Effect of HCQ on AnxA5 Resistance Assay in Antiphospholipid (aPL) Positive Patients With and Without Systemic Lupus Erythematosus (SLE)

Antiphospholipid Syndrome (APS) is an autoimmune disorder of blood clotting and pregnancy loss. It is associated with proteins called antiphospholipid antibodies (aPL) in the blood. Blood clotting in this disease occurs for several reasons; one reason involves the interaction of aPL with another protein found on the surface of the cells that line blood vessels (endothelial cells). This protein, called annexin A5 (AnxA5), forms a shield over the surface of these cells. The AnxA5 Resistance Assay is a blood test that can detect when there is a problem with the protective AnxA5 shield on endothelial cell surfaces.

This 12 week study will observe patients with persistent aPL in the blood who are starting a medicine called hydroxychloroquine (HCQ). The primary goal of the study is to compare results of the AnxA5 resistance assay from patients before they start taking HCQ and after they have taken it for 12 weeks to see if the results of the blood test change. Our secondary goal is to measure a variety of other blood tests before and after patients have started taking HCQ; these tests include D-dimer, Activated Protein C (APC) Resistance, and aPL titers/status (LA test, aCL ELISA, aß2GPI ELISA, and anti-Domain-I ß2GPI ELISA).

Inclusion criteria

• age 18 to 65
• new HCQ (200-400 mg/day) treatment (for all but 5 of 10 control subjects - see below)
• persistently positive aPL

Selected Exclusion Criteria:

• Steroid use greater than or equal to the equivalent of prednisone 0.5 mg/kg/day at the time of enrollment
• Heparin use at the time of enrollment
• Any immunosuppressive drug use within 3 months prior to screening
• HCQ use within the past 6 months prior to screening visit
• Another antimalarial agent treatment,
• Pregnant women, minors, mentally disabled, prisoners
• Acute thrombosis within 2 weeks prior to screening