Anti-phospholipid antibodies in HIV infection and SLE with or without anti-phospholipid syndrome: comparisons of phospholipid specificity, avidity and reactivity with beta2-GPI

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.

[Portal vein thrombosis in HIV-infected patients: report of four cases]

Portal vein thrombosis (PVT) seems rare among HIV infected patients. Even though, the report of such cases is of great interest because it may help to determine the factors of occurrence. We describe cases of PVT in 4 HIV-infected men, aged 32 - 64. Two of them were co-infected with hepatitis C virus (HCV). The four patients had a history of disseminated mycobacterial infection (one case of tuberculosis, 3 cases of mycobacterium avium complex infection) with abdominal lymphadenitis. Despite HAART, their immunodeficiency was profound (CD4: 65 to 216/mm(3)). At the time of diagnosis, two patients were treated with protease-inhibitor containing regimen: indinavir (one case), ritonavir-saquinavir (one case). PVT was revealed by haematemesis (one case), abdominal pain (ome case), anasarca (2 cases). In three patients, the diagnosis of PVT was confirmed by imagery (echo-doppler or angio- RMI), and for the last patient, PVT was found during the transjugular intrahepatic portosystemic shunt setup. A low level of C protein was diagnosed in one case. Cirrhosis was not found in HIV-HCV co-infected patients. Two patients died early after diagnosis, one patient died 3 years after the onset of symptoms. Various factors may cause the development of a PVT in HIV infected patient. Serious immunodeficiency, opportunistic infections such as tuberculosis and mycobacterium avium complex related infection with abdominal lymphadenitis can further the development of PVT. Protease-inhibitor might have facilitated the process. Due to the severe prognosis of advanced cases, early evocation of diagnosis is needed.

Cardiolipin polyspecific autoreactivity in two broadly neutralizing HIV-1 antibodies

The design of a human immunodeficiency virus-1 (HIV-1) immunogen that can induce broadly reactive neutralizing antibodies is a major goal of HIV-1 vaccine development. Although rare human monoclonal antibodies (mAbs) exist that broadly neutralize HIV-1, HIV-1 envelope immunogens do not induce these antibody specificities. Here we demonstrate that the two most broadly reactive HIV-1 envelope gp41 human mAbs, 2F5 and 4E10, are polyspecific autoantibodies reactive with the phospholipid cardiolipin. Thus, current HIV-1 vaccines may not induce these types of antibodies because of autoantigen mimicry of the conserved membrane-proximal epitopes of the virus. These results may have important implications for generating effective neutralizing antibody responses by using HIV-1 vaccines.

Seven antiphospholipid antibodies in HIV-positive patients: correlation with clinical course and laboratory findings

OBJECTIVE

To compare the clinical course of HIV-1-infected patients, their CD4+, CD8+ T lymphocytes, and viral loads (VL) with the levels of seven antiphospholipid antibodies (aPLs) before, during, and after the highly active antiretroviral therapy (HAART).

PATIENTS AND METHODS

aPLs were examined in patients (20 men, 10 women, aged 12-64 years, median 33 years) from the AIDS center of Western Bohemia before the initiation of HAART, and two (23 patients), and five (20 patients) years later. Flow-cytometry was used for CD4+ and CD8+ T lymphocytes analysis, commercial kits were used for VL-measurements, and commercial enzyme-linked immunosorbent assay (ELISA) was used to determine serum levels of anti-beta2-glycoprotein I (GPI) of immunoglobulin G (IgG) and IgA isotypes, and anticardiolipin levels (ACA) of IgG and IgM isotypes. APLs screening also included L-alpha-phosphatidic (ph) acid, L-alpha-phosphatidylethanolamine, L-alpha-phosphatidyl-DL-glycerol, L-alpha-phosphatidylinositol, and L-alpha-phosphatidylserine of IgG and IgM autoantibodies. Statistical analysis was performed using cut-off levels for immunoglobulin-isotypes of aPLs using 3 S.D. or 95th percentile calculated using Statgraphics-software.

RESULTS

In 14 of 21 patients treated by HAART an increased number of CD4+ T lymphocytes was detected, and in 14 of 21 patients VL decreased below detection threshold during the 5 years of observation. We did not observe correlations of aPLs with age, the initial low CD4+ and high number of CD8+ T lymphocytes, and the viremic levels over the entire observation period. We did not find the elevation of aPLs in 2 of 5 patients in stage C (AIDS). Ten of 11 HIV-positive homosexuals had positive aPLs, and the same result was seen in 7 of 10 patients infected through heterosexual intercourse. aPLs levels were significantly increased in 18 of 30 patients at the beginning of HAART. ACA IgG was elevated in 14 of 30 cases, IgG antibodies against L-alpha-ph-acid in 5 of 30, ph-ethanolamine in 10 of 30, ph-inositol in 9 of 30, and L-serine in 14 of 30, combined positivity of six aPLs together was detected in 10 HIV positive patients. Significantly decreased levels of aPLs because of HAART were found in eight patients. APLs were still present in only four patients after 5 years of the treatment. Abnormalities in blood clotting were not present in any of our patients.

CONCLUSION

Results of screening for seven aPLs in HIV-positive patients suggest that HAART also positively influences the autoimmune response represented by aPLs levels, but individual differences in aPLs levels were observed.

HIV infection and antiphospholipid antibody: literature review and link to the antiphospholipid syndrome

There is a high incidence of antiphospholipid antibodies, detected by assays for anticardiolipin or lupus-like anticoagulant, in HIV disease. However, a link to the antiphospholipid syndrome, with clinical thrombosis, is tenuous. We report a case of a 25-year-old man with undetermined risk factors for HIV presenting with possible antiphospholipid syndrome manifesting as necrotic skin lesions as the initial clinical presentation for HIV. We also review the literature exploring the association between HIV and antiphospholipid syndrome.

The prevalence, onset, and clinical significance of antiphospholipid antibodies prior to diagnosis of systemic lupus erythematosus

OBJECTIVE

To determine whether antiphospholipid antibodies (aPL) occur before the diagnosis of systemic lupus erythematosus (SLE) and before initial clotting events, and whether their presence early in the disease course influences clinical outcome.

METHODS

Serum samples obtained from 130 lupus patients before and after SLE diagnosis were screened for IgG and IgM aPL using an anticardiolipin (aCL) enzyme-linked immunosorbent assay. Medical records of all patients were carefully reviewed for data on the time of onset of SLE features meeting clinical criteria and on disease manifestations.

RESULTS

Twenty-four patients (18.5%) were positive for IgG and/or IgM aCL prior to SLE diagnosis. Anticardiolipin antibodies appeared from 7.6 years prior to SLE diagnosis to within the same month as SLE diagnosis, with a mean onset occurring 3.0 years before SLE diagnosis. Additionally, aCL presence early in the disease process seemed to predict a more severe clinical outcome; these patients eventually met an average of 6.1 of the 11 classification criteria for SLE, compared with 4.9 criteria for other patients (P < 0.001). The early aCL-positive population also had more frequent renal disease, central nervous system disease, thrombocytopenia, and clotting events. In this population, aCL preceded initial thrombotic events by a mean of 3.1 years.

CONCLUSION

Anticardiolipin antibodies in SLE patients tend to precede initial clotting events by several years. Furthermore, the presence of early, prediagnosis aPL seems to herald a more varied, severe clinical course with earlier onset in patients with SLE.

Anticardiolipin, anti-beta(2)-glycoprotein I and antiprothrombin antibodies in black South African patients with infectious disease

OBJECTIVES

To investigate IgG, IgM, and IgA, antiphospholipid antibodies (aPL), against cardiolipin (aCL), beta(2)-glycoprotein I (anti-beta(2)GPI), and prothrombin (anti-PT), in black South African patients with infectious disease. Unlike patients with systemic lupus erythematosus (SLE) and the antiphospholipid syndrome (APS), raised levels of aPL in infectious diseases are not usually associated with thrombotic complications.

PATIENTS AND METHODS

Serum samples from 272 patients with a variety of infectious diseases (100 HIV positive, 112 leprosy, 25 syphilis, 25 malaria, and 10 HCV patients) were studied and compared with autoantibody levels in 100 normal controls. All three aPL were measured using commercial enzyme linked immunosorbent assay (ELISA) kits.

RESULTS

Raised levels of all three aPL were found in all patient groups studied: aCL in 7%, anti-beta(2)GPI in 6%, and aPT in 43% of 100 HIV patients, in 29%, 89%, and 21% of 112 patients with leprosy, in 8%, 8%, and 28% of 25 patients with syphilis, in 12%, 8%, and 28% of 25 patients with malaria, and in 20%, 30%, and 30% of 10 HCV patients studied, respectively.

CONCLUSIONS

The prevalence of aCL and anti-beta(2)GPI in black South African HIV positive patients, or those with syphilis, malaria, or hepatitis C virus is lower than reported for mixed race or white populations. aPT were the most prevalent aPL detected in these patient groups, except in patients with leprosy, for whom anti-beta(2)GPI was the most prevalent, and where the spectrum of aPL was similar to that seen in patients with SLE and APS.

Anti-cardiolipin antibodies in sera from patients with periodontitis

Antiphospholipid antibodies are commonly found in patients with systemic lupus erythematosus or the antiphospholipid syndrome, and a subset of such antibodies is associated with prothrombotic events such as stroke and with adverse pregnancy outcomes and fetal loss. We examined sera from 411 patients who were clinically characterized as to their periodontal disease status for serum levels of beta2-glycoprotein I-dependent anti-cardiolipin autoantibodies (anti-CL). The prevalence of patients with chronic periodontitis (CP) and generalized aggressive periodontitis (GAgP) positive for anti-CL (16.2% and 19.3%, respectively) was greater than that in healthy controls (NP) and localized aggressive periodontitis (LAgP) patients (6.8% and 3.2%). Patients with these autoantibodies demonstrated increased pocket depth and attachment loss compared with patients lacking the antibodies. Analysis of the data indicates that patients with generalized periodontitis have elevated levels of autoantibodies reactive with phospholipids. These antibodies could be involved in elevated risk for stroke, atherosclerosis, or pre-term birth in periodontitis patients.

Free radical mediated peroxidative damage in systemic lupus erythematosus

Free radicals and damage caused by these molecular species are implicated in the pathogenesis of a variety of diseases, including autoimmune. Here we have examined oxidative damage, SOD activity and autoantibodies against SOD in systemic lupus erythematosus (SLE), a multifactorial disease with autoantibody production as an universal feature. We found significantly increased amounts of conjugated dienes in the SLE patients compared to normals (mean value of 0.917 vs 0.627, p = 0.0001) and MDA formation (6.96 vs 4.17 nmoles/microl, p = 0.0006) as well as decreased SOD activity. In addition, we found autoantibodies binding SOD by both ELISA and immunoblot. The presence of anti-SOD antibodies was associated with increased free radical damage in SLE patients. Heat inactivated anti-SOD autoantibodies were able to inhibit the activity of the enzyme. We propose that the inhibition of SOD by autoantibodies is, in part, responsible for the increased free radical damage seen in the disease.

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.

Antiphospholipid antibodies: discovery, definitions, detection and disease

Antiphospholipid antibodies (aPL) are immunoglobulins of IgG, IgM and IgA isotypes that target phospholipid (PL) and/or PL-binding plasma proteins. Detection of aPL in the laboratory is done currently by both immunoassays and functional coagulation tests. Convention defines aPL specificity in immunoassays according to the particular PL substrate present, for example aPS represents antiphosphatidylserine antibodies. This may be technically incorrect inasmuch as a particular PL may be responsible for binding and highly concentrating a specific plasma protein, the latter then becomes the target for the aPL. The binding of beta(2)GP-I (apolipoprotein H) to the negatively charged PL, cardiolipin (CL) provides a good example of this circumstance. In contrast, aPL which specifically prolong coagulation times in in vitro are called lupus anticoagulants (LA). The precise PL target(s) of the aPL responsible for LA activities are unknown and often debated. The persistent finding of aPL in patients in association with abnormal blood clotting and a myriad of neurological, obstetrical and rheumatic disorders often compounded by autoimmune diseases has led to an established clinical diagnosis termed antiphospholipid syndrome (APS). The common denominator for these APS patients is the presence of circulating aPL on two or more occasions and the observation of events attributable to abnormal or accelerated blood clotting somewhere in vivo. The purpose of this review is to collect, collate, and consolidate information concerning aPL.

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.

Prevalence of antiphospholipid and antiplatelet antibodies in human immunodeficiency virus (HIV)-infected Chilean patients

Antiphospholipid (aPL) and antiplatelet (aPlt) antibodies, found in patients with autoimmune diseases, are also detected in infectious diseases. The purpose of this study was to examine the prevalence of these antibodies in HIV patients and to evaluate an association of these antibodies with thrombocytopenia and/or thrombosis. Sixty-three HIV-seropositive patients and 52 normal controls were studied. Anti-cardiolipin (aCL), anti-beta(2) glycoprotein I (anti-beta(2)GPI), and antiprothrombin (aPT) antibodies were determined and the lupus anticoagulant (LA) test was performed. Antiplatelet antibodies (aPlt) were also determined. Seven out of 63 (12.7%) HIV patients were positive for aCL, four of 63 (6.3%) for anti-beta(2)GPI, and five of 63 (7.9%) for aPT. No patients studied were LA positive. Six out of 63 (9.5%) patients were positive for aPlt. One of them showed weak reactivity for GPIb-IX. The platelet count of patients (202+/-63 x 10(3) platelets/microL) was significantly lower than in the controls (343+/-6 x 10(3) platelets/microL) (P<0.001). There was no correlation between the presence of aPL and/or aPlt and thrombocytopenia. Of the HIV-infected patients, 22.2% presented aPL and 9.4% aPlt antibodies. In this study, the presence of aPL and aPlt antibodies was not associated with the development of thrombosis and/or thrombocytopenia.

HIV and autoimmunity

The association of immune dysfunction in patients with human immunodeficiency virus (HIV) infection and AIDS and the development of autoimmune diseases is intriguing. Yet, the spectrum of reported autoimmune phenomena in these patients is increasing. An infectious trigger for immune activation is one of the postulated mechanisms and derives from molecular mimicry. During frank loss of immunocompetence, autoimmune diseases that are predominantly T cell subtype CD8 driven predominate. There is evidence for B cell stimulation and many autoantibodies are reported in HIV patients. We propose a staging of autoimmune manifestations related to HIV/AIDS manifestations and the total CD4 count and viral load that may be beneficial in identifying the type of autoimmune disease and establishing the proper therapy. In stage I there is the acute HIV infection, and the immune system is intact. In this stage, autoimmune diseases may develop. Stage II describes the quiescent period without overt manifestations of AIDS. However, there is a declining CD4 count indicative of some immunosuppression. Autoimmune diseases are not found. During stage III there is immunosuppression with a low CD4 count and the development of AIDS. CD8 T cells predominant and diseases such as psoriasis and diffuse immune lymphocytic syndrome (similar to Sjogren's syndrome) may present or even be the initial manifestation of AIDS. Also during this stage no autoimmune diseases are found. In stage IV there is restoration of immune competence following highly active anti-retroviral therapy (HAART). In this setting, there is a resurgence of autoimmune diseases. The frequency of reported rheumatological syndromes in HIV-infected patients ranges from 1 to 60%. The list of reported autoimmune diseases in HIV/AIDS include systemic lupus erythematosus, anti-phospholipid syndrome, vasculitis, primary biliary cirrhosis, polymyosits, Graves' disease, and idiopathic thrombocytopenic purpura. Also, there is an array of autoantibodies reported in HIV/AIDS patients which include anti-cardiolipin, anti-beta2 GPI, anti-DNA, anti-small nuclear ribonucleoproteins (snRNP), anti-thyroglobulin, anti-thyroid peroxidase, anti-myosin, and anti-erythropoietin antibodies. The association of autoantibodies in HIV-infected patients to clinical autoimmune disease is yet to be established. With the upsurge of HAART, the incidence of autoimmune diseases in HIV-infected patients is increasing. In this review, we describe the various autoimmune diseases that develop in HIV/AIDS patients through possible mechanisms related to immune activation.

Primary anti-phospholipid antibody syndrome (APS): current concepts

Primary anti-phospholipid syndrome (APS) is a thrombophilic state characterized by recurrent arterial and venous thrombosis, recurrent pregnancy loss, and the presence of circulating anti-phospholipid antibodies that may be responsible for thrombophilia and pregnancy morbidity. Ophthalmologic features are present in 15-88% of the patients with primary APS, thus ophthalmologists are one of the first physicians to whom the patient will present. An accurate diagnosis may save the patient from recurrent, potentially life-threatening thrombosis. In the U.S.A., an estimated 35,000 new cases of APS-related venous thrombosis occur each year in a population that is several decades younger than the patient population typically affected by thrombosis. Clinical features, such as chorea, transverse myelitis, cardiac valvular lesions, and accelerated atherosclerosis, are hypothesized to be due to a direct tissue-antibody interaction and cannot be explained purely by thrombosis. The use of recently proposed, well-defined diagnostic criteria, and better standardization of laboratory assays for the anti-phospholipid antibodies should help enable epidemiological surveys to establish the prevalence of these antibodies in patients with thrombosis and in the general population. Diagnosis of APS should be considered in all patients with recurrent systemic or ocular thrombosis in the absence of known risk factors. Several well-designed prospective studies show an increased risk of thrombosis in the presence of medium to high antibody level. With ocular involvement in as many as 88% of APS patients, an ophthalmic assessment should be an integral part of the clinical work-up of any patient with suspected or confirmed APS. The presence of isolated ocular thrombophilia with persistently elevated anti-phospholipid antibodies or lupus coagulant should confirm the diagnosis of APS. Management of these patients must be a multi-disciplinary effort with either a rheumatologist or a hematologist having the overall responsibility for coordinating treatment and monitoring the patient's immune status and anticoagulation. Treatment of isolated ocular thrombophilia in the presence of moderate to high titers of antiphospholipid antibodies should be on the same principles as patients with APS to prevent recurrent ocular or cerebral thrombosis.

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.

Antiphospholipid syndrome induced by HIV

A 24-y-old male who developed necrotic lesions on the lower extremities together with testicular thrombosis necessitating orchiectomy, demonstrated high level IgG anticardiolipin (aCL) associated with acute HIV infection. This is one of the first cases describing a close relationship between viral infection and the classic antiphospholipid syndrome (APS). It is well documented that HIV patients may produce antiphospholipid antibodies (aPL), but the full-blown picture of the APS is distinctly uncommon with HIV or any other viral infection, possibly due to the overproduction of the IgM isotype rather than IgG aCL as in this case. The induction of thrombosis following infections has been well described in patients with catastrophic antiphospholipid syndrome (CAPS) but not in patients with the 'classic or simple' APS.

High level of anticholesterol antibodies (ACHA) in HIV patients. Normalization of serum ACHA concentration after introduction of HAART

Anticholesterol antibodies (ACHA) are natural antibodies against the 3beta-OH group of cholesterol. Since lipid disorders are common in HIV infection and HAART may further enhance dislipidaemia, we determined by using an ELISA method serum ACHA concentrations in HIV patients and healthy HIV-seronegative controls. ACHA levels were almost 4 times higher in the sera of 46 patients than in 110 controls. No difference in the specificity of ACHA was found between HIV-seropositive and HIV-seronegative sera. Binding of ACHA to cholesterol-coated plates from a HIV-seropositive serum was dose-dependently inhibited by preincubation with HIV-1(BA-L) preparation. Serum concentration of ACHA was significantly higher in the patients with low serum cholesterol levels than in those with normal cholesterol levels. HAART induced a marked drop of ACHA concentration. We found a significant negative correlation between the length of HAART and the ACHA levels. By contrast, HAART did not significantly influence total IgG concentration and titers of antibodies against 60 kD heat shock protein. Our findings indicate that high levels of ACHA in HIV-infection may contribute to the development of hypocholesterolaemia frequently observed in this disease.

Which antiphospholipid antibody tests are most useful?

Despite an active international effort to improve diagnosis and treatment of the antiphospholipid syndrome (Hughes syndrome), there remain problems of lack of standardization and lack of prospective and multivariate epidemiologic analysis which restrict the diagnostic and predictive ability of commercially available tests. Nevertheless, current published series provide some data from which strategic approaches can be used to maximize the efficiency and usefulness of available tests. For further updates on new research and developments of interest to physicians and patients with this syndrome, the following web sites may prove helpful: www.slrapls.org, www.hematology.org, www.acforum.org, www.americanheart.org, www.rarediseases.org, www.aarda.org, and www.lupus.org.

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.