Enhanced lipid peroxidation in patients positive for antiphospholipid antibodies

The mechanism leading to the formation of antiphospholipid antibodies (aPL) is still unknown, Because an in vitro study suggested that aPL may derive from pro-oxidant conditions, we sought a relationship between aPL and isoprostanes, indices of lipid peroxidation in vivo, Thirty patients with systemic lupus erythematosus have been studied. Seventeen (56.6%) were positive for aPL because they had lupus anticoagulant and/or high titer of anticardiolipin antibodies (aCL). Plasma levels of tumor necrosis factor (TNF) and urinary excretion of two isoprostanes, 8-epi-PGF(2 alpha) and IPF2 alpha-I, free radical catalyzed oxidation products of arachidonic acid, were measured. Patients with systemic lupus erythematosus had higher urinary excretion of 8-epi-PGF(2 alpha) and IPF2 alpha-I than controls; urinary excretion of the two isoprostanes was highly correlated (Rho = 0.74, P < .0001). Urinary 8-epi-PGF(2 alpha) was highly correlated with both aCL titer (Rho = 0.70, P < .0001) and TNF (Rho = 0.84, P < .0001). a measure of disease severity. Excretion of this isoprostane was also higher in those patients who exhibited aPL (P < .0001). Comparable correlations were observed with the isoprostane IPF2 alpha-I. No difference of 8-epi-PGF,, was observed between patients with and without previous history of thrombosis. This study, showing the existence of a close association between aPL and increased in vivo lipid peroxidation, supports the hypothesis that these antibodies may result from pro-oxidative conditions and suggests that inflammation may play an important role. (C) 1997 by The American Society of Hematology.