Immunoglobulin A Isotype of Antiphospholipid Antibodies Does Not Provide Added Value for the Diagnosis of Antiphospholipid Syndrome in a Chinese Population

Abstract

Objective Antiphospholipid syndrome (APS) is characterized by the presence of anti-phospholipid (aPL) antibodies. However, the relationship between the immunoglobulin (Ig) A isotype of aPL positivity and its clinical utility in APS diagnosis is controversial. Presently, we determine the clinical utility of IgA–aPL from consecutive patients in a large cohort from the Chinese population and patients with APS whose aPL profiles were obtained. Methods The detection of anticardiolipin (aCL) and anti-β 2 glycoprotein-Ⅰ (aβ 2 GPⅠ) antibodies of the IgA/IgG/IgM isotype by paramagnetic particle chemiluminescent immunoassay was carried out in sera from 7293 subjects. 153 primary APS (PAPS) patients and 59 patients with secondary APS (SAPS) were included in this study. Results In total, 1,082 out of 7,293 (2.55%) subjects had a positive IgA–aPL test, and the prevalence of isolated IgA–aPL was 0.29% (21/7,293) in the general population. The prevalence of IgA–aPL in the PAPS patients was 12.42% (19/153); however, only one patient (0.65%) presented with isolated IgA–aPL. Fifty (25.9%) of the SAPS had IgA–aPL, none of whom lacked IgG/IgM–aPL. The combination of the IgA isotype and the IgG/IgM isotype did not increase the diagnostic performance when compared with the IgG/IgM isotype of aCL or aβ 2 GPⅠ, respectively. IgA–aPL was not associated with clinical manifestation in patients with APS. Conclusion Isolated IgA–aPL is rare in the general population as well as in patients with APS. Whether in the laboratory or in clinical practice, the presence of IgA–aPL does not provide added value for the diagnosis of APS in the Chinese population.

Comparison of Different Test Systems for the Detection of Antiphospholipid Antibodies in a Chinese Cohort

“…However, no other significant association was observed for other clinical features or IgA isotype. Similar results could be observed in a study conducted by us recently in a large cohort with more than 7,000 patients (25). It had been reported that the prevalence of thrombocytopenia was 20 to 46% as a manifestation of primary APS, probably because aCL may bind activated platelet membranes and cause platelet destruction (26).…”

Longitudinal Analysis of Anti-cardiolipin and Anti-β2-glycoprotein-I Antibodies in Recent-Onset Systemic Lupus Erythematosus: A Prospective Study in Swedish Patients

“…Our own recent study based on a Swedish (mainly Caucasian) SLE population concluded that IgA aPL alone are of additional value only for patients with a high probability of APS, despite negative test outcomes for IgG/IgM aCL, anti-β2GPI and LA ( 23 ). Similar data were recently reported from a large Chinese population ( 24 ).…”

Evaluation of the Diagnostic Value of Non-criteria Antibodies for Antiphospholipid Syndrome Patients in a Chinese Cohort

“…Additionally, assessment of the diagnostic performance of aPS/ PT revealed a significant correlation between thrombotic events and pregnancy loss with IgG aPS/PT (25,26), which was confirmed by a recent study (27). Concerning aCL/ab2GpI IgA, a study recently conducted by us in a large Chinese population revealed little added diagnostic value (28). Few studies have explored all of the above non-criteria autoantibodies in the same patient groups, and their relations with more detailed clinical manifestations still need investigation.…”