The objective of this study is to further investigate for the presence of antibodies to endothelial cells and fibroblasts in patients and characterize the antigen specificity of autoantibodies in patients with different types of non idiopathic and non SSc-associated PAH, such as PAH associated with HIV infection, porto-pulmonary hypertension, congenital heart diseases, systemic lupus erythematosus, mixed connective tissue disease and Sjögren's syndrome