Antinucleosome antibodies may help predict development of systemic lupus erythematosus in patients with primary antiphospholipid syndrome.

Patients with primary antiphospholipid syndrome (PAPS) may evolve to systemic lupus erythematosus (SLE), even many years later. This makes differentiation between primary and secondary antiphospholipid syndrome a difficult task. Studies in murine models of lupus have shown that the development of antinucleosome (anti-NCS) antibodies may occur from the early stages of life. We therefore hypothesize that anti-NCS antibodies could help predict development of SLE in patients with PAPS. We studied anti-NCS antibodies in 18 PAPS patients (15 female, three male), followed for a mean of 11 years to evaluate the potential development of SLE. When PAPS was diagnosed, nine patients were positive for anti-NCS antibodies. Six of them developed clinical manifestations of SLE. In contrast, none of the patients who were negative to anti-NCS antibodies developed it. These findings suggest that anti-NCS antibodies could help predict which patients with PAPS may eventually develop SLE.