%0 Journal Article %T Heparin Increases HLA-G Levels in Primary Antiphospholipid Syndrome %A Joz¨¦lio Freire de Carvalho %A Ricardo M. de Oliveira %A Carlos Ewerton Maia Rodrigues %A Andr¨¦a Glezer %A Elo¨ªsa Bonf¨¢ %A Rosa Maria Rodrigues Pereira %J Clinical and Developmental Immunology %D 2012 %I Hindawi Publishing Corporation %R 10.1155/2012/232390 %X Objectives. The aim of this study was to investigate the HLA-G serum levels in Primary Antiphospholipid Syndrome (PAPS) patients, its impact on clinical and laboratory findings, and heparin treatment. Methods. Forty-four PAPS patients were age and gender matched with 43 controls. HLA-G serum levels were measured using an enzyme-linked immunosorbent assay (ELISA). Results. An increase in soluble HLA-G levels was found in patients compared to controls (3.35 (0–22.9) versus 1.1 (0–14), =0.017). There were no significant differences in HLA-G levels between patients with and without obstetric events, arterial thrombosis, venous thrombosis, or stroke. Sixty-six percent of patients were being treated with heparin. Interestingly, patients treated with heparin had higher HLA-G levels than ones who were not treated with this medication (5 (0–22.9) versus 1.8 (0–16) ng/mL, =0.038). Furthermore, patients on heparin who experienced obstetric events had a trend to increased HLA-G levels compared to patients who were not on heparin and did not have obstetric events (5.8 (0–22.9) versus 2 (0–15.2) ng/mL, =0.05). Conclusion. This is the first study to demonstrate that serum HLA-G levels are increased in APS patients. We also demonstrated that heparin increases HLA-G levels and may increase tolerance towards autoantigens. %U http://www.hindawi.com/journals/cdi/2012/232390/