Classical and additional antiphospholipid antibodies in blood samples of ischemic stroke patients and healthy controls

Classical antiphospholipid antibodies (aPLa) are found in 6–25% of blood samples from stroke patients. The frequency of novel aPLa antibodies in blood samples of CVA patients is not known. Enzyme-linked immunosorbent assays (ELISA) were performed on blood samples from 209 CVA patients (170 samples were obtained during the acute phase and 39 samples were from patients with complete carotid stenosis) and compared to 54 healthy controls. Subjects were tested for the presence of the classical aPL antibodies anticardiolipin (aCL) and anti-beta2-glycoprotein (aβ2gI), in addition to antiphosphatidylethanolamine (aPE), anti-phosphatidylserine (aPS), and Annexin V. All antibodies were tested for both IgM and IgG subclasses. Numeric analysis of the antibody titer levels (μ/ml) revealed a significantly higher subclinical titer by two standard deviations of many aPL autoantibodies among CVA patients (Pv < 0.05). However, according to the kit manufacturer’s cutoff value, no positive antibodies were found except a trend toward higher percentage of positive aPS IgG titer in the CVA group compared to controls (6.2 vs. %0; P = 0.077). According to the manufacturer’s cutoff, significantly higher levels of positive antibodies were not found among stroke patients. However, the absolute ELISA values of stroke patients were significantly higher. These results suggest that lower cutoff values than those used for APS diagnosis should be used for risk stratification of CVA among healthy individuals.