Immunologic studies and clinical follow-up HBsAg-positive polyarteritis nodosa.

Three patients with hepatitis B surface antigen (HBsAg)-positive polyarteritis nodosa (PAN) who are clinically well 4 1/2-5 1/2 years after their initial illnesses are described. In each case electron microscopic studies demonstrated the presence of aggregates of HBsAg in both acute and quiescent phase sera. One patient had a lower circulating HBsAg titer during the acute illness, while no change in serial HBsAg titers was observed in the other two patients. Two of the three patients showed lymphocyte transformation to purified HBsAg during the quiescent phase of the PAN. The role of immune complexes in the pathogenesis of HBsAg-positive PAN is discussed.