Diagnosis of antiphospholipid antibodies (APA)

Summary

Antiphospholipid-protein antibodies (APA) are a family of autoimmune and alloimmune immunoglobulins (IgG, IgM, IgA or mixtures) which were initially thought to react specifically with negatively-charged or neutral phospholipids. The detection of these antibodies and subsequent classification has been based on a variety of in vitro laboratory tests. Among the various methodologies utilized are: complement fixation, coagulation assays, radioimmunoassays (RIA), microtiter plate ELISA tests, and flow cytometry. The diversity of the various assays as well as the heterogeneity of patient populations have resulted in some confusion with respect to clinical relevance of various tests. Recent advances have identified several plasma proteins which appear to be the true antigenic targets for APA. Among these proteins are: beta-2 glycoprotein I (β₂GPI), prothrombin, annexin V, protein C, protein S, and high molecular weight/low molecular weight kininogens. There remains speculation as to whether the in vitro laboratory test results can be extrapolated to the in vivo activity of this family of antibodies.

Zusammenfassung

Antiphospholipid-Antikörper (APL-AK) bilden eine Familie autoimmuner und alloimmuner Immunoglobuline (IgG, IgM, IgA oder gemischt), von denen zunächst angenommen wurde, dass sie spezifisch mit negativ geladenen oder neutralen Phospholipiden reagieren. Der Nachweis dieser Antikörper und die spätere Einteilung basierten auf unterschiedlichen In-vitro-Testverfahren. Dazu gehörten: die Komplementbindung, Gerinnungstests, Radioimmunoassays (RIA), Mikrotiter-ELISA-Verfahren und die Durchflusszytometrie. Die Verschiedenartigkeit der eingesetzten Testverfahren und die Heterogenität der Patientenpopulationen haben für einige Verwirrung im Hinblick auf die klinische Bedeutung unterschiedlicher Verfahren geführt. In neuerer Zeit wurden mehrere Plasmaproteine identifiziert, die die echten antigenen Ziele für APL-AK zu sein scheinen. Zu diesen Proteinen gehören: Beta-2-Glykoprotein I (β₂GPI), Prothrombin, Annexin V, Protein C, Protein S und Kininogene hohen/niedrigen Molekulargewichts. Inwieweit sich die Ergebnisse der In-vitro-Testverfahren auf die In-vivo-Aktivität dieser Antikörperfamilie übertragen lassen, bleibt spekulativ.

Keywords

Antiphospholipid-protein antibodies (APA) - lupus anticoagulants (LA)

Schlüsselwörter

Antiphospholipid-Antikörper (APA) - Lupus Antikoagulanzien (LA)

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