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Abstract

Reactivity Profiles of Autoantibodies to Different Phospholipids and the Phospholipid-binding Protein ß2-Glycoprotein I in Patients with Clinical Symptoms Related to Thromboembolic and/or Vasculopathic Events with or without Connective Tissue Diseases by H.-P. Jaekel, D. Schmid, E.-W. Müller, V.Ziutelis, A. Trabandt, N.Grobe, S. Kaskel-Paul, H. Höh, B. Bauer, R. Sudik, A. Baldauf, E. Werle

To study the antigenic and epitope specificities of anti-phospholipid Ab in detail, we investigated 177 patients without (62 with APS-related systemic clinical symptoms, 115 with microangiopathies) and 164 patients with connective tissue diseases (CTD). Ab associated with primary APS (pAPS) seem to show a restricted specificity (phospholipid/β2-GPI-complexes), whereas those in secondary APS (sAPS) react additionaly with pure β2-GPI. Simultaneously, β2-GPI-independent Ab were also frequently present in both conditions (50% of all Ab-positive sera). In CTD patients. the reactivity profile "pure β2-GPI + phospholipid/β2-GPI-complexes" is significantly associated with clinically manifest sAPS. Comparing cardiolipin and phosphatidylserine as antigenic target, the overall concordance (crossreactivity?) between both assays was lower than expected (52%), being highest in pAPS (87%) and sAPS (65%). Based on these results, a two-step procedure for reliable serological diagnosis of APS could be recommended: Ab-screening using a mix of phospholipids complexed with β2-GPI (sensitivity > 90% for Ab concentrations above 20 U/ml) followed by an assay allowing the simultaneous detection of all relevant antigenic and epitope specificities.

DOI: Clin. Lab. 2003;49:345-355