The development of antiphospholipid antibodies in haemophilia is linked to infection with hepatitis C

No Association of Homocysteine, Anticardiolipin Antibody, and Anti-β2 Glycoprotein I Antibody With Portal Venous System Thrombosis in Liver Cirrhosis

Portal venous system thrombosis (PVST), a common complication of liver cirrhosis, is closely associated with thrombophilia. To explore the association of homocysteine (Hcy), anticardiolipin antibody (aCL), and anti-β2 glycoprotein I antibody (aβ₂GPI), which are possible thrombophilic factors, with PVST in liver cirrhosis. Overall, 654 non-malignant patients (219 with and 435 without liver cirrhosis) admitted between January 2016 and June 2020 were retrospectively evaluated. Presence of PVST, degree of main portal vein (MPV) thrombosis, and clinically significant PVST were identified. Hcy level, hyperhomocysteinemia (HHcy), aCL positivity, and aβ₂GPI positivity were compared according to the presence of liver cirrhosis and PVST. Positive aβ₂GPI was significantly more frequent in patients with liver cirrhosis than those without, but Hcy level and proportions of HHcy and positive aCL were not significantly different between them. PVST could be evaluated in 136 cirrhotic patients. Hcy level [10.57 μmol/L (2.71-56.82) versus 9.97 μmol/L (2.05-53.44); P = 0.796] and proportions of HHcy [4/44 (9.1%) versus 13/81 (16.0%); P = 0.413] and positive aCL [1/23 (4.3%) versus 10/52 (19.2%); P = 0.185] and aβ₂GPI [9/23 (39.1%) versus 21/52 (40.4%); P = 0.919] were not significantly different between cirrhotic patients with and without PVST. There was still no significant association of Hcy level, HHcy, aCL, or aβ₂GPI with PVST based on Child-Pugh classification, MPV thrombosis >50%, and clinically significant PVST. Hcy, aCL, and aβ₂GPI may not be associated with PVST in liver cirrhosis, suggesting that routine screening for Hcy, aCL, and aβ₂GPI should be unnecessary in such patients.

Anticardiolipin Antibodies in Hemophiliac and Nonhemophiliac Patients with Chronic Hepatitis C

Anticardiolipin antibodies (ACA) have been de tected in a variety of infectious diseases, especially viral infec tions. ACA also have been described in human immunodefi ciency virus (HIV)-infected hemophiliacs. Recently the pres ence of ACA in hemophiliac and nonhemophiliac patients with chronic hepatitis C virus has been reported. We performed a case-controlled study to establish if ACA are present in hemo philia and if they are due to the hepatitis C infection; and to confirm the association between ACA and hepatitis C infec tions in nonhemophiliac patients. Anticardiolipin antibodies have been studied in the serum of 62 hemophiliacs with chronic hepatitis C virus and in the control group (70 hepatitis C- negative patients with hemophilia or other clotting disorders). ACA were positive in only three hepatitis C-positive hemo philiac patients and in three hepatitis C-negative patients with hemophilia or other coagulation defects (first control group). No significant statistical differences were found in the groups (OR = 1.1; 95% CI 0.2-7.4, p = .6). Sixteen of 111 nonhe mophiliacs with chronic hepatitis C were positive for ACA while in 100 matched hepatitis C-negative subjects (second control group) anticardiolipin antibodies were positive in 9 pa tients. ACA tended to be higher in hepatitis C-positive nonhe mophiliac patients than in the control group, but the difference between the two groups was not statistically significant (OR = 1.7, 95% CI 0.7-4.4, p = .3). ACA do not seem to be associ ated with the chronic hepatitis C virus.

Antiphospholipid antibodies during infectious mononucleosis and their long term clinical significance

BACKGROUND

The prevalence of antiphospholipid antibodies (aPLs) during acute Epstein-Barr virus (EBV) infection may be as high as 30-60%. The role of these autoantibodies in the development of antiphospholipid syndrome (APS) is not clear.

OBJECTIVE

To investigate the prevalence, persistence and clinical significance of aPLs in a series of patients diagnosed with acute EBV infection.

STUDY DESIGN

A cohort of 94 patients aged 15 or older, recently diagnosed with acute EBV was retrieved. Serum samples obtained during diagnosis were tested for the presence of aPLs and anti-β2GP antibodies. Patients with positive sera for aPLs were assessed for the persistence of aPLs and the development of APS.

RESULTS

The prevalence of aPLs among 94 patients with acute EBV was 37.2%. Five of 27 available serum samples were also positive for anti-β2 glycoprotein (anti-β2GP) antibodies. Repeat testing for aPLs after a median of 21 months post acute infection (range 13-50 months) was performed in 17 of the 35 patients with positive aPL test. All 17 patients were found negative for aPL-IgG antibodies. Two of them had positive aPL-IgM antibodies and positive anti-β2GP antibodies. None of the patients who had positive aPLs experienced any manifestations of APS.

CONCLUSION

The disappearance of aPLs in the majority of the patients after acute EBV infection, along with the absence of consistent clinical findings, suggests that the detection of aPLs during acute EBV is not associated with the development APS over time.

Cell damage at the origin of antiphospholipid antibodies and their pathogenic potential in recurrent pregnancy loss

Antiphospholipid antibodies (APA) are associated with thrombosis, thrombocytopenia and fetal loss but they occur in a variety of diseases. Despite many efforts, a correlation between the specificity of particular subgroups of APA and particular clinical situations remains to be established. The antigens at the origin of APA remain to be identified. We discuss here the possible links between cell apoptosis or necrosis, leading to plasma membrane alterations, and the occurrence of APA in response to sustained stimulation. The pathogenic potential of APA is also considered with respect to recurrent pregnancy loss.

Antiphospholipid antibodies in haemophilia patients with severe bleeding tendency: cause, consequence or a consequential cause?

The prevalence, cause and the impact of antiphospholipid antibodies (APAs) on the clinical severity in haemophilia patients is poorly studied. We studied 72 severe seronegative (negative for HIV, HBsAg, HCV) haemophilia patients for the presence of four common APAs. Twenty-six (36.1%) were positive for any one of the APAs studied of which eight were positive only for anticardiolipin antibodies, three for beta2 glycoprotein (beta2GP1), four for prothrombin (PT) and six for anti annexin antibodies. Remaining six patients showed multi-specific antibodies. Further, clinically severe haemophilia patients (n = 37) showed higher prevalence of APAs as compared with the clinically milder group (n = 35) suggesting that these antibodies do not contribute in alleviating the clinical severity in haemophilia patients as has been observed with other inherited thrombophilia markers. The study of in vitro thrombin generation showed a higher endogenous thrombin potential (ETP) i.e. almost normal, in case of beta2GP1-positive patients as compared with patients with other types of APAs. High prevalence of APAs in clinically severe haemophilia patients may be a consequence of continuing tissue damage in the clinically severe group; as in India, clotting factor concentrates cannot be used ad lib because of financial constraints. Higher thrombin-generating potential in case of patients positive for beta2GP1 did not seem to have any impact on the clinical severity of haemophilia patients.

Anticardiolipin antibodies and vascular access thrombosis in Taiwanese haemodialysis patients with chronic hepatitis C: a retrospective study

Hepatitis C virus causes various extrahepatic immunologic abnormalities. Vascular access thrombosis (VAT) is a major cause of morbidity in chronic haemodialysis (HD) patients. Immunoglobulin-G anticardiolipin antibody (IgG-ACA) is strongly associated with venous and arterial thrombosis in patients with normal renal function. Previous investigations have reported the association of raised IgG-ACA titre recurrent with VAT in HD patient, and also few equivalent studies were reported the same in Taiwan. This study attempted to determine whether raised IgG-ACA titres are associated with increased risk of recurrent VAT in HD patients with chronic hepatitis C. This study enrolled 98 chronic hepatitis C patients undergoing HD. IgG-ACA titre and hepatitis C marker were measured for all subjects. Raised IgG-ACA titres were present in 29.6% (29/98) of patients. In both groups (raised and normal IgG-ACA), the type of shunt did not differ (p = 0.416). There was strong association between raised IgG-ACA titre and recurrent VAT (p = 0.0004). In predicting for more or one episodes of VAT using multiple logistic regression, synthetic graft (p < 0.0001), raised IgG-ACA titre (p = 0.039), presence of hepatitis B (p = 0.004) and haemodialysis duration (p = 0.039) were significant factors. The prevalence of raised IgG-ACA titres was 39.6% among chronic hepatitis C with HD patients. There was strong association between raised IgG-ACA titre and recurrent VAT, and this finding may be the consequence of pathogenetic role of raised IgG-ACA titres on the development of VAT status in HD patients with chronic hepatitis C.

Accidents vasculaires cérébraux révélant un syndrome catastrophique des anti-phospholipides associé à une hépatite virale C

INTRODUCTION

Very little cases of antiphospholipid syndrome (APLS) have been described among patients having chronic hepatitis C virus infection (HCV).

CASE REPORT

We report the observation of a 43-year-old woman who presented APLS diagnosed following recurrent strokes. Etiological investigations concluded on an association of APLS with HCV infection.

DISCUSSION

Besides being exceptional, this association raises certain etiopathogenic problems. Indeed while antiphospholipid antibodies (aPL) are frequently noted during chronic hepatitis C, they rarely generate thromboembolic complications.

Antiphospholipid antibodies before and after liver transplantation

OBJECTIVE

The aim of this study was to determine whether liver transplantation of patients with antiphospholipid antibodies (APA) is 1) adversely affected with vascular thrombosis and 2) whether such antibodies persist post transplantation.

METHODS

Twelve patients with APA awaiting transplant were identified and characterized biochemically and immunologically. Each had the level of APA determined using commercially available enzyme-linked immunoassay kits before, during, and after liver transplantation.

RESULTS

No patient in this series experienced a transplant-related vascular thrombosis. The titer of APA fell to levels at or below those present in normals and remained low in two of 12 or undetectable in 10 of 12 patients 1 yr after liver transplantation.

CONCLUSIONS

We reached the following conclusions: 1) Antiphospholipid positivity does not identify patients at high risk for post-transplant vascular thrombosis. 2) The levels of antiphospholipid present in sera pretransplant fell during transplantation and remained low or undetectable 1 month and 1 yr post transplantation.

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.

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.

Anticardiolipin antibodies in patients with liver disease

OBJECTIVE

Our aim was to test the hypothesis that anticardiolipin antibodies (aCL) may cause an antiphospholipid syndrome and thrombotic events in patients with liver disease.

METHODS

aCL were measured in 116 healthy controls and 372 patients with liver disease of different stage and etiology: 136 cases secondary to hepatitis C virus (HCV) infection, 139 due to hepatitis B virus (HBV) infection, 69 with alcoholic liver damage, and 28 cryptogenic in origin. Prior thrombotic events were recorded. The results were related to age, gender, stage, severity, and etiology of the liver disease, as well as to the occurrence of organ- and nonorgan-specific autoantibodies.

RESULTS

aCL were positive in 4.4% of controls and in 18.8% of patients (p < 0.0002). Patients with aCL were more frequently men with an advanced cirrhosis and simultaneous occurrence of anti-smooth-muscle antibodies (ASMA) in serum (p < 0.0006); their liver damage was often secondary to HBV (37.3%) or alcohol abuse (18.5%). At conditional logistic regression analysis, only the presence of ASMA (odds ratio [OR] = 3.02, 95% confidence interval [CI] 1.7-5.5, p = 0.0003), HBV (OR = 3.4, 95% CI 1.6-7.2, p = 0.0013), or alcoholic liver disease (OR = 5.3, 95% CI 2.3-12.2, p = 0.0001) were independently associated with aCL. Thrombosis was encountered in 24 patients (6.4%). At conditional logistic regression analysis, thrombosis was significantly associated with advanced age (OR = 1.07, 95% CI 1.0-1.1, p = 0.0094), development of hepatocellular carcinoma (OR = 17.8, 95% CI 1.6-196.0, p = 0.01), HBV etiology (OR = 6.3, 95% CI, 1.6-24.6, p = 0.0076), or cryptogenic liver disease (OR = 54.8, 95% CI 5-599.9, p = 0.001). Of the five patients with newly documented portal thrombosis during the follow-up, only one tested positive for aCL.

CONCLUSIONS

In patients with nonautoimmune liver disease, aCL production is an epiphenomenon of the liver damage and is not associated with thrombotic complications. These data do not support the hypothesis that HCV is a cause of the antiphospholipid syndrome.

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

Anticardiolipin antibodies (ACA) and lupus anticoagulant (LA) have been detected in patients with hepatitis C virus (HCV) infection and have been associated in autoimmune diseases (i.e. systemic lupus erythematosus) with an increased risk of thromboembolic events. Because of the high prevalence of HCV infection and the thrombotic risk described in thalassaemia we decided to investigate the prevalence of ACA and LA in a cohort of 68 thalassaemia patients. We found a high prevalence (34%) of beta2-glycoprotein I independent ACA in our thalassaemia patients which was related to HCV infection. None of patients developed any complications related to antiphospholipid antibodies (APL); therefore the clinical significance of positivity for APL in patients with HCV infection is at present unclear. In conclusion, the results of our study indicate that ACA in the serum of HCV-infected thalassaemic patients exhibit the characteristics of natural autoantibodies rather than those of the pathogenic autoantibodies that are found in patients with systemic lupus erythematosus.

Resistance to activated protein C in thalassaemic patients: an underlying cause of thrombosis

We evaluated 81 thalassaemia major and 4 thalassaemia intermedia patients (48 M, 37 F), median age 17 years; 62/85 patients were HCV-positive, 3/85 HIV-positive, 19/85 were splenectomized. Forty normal healthy children were recruited as the control group. The number of thrombotic events was studied retrospectively. Platelet poor plasma was filtered and quick-frozen at -70 degrees C until time of assay. APC resistance was measured in an activated thromboplastin time and results were expressed as normalized ratio. All tests were done with diluted 1 in 5 (v/v) factor V deficient plasma and with undiluted plasma. Molecular genetic investigation of factor V gene was performed with polymerase chain reaction, followed by digestion of amplified products with restriction enzyme Mnl I. Data obtained with molecular investigation revealed the presence of 4 heterozygous subjects for factor V Leiden (4.7%). Functional tests were able to detect all heterozygotes for factor V Leiden both with undiluted and with diluted plasma, and there were no false negative subjects. However, undiluted plasma revealed a greater number of false positive subjects (n=15) than did diluted plasma. Therefore, tests done with undiluted and diluted plasma revealed a 100% sensitivity, while specificity was 81% for undiluted plasma and 97% for diluted plasma. Only one thrombotic event was observed in one of the 85 studied patients, as a case of stroke in a thalassaemia intermedia patient with APC resistance. In the same patient an additional thrombogenic risk factor was represented by a pronounced haematocrit increase at the beginning of her transfusion regimen.

Prevalence and significance of anticardiolipin, anti-beta2 glycoprotein I and anti-prothrombin antibodies in chronic hepatitis C

Antiphospholipid antibodies have been demonstrated in chronic hepatitis C, but their clinical and pathogenetic significance remains elusive. We prospectively studied 115 patients (85 men, mean age 36.9 years) with chronic hepatitis C without cirrhosis and treated by alpha-interferon (alpha-IFN). Antiphospholipid determinations comprised anticardiolipin (ACA), anti-beta2-glycoprotein I and anti-prothrombin antibodies of the IgG and IgM classes. At entry, 24 patients (21%) were found to possess low to moderate ACA levels (18 IgG, two IgM and four both isotypes) compared with only 4/115 age- and sex-matched control subjects (3.5% P=0.001). ACA positivity rate increased to 31% (P=0.01) after a 6-month course of alpha-IFN treatment. In contrast, the prevalence of anti-beta2-glycoprotein I and anti-prothrombin antibodies was not significantly different from controls at either time point. The presence of ACA correlated with that of antinuclear antibodies (P=0.0002), but was not associated with parameters such as histological activity, viral burden and response to alpha-IFN, nor with a history of thrombosis or pregnancy loss. However, a non-significant trend of higher incidence of mild thrombocytopenia among ACA-positive patients was observed. We conclude that low-titre ACA positivity is a common finding in patients with chronic hepatitis C, especially following alpha-IFN treatment, but does not select a category with different clinical features. These data are in keeping with the absence of associated anti-beta2GPI and anti-prothrombin antibodies, and do not support a role for HCV infection in the pathogenesis of the antiphospholipid syndrome.

Prevalence of antiphospholipid antibodies in patients with chronic liver disease related to alcohol or hepatitis C virus: correlation with liver injury

Antiphospholipid antibodies (APAs) have been reported in various clinical conditions. However, the pathogenesis and clinical significance of these antibodies are still unclear. The objective of this study was to assess the prevalence of APAs in patients with chronic alcohol- or hepatitis C virus (HCV)-related liver disease and to evaluate their relation to the underlying liver disease. We prospectively studied 201 patients referred to an hepato-gastroenterology department, including 77 patients with a history of alcohol abuse (group I) and 124 with chronic HCV infection (group II), and 107 healthy subjects (control population). Liver biopsy was performed in all patients. In cirrhotic patients, the severity of the liver disease was assessed with the use of Child's classification, as modified by Pugh. Several biologic parameters, including lupus anticoagulant and anticardiolipin antibodies, were determined. Forty-eight percent of patients in group I and 33% of those in group II had APAs. Among cirrhotic patients, APAs were more frequent in patients with Child grade B or C than in those with grade A severity. In patients with chronic HCV-related liver disease, a correlation was found between APA levels and liver fibrosis (P = 0.009); no relation was found between APA levels and histologic liver disease activity (P = 0.25). In the control group, one subject was APA-positive. None had lupus anticoagulant. APAs seem to be frequently associated with chronic liver disease of various causes. These results suggest further investigations on the potential role of these antibodies in fibrosis or liver injury.

Autoimmune phenomena and hepatitis C virus in lymphoproliferative and connective tissue disorders

Since hepatitis C virus (HCV) infection is frequently detected in patients with lymphoproliferative or autoimmune disorders and since the virus may infect lymphocytes, the question is raised whether malignant transformation and autoimmune manifestations in the presence of HCV are HCV-related or merely fortuitous. A close association has been firmly established between HCV infection and essential type II mixed cryoglobulinemia (ECM), an indolent lymphoproliferative disorder characterized by cryoprecipitable immune-complexes (IC) that may evolve into classical non Hodgkin's lymphomas (NHL) retaining the ability to produce cryoprecipitable rheumatoid factor (RF). It is reasonable to consider HCV as one cofactor in lymphomagenesis, even if the precise pathogenetic relationship between HCV infection, the chronic presence of cryoprecipitable IC and the development of NHL have not been established yet. Several epidemiological studies have documented the ability of chronic HCV infection to favour the production of autoAb. It is not clear why only some patients with HCV infection develop autoAb, nor why the most frequent autoAb detected in HCV-infected subjects are cryoglobulins. Though a high prevalence of anti-HCV has been found in a variety of systemic and organ-specific autoimmune diseases, it is likely that several of these associations are fortuitous with the notable exception of membranoproliferative glomerulonephritis. As HCV can provoke or exacerbate inflammatory signs and cause the production of RF, it is reasonable to suspect that HCV infection may be able to trigger the development of some connective tissue diseases or to exacerbate their clinical course. Nonetheless, it is clinically prudent to conclude that the pathogenetic relationships of Sjögren syndrome, rheumatoid arthritis and polyarthritis with HCV infection are more likely to be regarded as mediated via the intermediate development of ECM.

[Distal gangrene and cryoglobulinemia related to hepatitis C virus infection with presence of anticardiolipin antibodies]

We report the case of a 63-year old women with toe gangrene, peripheral polyneuropathy, polyarthritis, histologically proven necrotizing vasculitis, in association with type III mixed cryoglobulinemia and hepatitis C virus (HCV) infection. Raised anticardiolipin antibodies (aCL) were found, without beta 2-glycoprotein I. HCV infection is associated with mixed cryoglobulinemia which can cause a vasculitis affecting various organs. The pathogenesis of production and clinical significance of aCL could be associated in this case with HCV infection.

Induction of anticardiolipin antibody and/or lupus anticoagulant in rabbits by immunization with lipoteichoic acid, lipopolysaccharide and lipid A

It still remains unclear how anti-phospholipid antibody develops in a specific patient group, however, it is possible that certain microorganism(s) may cause anti-cardiolipin antibody (aCL) development since aCL is frequently detected in patients with Treponema pallidum (TP) and/or other infectious diseases. Accordingly, we conducted an investigation to clarify whether or not anticardiolipin antibody (aCL) and/or lupus anticoagulant (LA) can be induced in rabbits by immunization with Gram-positive or -negative microorganism derivatives, such as lipoteichoic acid, lipopolysaccharide and lipid A. We detected the induction of SLE type-aCL (beta 2GPI-dependent) and LA in some rabbits immunized with lipid A and lipoteichoic acid, thereby suggesting that some microorganisms may contribute to even the production of pathogenic (SLE-type) antiphospholipid antibody.

Lupus anticoagulants/antiphospholipid-protein antibodies: the great imposters

Antiphospholipid-protein antibodies (APA) represent a family of immunoglobulins which recognize protein-phospholipid complexes. A variety of proteins have been implicated including: prothrombin, annexin V, beta 2-Glycoprotein I, and protein S. APA are detected utilizing either coagulation-based tests to identify lupus anticoagulants (LA) or solid phase ELISA assays to identify anticardiolipin antibodies (ACA). APA may be seen in a variety of different clinical settings including convalescence from infections, resulting from exposure to certain drugs, or in association with autoimmune diseases. Autoimmune APA have been linked to a variety of thromboembolic complications involving both arterial and venous sites. In addition, recurrent fetal loss has been linked to a APA. The underlying pathophysiology of the thromboembolic events remains controversial. Given the diversity of anatomic sites, more than one thromboembolic mechanism(s) is likely. Abnormalities of the protein C system most likely account for the venous thromboembolic events. Because of the spectrum of clinical complications, virtually any clinician may encounter patients with the APA syndrome (thrombosis, thrombocytopenia, recurrent fetal loss coupled with positive LA or ACA testing).

Cerebral ischemia in patients with hepatitis C virus infection and mixed cryoglobulinemia

We describe two women (ages 35 and 36 years) with cerebral ischemia, hepatitis C virus, and mixed cryoglobulinemia. One patient (case 1) was in otherwise good health when left parietal cerebral infarction developed, and she was found to have narrowing of the supraclinoid internal carotid artery siphon, anterior cerebral artery A1, and middle cerebral artery M1 segments bilaterally. Subsequent evaluation revealed abnormal liver enzymes, mixed cryoglobulinemia (type III), hypocomplementemia, and a high positive test result for rheumatoid factor. In the other patient (case 2), cerebral ischemia and seizures developed in the setting of previously documented mixed cryoglobulinemia (type II), membranoproliferative glomerulonephritis, and hypocomplementemia. In this patient, a brain biopsy demonstrated cerebral infarction. Hepatitis C virus infection was confirmed in both patients by polymerase chain reaction detection of hepatitis C virus RNA. These two cases document the occurrence of cerebral ischemia in patients with hepatitis C virus infection and mixed cryoglobulinemia. Testing for hepatitis C virus and cryoglobulins should be considered in selected patients with cerebral ischemia of inobvious cause.

The lupus anticoagulant/antiphospholipid syndrome

Lupus anticoagulants and anticardiolipin antibodies have been strongly associated with the risk of thrombosis, recurrent fetal loss, thrombocytopenia, and a number of other clinical manifestations that together have been referred to as the antiphospholipid syndrome. Despite growing evidence of the significance of this relationship, the pathogenetic mechanisms involved are largely unknown. Recent data suggest strongly that lupus anticoagulants (LACs) and anticardiolipin antibodies (ACAs) are antibodies to protein-phospholipid complexes rather than to phospholipids, as had originally been thought, and that other protein-phospholipid complexes, not recognized by standard assays for LACs or ACAs, may also exist in patients with the antiphospholipid syndrome. Although very recent experimental data may lead to new therapeutic approaches in this syndrome, at present we can only deal with the thrombotic risk by the use of long-term anticoagulation. This chapter reviews current methods of diagnosis, concepts of pathogenesis, and the basis for an approach to anticoagulation in patients at risk for thrombosis or other manifestations of the antiphospholipid syndrome.

Human immunodeficiency virus rather than hepatitis C virus infection is relevant to the development of an anti-cardiolipin antibody

We have investigated whether or not a relationship exists between anti-cardiolipin antibody (aCL) positivity and human immunodeficiency virus type 1 (HIV) and/or hepatitis C virus (HCV), and we have attempted to clarify which virus has close association with the development of aCL. We found that aCL positivity in HIV-infected patients was significantly higher than in HCV-infected patients. Furthermore, HIV/HCV dual-infected patients exhibited a higher aCL positivity than patients infected by HCV alone. From these results, we conclude that HIV rather than HCV plays an important role in the development of aCL.

Anti-cardiolipin antibodies are associated with anti-endothelial cell antibodies but not with anti-beta 2 glycoprotein I antibodies in HIV infection

HIV infection is associated with polyclonal increase in serum immunoglobulins and with elevated titers of serum antibodies to a variety of self antigens, including anti-phospholipid antibodies. In the present study, we found a high prevalence of 46.8% of serum IgG anticardiolipin antibodies (ACA) in a group of 111 unselected HIV-seropositive individuals. The presence of ACA was correlated with that of IgG antibodies to endothelial cells (AECA) but not with that of anti-beta 2 glycoprotein I antibodies, that were only found in 7.4% of the patients. The presence of IgG ACA was not associated with detectable lupus anticoagulant activity, nor with a history of thrombosis. Serum titers of ACA were not correlated with absolute numbers of circulating CD4+ cells. We found no relationship between the presence and titers of ACA, hypergammaglobulinemia, and serum titers of natural IgG autoantibodies to a panel of self antigens. Our results suggest that increased titers of ACA in HIV infection result from a biased expansion of B cell clones producing natural autoantibodies.