HIGH PREVALENCE OF ANTIPHOSPHATIDYLINOSITOL ANTIBODIES IN YOUNG-PATIENTS WITH CEREBRAL-ISCHEMIA OF UNDETERMINED CAUSE

Background and Purpose-Anticardiolipin antibodies (aCL) are associated with thrombotic phenomena including cerebral ischemia in young adults . Although aCL are directed to a neoepitope formed by phospholipid and beta 2-glycoprotein I (beta 2-GPI), immunoassays based on cardiolipin as target antigen are widely used. We previously demonstrated that 47 % of aCL-negative systemic lupus erythematosus (SLE) patients had anti phospholipid antibodies (aPL) to epitopes other than cardiolipin, and we found an association between aPL to noncardiolipin antigens and thr ombosis. We now assess the prevalence and clinical significance of non cardiolipin aPL in young adults with cerebrovascular disease of undete rmined etiology. Methods-Seventy-seven non-SLE patients, aged <51 year s, with cerebral ischemia were studied. Specificity of aPL were charac terized by ELISAs using 7 different phospholipids: cardiolipin (CL), p hosphatidylserine (PS), phosphatidylinositol (PI), phosphatidylglycero l (PG), phosphatidic acid (PA), phosphatidylcholine, and phosphatidyle thanolamine. Results-Thirty-four patients (44.1%), had aPL to 1 or mor e of the following antigens: 23.4% to CL, 18.2% to PS, 15.6% to PG, 14 .3% to PA, and 28.6% to PI. Fifty-nine patients (76.6%) were aCL negat ive. Of these subjects 23.4% showed aPL to noncardiolipin epitopes. PI was the specificity with highest prevalence in all subgroups, and in 6 patients anti-PI antibodies were the only detectable aPL. The bindin g of aPL to the different antigens was beta 2-GPI dependent. Conclusio ns-Our data demonstrate a high prevalence of aPL in young adults with cerebral ischemia of undetermined cause. PI was the specificity with h ighest prevalence, suggesting that anti-PI antibodies may be an immuno logical marker in young patients with cerebrovascular disease.