Rational Laboratory Diagnostics of Antiphospholipid Antibodies: Anti-Cardiolipin, Anti-β2-Glycoprotein I, Anti-Prothrombin and Anti-Annexin V Antibodies

A possible co-appearance of anticardiolipin (aCL), anti-β2-glycoprotein I (anti-β2-GPI), anti-prothrombin (aPT) and anti-annexin V (aANXV) antibodies of IgG, IgM and IgA class were studied in 58 patients with SLE alone and 32 patients APS in the view of rational laboratory diagnostics. The presence of anti-phospholipid antibodies (aPL) were defined by our in-house ELISA methods. Out of 17 aCL negative SLE patients 6 had other antigenically defined aPL antibodies. In 13 patients only IgA but not IgG and IgM anti-β2GPI were detected. Different combinations of aPL subsets were equally distributed in APS and SLE groups. The prevalence of aANXV were similar in APS and SLE patients which was not the case with other aPL. Our findings support the idea of measuring additional subsets of aPL (aPT and aANXV) in unclear cases. IgA (either aCL or anti-β2-GPI) improved neither the diagnostic specificity nor diagnostic sensitivity, but only increased the frequency of the total anti-β2-GPI.