Lupus anticoagulant, anticardiolipin antibodies and hepatitis C virus infection in thalassaemia

Hematological manifestations of antiphospholipid syndrome: Going beyond thrombosis

Thrombotic complications are a hallmark of antiphospholipid syndrome (APS). These vascular - arterial, venous, and/or small vessel - complications are well described and known to hematologists and healthcare providers caring for patients with this disease. In this review, we shed light on other hematological manifestations of the disease, including bleeding, thrombocytopenia, autoimmune hemolytic anemia, and thrombotic microangiopathy syndromes. While these manifestations are not bona fide clinical criteria for the diagnosis of APS, they frequently interact and contribute to the complexity of clinical management of APS.

Thalassemia and autoimmune diseases: Absence of evidence or evidence of absence?

The thalassemias are a group of inherited disorders of hemoglobin synthesis that continue to pause a global public health concern. The complex molecular and pathogenetic pathways involved in disease process lead to an array of comorbidities that require lifelong management. The disease and its treatment can also lead to alterations in immune function and a link to various autoimmune diseases has been frequently suggested. However, most data stem from single case reports and small studies that do not allow proper assessment of causal associations. Still, the high morbidity in thalassemia makes patients vulnerable to the added burden of coexisting autoimmune diseases, and special management considerations in this patient population are warranted. In this review, we explore insights and data from the literature on various autoimmune disease that have been observed in patients with thalassemia. The role of the thalassemia carrier state in modifying outcomes of patients with autoimmune diseases is also discussed.

Environmental Triggers of Autoreactive Responses: Induction of Antiphospholipid Antibody Formation

Antiphospholipid antibodies (aPLs) comprise a diverse family of autoantibodies targeted against proteins with the affinity toward negatively charged phospholipids or protein-phospholipid complexes. Their clinical significance, including prothrombotic potential of anti-cardiolipin antibodies (aCLs), anti-β2-glycoprotein I antibodies (aβ2-GPIs), and lupus anti-coagulant (LA), is well-established. However, the ontogeny of these pathogenic aPLs remains less clear. While transient appearance of aPLs could be induced by various environmental factors, in genetically predisposed individuals these factors may eventually lead to the development of the antiphospholipid syndrome (APS). Since the first description of APS, it has been found that a wide variety of microbial and viral agents influence aPLs production and contribute to clinical manifestations of APS. Many theories attempted to explain the pathogenic potential of different environmental factors as well as a phenomenon termed molecular mimicry between β2-GPI molecule and infection-relevant structures. In this review, we summarize and critically assess the pathogenic and non-pathogenic formation of aPLs and its contribution to the development of APS.

Stroke Associated With Recent Mycoplasma Pneumoniae Infection: A Systematic Review of Clinical Features and Presumed Pathophysiological Mechanisms

Introduction: An association between Mycoplasma pneumoniae (MP) infection and stroke has been described, especially in children. However, current knowledge on this rare potential cause of stroke is scant. The purpose of this systematic review of all published cases was to help better understand the relationships between recent MP infection and ischemic stroke on a clinical, radiological and pathophysiological perspective.

Material and Methods: A PubMed and Embase search was performed in September 2018 to identify all published cases of stroke occurring within 4 weeks after MP infection.

Results: Twenty-eight patients with ischemic stroke associated with MP infection were identified. Median age was 8 years (range: neonate to 57). The middle cerebral artery territory was involved in 25 (89%) patients. Fifteen (54%) patients had at least one arterial occlusion. Elevated D-dimer and/or fibrinogen was reported in 8 (29%) patients. Four patients had transient anticardiolipin IgM antibodies. Cerebrospinal fluid analysis showed pleocytosis in 7/20 (35%) patients (median: 19 leucocytes/μL, range: 10 to 63) and MP PCR was positive in 3/8 (38%) patients. The etiological work-up was considered inconclusive in 25 (89%) patients. Three (11%) patients died during follow-up, all of early respiratory deterioration. Neurological functional outcome was good in 22/27 (81%) patients.

Conclusion: The association between MP infection and ischemic stroke in children and young adults is rare. Underlying pathogenesis might include hypercoagulability and vasculitis. Most patients achieve a favorable recovery. Whether MP infection could be a long-term risk factor for stroke by promoting atherosclerosis is uncertain and deserves further investigation.

Rheumatological complications of beta-thalassaemia: an overview

Beta-thalassaemia, an autosomal recessive haemoglobinopathy, ranks among the most frequent monogenetic diseases globally. The severe form of the disease, beta-thalassaemia major, is accompanied by progressive involvement of multiple organ systems as a result of the disease pathophysiology as well as iron overload from blood transfusions on a regular basis. Some of the manifestations might also be caused by medications used to manage iron overload. The purpose of this review is to highlight the rheumatological complications of beta-thalassaemia, which include musculoskeletal manifestations, such as arthritis and arthropathies, joint effusions, osteoporosis, bone fractures and myalgias, in addition to CTDs, such as pseudoxanthoma elasticum. Rheumatologists are strongly encouraged to take part in a multidisciplinary approach to the management of this debilitating disease.

Redefining thalassemia as a hypercoagulable state

As the life expectancy of beta-thalassemia patients has markedly improved over the last decade, several new complications are being recognized. The presence of a high incidence of thromboembolic events, mainly in thalassemia intermedia patients, has led to the identification of a hypercoagulable state in thalassemia. In this review, the molecular and cellular mechanisms leading to hypercoagulability in thalassemia are highlighted, and the current clinical experience is summarized. Recommendations for thrombosis prophylaxis are also discussed.

[Antiphospholipid antibodies, antiphospholipid syndrome and viral infections]

Since the association between antiphospholipid antibodies and syphilis was first described, many other viral, bacterial and parasitic infections have been shown to induce antiphospholipid antibodies, notably anticardiolipin antibodies. These aPL are usually associated neither with anti-beta2 glycoprotein I antibodies (anti-beta2-GPI) nor with thrombotic events, even if cases of arterial and deep venous thrombosis have been reported in such circumstances. A literature review shows that anticardiolipin antibodies occur frequently in viral infections, particularly in HIV (49.8%), HBV (24%) and HCV (20%). The prevalence of anti-beta2 glycoprotein I antibodies (anti-beta2GPI) is lower (HCV: 1.7%, HIV: 5.6%, HBV: 3.3%) and there is no demonstrated association with a risk of thrombotic events or hematological manifestations defining antiphospholipid syndrome (APS). Regarding other viral infections, including viral hepatitis A, herpes virus (CMV, EBV, VZV), parvovirus B19 and HTLV-1 infections, only a few studies are available but data confirm the high prevalence of antiphospholipid antibodies at the acute phase. Finally, antiphospholipid antibodies, mainly anticardiolipin, are frequently associated with viral infections. Their presence may probably reflect an intense or chronic antigenic stimulation of the immune system. However, their evolution under antiviral therapy and correlation with the quality of the virological control and/or the immune restoration remain to be determined.

Antiphospholipid antibodies and hepatitis C virus infection in Iranian thalassemia major patients

Although the precise nature of Antiphospholipid antibodies is still not clearly defined, they are known to have association with thromboembolic events and have been found in hepatitis C virus (HCV) infection. Moreover, high prevalence of HCV infection and thrombotic risk is described in thalassemia. We aimed at investigating the prevalence of anticardiolipin antibodies (aCLAbs), lupus anticoagulant (LA), and their relation with HCV infection in Iranian thalassemic patients. Presence of anti-HCV antibody, serum HCV-RNA, aCLAbs, and LA activity was determined in 131 patients with thalassemia major (male/female: 63/68 aged 3-29 years) registered at thalassemia unit, Dastgheib Hospital, Shiraz, Iran. Sixty-one healthy controls were also included. Anti-HCV antibody was positive in 24 (18.3%), IgG aCLAbs in 56 (42.7%), and LA activity in 9 (6.9%) patients. 87.5% of patients positive for aCLAbs had a low titer of aCLAbs. Although none of the participants had a previous history of thrombosis, higher prevalence of aCLAbs was detected in thalassemic patients compared with controls. No significant difference in the prevalence of aCLAbs was found between HCV-infected and noninfected patients. A high prevalence of aCLAbs, the majority in low titers, was detected in Iranian thalassemic patients irrespective of previous history of thrombosis and presence of HCV infection.

Antiphospholipid syndromes in infectious diseases

Antiphospholipid antibodies are essential in the diagnosis of antiphospholipid syndrome (APS), or the classic "Hughes syndrome," which is a systemic disorder that is autoimmune in nature. They are also found in various infections in low titers without any evidence of thrombotic manifestations of APS. However, in a few infections, when antiphospholipid antibodies are associated with protein cofactor, there can be associated thrombosis. Different infections are also responsible for triggering a subset of lethal APS, acute catastrophic APS. This situation requires prompt diagnosis and aggressive treatment of the infection to prevent severe complications.

Antiphospholipid antibodies, antiphospholipid syndrome and infections

Since the association between antiphospholipid antibodies (aPL) and syphilis was first described, many other viral, bacterial and parasitic infections have been shown to induce antiphospholipid antibodies, notably anticardiolipin antibodies (aCL). A review of the literature shows that while aCL occur frequently in viral infections, particularly in HIV (49.75%), HBV (24%) and HCV (20%), it is very rarely associated with anti-beta2 glycoprotein I antibodies (anti-beta2GPI) and is not correlated with thrombosis risk or hematological manifestations of the antiphospholipid syndrome (APS). Concerning bacterial infections, aCL is often present in leprosy (42.7%), where it is frequently associated with the presence of anti-beta2GPI (44.8%), and in syphilis infections (8 to 67%), though without correlation with thrombotic events. Though few individual patients with unequivocal infection-induced aPL satisfy criteria for APS, the lack of statistical association with thrombotic events strongly argues against the identification of a true APS subset in this context. However, physicians should keep in mind the fact that an infection, generally bacterial, in patients with confirmed APS, may lead to catastrophic antiphospholipid syndrome with a possible fatal outcome.

Lupus anticoagulant and anticardiolipin antibodies in polytransfused beta thalassemia major

The currently used therapeutic strategies in beta thalassemia have prolonged the survival for many patients; this longer survival has been accompanied by the development of a number of unexpected complications, these include hemostatic derangements. The presence of anti-phospholipid antibodies (APA) (lupus anticoagulant, LA and anti-cardiolipid antibody, ACA) has recently been reported in polytransfused patients of beta thalassemia. In this study 50 patients with beta thalassemia major (beta-TM) who had received at least 20 transfusions were evaluated for presence of antiphospholipid antibodies and correlated with a number of clinical and hemostatic parameters. About 32% cases had developed a minor bleeding tendency and one also showed ecchymotic patch. None of the patients had thromboembolic episodes. LA was seen in 16% of cases. The mean age and number of transfusions were higher in LA positive patients as compared to LA negative patients however the results were not statistically significant. IgM ACA were detected in 6% of patients but no statistically significant correlation was found with age, number of transfusions, platelet count and coagulation parameters. IgG ACA were detected in 30% of cases and showed a significant correlation with number of blood transfusions (p = 0.016) and age (p = 0.031). Anti HCV antibodies were detected in 30% of patients out of which 1 had IgM ACA and 10 had IgG ACA. The latter showed a significant correlation with HCV infection. An increased incidence of LA and IgG ACA is found in polytransfused patients with beta-TM when compared to the normal healthy population but their clinical significance is yet not clearly understood.

Thromboembolic complications in β-thalassemia: Beyond the horizon

Patients with beta-thalassemia have a chronic hypercoagulable state with increased incidence of thromboembolic episodes. The thrombotic complications are more common in thalassemia intermedia than in regularly transfused thalassemia major. The pathophysiologic defects include inherent red cell defects, platelet abnormalities, deficiency of coagulation inhibitors, and additional acquired abnormalities like cardiac and liver dysfunction, hormonal deficiencies. These factors and possible preventive measures are discussed in this review. An illustrative case is also presented.

Antiphospholipid syndrome associated with infections: clinical and microbiological characteristics

Antiphospholipid antibodies (aPL) were originally detected in human serum almost 100 years ago when the Venereal Disease Research Laboratory (VDRL) test was described. A phospholipid called cardiolipin was the major tissue extract utilized in performing these tests. In 1983, cardiolipin was used for the first time as the antigen in solid-phase aPL specific assays for the now termed antiphospholipid syndrome (APS). Since then, many infections have been found to be associated with aPL positivity, although a pathogenic role for these antibodies was not usually obvious except in a few isolated cases.

Antiphospholipid syndrome: association between laboratory tests and clinical practice

Antiphospholipid antibodies are a wide and heterogeneous group of immunoglobulins, whose presence inpatients with arterial and venous thrombosis, and obstetrical complications defines the antiphospholipid syndrome. We systematically reviewed published articles on this syndrome to investigate the association between thrombosis and the most common antiphospholipid antibodies. Lupus anticoagulants were a clear risk factor for thrombosis, irrespective of the site and type of thrombosis, the presence of systemic lupus erythematosus, and the methods used to detect them. Anticardiolipin and anti 2-glycoprotein I antibodies were possible risk factors of thrombosis, at least in some selected situations. Conversely, the measurement of antiprothrombin antibodies was not helpful to define the patient's risk of thrombosis. These results are mainly due to the still far from optimal standardization of the methods to detect the various antiphospholipid antibodies.

Antiphospholipid syndrome associated with infections: clinical and microbiological characteristics of 100 patients

OBJECTIVE

To describe and analyse the clinical characteristics of 100 patients with antiphospholipid syndrome (APS) associated with infections.

METHODS

Patients were identified by a computer assisted search (Medline) of published reports to locate all cases of APS published in English, Spanish, and French from 1983 to 2003. The bilateral Fisher exact test was used for statistics.

RESULTS

59 female and 41 male patients were identified (mean (SD) age, 32 (18) years (range 1 to 78)): 68 had primary APS, 27 had systemic lupus erythematosus, two had "lupus-like" syndrome, two had inflammatory bowel disease, and one had rheumatoid arthritis. APS presented as a catastrophic syndrome in 40% of cases. The main clinical manifestations of APS included: pulmonary involvement (39%), skin involvement (36%), and renal involvement (35%; nine with renal thrombotic microangiopathy, RTMA). The main associated infections and agents included skin infection (18%), HIV (17%), pneumonia (14%), hepatitis C (13%), and urinary tract infection (10%). Anticoagulation was used in 74%, steroids in 53%, intravenous immunoglobulins in 20%, cyclophosphamide in 12%, plasma exchange in 12%, and dialysis in 9.6%. Twenty three patients died following infections and thrombotic episodes (16 with catastrophic APS). Patients given steroids had a better prognosis (p = 0.024). The presence of RTMA and requirement for dialysis carried a worse prognosis (p = 0.001 and p = 0.035, respectively).

CONCLUSIONS

Various different infections can be associated with thrombotic events in patients with APS, including the potentially lethal subset termed catastrophic APS. Aggressive treatment with anticoagulation, steroids, and appropriate antibiotic cover is necessary to improve the prognosis.

A peptide that shares similarity with bacterial antigens reverses thrombogenic properties of antiphospholipid antibodies in vivo

OBJECTIVE

The factors causing production of antiphospholipid (aPL) antibodies remain unidentified. Recently, studies have shown that aPL and anti-beta2Glycoprotein I (anti-beta2GPI) antibodies with pathogenic properties can be generated with peptides from bacterial and viral origin, that mimic regions of beta2GPI. These data suggest a molecular mimicry between bacterial/viral antigens and self-proteins. In this study we examined the ability of a synthetic peptide (named peptide A, NTLKTPRVGGC) that shares similarity with common bacterial antigens, to reverse aPL-mediated thrombosis in mice in vivo. Peptide A is also found in region I/II of beta2GPI. A scrambled form of peptide A (named scA, GTKGCPNVRLT) was used as a control.

METHODS AND RESULTS

Sera from 29 patients with APS bound to peptide A but not to peptide scA by ELISA in a dose-dependent fashion. Cardiolipin (CL) liposomes inhibited the binding of IgG-APS by ELISA to peptide A by 35% and to CL by 56%. The inhibition of binding to cardiolipin and to peptide A was enhanced by addition of beta2GPI to the liposomes. CL/peptide A liposomes but not peptide A alone inhibited the binding of IgG-APS to peptide A. beta2GPI alone did not inhibit binding of IgG-APS to peptide A, to beta2GPI or to CL. For the in vivo experiments, CD1 mice in groups of 20 were injected with affinity purified aPL antibodies or with control IgG-NHS twice intraperitoneally. Seventy hours after the first injection, and 30 min before the surgical procedure (induction of experimental thrombus) mice were infused i.v. in each group with either peptide A or with peptide scA. The femoral vein of the anesthetized mice were dissected to examine the dynamics of an induced thrombus in treated and control mice. The mean aCL titer of mice injected with aPL was 60 GPL units. Mice treated with aPL and infused with peptide scA produced significantly larger thrombi when compared to mice treated with IgG-NHS and peptide scA (2466+/-462 microm2 vs 772.5+/-626.4 microm2). Treatment with peptide A significantly decreased thrombus size in mice injected with aPL antibodies (1063+/-890 microm2 compared to 2466+/-462 microm2).

CONCLUSION

The data indicates that a synthetic peptide that shares similarity with common bacterial antigens and with regions of beta2GPI is capable to inhibit thrombogenic properties of aPL in mice. This may have important implications in designing new modalities of prevention and/or treatment of thrombosis in APS.

Antiphospholipid antibodies and pregnancy

Antiphospholipid antibodies, i.e. lupus anticoagulants and anticardiolipin antibodies, are associated with obstetric complications. Fetal death and recurrent spontaneous abortions represent the obstetric criteria of the antiphospholipid syndrome. They occur with similar frequences and have an overall prevalence of 15-20%. Lupus anticoagulants carry a risk 3.0 to 4.8 times, and anticardiolipin antibodies 0.86 to 20 times higher than controls. The mechanism(s) by which antiphospholipid antibodies cause these events still has to be defined: thrombosis in the placental vessels, and impairment of embryonic implantation have been proposed. Unfractionated or low-molecular-weight heparin, alone or in combination with low-dose aspirin, represent the current standard treatment of pregnant antiphospholipid-positive women for preventing recurrent obstetric complications. Upon treatment, the live birth rate increases from 0-40% to 70-80%. However, there is still an excessive frequency of maternal and/or fetal complications, indicating the necessity of a better calibration of the dosage, duration and timing of administration of heparin treatment.

Antiphospholipid antibodies and infections

Many infections have been found to be associated with antiphospholipid antibodies (aPL), although a pathogenic role for these antibodies has not usually been obvious except in a few isolated cases. Two types of aPL have been referred to as "autoimmune" and "infectious" types. This distinction, however, has subsequently been found not to be absolute.

Lupus anticoagulants are stronger risk factors for thrombosis than anticardiolipin antibodies in the antiphospholipid syndrome: a systematic review of the literature

To formally establish the risk of lupus anticoagulants and anticardiolipin antibodies for arterial and venous thrombosis, we ran a MEDLINE search of the literature from 1988 to 2000. Studies were selected for their case-control (11), prospective (9), cross-sectional (3), and ambispective (2) design. They provided or enabled us to calculate the odds ratio with 95% confidence interval (CI) of lupus anticoagulants and/or anticardiolipin antibodies for thrombosis in 4184 patients and 3151 controls. Studies were grouped according to the antibody investigated. Five studies compared lupus anticoagulants with anticardiolipin antibodies: the odds ratio with 95% CI of lupus anticoagulants for thrombosis was always significant. None of them found anticardiolipin antibodies were associated with thrombosis. Four studies analyzed only lupus anticoagulants: the odds ratio with 95% CI was always significant. The risk of lupus anticoagulants was independent of the site and type of thrombosis, the presence of systemic lupus erythematosus, and the coagulation tests employed to detect them. Sixteen studies served to assess 28 associations between anticardiolipin antibodies and thrombosis: the odds ratio with 95% CI was significant in 15 cases. Anticardiolipin titer correlated with the odds ratio of thrombosis. In conclusion, the detection of lupus anticoagulants and, possibly, of immunoglobulin G (IgG) anticardiolipin antibodies at medium or high titers helps to identify patients at risk for thrombosis. However, to take full advantage of the conclusions provided by the available evidence, there is an urgent need to harmonize investigational methods.

Anti-cardiolipin antibodies in patients with chronic viral hepatitis are independent of beta2-glycoprotein I cofactor or features of antiphospholipid syndrome

BACKGROUND

Although controversial, some authorities have implicated hepatitis C virus (HCV) as a cause of anti-phospholipid syndrome (APLS). Anti-cardiolipin antibodies (anti-CLAbs) in APLS are cofactor-dependent ('pathogenic' antibodies). We conducted a study in order to determine the prevalence of anti-CLAbs in HCV patients, and furthermore to address whether these autoantibodies are cofactor-dependent or not and whether they are associated with features of APLS. Patients with hepatitis B virus (HBV) were also evaluated in order to assess whether there are differences in the prevalence and the clinical significance of anti-CLAbs between these two major types of chronic viral hepatitis.

MATERIALS AND METHODS

One hundred and seventy-four consecutive HCV patients, 50 HBV patients and 267 healthy were investigated for the presence of anti-CLAbs and antibodies against beta2-glycoprotein I (beta2-GPI), which is the most important cofactor of the 'pathogenic' anti-CLAbs in APLS. IgG anti-CLAbs were determined by an in-house quantitative ELISA and anti-beta2-GPIAbs using a commercial ELISA kit.

RESULTS

21.3% of the HCV and 14% of the HBV patients tested positive for IgG anti-CLAbs (P < 0.0001 compared with healthy controls). Neither age, sex, certain epidemiologic and laboratory parameters nor the clinical status and the histologic findings were associated with anti-CLAbs detection in both diseases. 2.3% of the HCV (P < 0.05 compared with healthy controls) and 2% of the HBV patients tested positive for anti-beta2-GPIAbs. Presence of anti-CLAbs was not associated with features of APLS.

CONCLUSIONS

A significant proportion of the HCV and HBV patients had detectable IgG anti-CLAbs. However, the anti-CLAbs titres were relatively low, and in most cases seem to be cofactor-independent ('nonpathogenic'). The latter is further supported by the lack of their association with clinical features of APLS. Furthermore, anti-CLAbs appear to be detected irrespective of the demographic, laboratory, clinical and histologic status in both HCV and HBV. However, prospective studies of longer duration may be required in order to address whether anti-CLAbs in patients with chronic viral hepatitis are or are not of clinical importance.

Bacterial induction of autoantibodies to beta2-glycoprotein-I accounts for the infectious etiology of antiphospholipid syndrome

The antiphospholipid syndrome (APS) is characterized by the presence of pathogenic autoantibodies against beta2-glycoprotein-I (beta2GPI). The factors causing production of anti-beta2GPI remain unidentified, but an association with infectious agents has been reported. Recently, we identified a hexapeptide (TLRVYK) that is recognized specifically by a pathogenic anti-beta2GPI mAb. In the present study we evaluated the APS-related pathogenic potential of microbial pathogens carrying sequences related to this hexapeptide. Mice immunized with a panel of microbial preparations were studied for the development of anti-beta2GPI autoantibodies. IgG specific to the TLRVYK peptide were affinity purified from the immunized mice and passively infused intravenously into naive mice at day 0 of pregnancy. APS parameters were evaluated in the infused mice on day 15 of pregnancy. Following immunization, high titers of antipeptide [TLRVYK] anti-beta2GPI Ab's were observed in mice immunized with Haemophilus influenzae, Neisseria gonorrhoeae, or tetanus toxoid. The specificity of binding to the corresponding target molecules was confirmed by competition and immunoblot assays. Naive mice infused with the affinity-purified antipeptide Ab's had significant thrombocytopenia, prolonged activated partial thromboplastin time and elevated percentage of fetal loss, similar to a control group of mice immunized with a pathogenic anti-beta2GPI mAb. Our study establishes a mechanism of molecular mimicry in experimental APS, demonstrating that bacterial peptides homologous with beta2GPI induce pathogenic anti-beta2GPI Ab's along with APS manifestations.

Bacterial induction of autoantibodies to beta2-glycoprotein-I accounts for the infectious etiology of antiphospholipid syndrome

The antiphospholipid syndrome (APS) is characterized by the presence of pathogenic autoantibodies against beta2-glycoprotein-I (beta2GPI). The factors causing production of anti-beta2GPI remain unidentified, but an association with infectious agents has been reported. Recently, we identified a hexapeptide (TLRVYK) that is recognized specifically by a pathogenic anti-beta2GPI mAb. In the present study we evaluated the APS-related pathogenic potential of microbial pathogens carrying sequences related to this hexapeptide. Mice immunized with a panel of microbial preparations were studied for the development of anti-beta2GPI autoantibodies. IgG specific to the TLRVYK peptide were affinity purified from the immunized mice and passively infused intravenously into naive mice at day 0 of pregnancy. APS parameters were evaluated in the infused mice on day 15 of pregnancy. Following immunization, high titers of antipeptide [TLRVYK] anti-beta2GPI Ab's were observed in mice immunized with Haemophilus influenzae, Neisseria gonorrhoeae, or tetanus toxoid. The specificity of binding to the corresponding target molecules was confirmed by competition and immunoblot assays. Naive mice infused with the affinity-purified antipeptide Ab's had significant thrombocytopenia, prolonged activated partial thromboplastin time and elevated percentage of fetal loss, similar to a control group of mice immunized with a pathogenic anti-beta2GPI mAb. Our study establishes a mechanism of molecular mimicry in experimental APS, demonstrating that bacterial peptides homologous with beta2GPI induce pathogenic anti-beta2GPI Ab's along with APS manifestations.

Viral infections and antiphospholipid antibodies

OBJECTIVE

To study the relationship between viral infections and the induction of antiphospholipid (aPL) antibodies.

METHODS

We reviewed the medical literature from 1968 until 2000 using MEDLINE and the key words virus, infection, antiphospholipid, and anticardiolipin.

RESULTS

Anticardiolipin antibodies and/or lupus anticoagulant were associated with a number of viral infections, including hepatitis C virus, human immunodeficiency virus, cytomegalovirus, varicella zoster, Epstein-Barr virus, adenovirus, and parvovirus B. In many instances, the presence of these antibodies was associated with thrombosis.

CONCLUSION

The clinical significance of finding aPL antibodies in patients with viral infections remains unknown. In some patients, these antibodies may be transient and disappear within 2 or 3 months. In other susceptible individuals, they may persist and raise the question of whether infections may trigger the development of aPL antibodies in autoimmune diseases.

The antiphospholipid syndrome and infection

Infectious agents have been implicated in the induction of antiphospholipid (aPL) antibodies and the development of the antiphospholipid syndrome (APS). This review focuses on the types of aPL antibodies detected in infections and addresses whether these antibodies are of clinical importance in patients with infections. Hepatitis C virus (HCV) infection is given special attention because this virus has the propensity to induce various autoimmune phenomena. Several aspects are emphasized that should be considered carefully when interpreting results. Most of the published data agree that thrombophilia is not observed in patients with infections (including HCV) because aPL antibodies are mostly the natural or nonpathogenic type. Thus, we do not recommend routinely testing for HCV in patients with APS. However, not all infection-associated aPL antibodies are cofactor independent. For instance, infections are increasingly recognized as a major precipitating condition of the catastrophic variant of APS, perhaps via mechanisms of molecular mimicry. Therefore, it may be possible to prevent this devastating evolution if the infectious process is promptly recognized and exhaustively treated.

Cofactor dependence and isotype distribution of anticardiolipin antibodies in viral infections

BACKGROUND

Antibodies to cardiolipin (aCLs) are often detected in patients with autoimmune disorders or infectious diseases.

OBJECTIVE

To investigate the distribution of aCL isotypes and requirement of protein cofactor in viral infections in order to establish the importance, if any, of these antibodies in these infectious diseases.

PATIENTS AND METHODS

The isotype distribution of aCLs in the sera from 160 patients with infection caused by HIV-1 (n=40), hepatitis A virus (n=40), hepatitis B virus (n=40), or hepatitis C virus (n=40) was studied by standardised enzyme linked immunosorbent assay (ELISA) in the presence and absence of protein cofactor (mainly beta2-glycoprotein I). Serum samples from healthy volunteers and patients with syphilis and antiphospholipid syndrome were also included and served as negative and positive control groups respectively.

RESULTS

The prevalence of one or more aCL isotypes in serum of patients with HIV-1, hepatitis A virus, hepatitis B virus, or hepatitis C virus infection was 47%, 92%, 42%, and 17% respectively (principally IgM and/or IgA). Most of these antibodies were mainly cofactor independent.

CONCLUSIONS

The presence of aCLs in viral infections is principally cofactor independent, suggesting that cofactor dependence of the aCLs should be assessed to distinguish subjects most likely to suffer from clinical symptoms observed in the presence of these antibodies.

Should we include anti-prothrombin antibodies in the screening for the antiphospholipid syndrome?

Anti-prothrombin antibodies belong to the family of the antiphospholipid antibodies. Their prevalence ranges from 50 to 90% of antiphospholipid-positive patients, depending on the laboratory methodology employed for their detection. ELISA techniques are the most commonly used methods for their measurements, which allow a quick determination of their titer and isotype(s). Unfortunately, no well standardized assays are yet commercially available. The clinical relevance of anti-prothrombin antibodies as risk factors for thromboembolic events has been investigated by a number of retrospective and case-control studies. We reviewed 11 studies: data on 1,440 patients and 371 sex- and age-matched controls were available. Seven studies reported a significant association between anti-prothrombin antibodies and thrombosis by univariate analysis. Multivariate analysis was performed in five studies: only two of them confirmed the association. The sensitivity and specificity of anti-prothrombin antibodies for thrombosis were analysed according to the antibody isotype and to the arterial and/or venous site of thrombosis. The sensitivities are disappointingly low, particularly when the M isotype and arterial thrombosis are considered, whereas the specificities are somewhat better, even though they range widely. These data do not allow to recommend the measurement of anti-prothrombin antibodies in the routine laboratory workout of antiphospholipid-positive patients in order to define their thrombotic risk.

Hughes syndrome associated with cytomegalovirus infection

We report the case of a patient with an acute cytomegalovirus (CMV) infection who developed Hughes syndrome, manifested by a common iliac vein thrombosis. IgM anticardiolipin antibodies (aCL) appeared with the onset of the infection, followed later by IgG aCL. Five months later, both IgM and IgG aCL levels disappeared from the serum. This is the second case of Hughes syndrome associated with CMV infection to be reported in the literature.

Management of bleeding with uremia and liver disease

Bleeding can complicate the clinical course of both liver disease and uremia. The pathogenesis of bleeding in both syndromes is complex. A variety of options are available for treatment of uremic bleeding including desmopressin, erythropoietin, and estrogens. Bleeding complications of liver disease reflect the importance of this organ for the production of both coagulation factors and thrombopoietin. Careful assessment of both the patient's clinical situation and laboratory findings is important for tailoring therapy of the bleeding patient.

Auto-antibodies in hepatitis C

Hepatitis C virus (HCV) has been implicated in the development of a variety of autoimmune phenomena, some of which are well documented and include a panel of auto-antibodies shared with autoimmune hepatitis (AIH). Anti-nuclear (ANA) and smooth muscle (SMA) antibodies (markers of AIH type 1 [AIH-1]), have been demonstrated in 9-38% and 5-91% of cases respectively, whereas anti-liver/kidney microsomal type 1 (anti-LKM-1) and anti-liver cytosol type 1 antibodies (anti-LC1) (markers of AIH type 2 [AIH-2]), are definitely rarer, especially in adults. The presence of these auto-reactivities in chronic hepatitis C generates clinical overlaps and dilemmas in the correct classification and treatment of such patients. The immunopathological characterization of the auto-antibodies, anti-nuclear and smooth muscle antibodies in particular, combined with internationally defined criteria for the diagnosis of AIH is helpful in this clinical process. Thyroid auto-antibodies and cryoprecitable rheumatoid factors are also commonly detected in hepatitis C, while the occurrence of other auto-antibodies still awaits confirmation.