypothesis that platelet activation predisposes to thrombosis in the presence of chronic EC activation. These data also raise the possibility of distinguishing risk-prone APLA-positive individuals.

Anti-cardiolipin antibodies and overall survival in a large cohort: preliminary report

BACKGROUND

Anti-cardiolipin antibodies have been associated with both arterial and venous thrombosis, but their overall impact on all-cause or vascular mortality is unknown. In this study, we evaluated the influence of anti-cardiolipin antibodies on all-cause and vascular mortality.

METHODS

All individuals who fulfilled the inclusion criteria (completeness of data, no admission from an intensive care unit, unique identification with name and date of birth) and whose anti-cardiolipin antibodies were measured between October 2002 and February 2004 were included in this study (n = 4756; 64% female; median age, 46 years). Death/survival and cause of death were obtained from the Austrian Death Registry. The median observation period was 1.5 years, and the study comprised 7189 person-years.

RESULTS

During the study period, 184 patients (3.9%) died. There were no associations between either anti-cardiolipin IgM or IgG antibodies and both vascular death and noncancer mortality as outcome variables in a Cox regression analysis adjusted for age and sex. In contrast, the risk of cancer-related mortality was increased 2.6-fold.

CONCLUSIONS

Anti-cardiolipin antibodies are associated with cancer mortality, likely as an epiphenomenon of malignancy, but they are not predictive of vascular mortality or noncancer mortality. Hence, although a clear association between anti-cardiolipin antibodies and (mostly nonfatal) vascular events has been described in the literature, our data indicate that this finding is not necessarily associated with an increase in vascular mortality.

Redox-reactive autoantibodies: Detection and physiological relevance

We recently described a hitherto unrecognized family of autoantibodies that become unmasked (detectable) subsequent to oxidation-reduction (redox) reactions. These masked redox-reactive autoantibodies are not detectable by using conventional immunoassays. Additional experimentation has demonstrated that autoantibodies in the blood of patients with autoimmune diseases can be masked (become undetectable) by exposure to oxidizing agents. Simultaneous masking and unmasking of different autoantibodies in a given patient's serum or plasma is evidence that immune complexes are not the source of redox-reactive autoantibodies. We propose that a mechanism responsible for unmasking-masking antibody specificities requires nitrosylation of tyrosine residues in the hypervariable or complementarity determining regions of the antibodies' antigen-binding sites. Other laboratories, selected by us for their respective expertise, have studied our redox-reacted and control serum and/or antibody preparations and have found an expanding array of autoantibody specificities. The gathering data suggest that certain autoimmune diseases may involve redox disorders rather than a failure to deplete, suppress, tolerate or divert self-directed B cell activity. The persistence and fluctuation of redox-reactive autoantibodies suggest that they are manifestations of an as yet undefined natural selective pressure on the evolution of the immunological system. We propose that they are the "contrivances" suggested by Paul Ehrlich more than a hundred years ago, and that these antibodies perform important physiological and pathophysiological functions.

Anti-Phospholipid Antibodies against Phosphatidylinositol, and Phosphatidylserine are More Significant in Reproductive Failure than Antibodies against Cardiolipin only

PROBLEM

The humoral immune response to phospholipids was investigated in women with reproductive failure [1073 women after one in vitro fertilization (IVF), 853 women after two and more IVF, 627 women after three and more repeated spontaneous miscarriages or missed abortions, 412 women after diagnostic laparoscopy] and compared with that of 391 healthy fertile women.

METHOD OF STUDY

Sera from all women in the study were tested by enzyme-linked immunosorbent assay (ELISA) for the detection of IgG, IgA, and IgM isotypes of antibodies against seven phospholipids (aPLs), i.e. cardiolipin, L-phosphatidylserine, phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, phosphatidylacid as well as against beta2-glycoprotein I.

RESULTS

Patients after two and more IVF (48 and 50%, respectively), patients with three and more repeated spontaneous miscarriages (50 and 46.5%, respectively) are associated with significantly higher serum levels of aPLs against inositol, and L-serine (P < 0.01). A quarter of them were positive for three and more aPLs.

CONCLUSION

It seems that determination of aPLs only against cardiolipin in reproductive failure is not sufficient for obstetric-gynecology diagnosis as the primary anti-phospholipid syndrome. Our long-ranging study (from 1998 to 2003) shows the necessity to test for a complete aPLs profile. Sera from patients after two and more IVF procedures, and sera from women after three and more repeated abortions are immunologically more active than sera from women after one unsuccessful IVF and sera from women after diagnostic laparoscopy. This important result is very significant for future treatment.

Autoantibodies unmasked by redox reactions

Blood from healthy donors was found to contain a variety of autoantibodies after being cultured overnight in commercial blood culture bottles. Paradoxically some autoantibodies in the blood of patients with autoimmune diseases were no longer detectable when similarly cultured. By a process of elimination it was revealed that hemin was responsible for the conversion of antibody-negative blood to antibody-positive blood, as well as for the conversion of antibody-positive blood to antibody-negative blood. By using a purified component system of hemin and immunoglobulin, and an iron-free congener of hemin, we have shown that the appearance and/or disappearance of antibodies occur uniquely in the presence of coordinated iron and in the absence of antioxidants such as vitamin C. The oxidation-reduction (redox) reactions used to demonstrate the appearance and disappearance of autoantibodies have been performed in vitro. Whether the reactions we have observed have a parallel in vivo remains to be determined. It is clear from our findings that normal individuals have immunoglobulin molecules which can exhibit autoantibody binding capacity, and that at least some autoantibodies in autoimmune individuals can have their binding capacity masked by exercise of a natural redox system. These preliminary findings need further investigation but they already hint that some of our apparently well based views on autoimmunity might be expanded to include a role for masked and unmasked autoantibodies.

Anti-phospholipid antibodies restore mesenteric ischemia/reperfusion-induced injury in complement receptor 2/complement receptor 1-deficient mice

Complement receptor 2-deficient (Cr2(-/-)) mice are resistant to mesenteric ischemia/reperfusion (I/R) injury because they lack a component of the natural Ab repertoire. Neither the nature of the Abs that are involved in I/R injury nor the composition of the target Ag, to which recognition is lacking in Cr2(-/-) mice, is known. Because anti-phospholipid Abs have been shown to mediate fetal growth retardation and loss when injected into pregnant mice, we performed experiments to determine whether anti-phospholipid Abs can also reconstitute I/R injury and, therefore, represent members of the injury-inducing repertoire that is missing in Cr2(-/-) mice. We demonstrate that both murine and human monoclonal and polyclonal Abs against negatively charged phospholipids can reconstitute mesenteric I/R-induced intestinal and lung tissue damage in Cr2(-/-) mice. In addition, Abs against beta2 glycoprotein I restore local and remote tissue damage in the Cr2(-/-) mice. Unlike Cr2(-/-) mice, reconstitution of I/R tissue damage in the injury-resistant Rag-1(-/-) mouse required the infusion of both anti-beta2-glycoprotein I and anti-phospholipid Ab. We conclude that anti-phospholipid Abs can bind to tissues subjected to I/R insult and mediate tissue damage.

Innate autoimmunity

The adaptive immune system has evolved highly specific pattern recognition proteins and receptors that, when triggered, provide a first line of host defense against pathogens. Studies reveal that these innate recognition proteins are also self-reactive and can initiate inflammation against self-tissues in a similar manner as with pathogens. This specific event is referred to as "innate autoimmunity." In this review, we describe two classes of autoimmune responses, that is, reperfusion injury and fetal loss syndrome, in which the recognition and injury are mediated by innate immunity. Both disorders are common and are clinically important. Reperfusion injury (RI) represents an acute inflammatory response after a reversible ischemic event and subsequent restoration of blood flow. Findings that injury is IgM and complement dependent and that a single natural antibody prepared from a panel of B-1 cell hybridomas can restore injury in antibody-deficient mice suggest that RI is an autoimmune-type disorder. Fetal loss syndrome is also an antibody- and complement-dependent disorder. Although both immune and natural antibodies are likely involved in recognition of phospholipid self-antigens, inhibition of the complement pathway in rodent models can block fetal loss. As new innate recognition proteins and receptors are identified, it is likely that innate responses to self represent frequent events and possibly underlie many of the known chronic autoimmune disorders normally attributable to dysregulation of adaptive immunity.

Current debates in antiphospholipid syndrome: the acquired antibody-mediated thrombophilia

Antiphospholipid (APL) syndrome is the most common form of acquired thrombophilia. It can cause significant morbidity and even mortality. The term "APL antibodies" represents a heterogeneous group of antibodies associated with this disorder. Currently no single assay can identify every APL antibody. Clinically relevant APL antibodies are mainly anticardiolipin antibodies (ACA) detected by solid phase enzyme-linked immunosorbent assay (ELISA) and lupus anticoagulants (LA) demonstrated by in vitro coagulation assay. However, there are some other antibodies associated with the APL syndrome (i.e., subgroup APL antibodies). ACAs, LAs, and subgroup APL antibodies represent intersecting, but non-identical, subsets of autoantibodies. Thus, those autoantibodies may coexist or may occur independently. Any organ system and any size of vessel can be affected during the clinical course of the disease. Therefore, the APL syndrome can manifest itself in a wide variety of clinical thrombotic features. Fetal loss and pregnancy morbidity represent a specific challenge. Despite tremendous advances in the understanding of the pathogenesis of APL syndrome during the past decade, the mainstay of management is still anticoagulation. However, there is no general agreement regarding the duration and intensity of anti-coagulant therapy. In this review, we focused on the current dilemmas and their present clarifications in the wide clinicopathologic spectrum of APL syndrome and APL antibody-related distinct pathologic conditions.

The appearance and disappearance of antiphospholipid autoantibodies subsequent to oxidation–reduction reactions

The mechanisms that cause the appearance of autoantibodies are not understood. Compared to normal antibody production, factors responsible for autoantibody synthesis are more complex; they are thought to disrupt the normal mechanisms proposed to eliminate or down-regulate self-antibodies or to interfere with anti-self-receptor editing. Data presented show that autoantibodies exist in the blood of all normal individuals. The autoantibodies appear after simple oxidation-reduction (redox) reactions and react by ELISA, immunofluorescence, flow cytometry, Western blots, and in lupus anticoagulant (LA) assays. Antiphospholipid antibody (aPL) specificities detected after redox are cardiolipin (aCL), antiphosphatidylserine (aPS), antiphosphatidylethanolamine (aPE), antiphosphatidylcholine (aPC), and LA. These antibody activities were confirmed in several outside laboratories. The aPL isotypes detected in ELISA are plasma protein-dependent and include IgG, IgA, and IgM. Oxidizing agents tested to date include hemin, KMnO4, and NaIO4. Furthermore, aPL appear after exposure to direct current (DC)-mediated electromotive force. Alternating current (AC) is ineffective. Commercial IvIg preparations, also a source of IgG autoantibodies, provide a less complex milieu than plasma or serum for studying the biology of aPL redox-mediated mechanisms. Inhibition of hemin-mediated IvIg aPL conversion can be achieved by the addition of antioxidants, e.g., ascorbic acid, hemopexin, apotransferrin, and by addition of normal plasma or serum. Remarkably, the aPL specificities in the blood of autoimmunity patients disappear subsequent to application of redox reactions. These data document the hitherto unknown existence of redox-reactive autoantibodies in all normal individuals. The evolutionary persistence of these redox-sensitive antibodies raises interesting possibilities about their potentially beneficial role in immunological homeostasis.

Antiphospholipid antibodies and renal transplantation: a risk assessment

Data from 110 transplanted patients show that the presence of antiphospholipid antibodies (aPL) at the time of transplantation is an important risk factor for early renal allograft failure. Sera were tested for IgG, IgM and IgA to CL, PS, PE and PC. Haemodialysis patients had a significantly higher incidence of aPL compared to patients who did not receive haemodialysis (P = 0.0171). aPL-positive ESRD patients on peritoneal dialysis (CAPD) or who had never received haemodialysis were at maximal risk; 100% failure (P = 0.0022). aPL-positive patients receiving haemodialysis were not at such risk. Biopsy findings from the failed kidneys show abundant fibrin deposition in the microvasculature. Serial blood samples from transplanted patients showed aPL titres to decrease immediately after transplant and increase after removal of the failed graft, indicating that aPL specifically target the allografts. To confirm this, we were able to isolate aPL from a failed graft after transplant nephrectomy. Ninety-seven per cent of the aPL-positive patients' historic pre-transplant serum samples demonstrated the presence of the same aPL specificity detected in the final crossmatch sera. The exposure to heparin during haemodialysis suggested to us that heparin reduces the risk of clotting in aPL positive transplant candidates. To lessen the risk of graft loss in aPL positive kidney transplant patients (including CAPD), subcutaneous heparin was administered peri- and post-operatively. To date, none of the heparin-treated aPL-positive transplanted patients suffered an early graft loss. Further, they experienced fewer rejection episodes requiring biopsy and thus are prescribed less steroid therapy than patients not treated with heparin.