Immunological studies in 'primary' idiopathic pulmonary hypertension

It has been suggested by several authors that so called 'primary' pulmonary hypertension may have an 'autoimmune' basis because of the clinical association of this condition with Raynaud's phenomenon, polyarthritis and its not infrequent association with other conditions affecting connective tissue, such as progressive systemic sclerosis (PSS) and systemic lupus erythematosus (SLE), often in the absence of pulmonary parenchymal disease. In addition, serum protein abnormalities, positive antinuclear factors and the occasional positive rheumatoid flocculation tests or false/positive Wasserman reaction have also been noted. Data are presented on 9 patients with this condition, in whom not only was there a high frequency of antinuclear factor present (ANA) but in addition, a higher than average incidence of antibodies to smooth muscle (SMA). Screening for antibodies to DNA, extractable nuclear antigens, anticentromere antibodies and antibodies to cardiolipin were uniformly negative. The significance of these negative results are briefly discussed.