The value of IgA antiphospholipid testing for diagnosis of antiphospholipid (Hughes) syndrome in systemic lupus erythematosus.

OBJECTIVE: It is recognized that the presence of IgG and IgM anticardiolipin antibodies (aCL) and lupus anticoagulant (LAC) is associated with thrombosis in patients with antiphospholipid syndrome (APS). Some reports have shown that testing for IgA anticardiolipin and anti-beta2-glycoprotein antibodies (anti-beta2-GPI) provides extra diagnostic help in patients with APS, while other authors could not support this data. We designed this cross sectional study to determine the prevalence of IgA aCL, anti-beta2-GPI, and antiprothrombin antibodies and to study their clinical significance in a large cohort of patients with systemic lupus erythematosus (SLE). METHODS: This study comprised 134 SLE patients (126 women; median age 37.5 yrs, range 16-72). The median duration of the disease was 9 years, range 0.1-38. Of these, 55 (41%) had a history of thrombotic events: 22 (40%) presented an arterial event, 22 (40%) a venous event, and 11 (20%) both arterial and venous events. Of 49 women who had been pregnant, 18 (37%) gave a history of recurrent pregnancy loss. Thrombocytopenia was present in 14/127 patients (11%). Forty patients (30%) were diagnosed as APS secondary to SLE, 23 (17%) had IgG/M aCL and/or LAC without clinical features of APS, and 71 (53%) were SLE patients who were repeatedly negative for IgG/M aCL or LAC. IgG, IgM, IgA aCL and anti-beta2-GPI were detected by ELISA. Antibodies directed to prothrombin were detected by 2 ELISA using prothrombin coated on irradiated plates (aPT) and phosphatidylserine/prothrombin complex (aPS/PT) as antigen. RESULTS: IgA aCL were found in 18/134 (13%) patients. Of these, 3 (17%) had IgA aCL as well as IgG/M aCL, and 2 (11%) had IgG/M aCL and anti-beta2-GPI. Of the 18 patients positive for IgA aCL, 8 were also positive for LAC. Of these, one (5%) patient had IgA aCL as well as other isotype of aCL, and 7 (39%) patients had both aCL and anti-beta2-GPI. None of these patients had binding of IgA aPT or aPS/PT. Of the entire group of 18 patients, 5 (28%) had IgA aCL as the sole aPL. Four of 5 of these patients were diagnosed as SLE but had no antiphospholipid (aPL) related clinical manifestations. We found no association between the presence of IgA aCL and clinical manifestations of APS. IgA anti-beta2-GPI were found in 8/134 (6%) patients. Of these, one (12.5%) had IgA anti-beta2-GPI as well as IgG/M anti-beta2-GPI and aCL. Of the 8 patients positive for IgA anti-beta2-GPI, 6 (75%) were also positive for LAC. Of these, one (12.5%) patient presented with IgA anti-beta2-GPI along with other isotypes of aCL, and 4 (50%) patients with aCL and other isotype of anti-beta2-GPI. One patient (12.5%) had IgA anti-beta2-GPI along with LAC only, and one patient (12.5%) who was diagnosed as SLE had no aPL related clinical manifestation but had IgA anti-beta2-GPI as the sole aPL. CONCLUSION: IgA aCL and anti-beta2-GPI are found in SLE, usually along with IgG and/or IgM isotypes. Testing for IgA aCL and anti-beta2-GPI is not a helpful screening test and does not contribute to the recognition of APS in SLE. IgA aPT and aPS/PT are not present in patients with SLE, therefore there is no need to test for these antibodies.     

IgA anticardiolipin and anti-beta2-glycoprotein I are the most prevalent isotypes in African American patients with systemic lupus erythematosus.

BACKGROUND: Ethnicity plays a role in the prevalence, isotype distribution, and clinical significance of anticardiolipin (aCL) and anti-beta2-glycoprotein I (anti-beta2-GPI) antibodies in patients with systemic lupus erythematosus (SLE). Few studies have been done in the African American population. METHODS: Serum samples from 100 African American patients with SLE were tested for IgG, IgM, and IgA aCL and anti-beta2-GPI antibodies by enzyme-linked immunosorbent assay (ELISA). Computerized clinical data on these patients were reviewed with a specific focus on clinical manifestations of antiphospholipid syndrome (APS). RESULTS: Positivity for at least one isotype of aCL antibodies was found in 33% of the patients, whereas 28% were positive for at least one isotype of anti-beta2-GPI antibodies. IgA was the most prevalent isotype for both antibodies; 24% of the patients in the aCL ELISA and 19% in the anti-beta2-GPI ELISA were positive for IgA. Positivity for both aCL and anti-beta2-GPI in the same patient was seen more frequently with the IgA isotype. Fewer than half of the patients positive for aCL antibodies had medium-to-high levels of antibodies. A few patients had presented thrombotic manifestations, and these patients were positive for aCL (P = 0.01) and anti-beta2-GPI antibodies (P = 0.02). No other manifestations of APS could be significantly correlated with the presence of these antibodies. CONCLUSIONS: Our results show that IgA is the most prevalent isotype among the African American patients with SLE studied. The predominance of the IgA isotype and the low prevalence of medium-to-high levels of aCL antibodies may account for the low frequency of clinical manifestations of APS in these patients.     

High prevalence of antiphospholipid antibodies in leprosy: evaluation of antigen reactivity

Antiphospholipid antibodies (aPL) have been reported not only in autoimmune disorders but also in various infectious diseases. Accumulating evidence indicates that beta2 glycoprotein I (beta2GPI) and prothrombin are the main proteins to which autoimmune aPL bind. The aim of this study was to evaluate the prevalence of different aPL in patients with leprosy. We included 51 outpatients (42 lepromatous and 9 borderline leprosy) without any clinical feature of the antiphospholipid syndrome (APS). 35 had lupus anticoagulant and 31 had anticardiolipin antibodies (aCL). Anti-beta2GPI antibodies were highly positive in 29/51 and anti- prothrombin antibodies (anti-II) were detected in 23/51. Almost all aCL and anti-beta2GPI were of IgM isotype, while IgG isotype was more frequent among anti-II. No statistical difference was found when aPL were evaluated in patients grouped according to their bacteriological status. Furthermore, patients under treatment (n=33) had a similar frequency of positive aPL compared to patients in vigilance (n=14). Assessing the specificity of antibody binding to CL and beta2GPI in ELISA by means of inhibition studies with cardiolipin-beta2GPI liposomes, leprosy and APS sera showed a similar behaviour. Comparable results were also found in both groups of patients when inhibition experiments with lysate of Mycobacterium leprae were carried out. In summary, leprosy-related aPL resemble those found in patients with APS but the immunoglobulin isotype is different, with IgM much more prevalent in leprosy patients.     

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 and anti-beta2 glycoprotein I antibodies in Indian patients with systemic lupus erythematosus: association with the presence of seizures

The aim of this study was to examine whether the clinical features of antiphospholipid antibody syndrome are associated with anti-cardiolipin and anti-beta2 glycoprotein I antibodies in Indian patients with SLE. Seventy-six patients (71 females), who fulfilled 1982 ACR criteria for SLE, were prospectively studied for the clinical features of antiphospholipid antibody syndrome (APS), and their sera were analysed for the presence of IgG/IgM/IgA anti-cardiolipin antibodies (aCL) by an in-house ELISA and, in 65 of them, for the presence of IgG anti-beta2 glycoprotein I antibodies (anti-beta2 GPI) by a commercial kit. Thirty-nine (51%) patients were positive for aCL, all of which were positive for IgG aCL, either alone (79.6%) or along with IgM and/or IgA. Twenty-seven (69.3%) out of 39 aCL-positive and seven (26.9%) out of 26 aCL-negative sera were positive for IgG antibodies to beta2 GPI. There was a significant correlation (r = 0.66, P < 0.05) between the levels of aCL and anti-beta2 GPI antibodies. Forty-one patients had features of definite or suggestive APS. Thrombocytopenia, recurrent pregnancy loss and CNS manifestations (seizures eight, infarct one) were seen in 20, 13 and nine patients, respectively. Thrombosis of the peripheral vessels was seen in only one patient. Only the presence of seizures was significantly associated with the presence of aCL and anti-beta2 GPI antibodies (P < 0.05). The characteristic association of definite APS (recurrent pregnancy loss and arterial/venous thrombosis) was lacking.     

Anticardiolipin and anti-beta2glycoprotein-I antibodies in patients with systemic lupus erythematosus: comparison between Colombians and Spaniards

We studied the prevalence, isotype distribution, and clinical significance of anticardiolipin (aCL) and anti-beta2glycoprotein I (anti-beta2GPI) antibodies in two populations of patients with systemic lupus erythematosus (SLE), 160 Colombians and 160 Spaniards. All sera were tested in our laboratory by enzyme-linked immunosorbent assay (ELISA) for IgG, IgM, and IgA aCL, as well as IgG and IgM anti-beta2GPI. Positive results for at least 1 of the 3 aCL isotypes were found in 40 Colombians (25%) and 55 Spaniards (34%). IgG aCL was the predominant isotype in both populations. Positive results for at least 1 of the anti-beta2GPI isotypes were found in 34 Colombians (21%) and 29 Spaniards (18%). IgG anti-beta2GPI was the dominant isotype in Colombians, while IgM was predominant in Spaniards. Positivity for anti-beta2GPI in aCL-positive patients was present in 77% in the Colombian group and 50% in the Spaniard group. Among Colombians, IgG aCL and anti-beta2GPI correlated with thrombosis, fetal loss, and thrombocytopenia. Among Spaniards, IgG aCL and IgG anti-beta2GPI correlated with thrombosis, fetal loss, and livedo reticularis. For detecting thrombosis and fetal loss, aCL ELISA was more sensitive than anti-beta2GPI in Spaniards, and anti-beta2GPI ELISA was more specific than aCL in both populations.     

Prevalence and clinical correlates of anti-phospholipid antibodies in South Africans with systemic lupus erythematosus

OBJECTIVE: To determine the prevalence and clinical correlates of anti-phospholipid antibodies (aPL), including anti-cardiolipin antibodies (aCL), lupus anti-coagulant (LA), anti-beta2-glycoprotein 1 (abeta2GP1), and anti-prothrombin (aPT) antibodies, in Black South African patients with systemic lupus erythematosus (SLE). METHODS: A cross-sectional study of 100 SLE patients in whom clinical characteristics, including features of the anti-phospholipid syndrome (APS), disease activity, and damage were documented, and sera tested for aCL, abeta2GP, and aPT of all isotypes, and LA. RESULTS: Positive aCL, abeta2GPI, aPT, and LA were found in 53, 84, 20, and 2 patients, respectively. Immunoglobulin (Ig)A aCL and IgG abeta2GPI were the commonest aCL (49.1%) and abeta2GPI (47%) isotypes, respectively. IgA abeta2GPI were associated with both a history of thrombosis alone (p<0.05) and a history of any clinical feature, thrombosis, and/or spontaneous abortion of the APS (p<0.05); IgA aCL were associated with a history of any clinical APS event (p<0.05); and abeta2GPI of any isotype were associated with a history of arthritis (p<0.001). CONCLUSION: Our findings provide further evidence that screening for abeta2GPI and IgA aCL isotypes may improve the risk assessment for APS in SLE patients of African extraction. Further prospective studies are warranted to determine the clinical utility of these tests and to elucidate the genetic basis for the increased IgA aPL response in SLE patients of African extraction.     

Anti-beta2-glycoprotein I: prevalence, clinical correlations, and importance of persistent positivity in patients with antiphospholipid syndrome and systemic lupus erythematosus

OBJECTIVE: Antibodies to beta2-glycoprotein I (anti-beta2-GPI) are found in a large percentage of patients with primary or secondary antiphospholipid syndrome (APS). Our aim was to identify the prevalence and clinical correlation of these antibodies in patients with APS and systemic lupus erythematosus (SLE), in comparison to anticardiolipin (aCL) and the lupus anticoagulant (LAC). We investigated whether serial samples improve clinical utility. METHODS: Serum samples for anti-beta2-GPI (IgG, IgM, IgA), aCL (IgG, IgM, IgA), and LAC (by dilute Russell viper venom time; RVVT) were collected from 418 consecutive patients with SLE or APS between October 2002 and March 2003. Clinical and serologic data of these patients were analyzed. RESULTS: A total of 185 (44.5%) patients were positive for anti-beta2-GPI, 55.3% were positive for aCL, and 31.1% for LAC. Anti-beta2-GPI was more common in Caucasians than in African Americans (p = 0.098). IgM and IgA were the most frequent isotypes of anti-beta2-GPI. aCL and anti-beta2-GPI were highly associated (p < 0.0001 to p = 0.0177, depending on isotype). A positive association was found between the presence of the LAC by dilute RVVT and anti-beta2-GPI IgG (p < 0.0001), IgM (p < 0.0001), and IgA (p = 0.0002) antibodies. Persistent positivity increased the association of venous and arterial thrombosis with anti-beta2-GPI (IgG and IgM isotypes). Pregnancy loss, seizures, and migraines were not associated with anti-beta2-GPI. IgA anti-beta2-GPI was not significantly associated with any manifestation of APS. CONCLUSION: The prevalence of anti-beta2-GPI IgM and IgA was very high in our population. Measurement of anti-beta2-GPI IgG is clinically useful in identifying patients with SLE at higher risk for venous and arterial thrombosis. Persistent positivity increased the association of IgG anti-beta2-GPI with venous thrombosis and anti-beta2-GPI IgM with arterial thrombosis. IgA anti-beta2-GPI was not significantly associated with APS manifestations.     

Real world experience with antiphospholipid antibody tests: how stable are results over time?

OBJECTIVE: To determine the stability and the degree of variation of antiphospholipid antibody (aPL) results over time in a large cohort of well evaluated aPL positive patients; and to analyse factors contributing to aPL variation and the validity of aPL in a real world setting in which aPL tests are done in multiple laboratories. METHODS: The clinical characteristics, drug treatment, and 1652 data points for lupus anticoagulant (LA), anticardiolipin antibodies (aCL), and anti-beta2 glycoprotein I antibodies (anti-beta2GPI) were examined in 204 aPL positive patients; 81 of these met the Sapporo criteria for antiphospholipid syndrome (APS) and 123 were asymptomatic bearers of aPL. RESULTS: 87% of initially positive LA results, 88% of initially negative to low positive aCL results, 75% of initially moderate to high positive aCL results, 96% of initially negative to low positive anti-beta2GPI results, and 76% of initially moderate to high positive anti-beta2GPI results subsequently remained in the same range regardless of the laboratory performing the test. Aspirin, warfarin, and hydroxychloroquine use did not differ among patients whose aCL titres significantly decreased or increased or remained stable. On same day specimens, the consistency of aCL results among suppliers ranged from 64% to 88% and the correlation ranged from 0.5 to 0.8. Agreement was moderate for aCL IgG and aCL IgM; however, for aCL IgA agreement was marginal. CONCLUSIONS: aPL results remained stable for at least three quarters of subsequent tests, regardless of the laboratory performing the test; the small amount of variation that occurred did not appear to be caused by aspirin, warfarin, or hydroxychloroquine use.     

IgM, but not IgA rheumatoid factor interferes with anti-cardiolipin and antiβ2 glycoprotein I measurements: a quantitative analysis

IgM rheumatoid factor (RF) is sometimes referred to as capable of causing interference in the IgM anti-cardiolipin (aCL) testing. Published guidelines are, however, inconsistent, and evidence regarding the interference is limited. Our goal was investigate IgM and IgA RF cross-reactivity and/or interference in IgM and IgA aCL and anti-β2 glycoprotein I (aβ2GPI) testing. Serum specimens with high IgM and IgA RF levels were tested for IgG, IgA and IgM aCL and aβ2GPI antibodies to examine cross-reactivity. Samples containing IgG aCL and aβ2GPI antibodies were spiked with IgM (and IgA) RF, and samples with high RF levels were spiked with IgG aCL antibodies. The mixtures were tested for IgM and IgA aCL and aβ2GPI antibodies. Specimens with high IgM and IgA RF concentrations did not test positive for IgM or IgA aCL and aβ2GPI antibodies (except one weak positive IgA aβ2GPI result), indicating the lack of cross-reactivity. In the spiked specimens, addition of IgM RF caused significant positive bias in the measurement of both aCL and aβ2GPI antibodies of IgM isotype in the presence of IgG aCL and aβ2GPI antibodies. The threshold for triggering significant interference was 318(?)IU/ml for IgM RF, and 77?GPLU/ml for IgG aCL. Neither IgM, nor IgA RF, however, affected the IgA antiphospholipid (aPL) antibody testing. IgM RF can cause a false-positive IgM aCL result in the presence of IgG aCL antibodies. In studies on the prevalence and clinical significance of IgM aPL antibodies, RF interference should be considered and RF testing should be performed.     

Valine/valine genotype at position 247 of the beta2-glycoprotein I gene in Mexican patients with primary antiphospholipid syndrome: association with anti-beta2-glycoprotein I antibodies

OBJECTIVE: To determine the polymorphism at position 247 of the beta(2)-glycoprotein I (beta(2)GPI) gene in Mexican patients with antiphospholipid syndrome (APS) and to compare these data in patients with or without antibodies to beta(2)GPI and with the clinical manifestations of APS. METHODS: We studied 39 patients with primary APS and compared them with 106 clinically healthy subjects. Polymorphism was determined by polymerase chain reaction-restriction fragment length polymorphism. The presence of "true" anticardiolipin (aCL) antibodies, beta(2)GPI-dependent aCL antibodies (IgG and IgM), and phospholipid-free anti-beta(2)GPI antibodies (IgG isotype) were detected by enzyme-linked immunosorbent assay (ELISA) utilizing nonirradiated ELISA plates. Clinical manifestations associated with antiphospholipid antibodies were also evaluated. RESULTS: We found no significant differences in the genotype expression between the control group and the primary APS patients (13% with VV, 52% with VL, and 35% with LL versus 23% with VV, 51% with VL, and 26% with LL, respectively). In contrast, anti-beta(2)GPI-positive patients had significantly higher frequencies of the VV genotype and V allele expression than the control subjects and the anti-beta(2)GPI-negative patients. These genotype and allele frequencies were also significantly higher in patients with arterial thrombosis than in patients without it. Anti-beta(2)GPI-negative patients without arterial thrombosis did not express the VV genotype. We found no differences in the Val/Leu(247) polymorphism of the beta(2)GPI gene in primary APS patients with or without "true" aCL antibodies or in primary APS patients with or without beta(2)GPI-dependent aCL antibodies. CONCLUSION: Our results suggest that the VV genotype at position 247 of the beta(2)GPI gene may play a role in the generation of anti-beta(2)GPI antibodies and perhaps in the expression of arterial thrombosis in primary APS.     

Anti-beta2 glycoprotein I and anticardiolipin antibodies in leptospirosis, syphilis and Kala-azar

OBJECTIVE: Reports have shown that anticardiolipin (aCL) antibodies present in patients with autoimmune diseases are dependent on the cofactor,beta2 glycoprotein I (beta2 GPI), as opposed to aCL antibodies seen in infectious diseases such as syphilis, HIV hepatitis C, etc. The assay for anti-beta2GPI antibodies has been reported to be more specific for antiphospholipid syndrome (APS). However, the prevalence of these antibodies in diseases such as leishmaniasis and leptospirosis remains unknown. The aim of the present study was determine the prevalence of antibodies to cardiolipin and to beta2GPI in patients with different infectious diseases, including leptospirosis, syphilis and leishmaniasis. METHODS: Samples from patients with Kala-azar (visceral leishmaniasis), syphilis or leptospirosis were tested for IgG and IgM anticardiolipin and IgG anti-beta2GPI antibodies by ELISA. RESULTS: In patients with Kala-azar the prevalence of IgG aCL, IgM aCL and anti-beta2GPI was 6% (2/30), 3% (1/30) and 53% (16/30), respectively. In syphilis the prevalence was 18% (14/74), 13% (10/74) and 10% (8/70), respectively. In leptospirosis the frequency of these antibodies was 23% (9/39), 10% (4/39) and 17% (6/34), respectively. There was no statistical correlation between aCL and anti-beta2GPI antibodies in these diseases. DISCUSSION: This study clearly shows a significant prevalence of anti-beta2GPI antibodies in leptospirosis and leishmaniasis and syphilis. This indicates that the assay for antibeta2GPI antibodies should be thoroughly validated before it is introduced as a definitive tool for the diagnosis of APS, testing a larger number of sera from patients with a wider range of clinical conditions.     

Antiphospholipid (Hughes') syndrome in African-Americans: IgA aCL and abeta2 glycoprotein-I is the most frequent isotype.

Antiphospholipid (Hughes') syndrome (APS) has not been reported in African-Americans (A-A) as frequently as in other ethnic groups. We describe eight A-A female patients with APS, including two cases of primary APS (PAPS), four with APS secondary to systemic lupus erythematosus (SLE), one with Sj?gren's syndrome, and one with overlap connective tissue disease (CTD). Their mean age was 34 y (range 24-47 y). Patients were followed for a mean of 6 y (range 0.3-11 y). During follow up, both anticardiolipin (aCL) and anti-beta2glycoprotein-I (abeta2GPI) antibodies were measured in stored sera by enzyme-linked immunosorbent assay (ELISA). IgA was the most frequent isotype of aCL and abeta2GPI, and co-occurred with the IgM isotype in three of four patients with neurologic manifestations.     

Clinical significance of IgA anticardiolipin and anti-β2-GP1 antibodies in patients with systemic lupus erythematosus and primary antiphospholipid syndrome

The objectives of this study were to estimate the prevalence of IgA anticardiolipin antibodies (aCL) and anti-beta(2)-glycoprotein 1 antibodies (abeta(2)-GP1) in a large number of patients with systemic lupus erythematosus (SLE) and primary antiphospholipid syndrome (PAPS) and to examine possible associations between the clinical manifestations of the APS and the levels of IgA aCL and abeta(2)-GP1. We also assessed the operative characteristics of IgA aCL and abeta(2)-GP1. We retrospectively studied 130 patients with SLE and 35 patients with PAPS. In all patients we measured IgG, IgM, and IgA aCL and abeta(2)-GP1 and recorded any of the clinical manifestations of the APS. IgA aCL were positive in 8.5% of patients with SLE and in 40% of patients with PAPS. Positive IgA abeta(2)-GP1 were found in 17.7% of patients with SLE and in 25.7% of patients with PAPS. IgA aCL were associated with a history of venous thrombosis, thrombocytopenia, and recurrent fetal loss. In contrast, we could not establish significant associations between IgA abeta(2)-GP1 and any of the clinical manifestations of the APS. Measurement of the IgA in addition to IgG and IgM aCL hardly changed the operative characteristics of aCL testing, while measurement of the IgA in addition to IgG and IgM abeta(2)-GP1 increased sensitivity but with a greater loss in specificity. IgA aCL is significantly associated with more than one of the clinical manifestations of the APS in contrast to the IgA abeta(2)-GP1. Routine measurement of the IgA isotype of both aCL and abeta(2)-GP1 does not improve the operative characteristics of aCL and abeta(2)-GP1 and therefore is not recommended at present.     

Autoimmune antiphospholipid antibodies and cryoglobulinemia

In addition to their role in the thrombotic manifestations of the antiphospholipid syndrome (APS), autoimmune antiphospholipid (aPL) antibodies may also be responsible for direct injury to the blood vessel wall, although the mechanism is unclear. Cryoglobulinemia has been reported infrequently in patients with APS and is one potential means of blood vessel injury. The aim of the present study was to determine if autoimmune aPL antibodies and their target antigens contribute to the formation of cryoprecipitates. Cryoglobulins were identified and isolated from 5 of 8 patients with autoimmune aPL antibodies. Using identical concentrations of immunoglobulins isolated from matched sera and washed cryoprecipitates there was a significant enrichment (at least 100%) of aCL antibodies in the cryoprecipitates from 4 of 5 patients. This involved IgG, IgM and IgA isotypes with specificity for both beta2-glycoprotein I (GPI) and prothrombin (PT). The target antigens were detected in cryoprecipitates from all 5 aPL positive patients and in cryoprecipitates from 3 controls. These results suggest that anti-beta2-GPI and anti-PT antibodies in association with their target antigens are integrally involved in the formation of cryoprecipitates in patients with autoimmune aPL antibodies and provide insight into a potential mechanism for blood vessel injury.     

High titer of serum antiphospholipid antibody levels in adult Henoch-Schönlein purpura and cutaneous leukocytoclastic angiitis

OBJECTIVE: To investigate a possible role of antiphospholipid (aPL) antibodies in adult Henoch-Sch?nlein purpura (HSP) and cutaneous leukocytoclastic angiitis (CLA). METHODS: We reviewed the records of 30 HSP and 8 CLA adults with an initial cutaneous manifestation of palpable purpura on their lower extremities between 2003 and 2007. Eight microscopic polyangiitis (MPA) patients and 30 healthy persons were recruited as controls. Serum anticardiolipin (aCL), anti-phosphatidylserine-prothrombin complex (anti-PS/PT), and anti-beta(2)-glycoprotein I (anti-beta(2)GPI) antibody levels in HSP, CLA, MPA patients, and healthy controls were measured by enzyme-linked immunosorbent assay. RESULTS: Twenty-two HSP patients (73%) were positive for serum IgA aCL antibodies. Nineteen (63%) had IgA anti-PS/PT antibodies and 4 (13%) had IgA anti-beta(2)GPI antibodies. IgA aCL and anti-PS/PT antibodies showed a significant correlation (P = 0.007). Twenty (67%) HSP patients had IgM anti-PS/PT antibodies and 6 (20%) had IgG anti-PS/PT antibodies. Six (75%) CLA patients had IgM anti-PS/PT antibodies and 2 (25%) had IgG anti-PS/PT antibodies. In contrast, aPL antibodies were not found in any MPA patients or normal controls. Serum IgA aCL antibody levels in HSP patients showed a significant correlation with serum IgA and C-reactive protein (CRP) levels (P = 0.030 and 0.039, respectively). A positive correlation between CRP and serum IgA anti-PS/PT antibody levels was observed in HSP patients (P = 0.023). Serum IgA aCL antibody levels were also significantly associated with proteinuria according to urinalysis (P = 0.024). CONCLUSION: Serum levels of IgA aCL and anti-PS/PT antibodies were elevated in adult HSP, suggesting that serum IgA antibodies may play some role in adult HSP. IgA aCL and/or anti-PS/PT antibodies could serve as markers for adult HSP and should be monitored as an indicator of adult HSP activity. Small-vessel vasculitis could be dependently associated with the presence of IgM anti-PS/PT antibodies. These findings suggest that aPL antibodies are closely related to the pathogenic factors that trigger the development of vasculitis.     

Antiphospholipid antibodies in acute coronary syndrome

Antiphospholipid (aPL) antibodies entailing anticardiolipin (aCL) and anti-beta2 glycoprotein I (anti-beta2GPI) antibodies may be involved in a number of vascular diseases including coronary artery diseases (CAD) or stroke. Here we assessed the presence of aPL antibodies in acute coronary syndrome (ACS). The frequency of anti-beta2GPI antibodies was significantly higher (14.4%) in ACS in comparison to control healthy subjects (2%). In addition, serum concentrations of anti-beta2GPI antibodies were also increased in ACS. Anti-beta2GPI antibodies of the IgA isotype might be the most relevant for the onset and outcome of ACS. Regarding subclasses of ACS, anti-beta2GPI IgA antibodies were elevated in unstable angina (UA) and myocardial infarction with ST elevation (STEMI), but not in myocardial infarction without ST elevation (NSTEMI). The involvement of anti-beta2GPI antibodies in ACS was more pronounced in men than women, and in younger rather than older patients. Finally, anti-beta2GPI antibodies in ACS were associated with previous stroke, but not with hypertension or previous myocardial infarction. Thus, anti-beta2GPI antibodies may be involved in the thrombotic events underlying ACS.     

Value of IgA anticardiolipin and anti-beta2-glycoprotein I antibody testing in patients with pregnancy morbidity

OBJECTIVE: To study the prevalence of IgA antiphospholipid antibodies, particularly anticardiolipin antibodies (aCL) and anti-beta(2)-glycoprotein I (abeta(2)GPI), in a cohort of patients with pregnancy morbidity. PATIENTS AND METHODS: Serum samples from four groups of patients were studied by an in house enzyme linked immunosorbent assay (ELISA). Group I: 28 patients with primary antiphospholipid syndrome (PAPS) (median age 32.5 years, range 25-34). Twelve patients had a history of thrombosis. All were positive for IgG/M aCL or lupus anticoagulant (LA), or both. Group II: 28 patients with unexplained pregnancy morbidity (median age 35 years, range 23-48). Seven had history of thrombosis. Nine patients were positive for IgG/M aCL. None from this group fulfilled Sapporo criteria for APS. Group III: 28 patients with systemic lupus erythematosus (SLE) (median age 34 years, range 25-52). Eleven had a history of thrombosis. Twenty one patients had IgG/M aCL and/or LA, but only 19 fulfilled Sapporo criteria for APS. RESULTS: IgA aCL were found in 12, 6, and 14 patients from the groups with PAPS, unexplained pregnancy morbidity, and SLE, respectively. Most patients had these antibodies together with IgG/IgM aCL. Three patients from the group with unexplained pregnancy morbidity and two with SLE had IgA aCL alone. IgA abeta(2)GPI was present in one patient from each group. All IgA abeta(2)GPI were present together with IgG and/or IgM abeta(2)GPI. CONCLUSIONS: The prevalence of IgA aCL is high in patients with pregnancy morbidity, although IgA aCL are usually present together with IgG and/or IgM aCL. IgA abeta(2)GPI are not useful in identifying additional women with APS and pregnancy morbidity.     

Prevalence of Anticardiolipin and Anti-β<Subscript>2</Subscript>-Glycoprotein I Antibodies in Celiac Disease

The aim of this study was to evaluate the prevalence of anticardiolipin antibodies (aCL) and anti-β₂-glycoprotein I antibodies (aβ2GPI) in patients with celiac disease and to analyze the clinical features of antiphospholipid syndrome in these patients. We conducted a prospective case-control study based on the evaluation of IgG, IgM and IgA aCL, and IgG and IgA aβ2GPI in celiac disease patients and in controls. All patients were asked about any occurrence of thrombotic manifestations. In addition, women were asked about pregnancy morbidity. Fifty celiac disease patients and 50 healthy controls were studied. IgM aCL were not detected in study group or in controls. IgG aCL were found in two patients and in one control. IgA aCL were significantly more frequent in celiac disease patients compared with controls (13/50 (26%) vs. 2/50 (4%), p=0.004, OR [95% CI]=9.09 [1.81–50]). There was no statistically significant difference for the prevalence of IgG and IgA aβ2GPI between patients and controls. Clinical features of antiphospholipid syndrome were noted in two patients with negative antibodies. Prevalence of IgM and IgG aCL and of aβ2GPI were not increased in celiac disease. IgA aCL were more frequently detected in celiac disease. However, no clinical features of antiphospholipid syndrome were noted.     

Clinical utility of laboratory tests used to identify antiphospholipid antibodies and to diagnose the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is defined by thrombotic and/or obstetric events together with the presence of antiphospholipid antibodies in plasma of patients. The original laboratory criteria of APS included lupus anticoagulants (LA) and/or IgG/IgM anticardiolipin antibodies (aCL). They were recently updated with the addition of IgG/IgM anti-beta2 glycoprotein I antibodies (anti-beta2GPI), a better definition of "medium to high antibody titer," and the extension to 12 weeks of the "persistence in time." The revised criteria represent an improvement; however, the potential overdiagnosis of APS remains possible, thus putting patients at risk of overtreatment. To reduce this possibility, proposals have been made to implement strict guidelines for the performance of the LA assay, to exclude aCL measurements in their current application from the criteria, and to limit the measurement of anti-beta2GPI to the G isotype. This should also help in simplifying the laboratory workup of patients being investigated for APS.